Mars in the Age of New Space Launchers

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Journal of the British Interplanetary Society

VOLUME 71 NO.5 MAY 2018 Mars in the Age of New Space Launchers

AN EARTH-MOON-MARS Passenger Transport Pyramid Stephen Ashworth THE MARTIANS: Space Age Visions of Journeys to the Red Planet Stephen Baxter MARS COLONISATION The Health Hazards and Exposure Control John R. Cain IMPLICATIONS FOR RESOURCE UTILIZATION ON MARS: Recent Discoveries and Hypotheses Fabrizio Bernardini, Nathaniel Putzig, Eric Petersen, Angel Abbud-Madrid & Valentina Giacinti THE LAWS OF MARS COLONISATION – a Legal Analysis Raphaël Costa

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ISSN 0007-084X PUBLICATION DATE: 30 NOVEMBER 2018 Submitting papers International Advisory Board to JBIS

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158 Introduction

159 THE MARTIANS: Space Age Visions of Journeys to the Red Planet Stephen Baxter

165 AN EARTH-MOON-MARS Passenger Transport Pyramid Stephen Ashworth

178 MARS COLONISATION The Health Hazards and Exposure Control John R. Cain

186 IMPLICATIONS FOR RESOURCE UTILIZATION ON MARS: Recent Discoveries and Hypotheses Fabrizio Bernardini, Nathaniel Putzig, Eric Petersen, Angel Abbud-Madrid & Valentina Giacinti

190 THE LAWS OF MARS COLONISATION – a Legal Analysis Raphaël Costa

From the Editor It has come to our attention that due to a printing error, some copies of the March issue of JBIS were circulated with the first two and last two pages missing. If your copy was so affected, please call or email theJBIS office (see left) and we will replace it free of charge. Our apologies for any inconvenience caused. Roger Longstaff, Editor

OUR MISSION STATEMENT The British Interplanetary Society promotes the exploration and use of space for the benefit of humanity, connecting people to create, educate and inspire, and advance knowledge in all aspects of astronautics.

JBIS Vol 71 No.5 May 2018 157 INTRODUCTION

Introduction Mars in the Age of New Space Launchers

The Mars Symposium at the BIS in London, 28 February and 1 March. From left to right: Mark Hempsell, Alan Bond, Bob Parkinson, Richard Osborne, David Todd, Stephen Ashworth.

ver since there was an understanding of the real- arises is: how might this new capability affect approaches to ities of the Solar System and its planets, visiting getting humans to Mars? It was to explore this question that Mars has been a key aspiration of interplanetary the British Interplanetary Society held a two-day Symposium flight. From the late nineteenth century onwards, entitled “Mars in the Age of New Space Launchers” on 28 Feb- E science fiction has speculated about flights between ruary and 1 March 2018. Earth and Mars. As time passed the true nature of Venus was discovered, ruling it out as a target, and the Moon (at least The event attracted sixteen very diverse talks, and we have in popular imagination) became perceived as just a boring papers based on five of these talks in this special issue of JBIS. lump of rock. Thus Mars with its more Earth-like qualities They reflect the multifarious issues that need to be considered became the pre-eminent target for the next big human mis- and resolved before the adventure of human flight to Mars sion. A more objective and rational assessment may show can be attempted, including not just technical issues but ar- other important destinations that will also need to be reached chitectural strategies and legal aspects. The first day of the for complete understanding and exploitation of the Solar Sys- symposium showed that, while the capability of these new tem, but Mars remains pivotal as both a technological and a launchers will not in and of itself transform the feasibility of scientific goal of interplanetary exploration. reaching Mars, it is an essential foundation. The second day showed that our understanding of what we can do when we Hopefully, after many false starts, we are now entering a get there continues to grow. new age in which this goal is made achievable through the appearance of launch systems that offer higher capacity, higher reliability and lower cost. The Space Launch System, the The Organising Committee reusable vehicles under development by SpaceX and Blue Or- Stephen Ashworth igin, and Reaction Engines’ Skylon spaceplane are all offering Mark Hempsell potentially transformational capability. So the question that Richard Osborne

158 Vol 71 No.5 May 2018 JBIS JBIS VOLUME 71 2018 PAGES 159-163

THE MARTIANS: Space Age Visions of Journeys to the Red Planet STEPHEN BAXTER c/o Christopher Schelling, Selectric Artists, 9 Union Square #123, Southbury, CT 06488, USA email [email protected]

This paper is a study of post-World War II technological and fictional visions of crewed voyages to Mars. Stories of Mars have long inspired engineers who dreamed of going there. But since 1945, successive generations of engineers have developed schemes to reach Mars based on then-contemporary technology, and much of the relevant science fiction has rather been framed by the engineers’ plausible logic. With time the available space technology has evolved, and with it the Mars plans and the fictional visions. Thus Robinson’sMars trilogy (1993-1996) showed pioneers reaching the Red Planet in craft derived from then-contemporary shuttle-era technology. Similarly today new visions of journeys to Mars, in fact and in fiction, will be derived from the new space launcher technologies.

Keywords: Science fiction, BIS, Mars, Mars Direct, Mars Base Camp, new space launchers

1 INTRODUCTION: FROM IMAGINATION TO REALITY tober 19, 1899, seventeen-year-old Goddard climbed a cherry tree in his backyard and ‘imagined how wonderful it would The conference for which this paper was intended as a con- be to make some device which had even the possibility of as- tribution concerned the use of modern space launcher tech- cending to Mars…when I descended the tree, existence at last nology as a stepping-stone to Mars. The paper surveys a deep- seemed very purposive.’ er context of the subject. Over the decades since the Second World War, many such studies of crewed voyages to Mars have Similarly, the German-language Two Planets by Wells’ been made based on then-contemporary space technology – rough contemporary Kurd Lasswitz inspired the young Wer- and, in parallel, science fiction (SF) extrapolations have been nher von Braun and his fellow rocketry enthusiasts [5], as well developed on the same basis. (This paper will focus on selected as less glamorous but no less celebrated figures in the field of examples of the fiction; more complete surveys of Mars in SF astronautics such as interplanetary trajectory analyst Walter are available [1].) Hohmann, who asked himself, ‘How do you get up there?’ [6] In this era, as the BIS’s own slogan suggests, imagination led Each generation since the war seems to have thrown up the reality. dreamers of Mars – both writers and engineers – who surveyed the astronautical landscape as it existed around them, and But, in fact, at first the SF writers were slow to pick up on asked, ‘How could we use this stuff to get to Mars?’ the potential of the rocket, in particular. The most significant pre-World War II fictional depiction of rockets as a means of Long before the 1940s, of course, fictional visions of Mars space travel appears to have been Fritz Lang’s movie Die Frau had inspired engineers to dream of going there. For example Im Mond (1929) [7], for which Lang had hired rocketry experts the pioneering rocketry engineer Robert Goddard [2] longed Hermann Oberth and Willy Ley as technical advisors. to reach the inhabited world depicted by H.G. Wells in The War of the Worlds [3], which he read as a serial in the Boston Then the V-2s landed on London. Post in 1898. Goddard seems to have been impressed that the Martians used recognisable technology to cross space, specif- 2 BETWEEN V-2 AND VIKING ically a huge cannon. For Wells, the cannon had a metaphori- cal meaning: the Martians were firing missiles at the Earth, as After 1945, as the first practical space technologies emerged one naval ship fires on another. As a means of space travel a from wartime developments, SF writers dreaming of Mars cannon is implausible, but at least Wells’s cannon was compa- became more willing to follow the maturing visions of the as- rable to contemporary engineering, not impossibly advanced, tronomers and engineers, rather than take the imaginative lead and certainly not fantastical, like the quasi-magical means by as before. Although there could still be rampaging intelligent which Burroughs’ John Carter would dream his way to Mars Martians in some fictions, such as the Ice Warriors of the BBC’s [4]. Maybe, the young Goddard seems to have thought, there Doctor Who (1963-present), more serious SF saw Mars and ac- was a better way to get to Mars. According to his diary, on Oc- cess to it in a conceptual scientific and technological framework that was becoming too well-defined to be plausibly ignored: we started to understand what Mars was, and how to get there. This paper was prepared for the “Mars in the Age of New Space Launchers Symposium”, London, 28 February – 1 March 2018. In particular the fiction writers seized on the exciting poten-

JBIS Vol 71 No.5 May 2018 159 STEPHEN BAXTER tial of the legacy of German chemical-propulsion rocketry, as ered by sunlight, a dew trap inside a smashed water tank, and well as the possibilities of nuclear rocketry, with an authorita- extracts oxygen from the atmosphere by fractional distillation. tive early study of the latter (and the first study not to be clas- He even builds a kind of tricycle, and a half-track surface rover. sified) given in the pages of JBIS [8]. Other influential studies And Holder discovers life on Mars, some of it intelligent. Hold- in JBIS and elsewhere included work on space stations, some er is ultimately saved by a very surprised American expedition. building on pre-war work [9]. In the real 1956, engineers from Rolls Royce and de Hav- With such technologies soon to be available, the explora- illand were preparing to launch Black Knight and Blue Streak tion and colonisation of Mars came to be seen as an inevita- rockets from the Woomera test range [15]. The M76, evidently ble outcome of an orderly, large-scale expansion into space, driven by liquid chemical fuel propulsion, is 200’ tall and 51’ supported by an extensive, multipurpose infrastructure. This wide at the base (p15) (61m by 16m). This is somewhat larger anticipated such well-known studies as Wernher von Braun’s than Britain’s mightiest real-world rocket, the Blue Streak (61’ coherent plan for space travel, publicised in Collier’s magazine tall by 10’ diameter, 19m by 3m). But by comparison the Saturn articles (1952) [10]. V was 363’ tall and 33’ wide at the base (111m by 10m); the volume of M76 is at least of the same order of magnitude as Thus in Clarke’s The Sands of Mars (1951) [11], set around the Saturn. So Gordon’s technical plausibility is thin, but not the year 2000 (we are told it is a century after the publication non-existent. Indeed, Hill [15] (p331) has suggested that Brit- of Wells’s The War of the Worlds (p185)), the atomic-powered ish rocketry technology c. 1964 could have been used to build two-thousand-tonne liner Ares makes its maiden flight to a launcher capable of launching a Gemini-class spacecraft to Mars, taking three months. In his imagining of the Ares Clarke orbit, using a Blue Streak with a hydrogen-fuelled second stage built on the designs suggested by the JBIS rocketry papers, and and augmented by four Black Knight strap-on boosters. as explicated in his own non-fiction studies [12]. ThusAres is launched from ‘Space Station One’ (Chapter 1), designed as a A higher profile Crusoe-on-Mars story was the movie point of transfer between chemical-rocket planetary ferries and Robinson Crusoe on Mars (Paramount, 1964), directed by By- atomic-powered interplanetary ships – atomic rockets being ron Haskin, who had previously made The War of the Worlds banned from Earth’s atmosphere. Similarly Phobos was devel- (1953). Commander Christopher (Kit) Draper, USN, and oped as a docking station at Mars (p209). test-animal monkey Mona are the only survivors of the crash on Mars of the NASA ship Mars Gravity Probe 1. This is anoth- All this has evidently been developed quickly – fifty years er Clarke-like, relatively hospitable Mars, which Draper is able from the V-2 to Ares - but in this reality Mars was an inviting to explore in shirtsleeves and an oxygen mask – yet still aus- world, with native life, and an atmosphere clement enough for tere; the landscape sequences were shot in Death Valley. This is visitors to be able to walk around in the open air in nothing no Barsoom [4]. As far as space technology goes, while we see but a face-mask. Such a Mars would surely have motivated nothing of the launch systems that bring Probe 1 to Mars, by well-supported space programmes – and this Mars was capa- 1964 the Saturn-Apollo lunar mission designs were becoming ble of supporting expansive human colonies which would, in current. So Probe 1 is a NASA mission, and the movie borrows Clarke’s novel, dream of rebellion and independence. something of Apollo’s lunar-orbit-rendezvous design strategy, with dedicated landers separating from a mother ship in Mar- But was it even necessary to wait for the development of tian orbit – and a crew of military veterans, as opposed to civil- atomic rocketry to go to Mars? Atomic rocketry designs would ian engineers like Gordon Holder. remain paper studies until the inception of the American Pro- ject Rover in 1955 – but chemical-fuel rockets had of course The movie does bear striking similarities to Gordon’s book been flying since 1942 and the first V-2. – as, indeed, would the later movie The Martian (2014) (see below) – though no credit is given. The movie does however cred- And, in the 1950s, in the Australian desert, using chemi- it the original Crusoe story by Daniel Defoe, which, of course, cal propellants, the British were quietly building a space pro- is safely out of copyright. gramme of their own. These examples serve to illustrate what appear to have be- Thus Rex Gordon’sNo Man Friday (1956) [13] depicts a come the classic story-telling themes for the Mars of the sec- British manned Mars flyby shot, the Gordon's M76, launched ond half of the twentieth century (though many narratives are from Woomera – a venture that leads to the stranding of a possible [1]). Gone are the canals; gone is intelligent life. Now lone astronaut on the planet. ‘Rex Gordon’ was a pseudonym Mars was an arena for human adventure and achievement, of- of Stanley Bennett Hough (1917-1998) [14], who had served ten falling into two broad categories: ‘Mayflower’ stories and as a wireless operator on merchant and passenger ships, and ‘Crusoe’ stories. Thus The Sands of Mars was a ‘Mayflower’ sto- survived a sinking during World War II. His fiction was tech- ry, showing the early decades of the permanent habitation of nically astute and his characters deep, though his outlook on the planet – a frontier tale of breaking ground in a strange land humanity as a whole could be bleak. and tension with the homeland. ‘Crusoe’ tales – or as the jar- gon has it, ‘Robinsonades’ [16] - feature small crews, even just And his Martian Crusoe was a hero characteristic of post- individuals, on very early, small-scale, edge-of-the-envelope World War II Britain, the ‘new Elizabethan Age’ (p2). Gordon missions, with some flaw that causes catastrophe. Such a story, Holder, son of a Manchester butcher, is one of a seven-man as the name suggests, was No Man Friday. The ‘Robinsonades’ crew serving as a fuel engineer. Stranded and alone on Mars, break down further into a variety of much-used tropes, includ- Holder pleasingly gets on with the work of survival: ‘It was true ing: the core shipwreck-victim story of endurance and survival; that Mars had no breathable atmosphere, no potable water, and the story of a tremendous trek across the wilderness, recalling, no sign of any source of food. So what? You might say that I had for example, forebears from the legends of the Wild West like been born with a spanner in one hand and a blueprint in the the Hugh Glass story dramatised in Punke’s The Revenant [17] other . . .’ (p41). Holder mines the wreck to build turbines pow- – and, as the space programmes matured, the ‘Apollo 13’ tale

160 Vol 71 No.5 May 2018 JBIS THE MARTIANS: Space Age Visions of Journeys to the Red Planet of the heroic efforts of Mission Control (or some equivalent But in 1986 the only human spaceflight technology availa- back on Earth) to bring the threatened astronauts home. Such ble to the West was the Space Shuttle. tales helped to cement an anticipated interplanetary future for mankind in the public imagination. 4 A GREEN MARS

Then the first space probes reached Mars. By the early 1990s the Space Shuttle had been flying for a decade, and space visionaries were looking for ways to leverage 3 MARINER’S MARS the then-available technology to meet more expansive goals, such as by stretching shuttle technology to create a heavy-lift In the 1960s, as Apollo-Saturn technology evolved, study booster [23], or by using a rocket pack to boost the shuttle’s groups in the NASA centres and beyond had been considering external fuel tank (ET), otherwise destroyed, up to orbit and the wider uses, beyond the Moon landings and direct applica- to exploit it, rather as the original Skylab proposals had been tions programmes such as Skylab, to which such technology based on refurbishing a spent Saturn S-IVB stage in orbit. Per- could be put (see for example [18]). Perhaps Apollo-Saturn haps ETs could be developed as the basis of a lunar habitat, one could be the basis of Mars flights, if enhanced with a NER- study suggested [24]. VA-based nuclear stage, or even simply using chemical propellants, for example by using the Saturn second stage, refuelled And so ETs are the means by which the ‘first hundred’ col- in orbit, as an interplanetary booster. The author’s own novel onists travel to Mars in Kim Stanley Robinson’s mighty Mars Voyage (1996) [19] was an alternate-history depiction of such trilogy (1993-6) [25] [26] 27]. The spacecraft, another Ares, is lost possibilities, in which Apollo-Saturn technology is used to launched from Earth orbit on December 21st 2026. The ship is reach Mars in 1986. The only entirely new technological com- based on eight hexagonal ‘tori’, each assembled from six ETs, ponent is a Mars lander. strung along a ‘hub’, a spine itself assembled from Russian equivalents of ETs. The tori are linked to the hub by narrow However the scientific returns from the first real-world spokes. At one end of this stack is a propulsion module, at the space probes to Mars, starting with Mariner 4’s 1964 images of other a counter-rotating observation platform. This craft is a cratered, almost moonlike landscape, made the planet seem cost-effective but ungainly, looking ‘like a piece of agricultural a much less desirable destination, and in America the momen- machinery’ ([25] p49). And it might present some technical tum for post-Apollo Mars programmes was quickly lost [20]. challenges. After it is assembled in Earth orbit, the stack is The possibility mooted by Spiro Agnew’s Space Task Group in subject to some tough accelerations, with a one-gravity thrust 1969 of nuclear-rocket missions to Mars as early as the 1980s injecting it into a nine-month Hohmann trajectory to Mars, – at a cost of $8bn a year by the late 1970s ([20] p74) – was and then an aerobraking manoeuvre at Mars. Those attaching abandoned, in favour of building the STS, the Space Transpor- spokes at right angles to the direction of thrust would appear tation System: the Space Shuttle. to be a design weakness.

Meanwhile, for the fiction writers, it barely seemed pos- Robinson’s extraordinary drama of colonisation, rebellion sible to tell any human story about the newly revealed Mars and terraforming on Mars is a series that would prove hugely at all. In fact, the number of fictional works set on Mars and influential in the genre as a once much-loved planet was re- the other planets of the solar system dipped markedly in the discovered – but unlike Clarke’s imagining [11] there was no 1970s and ‘80s [1], in favour of Star Trek sagas of interstellar atomic-powered space liner now. This saga of the development exploration, set in an arena where there could still be realis- of a new world was predicated on the recycling of the throwa- tic hope of finding a habitable ‘final frontier’. One compelling way drop tanks of a space truck. work from this period is Man Plus (1976) [21], by veteran American writer Frederik Pohl. Set in the 2020s (p109), with a By the 1990s, however, a much more radical route to Mars pollution-choked, over-populated, overheating Earth drifting was already emerging in the engineers’ imagination. towards global war, the US leads a desperate effort to colonise Mars, as a last hope to save ‘the Free World’. But whereas 5 MARS DIRECT only twenty-five years earlier Clarke [11] showed colonists on Mars strolling in the open with little more protection than a The background to Robert Zubrin’s ‘Mars Direct’ studies [28] warm coat and an oxygen mask, now the only way a human (1996) was President George H.W. Bush’s ‘Space Exploration can inhabit Mars is through the grace of the ‘Exomedicine Initiative’ of 1989, which had called for a new, expansive, for- Programme’ (p9), as a rebuilt cyborg, with faceted eyes and ward-looking programme for American spaceflight. NASA’s batlike solar-cell wings. The core of the book is body horror, response was what became known as the ‘Ninety-Day Study’, based on the ‘savage, sadistic torturing’ (p31) necessary to a monumental scheme invoking Earth-orbital facilities, lunar make a human fit to survive on the hostile new Mars. orbital stations and surface bases, and, finally, 1000-tonne spaceships bound for Mars. Zubrin referred to this $450bn However, from this low point, the scientists’ vision of Mars scheme as ‘Battlestar Galactica’ ([28] p46); to nobody’s sur- slowly evolved. Challenging it might be, but Mars could still prise, it was never funded. bear water at the poles, and in deep aquifers. Perhaps it was once warm and wet, long enough to have spawned life. And, In response, in 1990 a team from Martin Marietta led by with its giant volcanoes and sprawling canyons (on a world Zubrin presented a new strategy to get to Mars, called ‘Mars once thought to be more or less flat), Mars came to seem an Direct’: ‘the plan allows us to accomplish a manned Mars mis- attractive, if challenging destination after all – and certainly sion with what amounts to a lunar-class transportation class one of great scientific interest. The development of a ‘Mars -Un system’ [28] (p261). The core of it was a scheme to manufac- derground’ network of enthusiasts, and a NASA conference on ture rocket propellant in situ on Mars, from the raw materi- Mars in 1986 [22] – the first since the Viking days – inspired a als of the environment. (In this key element Zubrin and his new wave of thinking about ways to reach Mars. colleagues seem to have been inspired by a short JBIS paper

JBIS Vol 71 No.5 May 2018 161 STEPHEN BAXTER by consultant engineer James French, published in 1989 [29] sense of wonder as the travellers cross such marvels as the Valles ([28] p57).) Even a nodding acquaintance with the rocket Marineris – but he is also expert at the detail, such as the texture equation will indicate that removing the need to carry return of the Martian dust, a feature he studied as part of the Pathfind- propellant all the way to Mars should reduce mission size and er team. And, too, he points out that the Martian environment costs drastically. Zubrin and his co-workers estimated that is complex and unknown. Thus a trace of sulphur radicals in Mars Direct would incur one-tenth the cost of NASA’s refer- the Martian dirt wrecks the crew’s ERV fuel system. Given such ence design mission of the time ([28] p261). unknowns, the Mars Direct strategy of running automated fac- tories for years in such an environment seems more ambitious And again the Mars Direct scheme builds on then-availa- than Zubrin and other advocates might admit. ble technology, in this case heavy-lift boosters based on Space Shuttle technology. These would send an uncrewed Earth Zubrin’s Mars Direct vision also underpinned Andy Weir’s Return Vehicle (ERV) to Mars, along with an automated fac- hugely popular The Martian [32] (2014), and Ridley Scott’s tory for manufacturing propellant from the Martian atmos- 2015 movie of the book, a good-humoured saga in which the phere. The stratagem was designed for safety; the human crew classic Crusoe-on-Mars story was returned to the mass con- would not launch until their return ship was safely on Mars sciousness with a vengeance. Things go wrong for theAres 3 and fuelled up, and a second ERV would follow them from mission when (somewhat implausibly) a Martian wind storm Earth, landing close by as a further abort option if necessary knocks out comms and threatens to tip over their Earth return – or to be used for a follow-on mission if not. This bare-bones vehicle, and the crew are forced to abort to orbit – leaving one but apparently feasible plan was enthusiastically supported by astronaut, Mark Watney, behind. The scenario does dramatise the Mars Society and other groups, energetically promoted by one notable aspect of the Mars Direct plan, that there are al- Zubrin himself, and ultimately taken seriously by NASA. ways multiple backup options available: in this case (just as in Landis’s novel), the availability of a second Earth-return vehi- Zubrin’s own First Landing [30] (2001) is both a fictional- cle a not-impossible drive away. The first section of the movie ised portrayal of the Mars Direct scheme, and a portrait of the is the most effective - before NASA becomes aware of the situ- cultural, political and institutional tensions that, in Zubrin’s ation and gets in touch - when Watney, entirely isolated, drags mind, necessitated the scheme in the first place. In 2011 a himself up from a pit of despair at his stranding, and scrapes crew successfully lands on Mars close by their ERV, and the together the means to survive. It is a sequence that climax- ‘rebel yell’ of a triumphant crew member is compared to the es in Watney’s laconic response to the emergence of the first confusion of a ‘somewhat overstuffed . . . manager’ in Mission green potato plant, growing in Martian dirt in his scratch-built Control, back at Houston (p17). The pioneers of Mars must greenhouse: ‘Hey there.’ break free of hidebound, obstructive Earth. Zubrin makes this lesson to the readers abundantly clear with a fast-forward ep- 6 DISCUSSION AND CONCLUSIONS ilogue set in 2034 showing a nascent Mars colony called ‘New Plymouth’: ‘Here on Mars, we have a chance to open a new In the immediate post-war period, SF writers and visionary frontier that can breathe life back into our civilisation’ (p241). engineers alike seized on the exciting possibilities offered by the wartime legacy of rocketry and nuclear energy to spin new, Mars Direct was featured in a number of other fictional apparently plausible dreams of journeys to Mars. With time, works, including the Brian de Palma movie Mission to Mars the technological basis of such visions evolved as the availa- (2000), and, perhaps most significantly, Geoffrey A. Landis’s ble technology was developed or abandoned. And thus today, Mars Crossing [31] (2000). Landis is a writer of well received the latest engineering visions of Mars, such as Lockheed Mar- SF – this, his first novel, was an award-winner. But he is also a tin’s Base Camp approach [33], are built on a newly available NASA researcher who worked on the Pathfinder mission, and infrastructure of multipurpose hardware, including the new so his novel is exceptionally well informed. Mars Crossing is an space launch systems, developments of ISS modules and the enthralling ‘Crusoe’ story of a Mars-Direct programme gone SLS-Orion system. wrong, as the surviving crew must trek six thousand kilometres from the Martian equator to the only available return craft on Perhaps with such tools the century-old dreams of travel to the northern ice cap. Landis is a particularly authoritative guide Mars will be fulfilled at last – preceded, perhaps, by a new wave during this Revenant-like odyssey. He is capable of evoking true of Mars fiction.

REFERENCES

1. SFE: The Encyclopaedia of Science Fiction entry on Mars, http://www. 8. L. R. Shepherd, A. V. Cleaver, “The Atomic Rocket”,JBIS , vol. 7, pp185- sf-encyclopedia.com/entry/mars, accessed November 5 2017. 194; vol. 7, pp234-241; vol. 8, pp23-27, 1948-49. 2. Britannica entry on R.H. Goddard, https://www.britannica.com/ 9. H. L. Ross, “Orbital Bases”, JBIS, vol. 8, pp. 1-19, 1949 biography/Robert-Goddard accessed November 5 2017. 10. A. Ryan, ed., Across the Space Frontier, Viking Press, 1952. 3. H. G. Wells, The War of the Worlds, London, 1897. 11. A. C. Clarke, The Sands of Mars, London, 1951. Page numbers from the 4. E. R. Burroughs, A Princess of Mars, New York, 1917. 2001 Gollancz The Space Trilogy omnibus. 5. K. Lasswitz, Auf zwei Planeten, (“On Two Planets”), Berlin, 1897. For 12. A. C. Clarke, Interplanetary Flight, London, 1950. the book’s influence see an afterword by M.R. Hillegas in the 1971 13. R. Gordon, No Man Friday, London, 1956. Page numbers from the 1977 Southern Illinois University Press edition. NEL edition. 6. M. Hohmann, Biographische Daten Zum Leben und Werken von Walter 14. SFE: The Encyclopaedia of Science Fiction entry on Rex Gordon, http:// Hohmann, Oldenbourg, 1925. (1994 edition). www.sf-encyclopedia.com/entry/gordon_rex, accessed November 5 7. SFE: The Encyclopaedia of Science Fiction entry on Rockets, http:// 2017. www.sf-encyclopedia.com/entry/rockets, accessed November 5 2017.

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15. C. N. Hill, A Vertical Empire, London, 2012. 24. C. B. King et al, "Lunar habitat concept employing the Space Shuttle 16. SFE: The Encyclopaedia of Science Fiction entry on Robinsonades, external tank", Journal of Spacecraft and Rockets vol. 2 pp225–6, 1990. http://www.sf-encyclopedia.com/entry/robinsonade, accessed 25. K. S. Robinson, Red Mars, London, 1992. Page numbers from the 1996 November 5 2017. Voyager edition. 17. M. Punke, The Revenant, New York, 2002. 26. K. S. Robinson, Green Mars, New York, 1994. 18. M. W. J. Bell, “An Evolutionary Program for Manned Interplanetary 27. K. S. Robinson, Blue Mars, New York, 1996. Exploration”, Journal of Spacecraft and Rockets, vol. 1, pp625-630, 1967. 28. R. Zubrin, The Case for Mars, New York, 1996. 19. S. Baxter, Voyage, London, 1996. 29. J. R. French, “Rocket Propellants from Martian Resources”, JBIS vol. 42, 20. J. M. Logsdon, After Apollo?, New York, 2015. pp167-70, 1989. 21. F. Pohl, Man Plus, New York, 1976. Page numbers from the Gollancz SF 30. R. Zubrin, First Landing, New York, 2001. Masterworks edition, 2000. 31. G. Landis, Mars Crossing, New York, 2000. 22. D. B. Rieber, ed., “NASA Mars Conference, July 21-23, 1986,” American 32. A. Weir, The Martian, New York, 2014. Page numbers from the 2014 Del Astronautical Society, New York, 1988. Rey UK edition. 23. Encyclopedia Astronautica link on the Shuttle-C, http://www. 33. “Base Camp – a Terminus for Mars”, SpaceFlight vol. 59 pp458-463, 2017. astronautix.com/s/shuttlec.html accessed November 7 2017.

Received 16 March 2018 Approved 25 June 2018

JBIS Vol 71 No.5 May 2018 163

JBIS VOLUME 71 2018 PAGES 165-177

AN EARTH-MOON-MARS Passenger Transport Pyramid

STEPHEN ASHWORTH Researcher, Initiative for Interstellar Studies, 49 Princes Street, Oxford OX4 1DE, UK email [email protected]

A transport pyramid is a pattern of activity in which shorter, cheaper journeys are made more frequently than longer, more expensive ones. This pattern is applied to passenger transport between Earth, low and high Earth orbits, the Moon and Mars, with implications for how the setting up of such a network should be approached, and the likely timeline for the successful emergence of different elements. Since architectures for human access to the Moon and Mars are still in flux, the author’s own architecture solutions are used for these parts of the transport network. Drawing on the work of Zubrin, Weaver and others, the plan for human access to Mars presented here is described as Mars Semi-Direct Heavy.

Keywords: Space exploration, Space settlement, Space transport architectures, Moon, Mars, Robert Zubrin, Mars Semi-Direct

1 THE TRANSPORT PYRAMID It is therefore surprising that present-day discussions of astronaut visits to the Moon and Mars typically treat such activi- It is a commonplace of everyday experience that short-range ties in isolation from other space traffic. The relevant historical journeys are made more frequently than long-range ones. Thus parallels suggest that this is short-sighted. The great maritime the typical citizen of a developed country may make daily trips voyages of the terrestrial age of exploration (15th to 18th cen- within their home town, weekly or monthly trips between cit- turies) were based on the prior growth of shipbuilding tech- ies, and semi-annual or annual international or intercontinen- nologies and maritime trade volumes on shorter-range routes. tal journeys. A voyage around the world or a visit to the North The Antarctic continent was only opened up to sustainable ac- Pole, to the summit of Mount Everest or into space might be a cess through the development of aircraft, and the first aircraft once-in-a-lifetime event. The longer-range journeys, requiring which reached the South Pole – a Ford Trimotor (1929); a navy greater investments of time, cost and preparation, appear high- variant (R4D-5) of the Douglas Dakota DC-3 (1956); and an er up a notional pyramid of travel activity; the shortest-range air force Douglas C-124 Globemaster (1956) – again rested on journeys form the base. decades of growth for large-scale commercial and military purposes closer to home.

This paper was delivered to the “Mars in the Age of New Space The pattern of history therefore suggests that sustainable Launchers Symposium”, London, 28 February–1 March 2018. astronaut access to the Moon, and even more so to Mars, will

Fig.1 Two cartoons with which the author attempted to introduce discussion of the pyramid architecture to the European Space Agency at its Exploration Workshop in Edinburgh, January 2007.

JBIS Vol 71 No.5 May 2018 165 STEPHEN ASHWORTH each in their turn require an appropriate economic and tech- and from Mars. nological base in the form of a larger number of shorter-range flights in near-Earth space, thus taking their place at the top of Clearly the factor of ten difference between neighbouring a much larger pyramid of activity (Fig. 1.). levels of activity is illustrative only. A viable space economy might function with a smaller or a larger difference. The point The purpose of this paper is to present a simplified model is to illustrate the sharp contrast such a scenario makes with incorporating several different manned spaceflight activities in the conventional paradigm in which, say, astronaut activities in order to illustrate how such a pyramid structure might be real- low Earth orbit need to be curtailed in order to free up funds ised in the near-Earth space environment, and thus to inform for activities beyond low Earth orbit. Such a paradigm is re- discussions about its relevance to current planning. (The term quired by the presumption that all manned space activities are “manned” is of course always used in its non-gender-specific paid for out of public funds, or, in other words, that those ac- sense.) tivities do not constitute a self-sustaining part of the economy.

2 REQUIREMENTS In the case of unmanned satellite launches, the large proportion of commercial payloads shows that the launch industry is The following top-level requirements are employed in order to now a self-supporting part of the economy, no longer depend- constrain the discussion within realistic limits. ent upon public subsidy. For example, in the period 2010 to early 2018, SpaceX achieved 50 Falcon 9 launches (49 of which • Th e growth is assumed of affordable and sustainable hu- were successful), of which 54% were launches of commercial man access to the Moon and Mars for the full range of payloads. During the same period the Ariane 5 made 48 suc- activities which might be carried out there (science, ex- cessful launches, all but six of which were for commercial cus- ploration, tourism, mining, manufacturing, political and tomers. military purposes). Since the bulk of these activities require surface infrastructure, activities at the Moon and The question which this paper addresses is what the pattern Mars are therefore focused on surface landing-sites which of human space travel might look like after a change of para- act as safe haven, industrial centre and nucleus of human digm to a situation where the costs of manned flights are sim- settlement. ilarly dominated by private (personal and commercial) rather than public money. • A fully reusable heavy-lift rocket shall be assumed to be available on Earth, capable of launching a useful payload A note on timing: the current passenger traffic (2012-2017) of 100 tonnes into low Earth orbit. to and from low Earth orbit is 11 to 15 astronauts per year. The above scenario therefore assumes a 1,000-fold increase in ac- • E xtraterrestrial mining and propellant manufacture shall tivity. A wide range of growth rates are possible, and are likely be assumed, based on the following resources: lunar mare to vary in time as markets, technologies and price levels ma- ilmenite and pyroxene as a source of oxygen, and Mars sur- ture. Let it be assumed that, once commercial passenger space- face carbon dioxide and water ice as a source of methane flight is regularly available sometime after 2020, growth of this and oxygen. (Sub-surface volatiles from the asteroids, the traffic proceeds at the rate of 20% per annum, thus doubling Martian moons and the lunar poles are an intriguing pos- in size every four years. Then a 1,000-fold increase is achieved sibility, but their use on an industrial scale is assumed to be after about 38 years of growth, placing the scenario no earlier further in the future than the timeline considered here.) than around the year 2060.

• N uclear power generation may be used for propellant ex- Critical for the success of this pattern is that the price of a traction at locations remote from Earth. (Nuclear thermal passenger ticket into space should progressively fall by at least rocket propulsion would be extremely helpful to have, but two orders of magnitude from current levels as technologies it is considered politically and technologically safer to mature and economies of volume come into play. manage without it for the present purpose.) If the start of a virtuous cycle of falling prices and rising traf- • All chemical rocket propulsion shall use methane/oxygen fic is postponed beyond the early 2020s, or if the growth rate propellants with an exhaust velocity of 3.7 km/s, and a assumed above is too optimistic, or both, then such a scenario mass mixture ratio of 1:3.5. (Hydrogen fuel is an alterna- could take very much longer to emerge. tive possibility, but its more severe technological demands suggest that vehicles using methane might be more robust 3 LOW EARTH ORBIT ACTIVITY and economical, despite their lower exhaust velocity.) As stated in the requirements listed above, all transport activ- These requirements shall be used to develop the following ities are based on the use of a large, fully reusable launch vehi- pyramid scenario: cle which can deliver a variety of 100-tonne spacecraft to low Earth orbit. (In practice, this would be a class of similar vehi- • 10,000 passengers/year to and from low Earth orbit. cles from competing manufacturers in America, Russia, China and perhaps elsewhere.) • 1,000 passengers/year to and from highly eccentric Earth orbit with a sightseeing lunar encounter. For low Earth orbit passenger transport, the spacecraft – a Low Orbit Shuttle of total launch mass 100 tonnes – is con- • 100 passengers/year to and from a lunar surface settle- ceived as a spaceplane-like vehicle carried to orbit as payload ment. on the large launch vehicle. It carries 100 passengers on each short-haul trip to orbit and back (one passenger per tonne of • 10 passengers per two-year Earth-Mars synodic period to vehicle; compare a passenger aircraft such as the Airbus A319

166 Vol 71 No.5 May 2018 JBIS AN EARTH-MOON-MARS Passenger Transport Pyramid

bic metres with artificial gravity, and 4,000 cubic metres with microgravity. Rotating at 2 r.p.m., the gravity level at 64 metres from the axis is 0.29 gee, thus intermediate between lunar (0.16 gee) and Martian (0.38 gee) surface gravity.

Each Station is capable of further expansion to a total of 20 gravity modules, at which point the modules will form a complete ring. This, however, is not necessary at the 100 passenger occupancy level.

At the stage envisaged in the current scenario, each Station is composed of sixteen 75-tonne units, and the two stations together account for 32 units. A lifetime in the region of 16 years per module would require replacement modules to be launched at the rate of two per year, requiring two additional heavy-lift launches per year.

The total launch activity for passenger traffic between Earth’s surface and low Earth orbit at the level assumed here is therefore 102 heavy-lift launches per year. The initial capital infrastructure cost in space is represented by 32 heavy-lift launches.

4 HIGH EARTH ORBIT ACTIVITY

4.1 General considerations

Potentially the most interesting high Earth orbit would be a Fig.2 Low Earth orbit (LEO) activity: (1) LEO Station built up highly eccentric one with perigee not far above low Earth orbit, module by module; (2) Low Orbit Shuttle delivers 100 passengers apogee close to or beyond the Moon’s orbit, such that a close to Station; (3) Low Orbit Shuttle returns passengers to Earth, encounter with the Moon once every one or two orbits is possi- another is launched with the next batch of 100 passengers. ble. The potential attractiveness of such an Earth-Moon cycler orbit as a tourist destination is obvious, as it offers alternately close-up and distant views of both Earth and Moon. Being a which carries about two passengers per tonne of maximum station rather than a vehicle, large masses of radiation shielding take-off weight) (Fig. 2.). and other supplies can be accumulated over periods of years to decades, providing the maximum possible security for its hu- Then the traffic level of 10,000 passengers per year requires man occupants. 100 heavy-lift launches per year. The concept of an Earth-Moon cycler goes back at least as far A larger number of launches of smaller vehicles is also pos- as a Technical Note written by Arthur J. Schwaniger for NASA sible, plausibly including one- or two-stage winged spaceplanes in 1963, in which he explored the symmetrical free-return tra- which ascend to orbit under their own power, such as Skylon jectories which were afterwards used for the Apollo missions [1]. Here, however, the equivalent traffic in heavy-lift launches [2]. He discussed both flight paths which made a figure-of- is used for ease of comparison. eight loop around the Moon, with closest approach to the lunar surface over the far side (“circumlunar trajectories”), and ones If the typical stay time in orbit is one week, then there will which encountered the Moon after apogee, made their closest be 200 people in orbit at any one time. Two Low Earth Orbit approach to the surface over the near side and retreated to a Stations each receive weekly visits of the Low Orbit Shuttle, second apogee (“cis-lunar trajectories”). The latter kind of or- and each Station accommodates 100 visitors at a time. One Sta- bit, when adjusted such that the distance of closest approach tion might be designed for microgravity research, the other for was 2150 km (412 km altitude above the lunar surface), would space tourism. have a period equal to one lunar sidereal month and would therefore be periodic. Each Station is constructed from 75-tonne modules, leaving a margin of up to 25 tonnes for the tug which must tow them The investigation of circumlunar trajectories which encoun- from their initial orbit, assumed to be at around 250 km alti- ter the Moon in a figure-of-eight pattern on one orbit out of tude, up to the station orbit at 400 km altitude, and manoeu- two has not yet to my knowledge been thoroughly investigated, vre the module into position. The 75-tonne payloads for this but would be an important study. These flight paths would be construction work may be pressurised modules, 20 metres long more suitable for carrying passengers bound to and from the and 8 metres diameter with 1,000 cubic metres of living space, lunar surface, due to their shorter flight times on the circum- or they may be 60-metre trusses with an access tunnel contain- lunar leg, though they would then be empty for every alternate ing a lift and a ladder. Four modules form the central axis of orbit in which they reach apogee when the Moon is on the op- the station, four trusses radiate outward, and two modules are posite side of its orbit. mounted at the far end of each truss, one interfacing directly with the truss, and the other docked to it and supported by a The alternative of a space station in geostationary Earth or- tether running back to the station’s axis. The total pressurised bit has occasionally been proposed [3]. However, the placing volume (excluding the radial access tunnels) is then 8,000 cu- of a station into a highly eccentric Earth orbit which reaches

JBIS Vol 71 No.5 May 2018 167 STEPHEN ASHWORTH from a few hundred km altitude out to lunar distance has the following practical advantages:

• Lower ∆V cost of reaching it from low Earth orbit (3.2 km/s, as opposed to 3.9 km/s to reach geostationary orbit).

• Lower ∆V cost of returning to an orbit which intersects Earth’s atmosphere for aerobraking (less than 0.1 km/s near apogee, as opposed to 1.5 km/s from geostationary orbit).

• Optimum placement as an Earth terminus for robotic miners operating among near-Earth asteroids, as demonstrated by John S. Lewis [4].

• O ptimum placement as a tourist destination by virtue of its constantly changing views, including spectacular close-ups of the Moon.

• U tility for transporting passengers between the vicinity of Earth and that of the Moon in secure accommodation.

Therefore stations in highly eccentric Earth orbits will be more economically attractive than ones in geostationary orbit.

4.2 Earth-Moon Cycler Stations

Starting docked to one of the two Low Earth Orbit Stations, a High Orbit Shuttle will need a ∆V of about 3.4 km/s to reach an Earth-Moon Cycler Station and return, aerobraking either back into low Earth orbit or directly down to the Earth’s surface. Using methane and oxygen propellants, a 100-tonne vehicle requires 60 tonnes of propellants, leaving 20 tonnes for the basic vehicle (tanks, engines, attitude control system and aeroshell) and 20 tonnes for the payload. It is assumed that the payload is Fig.3 Earth-Moon cycler orbit (EMCO) activity: (1) Cycler a passenger module which can seat 20 passengers (Fig. 3.). Station built up module by module in EMCO; (2) High Orbit Shuttle launched to LEO Station; (3) High Orbit Shuttle takes Earth-Moon Cycler Stations resemble those in low Earth 20 passengers to Cycler Station; (4) After one orbit with a lunar orbit, but are smaller and require greater radiation shielding encounter, High Orbit Shuttle returns its passengers to LEO since they fly through and beyond the Van Allen belts. The lat- Tanker launched to LEO to refuel High Orbit Shuttle for next trip. ter requirement is satisfied by giving all pressurised modules a surrounding jacket of water and/or plastics with a thickness of 200 kg/square metre [5]. Since a thickness of 100 kg/square near apogee and a propulsive landing back on Earth, assuming metre was already assumed for the structure of the low Earth that the mass budget stated is sufficient for it to aero brake from orbit modules, giving a basic structural mass of 60 tonnes for a translunar re-entry speeds, an operation in which the Tug is module with a surface area of 600 square metres, an additional assisted by the fact that by that stage it contains mainly empty 60 tonnes per pressurised module remains to be supplied. propellant tanks and thus has a low ballistic coefficient.

In order to place each 75-tonne module into highly eccentric The basic mass of each Cycler Station is 450 tonnes, to which Earth orbit, two 100-tonne High Orbit Tugs are required. Each the additional radiation shielding may be added in the form of Tug is assumed to have dry mass 20 tonnes (including tanks, water to be piped into hollow walls, or of plastic panels to be engine, attitude control system and aeroshell), and propellant installed internally (the access tunnels, being used only briefly, mass 80 tonnes. The first Tug docks with the payload in low are not reinforced in this way, requiring the human occupants Earth orbit, tows it through about 2 km/s into an intermediate to refrain from transferring between the gravity and zero-grav- orbit and returns to Earth. The second, or the first tug again ity areas of the station during solar storm conditions). The after being refuelled and relaunched, performs the same 2 km/s necessary 240 tonnes of additional shielding can be packaged from low Earth orbit alone in order to match velocities with the into three deliveries of 80 tonnes each. In order to set up each payload, then docks with it and tows it the remaining 1.2 km/s Cycler Station a total of 9 deliveries of 75 to 80 tonnes each is into Earth-Moon cycler orbit before itself returning to Earth. required, and therefore 27 heavy-lift launches from Earth. There is some propulsive margin in this scheme, and loads of up to 90 tonnes can in fact be placed on an Earth-Moon cycler The Cycler Stations are assumed to be on trajectories which orbit in this way (a fact which will be used when discussing encounter the Moon on one orbit out of two (or possibly three; lunar surface operations in section 5 below). the question invites more detailed analysis, as does the question of how the orientation of the semi-major axis is perturbed Each Tug is left with at least 1 tonne of propellants, giving it a by the sun and by the lunar encounter itself). To a first approx- propulsive surplus of at least 0.18 km/s for a small deorbit burn imation, then, the non-encounter orbit lasts 20 days and the

168 Vol 71 No.5 May 2018 JBIS AN EARTH-MOON-MARS Passenger Transport Pyramid encounter orbit about 8 days, being truncated by the encounter Earth for each mission, it is also possible that each Shuttle itself. A total of two stations need to be in use, their orbital could remain in orbit for periods of several months up to sev- major axes being offset by perhaps 45° (see section 5.2 below). eral years, being refuelled by one Tug launch on each return to Each station comprises two axial modules, two radial trusses low Earth orbit, the Tug in this case acting as a Tanker. The ex- and two gravity modules for a total pressurised volume (extra complexity of the refuelling operation is balanced by a mass cluding the radial access tunnels) of 4,000 cubic metres. gain: three Tanker launches are capable of refuelling High Or- bit Shuttles about four times. But for the present it is assumed Since radiation shielding does not deteriorate with use, it may that each High Orbit Shuttle flight accounts for one heavy-lift be recycled whenever a module is retired and replaced. A water launch from Earth. jacket, for example, may be pumped out of an old module and into a new one before the old one is discarded, or pieces of inter- The launch rate required to sustain cis-lunar activity on this nal plastic panelling may be removed manually and transferred scale is therefore 50 launches of High Orbit Shuttles or of their to another module. Once the two Earth-Moon Cycler Stations refuelling Tankers, plus one of a replacement station module have been set up, therefore, and assuming a module lifetime of and two of High Orbit Tugs to tow that module into position, about 12 years, the launch rate required to maintain them is one thus a total of 53 heavy-lift launches per year. module per year, thus three heavy-lift launches per year. Launch activity at the same level for about one year is suffi- The market for radiation shielding materials (water and cient to set up the two Cycler Stations. The initial capital infra- plastics) in highly eccentric Earth orbits is a potential driver for structure cost in space is represented by 54 heavy-lift launches. near-Earth asteroid mining activities, and earlier for the prospecting of these objects for the necessary raw materials. Such 5 LUNAR SURFACE ACTIVITY an industry provides a foot in the door to the use of asteroid resources, since its products do not need to be highly refined The system described in section 4.2 above brings regular com- before use. mercial passenger transport activities into the vicinity of the Moon. The next step is a surface base on the lunar surface On approach to perigee, each station receives two High Or- acting as a hotel for adventure tourism as well as a laboratory, bit Shuttles carrying 40 visitors who will be accommodated on mining and manufacturing centre (Fig. 4.). the station for the encounter phase of its cycle. For the non-encounter phase the station is left empty. With a total of 80 people 5.1 Lunar surface to low lunar orbit visiting cis-lunar space every lunar month, the annual traffic is about 1,000 people, in accordance with the scenario given in Whether the first lunar base would be optimally located in the section 2 above. lunar maria or the highlands (including the poles) is a question which need not be addressed at the current level of analysis. While each High Orbit Shuttle could be launched from Schwaniger noted that cycler trajectories around the Moon

Fig.4 Lunar surface activity: (1) Lunar Lander and surface infrastructure installed on the Moon module by module; (2) Tanker launched to Cycler Station; (3) High Orbit Shuttle takes 20 passengers to from LEO Station to Cycler Station, where it refuels from Tanker; (4) High Orbit Shuttle takes 20 passengers from Cycler Station to low lunar orbit (LLO). Lunar Lander takes 20 passengers from lunar surface to LLO. The two vehicles rendezvous and dock; (5) After exchanging passengers and cargo, High Orbit Shuttle returns to Cycler Station and Lunar Lander returns to lunar surface; (6) Tanker returns to Earth, and High Orbit Shuttle returns its passengers to LEO.

JBIS Vol 71 No.5 May 2018 169 STEPHEN ASHWORTH need not be limited to the Moon’s orbital plane, and may pass about 25 times per year, it will only be necessary to send up a over the lunar poles. Orbital solutions will therefore exist for Tanker to one of those stations on one visit out of five. Since it transport links between the Earth-Moon cycler stations de- already hosts two High Orbit Shuttles, the Cycler will require at scribed in section 4 above and the lunar surface, via transport least three docking ports for the purpose. nodes in low lunar orbit or at the Earth-Moon L1 point. Five flights per year of the Lunar Lander are also needed to The system proposed here rests on a Lunar Lander of mass maintain this service. If it is assumed that each Lander is re- 90 tonnes on the lunar surface when ready to launch to orbit. tired after five round trips to orbit and back, a new Lander will As a first approximation, it is assumed that the lander refuels need to be delivered every year, adding three heavy-lift launch- on the Moon with lunar oxygen and in low lunar orbit with es to the flight manifest. methane brought from Earth. It is noted that oxygen is available from rocks anywhere on the Moon’s surface, but particularly The additional launch rate required to maintain a traffic of from the minerals ilmenite and pyroxene which form a major 100 lunar surface visitors per year is therefore 18 heavy-lift constituent of mare basalts [4, p.69]. If volatiles such as water launches per year. and carbon dioxide are found to be accessible in permanently shadowed regions at the poles, then the Lunar Lander may be The initial capital infrastructure cost on the lunar surface able to completely break its dependence on fuel brought from needs to cover accommodation for at least 20 people, plus min- Earth, but that will not be assumed here. ing, propellant manufacturing, maintenance and other facilities. If it is assumed for the present that about ten lunar land- The ∆V between the lunar surface and low lunar orbit is ings are required to emplace these facilities, then the initial cost about 1.75 km/s each way. The Lunar Lander will need a dry is represented by 30 heavy-lift launches. mass of 35.7 tonnes, of which 20 tonnes may be allocated to a payload consisting of a passenger module with seats for 20 lu- 5.3 New technology to reduce the launch burden on Earth nar travellers. Before each launch from the surface the Lander needs to load 46.7 tonnes of locally manufactured oxygen. It Given the assumed capacity to low Earth orbit of 100 tonnes, already has on board 7.6 tonnes of methane, loaded at its pre- new technology has not hitherto been really necessary. But vious orbital rendezvous. with the introduction of manoeuvres between Earth-Moon cycler orbit and the lunar surface, larger ∆V requirements have 5.2 Cycler orbit to low lunar orbit appeared, and these may be expected in due course to promote the adoption of new technologies. The link between the Earth-Moon Cycler and the Lunar Lander in low lunar orbit is made by a High Orbit Shuttle. A ∆V of The most obvious development would be of nuclear thermal about 1.25 km/s is required in each direction. The High Orbit rocket propulsion. An exhaust velocity in the region of 10 km/s Shuttle presented in section 4 above arrives at the Cycler, how- would make manoeuvres near the Moon far more practical ever, with only 2 tonnes of propellants remaining in its tanks. A by allowing them to be carried out by a single vehicle of 100 Tanker therefore must be sent out to that station, requiring the tonnes in low Earth orbit, which would still have a mass of over assistance of two Tugs in order to arrive with full tanks. Each 70 tonnes after having reached the cycler orbit. The launch bur- lunar landing thus accounts for an additional three heavy-lift den on Earth for activities beyond low Earth orbit would then launches from Earth. be reduced by two-thirds. A healthy space industry could well go down this route after chemical propulsion has performed The Tanker docks with the High Orbit Shuttle in the vicinity the trailblazing function of developing the markets and prov- of the Cycler and transfers to it 47.5 tonnes of propellants, plus ing that investment in higher technology will pay off. 13.5 tonnes of cargo for the Moon (either 13.5 tonnes of methane fuel for the Lunar Lander, or else general cargo if fuel has Nuclear thermal rockets were tested in the NERVA pro- been sourced on the Moon). The High Orbit Shuttle departs gramme in the United States in the 1960s, achieving a vacuum the Cycler with a mass of 103 tonnes. This falls to 73.5 tonnes exhaust velocity of 8.3 km/s, but in 1972 after a series of suc- after it reaches low lunar orbit, where it meets with the Lunar cessful ground tests the effort was cancelled, and no nuclear Lander, docks with it, exchanges passengers and transfers the rocket has yet flown. 13.5 tonnes of cargo or excess methane fuel. Its mass is now down to 60 tonnes. It returns to the other Cycler Station (which In the same year Alan Bond proposed a new and more effi- will arrive in the vicinity of the Moon 3 to 4 days after the first cient design in which the hydrogen exhaust is heated by a fis- Cycler if their major axes are offset by 45°) with a margin of 3 sion reactor without directly passing through it (an intermedi- tonnes of propellants remaining, sufficient for it to return to ate lithium loop transfers the heat to the propellant). A major Earth at that station’s next perigee. advantage of this system is that it facilitates ground testing: the reactor and the rocket can be tested separately without gen- The routine use of in-orbit propellant transfers on this ser- erating an environmentally unacceptable plume of radioactive vice, both at the Cycler Station and in low lunar orbit, will exhaust. Another advantage is that it lifts the calculated exhaust prove useful in maturing the technology for application further velocity to the unprecedented level of 12.75 km/s [6]. afield, as will be seen in section 6.2 below. Bond’s collaborator Mark Hempsell has adopted this engine Given a traffic of 100 passengers per year between Earth- in a new design proposal for his Scorpion spacecraft [7]. It is Moon cycler orbit and the lunar surface, five High Orbit Shut- expected that more will be heard of this concept in the future. tles per year need to be refuelled at the Cycler in order to link up with a Lunar Lander, therefore five Tanker flights are re- However, in view of the commercial motivations assumed quired, which account for an additional 15 heavy-lift launches for the bulk of space activity in the present scenario, rather from Earth. Since the Moon is being visited by Cycler Stations than special missions conducted by government agencies, it is

170 Vol 71 No.5 May 2018 JBIS AN EARTH-MOON-MARS Passenger Transport Pyramid preferred here to keep the technological assumptions as con- the manned vehicle had a mass of 25 tonnes (excluding aero servative as possible. The investigation of nuclear options will brake and propulsion stage for landing), and was accompanied not therefore be pursued further here. by its burnt-out rocket stage, which would be used as a coun- terweight to generate about half a gee of artificial gravity. After 6 MARS ACTIVITY a tour of duty on Mars, each crew of four astronauts would return to Earth in a vehicle of mass no greater than 14 tonnes af- 6.1 General considerations ter the trans-Earth propulsion phase had been completed [10, table 4.5 on p.93]. Transporting human passengers between the Earth-Moon system and Mars is extremely difficult using present-day technol- The Mars Direct design achieved extreme economy and ogies, as is evidenced by the succession of plans for achieving simplicity by using only spacecraft intended to land on Mars. this which have been proposed and then laid aside since the By contrast, the traditional approach has been to employ a mix- first such serious programme conceived by Wernher von Braun ture of orbiters and landers, after the pattern of the Apollo pro- in 1948 [8]. gramme, and exemplified at Mars itself by the Viking 1 and 2 robotic probes in the 1970s, which were flown in orbiter/lander Careful consideration of the options based on the use of pairs. The flight plan for the return to Earth is then dependent chemical rocket propellants and currently available technolo- upon lunar or Martian orbit rendezvous between the orbiter gies convinced the present author that they tend to lead to a and the returning lander, a mission design first conceived by dilemma between two possible outcomes: the Russian theoretician Yu. V. Kondratjuk, and later promoted by John C. Houbolt for the Apollo programme [11]. • Either a maximalist design, based around an interplanetary spacecraft massing hundreds up to over a thousand A third general architecture has been promoted in recent tonnes, which maximises safety in transit but then re- years by Gemini and Apollo astronaut Buzz Aldrin, based on quires economically ruinous quantities of propellants to the use of Earth-Mars cycler stations (stations, not vehicles, be launched from Earth into orbit, as well as incurring the when they do not make propulsive manoeuvres apart from complexity costs of numerous in-space rendezvous and those small adjustments of velocity required to maintain them docking manoeuvres. on station) [12, 13]. While in principle an attractive option, the simplest use of a cycler station on a 2.14-year orbit with Earth • Or a minimalist design, based around an interplanetary and Mars encounters on every orbit leads to relatively high en- spacecraft of less than fifty tonnes, small enough to be counter velocities. launched in a single throw of a Saturn-V-sized launch vehicle, but which is then too small to guarantee the health Aldrin and his associates at Purdue University have devel- and safety of the occupants. oped alternative trajectories which reduce those velocities by the use of low-thrust solar-electric propulsion, or by adding The maximalist pattern has typified space agency approach- multiple Earth encounters between each Mars encounter. But es to the problem. An example from the European Space Agen- even in the case of alternate Earth and Mars flybys the pas- cy’s Aurora programme is the study “Human Missions to Mars: senger load factor over a complete orbital cycle is only around Overall Architecture Assessment”, carried out by ESA’s Con- 23% (a 6-month interplanetary transfer with people on board current Design Facility at ESTEC in 2003-2004 [9]. The design is followed by a 20-month period when the cycler is empty). A which was produced based each individual Mars flight on a further problem is that the schedule at Earth or Mars for astro- large number of launches of expendable heavy-lift vehicles (21 nauts to join the cycler is relatively inflexible. Russian Energia rockets carrying payloads of up to 80 tonnes each). No conclusions regarding the desirability of moving to Why would Mars landers need to be supported by orbit- reusable launch vehicles, or what markets might provide a sup- ing vehicles which remain in space? The answer is the greater porting commercial basis for such activity, were drawn. Mean- efficiency of a system whose parts are specialised for specif- while the payback from each flight would include no more than ic functions. An interplanetary habitat is for long-duration 30 days of surface activity (within a mission duration of over life-support in deep space, with all the living volume, multiple 31 months) by only three of the six astronauts, and the use of pressurised compartments, backup systems, radiation protec- successive flights to build up surface infrastructure and hence tion and artificial gravity that function implies. A lander is a exploration capabilities was ruled out. ferry vehicle to support human life for no more than a couple of days during the transfer between orbit and the ground. In Reacting against the large scale of this style of exploration any system designed for permanence and growth, large pres- and its disappointingly meagre return, exemplified to an even surised structures on the Martian surface should soon become greater degree in the NASA studies which had been triggered available for habitation, removing the need for newly arrived by the elder President Bush’s Space Exploration Initiative of astronauts to camp out in their landing vehicles. 1989, Robert Zubrin and his collaborator David Baker proposed instead a minimalist programme which they dubbed The disadvantages of the orbiter/lander architecture are Mars Direct [10]. Manned vehicles would be sent to Mars with however twofold: the greater launch costs for the propellant single launches of a Saturn-V-comparable heavy-lift launch ve- needed to move the relatively heavy orbiter onto and off its in- hicle. Along the way Zubrin produced many valuable insights terplanetary trajectories, and, in common with the cycler, the into the subject, notably concerning the use of Mars surface low passenger load factor of that orbiter – it spends most of its resources for refuelling and surface rendezvous for enhancing time in space empty and waiting for the next interplanetary safety while on Mars. flight to begin.

His plan, however, rested upon the small size of the space- For the present purpose, focused upon manned spaceflight, craft making the long-haul interplanetary crossing. Outbound, electric and solar-sail propulsion are not considered. The for-

JBIS Vol 71 No.5 May 2018 171 STEPHEN ASHWORTH mer suffers from issues regarding the specific mass of power Practical realisation of the technologies required for the generating equipment, whether solar or nuclear, and both suffer futurist option, attractive as they are, appear still to be some from low thrust, and consequently from extended flight times way in the future. On the other hand, the compromise option and, in the vicinity of a planet, dynamic inefficiency. For the has recently been made much more credible with the devel- present, it is merely observed that once a high-thrust chemical opment of reusable launch vehicles by the American company (or indeed nuclear) propulsion system has provided the ma- SpaceX. The company is now progressing confidently towards jor velocity changes required at planetary arrival or departure, construction of a much larger fully reusable rocket (the “BFR”) low-thrust propulsion may be found useful for modifying an capable of delivering 150 tonnes to low Earth orbit in the early existing interplanetary trajectory for greater overall effective- 2020s. Indeed, without rapid and efficient launch vehicle reus- ness. Low-thrust propulsion may also be useful for delivering ability the scenario developed in sections 4 and 5 above would unmanned cargo ships, for which speed is not so important, in not be practical. support of a manned operation. These facts drive the Mars architecture towards the compro- Chemical and nuclear rockets both demand large amounts mise option. of propellant. Their efficiency is improved the greater the number of refuelling stops provided. 6.2 Mars Semi-Direct Heavy

Robert Zubrin’s Mars Direct proposal has brought the sub- The following Mars architecture is used as the basis for further ject of refuelling with methane and oxygen propellants on the discussion (Fig. 5, opposite). surface of Mars into the mainstream, and this has recently been adopted by Elon Musk for his own proposed Mars programme While a larger launch vehicle for Mars missions, such as the [14]. Zubrin assumed for this purpose the import of a small one now under development by SpaceX, would be desirable, quantity of liquid hydrogen feedstock. But recent results from the present discussion will stay with a 100-tonne payload ca- the Mars Reconnaissance Orbiter leave little doubt that large pacity to low Earth orbit. This is for two reasons: for ease of quantities of nearly pure ice exist close to the surface in the comparison of Mars launch activity with volumes of launch form of glaciers at mid-latitude locations. Fabrizio Bernardini activity for other destinations, and in order to illustrate the ef- has described how the presence of lobate debris aprons on the fect of using the same vehicle, without modifications, for both surface of Mars, such as in the Deuteronilus region at 45° north commercial and non-commercial purposes. latitude, supports the inference of near-surface glaciers from the radar data [15, 16]. The Mars Semi-Direct plan reached by Robert Zubrin in discussion with Dave Weaver of NASA-Johnson is taken as the While early missions may therefore continue to carry hy- starting-point [10, p.67-69; 17]. But Zubrin’s outbound trans- drogen feedstock for their Mars surface refuelling operations, port vehicle and habitat on Mars is combined with his Earth only a small investment in robotic mining technologies should return vehicle into a single Mars Lander which transports the very quickly be able to make unlimited quantities of water crew in both directions. available. If the first manned Mars flights do indeed take place on the schedule shown in section 7.4 below, prior advances in The Mars Lander is supported by three similar vehicles: a robotics are likely to make the use of hydrogen brought from Mars Cargo Lander, which carries cargo one-way to Mars, a Earth unnecessary from the outset. Mars Tanker, which carries propellants to low Mars orbit for use on the return to Earth, and the same Tug as used earlier, The ∆V to launch from the Martian surface into low Mars which does not venture further than Earth orbit but propels the orbit is, however, quite high (4.0 km/s), and this fact makes it other elements on their departure to Mars. All four variants are desirable to refuel in Mars orbit as well. Many writers, from based on the same airframe and employ aerobraking on arrival Arthur C. Clarke onwards, have pointed out the potential val- at Earth or Mars. All four have a mass of 100 tonnes as deliv- ue of the Martian moons Phobos and Deimos for this purpose ered to low Earth orbit, taken as a circular Earth orbit at 250 [4, p.179]. Lewis, a specialist in asteroids and space resourc- km altitude, and are driven by the same methane/oxygen rock- es, expects the moons to contain a substantial fraction of their et engines as before. Their masses are summarised in Table 1. subsurface mass in the form of water ice [4, p.176]. But the technologies for autonomous robotic mining and processing of Rather than using a missile or spaceplane geometry, the four resources in a dusty microgravity vacuum environment have not yet begun practical testing, and the long flight times to reach near-Earth asteroids where this testing might begin indi- TABLE 1 Spacecraft masses used in Mars Semi-Direct Heavy, cate that it will be a prolonged process. as delivered to low Earth orbit

While weighing the pros and cons of all these options, none Dry Propellant Payload Total of which appear to be ideal, the present author noted two pos- Vehicle mass mass mass mass sible ways out of the dilemma: (tonnes) (tonnes) (tonnes) (tonnes)

• The futurist option, introducing high technology ele- Mars Lander 50 35 15 100 ments, particularly nuclear thermal propulsion and ro- 20 52 28 100 botic in-space mining of propellants from near-Earth Cargo Lander asteroids and from Phobos. 80 - 100 • The compromise option, which takes a minimalist start- Tug 20 ing-point, increases the masses of manned interplanetary - spacecraft towards more realistic levels and accepts the Tanker 25 75 100 higher launch costs.

172 Vol 71 No.5 May 2018 JBIS AN EARTH-MOON-MARS Passenger Transport Pyramid

Fig.5 Mars surface activity: (1) Cargo Lander installed on Mars; (2) Two Mars Landers launched to Mars, travelling in tandem through interplanetary space (heliocentric transfer orbit = HTO), and separating to orbit and land individually; (3) Two Tankers launched to low Mars orbit (LMO); (4) An Earth year and a half later, Mars Landers refuel on surface, return to orbit; (5) Mars Landers refuel in low Mars orbit, return to Earth. Tankers land on Mars. spacecraft are conceived as capsules, with a maximum diameter at the heat shield of about 10 metres. This requires their Each manned launch to Mars can use the same profile, main engine to fire through a hatch in the heat shield. It will though after the mass required for the pressurised crew cabin be recalled that the Space Shuttle employed such hatches to al- is taken into account the remaining margin for carrying pay- low its landing gear to deploy after re-entry, and to close the load is not large. The cabin is conceived as an upright cylinder fuel and oxidiser conduits from the External Tank after launch. with diameter 6 metres and height 6 metres, providing 170 cu- One advantage of this design for the Lander is the possibility bic metres of habitable volume on three decks, and a surface of closing the engine hatch after touchdown on Mars and thus area of 170 square metres. The walls are assumed to be made protecting the engine from windblown dust during the vehi- of a plastic composite material with an areal density of 100 cle’s year and a half sojourn on the surface. kg/square metre in order to protect against solar storm radiation, leading to a mass for the cabin of at least 17 tonnes. After Like the Apollo command module, they have a docking port subtracting this mass and the basic vehicle mass of 20 tonnes with a crew access hatch in the nose, and another crew access from the mass landed on Mars of 48 tonnes, the payload (crew, hatch in the side for use after landing. their supplies, and equipment for use on Mars such as wheeled rovers) must fit within the remaining mass budget of no more All heliocentric Earth-Mars transfer ellipses are assumed to than 11 tonnes (a figure which rises to 18 tonnes at the most span 150° of heliocentric longitude between departure and ar- favourable Earth-Mars position, due to its lower propulsion rival. Depending upon the position of Mars in its relatively ec- requirement). centric orbit, the corresponding time of flight between the two planets varies between 6 and 8 months, and the outbound jour- This payload capacity on the manned Lander can be approx- ney from low Earth orbit to the Martian surface using aero- imately doubled (the mass landed on Mars rises to 63 tonnes for braking at Mars is found to require a propulsive ∆V of between each Lander) by use of a triple launch from Earth, in which two 4.1 and 4.6 km/s. Preliminary calculations are made using the Tugs take it in turn to tow each Lander into higher Earth orbits worst case of 4.6 km/s in order to qualify the system for use prior to departure. (This would, however, make aerobraking at throughout the Earth-Mars orbital cycle. Mars more difficult.) After separation each Tug returns to Earth for re-use. In both the double and the triple launch profile, each Every unmanned cargo launch to Mars requires two heavy- Lander docks with one Tug at a time in the same nose-to-nose lift launches from Earth: a Cargo Lander, and a Tug. The configuration as was used by Gemini-Agena in the 1960s, and two vehicles dock in low Earth orbit and the Tug propels the finally the two Landers, being raised into the same highly ec- docked combination through 1.86 km/s. The Tug separates centric orbit, rendezvous and dock with each other and share with 1 tonne of propellant remaining and returns to Earth for the final trans-Mars injection burn at their next perigee pass. re-use, while the Cargo Lander proceeds under its own propulsion. After landing on Mars the Cargo Lander has a mass of 48 In interplanetary space the landers undock while remaining tonnes, of which 28 tonnes is useful payload. connected by a tether, by means of which they rotate in order to

JBIS Vol 71 No.5 May 2018 173 STEPHEN ASHWORTH provide artificial gravity. Since they are of equal mass, a rate of Meanwhile two Landers on the surface prepare for reflight 2 rotations per minute will generate lunar surface gravity with by manufacturing their propellants from local resources in a tether length of 72 metres, and Martian surface gravity with the manner described by Zubrin [10, p.57-61, 148-156]. Un- a tether length of 170 metres. This is the method of providing like Mars Direct, each Lander which brings a crew to Mars is gravity en route described by Zubrin [10, p.121-126]. It will be capable of returning the same crew to Earth. In this way the observed that such a system is already partly technologically use of each Lander as a transport vehicle is maximised. It is mature in the form of the parachute lines used on all capsules not intended for long-term surface habitation. The philoso- returning to Earth from the 1960s onwards, but that methods phy adopted by Mars Semi-Direct Heavy is to send inflatable for the deployment, control and retraction of the tether have modules on cargo flights as early as the first manned mission yet to be brought to flight status. in order to begin to create permanent liveable accommodation larger and more secure than that possible in a lander vehicle, The disadvantage of using a tether as opposed to a solid truss and with additional radiation and thermal protection from a is that the vehicles are subject to the build-up of oscillations roof layer of local regolith. around the axis connecting them. This may be addressed by using a cluster of several lines attached to a motorised rotating Under current conditions it may be assumed that any wheel. When a motion sensor detects an oscillation, it activates manned Mars exploration programme will be driven primar- the motor to untangle the tether lines at the moment when they ily by visionary entrepreneurs rather than government offi- are twisted to the maximum and the angular velocity of the cials, putting a higher priority on the creation of a secure base Lander vehicle is temporarily close to zero, thus damping out on the surface of Mars rather than on pursuing pure science. the unwanted motion. This will entail establishing a local shelter and power supply, and local production of rocket propellants, food, water, oxy- An extra cable running alongside the tether lines, with at- gen and spare parts as quickly as possible. Once these basic tachment points for a safety harness and capable of being necessities have been taken care of, science may proceed in a wound up or down, would allow crew members to spacewalk secure environment, in parallel with the continued growth of from one Lander to the other in case of need. Each Lander is the base itself. therefore able to shelter the crew of the other in the case of a major malfunction which renders the other Lander inoperable. For the return to Earth, each Lander loads 125 tonnes of A major advantage of flying two independent Landers together locally produced propellants for a take-off mass of 175 tonnes. is that they can back each other up against the possibility of an After launching into low Mars orbit, a ∆V of 4.0 km/s, it has a Apollo 13 type of accident. This removes a serious vulnerability mass of 59 tonnes. The margin of 9 tonnes of propellants allow from the original Mars Direct plan. it the abort option of a return to the surface in case of need. It makes a rendezvous with the Tankers, and is shortly followed On arrival at Mars the Landers separate and proceed sepa- by the other Lander. Each Lander takes on around 36 tonnes rately to aero brake into low Mars orbit and subsequently de- of propellants from the Tankers, using procedures honed by scend to the surface. An orbital manoeuvring and landing ∆V over a decade of experience with propellant transfer in lunar of 0.6 km/s is assumed to be adequate for this purpose. orbit as described in section 5.2 above. The Tankers may use their remaining propellant to land at the surface base, where Finally, every return to Earth flight is again undertaken by they may be cannibalised for spare parts and used for static two Landers travelling together. Since they launch from the tank storage. Each tanker needs 4 tonnes of propellants for this surface separately, they must rendezvous and dock in space, purpose. Alternatively they may remain in orbit and be refilled and since any delay to the launch of the second Lander would by the Mars-based Tanker flights described above. render a rendezvous in heliocentric orbit difficult or impossible, that rendezvous must take place in Mars orbit. Given that As on the outbound journey, the two Landers make their the return to Earth architecture will therefore use Mars orbit departure into heliocentric space while docked together. Dur- rendezvous, there is no reason to be shy of and every reason ing the interplanetary journey they back each other up against to include rendezvous with an orbiting propellant depot at the malfunctions, and use each other as counterweights for artifi- same time. cial gravity production.

The Tanker or cluster of Tankers docked together to form The bottom line in all this is that an early manned Mars ex- that depot may be supplied from Earth or from Mars. In the pedition envisaged along the lines of Mars Semi-Direct Heavy first instance the source of supply will be Earth. Launch of a will require a total of ten or twelve heavy-lift launches to send Tug acting as a Tanker (dry mass 20 tonnes, propellant mass two Landers, one Cargo Lander and two Tankers to Mars. Each 80 tonnes in low Earth orbit) with one other Tug to give it an Lander may carry three, four or five astronauts. initial boost results in delivery of that vehicle to low Mars orbit with around 40 tonnes of propellant to spare. As and when conditions allow people to stay on Mars permanently, the programme enjoys a saving every time a Tank- When the reliability of the vehicles at Mars has been demon- er flight becomes unnecessary. This presumes confidence that strated, an alternative option is to send a Tanker to land on the Martian surface conditions, particularly the gravity level, pose surface of Mars. With a dry mass of 25 tonnes (accounting for no health hazards. Since some three decades of experience will the extra propellant tankage required), it loads 175 tonnes of exist at this point in low gravity research on the various rotat- locally manufactured propellants. In this configuration it can ing space stations in the Earth-Moon system, the consequences deliver 38 tonnes to orbit before returning to the surface and of exposure to low levels of gravity should be fairly well under- repeating the mission. As growth occurs in both the surface stood even before the first Mars mission takes place. industrial capacity and the number of flights of which each vehicle is capable, the low Mars orbit refuelling industry becomes The initial capital infrastructure cost on the Martian sur- progressively more independent of Earth. face comprises the precursor unmanned flights needed to

174 Vol 71 No.5 May 2018 JBIS AN EARTH-MOON-MARS Passenger Transport Pyramid demonstrate Mars surface refuelling in practice, to establish TABLE 2 Heavy-lift launch activity in the present scenario some basic habitable surface infrastructure and a supply dump in advance of the arrival of the first humans, and to emplace Running Capital Passengers a global network of automatic weather stations to supply the launches launches carried real-time atmospheric pressure data needed for accurate aerobraking as well as acting as navigational transponders. If four Low Earth orbit activity 102 32 10,000 such flights are assumed, then the capital cost is represented by 53 54 1,000 8 heavy-lift launches. Cis-lunar activity

7 CONCLUSIONS Lunar surface activity 18 30 100 Mars surface activity 12 8 10 7.1 Heavy-Lift Launch Vehicle Use

The heavy-lift launch activity required to maintain the scenario developed above, and the initial flights required to establish TABLE 3 Relative costs and prices of different space activities the necessary extraterrestrial infrastructure, are summarised in in the present scenario Table 2. All figures are annual launch rates, except those for Mars, which are per 26-month Earth-Mars synodic period. Equivalent no. of Example ticket price launches per head per head Once the space economy is functioning at this level, a total of 173 launches take place every year devoted to activities Low Earth orbit activity 0.01 $250,000 in the Earth-Moon system, and a further 12 launches every 2 years or so devoted to Mars exploration. Cis-lunar activity 0.07 $1,750,000 $7,000,000 Traditionally the prospect of devoting a dozen heavy-lift Lunar surface activity 0.28 launches to assembling a Mars expedition has been seen as an Mars surface activity 1.36 $34,000,000 extremely difficult task, one which could only be contemplat- ed by a global consortium of national space agencies. But the scenario developed here puts it in a fresh context: one in which seven or eight Saturn-V-scale launch vehicles worldwide each the total market value of all the activity surrounding a single make launches every couple of weeks, with a lifetime for each heavy-lift launch, including the launch itself, use of the asso- vehicle perhaps between 10 and 100 flights. Global launch ac- ciated extraterrestrial infrastructure, amortisation, staff costs, tivity proceeds at the rate of three or four per week. The Mars consumables, tax, profit margin and so on, is $25 million. This programme, which adds around another two launches a week figure is entirely speculative, and is intended to illustrate com- for a two-month period every couple of years, represents only parative rather than absolute costs and prices. The results are 6.5% of the total activity in that year. shown in Table 3.

The launch vehicles have already been paid for by mass mar- The conclusion of this part of the study is therefore that kets in space tourism, microgravity manufacturing and univer- while low Earth orbit may become relatively accessible to the sity research, so that it would plausibly not represent too much successful professional classes of the developed world over the of a burden for a transport company to divert a relatively small next few decades, a close-up flyby of the Moon will be almost proportion of its launches for private, unprofitable ends, par- an order of magnitude more expensive, lunar surface access ticularly if working in partnership with other companies for four times more expensive still, and a seat on a flight to Mars this purpose as well as with governments. five times more expensive again. But even the high cost of sending astronauts to Mars is still low enough, on the present 7.2 Comparative Costs and Prices scenario, to allow governments and large private companies to begin to do so. One may gain a rough appreciation of the relative costs of different activities if it is assumed that the technologies have Such activity would provide a stimulus to investors to de- evolved to maturity (another reason for setting aside the ad- velop the higher-technology options which, in the long run, vanced technologies noted above for the present exercise) and will be necessary if the prospect of opening up large-scale pas- if costs and therefore prices are broadly proportional to num- senger transport between Earth, the Moon and Mars is to be bers of heavy-lift launches required. It is further assumed that realised. capital costs are amortised over ten years. It should be clear that the rising costs for the more ambi- For each of the four activities, a per capita cost is found by tious ventures are caused by their greater physical demands adding one-tenth of the capital launches to the annual run- on infrastructure and propulsion, at a constant technology ning launches, and dividing by the annual number of passen- level for all activities, and are not a mere artefact of the in- gers carried. To the cost of going to high Earth orbit must be itial assumption of a pyramid architecture. On the contrary, added the cost of low Earth orbit, and to the cost of visiting the pattern shown here illustrates why a pyramid of activity is the lunar surface must be added the costs of going to low and appropriate for a well-developed space transport industry. But to high Earth orbit. However, the Mars infrastructure is func- if the introduction of new technologies is able to flatten the tionally independent of the other activities and is costed inde- price structure, then it will presumably also flatten the pyra- pendently. mid itself by raising the numbers of people travelling to the Moon and Mars relative to those who venture no further than Finally, an example ticket price is given assuming that a space hotel in low Earth orbit.

JBIS Vol 71 No.5 May 2018 175 STEPHEN ASHWORTH

7.3 Environmental Impact Statement • Regular flights to Mars begin around 2059, when 10,000 people are already flying to orbit and back, 1,000 to a cir- The environmental impact of a space transport industry op- cumlunar sightseeing trip, and 100 to the lunar base and erating on a scale on the order of 200 Saturn V-equivalent return per year. launches per year needs to be assessed. This shall be done using the energy produced by fuel burnt in the atmosphere as a sur- However, the long-term growth rate of 20% per annum is rogate for environmental effects. purely speculative, and is chosen merely to bring flights to Mars within the lifetime of a proportion of readers of this paper. Even A rough concept design for a suitable launch vehicle is as if growth is smooth the rate at which it proceeds could well be follows: first stage, 1,800 tonnes (180 t dry mass, 1620 t propel- quite different in practice, and the growth of manned space- lants), second stage, 500 tonnes (50 t dry mass, 450 t propel- flight activities since 1961 has so far been anything but smooth. lants), total vehicle mass inclusive of 100 tonne payload, 2,400 tonnes. The total propellant mass burnt for each launch is 2,070 As a formal exercise in prediction, therefore, the scenar- tonnes, comprising 460 tonnes of methane and 1,610 tonnes of io presented here is of no value. The future development of liquid oxygen. manned space transport systems is as unpredictable now as it was in, say, the 1950s, when a pattern of logical progress from If launch vehicle activity is 200 launches per year, the total low Earth orbit space stations towards the first lunar landings methane/oxygen bipropellant burnt is 414,000 tonnes/year. around the turn of the century was anticipated. It will continue to depend on personalities and politics, and may well see more The calorific value of methane is 50 MJ/kg. The energy re- of the abrupt and surprising advances and retreats that have quired to liquefy air and extract the oxygen is about 2.5 MJ per already characterised the first half century of the space age. 3.5 kg, and this figure shall be used to account for the additional energy cost of using liquid oxygen rather than taking it from But on the other hand, it is arguable that a broader long- the air in flight. The energy equivalent of 4.5 kg of methane and term pattern exists which individual officials and entrepreneurs oxygen bipropellant is then 52.5 MJ, equivalent to 11,667 MJ/ neglect at their peril. One such prominent actor at the present tonne. The energy consumption of each rocket launch is 24.15 is Elon Musk. At the International Astronautical Congress in million MJ, and the consumption of 200 such launches is 4.83 2016 and again in 2017 he stunned audiences with plans for billion MJ. a great leap forward to Mars using vehicles of revolutionary design and unprecedented size [14]. Coming from the founder The calorific value of jet fuel or kerosene is about 43 MJ/ and CEO of a company which in 2017 successfully launched 18 kg. Worldwide commercial aviation fuel consumption in 2017 satellites, developed return of the first-stage booster to a soft was about 270 million tonnes, with a calorific value of 11,600 touchdown in reflyable condition to a routine occurrence, and billion MJ. in February 2018 demonstrated a near-perfect launch of the world’s largest operational launch vehicle, such plans must be The proposed industry of 200 Saturn V-class launches per taken seriously. year is therefore equivalent in terms of fuel consumption to 0.04% of the already existing global aviation industry. To the There is a historical precedent for such a technological leap extent that similar fuels are being burned with similar waste into the future: Isambard Kingdom Brunel’s ship the Great products at similar levels in the atmosphere, this quantity of Eastern of 1859, designed with irrefutable logic to be large activity may be taken as a surrogate for environmental impact, enough to carry all the coals necessary for a non-stop voyage with the conclusion that such impact will be extremely small in to Australia. In the end the ship was not a financial success, comparison with existing economic activities. and – a warning for Mr Musk – she never made the voyage for which she had been intended. Her immense size by the stand- 7.4 Timescale ards of the time was not surpassed until the Oceanic of 1899 (in length) and the Celtic of 1901 (in gross tonnage). But the Oce- If one assumes steady growth at the rate of 20% per annum anic and Celtic were launched into an industry which over the over a period of several decades, starting with about 10 space intervening forty years had matured to the point that such large travellers to low Earth orbit per year in 2020, then the level of ships were not only economically viable, but quickly surpassed 100 passengers per year would be achieved in about 2033, 1,000 by even larger vessels every few years. per year in 2046 and 10,000 per year in 2059. One may well ask, therefore, whether Mr Musk’s flippant- The largest market may be expected to be for space tourism, ly named BFR/BFS Mars vehicles will turn out to be his Great with microgravity research and manufacturing the next largest Martian in the same way – launched forty years before the ma- [18]. Government science and exploration would form a rela- turing of the markets and technologies needed to sustain them. tively small fraction of overall activity. A similar period, too, before the maturing of the lifestyles and the mining, construction, production and recycling technolo- The pyramid philosophy would then suggest the following gies needed to sustain growing numbers of people in civilised pattern of progress: conditions at the intended destination.

• Regular Earth-Moon travel in cycler stations begins The scenario developed in this paper suggests that four dec- around 2033, when 100 people are already flying to orbit ades from the present (2018) would be a reasonable minimum and back per year. estimate of the time required for the maturation of space technologies and markets to the point where human access to Mars • R egular lunar surface activities begin around 2046, when becomes both realistic and sustainable. 1,000 people are already flying to orbit and back, and 100 people to a loop around the Moon and back per year. Clearly, a heroic effort in the mould of the Apollo pro-

176 Vol 71 No.5 May 2018 JBIS AN EARTH-MOON-MARS Passenger Transport Pyramid gramme would be able to send astronauts to Mars, and bring Author's note them back to Earth, on a very much quicker timescale. But it has been argued here that such a programme will, like Apollo, This paper is adapted and extended from a presentation given not be resilient against cancellation until the supporting econ- by the author at the British Interplanetary Society symposium omy – the base of the pyramid of transport activity – has had “Mars in the Age of New Space Launchers”, held in London on time to grow and mature. 28 February and 1 March 2018.

REFERENCES 1. M. Hempsell and A. Bond, “Skylon: An Example of Commercial 10. R. Zubrin with R. Wagner, The Case for Mars: The Plan to Settle the Red Launcher System Development”, JBIS, vol.67, pp.434-439, 2014. Planet and Why We Must, Touchstone, 1997. 2. A. J. Schwaniger, NASA Technical Note D-1833, “Trajectories in the 11. Yu. V. Kondratjuk (original name: Aleksandr Ignatevich Shargei), Earth-Moon Space with Symmetrical Free Return Properties”, Lunar Zavoevanie mezhplanetnykh prostranstv (1929). See S. A. Gerasjutin, Flight Study Series, vol.5, George C. Marshall Space Flight Center, “Das rätselhafte Schicksal des Juri Wassiljewitsch Kondratjuk”, Huntsville, Alabama, June 1963. Raumfahrt Concret, 101, p.46-49 (2018). 3. D. Webber, “Seven Steps to Space Settlement”, Spaceflight, vol.57, 12. B. Aldrin with L. David, Mission to Mars: My Vision for Space pp.468-470, December 2015. Exploration, National Geographic Society, 2013, pp.195-199. 4. J. S. Lewis, Mining the Sky: Untold Riches from the Asteroids, Comets, 13. D. F. Landau, J. M. Longuski and B. Aldrin, “Continuous Mars and Planets, Helix Books, Addison-Wesley, 1996, p.125. Habitation with a Limited Number of Cycler Vehicles”, JBIS, vol.60, pp.122-128, 2007. 5. M. Hempsell and R. Moses, “The Impact of Radiation Protection on the Design of Space Habitats”, JBIS, vol.61, pp.146-153, 2008, Fig.3 on p.148 14. E. Musk, “Making Humans a Multi-Planetary Species”, New Space, vol.5, and §3.4 on p.149. no.2, pp.46-61, 2017 (https://doi.org/10.1089/space.2017.29009.emu). 6. A. Bond, “A Nuclear Rocket for the Space Tug”, JBIS, vol.25, pp.625-41, 15. C. M. Dundas et al., “Exposed subsurface ice sheets in the Martian mid- 1972. latitudes”, Science, vol.359, issue 6372, pp.199-201, 12 Jan 2018 (https:// doi.org/10.1126/science.aao1619). 7. M. Hempsell, “Scorpion: A Design Study for Lunar-Martian Transportation”, presentation at the British Interplanetary Society 16. F. Bernardini, presentation at the British Interplanetary Society symposium “Mars in the Age of New Space Launchers”, London, 28 symposium “Mars in the Age of New Space Launchers”, London, 28 February and 1 March 2018. February and 1 March 2018. 8. W. von Braun, Das Marsprojekt, Umschau Verlag, 1952. First published 17. R. Zubrin and D. Weaver, “Practical Methods for Near-Term Piloted in English as The Mars Project, transl. H. J. White, University of Illinois Mars Missions”, AIAA 93-2089, 29th AIAA/ASME Joint Propulsion Press, 1953. Conference, Monterey, California, 28-30 June 1993. Republished in JBIS, July 1995. 9. S. Ashworth, “Europe’s Martian dream: ESA’s first design study for sending astronauts to Mars”, Spaceflight, vol.48 no.4, p.136-139, April 18. D. Ashford, Spaceflight Revolution, Imperial College Press, 2002, ch.6, 7, 2006. 11.

Received 7 June 2018 Approved 3 July 2018

JBIS Vol 71 No.5 May 2018 177 JBIS VOLUME 71 2018 PAGES 178-185

MARS COLONISATION The health hazards and exposure control JOHN R. CAIN Hookstone Chase, Harrogate, North Yorkshire, UK email [email protected]

Astronauts will eventually travel to, land on Mars and subsequently begin to explore the red planet prior to the establishment of settlements. However, this will only be possible if the hazards to which the astronauts will be exposed and the associated health effects are effectively controlled. This paper will identify the hazards likely to be encountered by astronauts during the journey to Mars and during working and living on Mars. These hazards will include the chemical, physical, biological and psychological aspects for example, exposure to toxic dust, radiation, microbes and stress/isolation respectively. This will be followed by a brief discussion of the need for health exposure risk assessments to ensure that the exposure to the health risks will be well controlled. A description of the measures likely to be available to mitigate exposure to the Martian health hazards for example, methods to reduce toxic dust levels in and around spacecraft and colonies together with the effective design of spacesuits, will be outlined.

Keywords: Hazards, Astronaut exposure, Risk assessment, Astronautical hygiene

1 INTRODUCTION Earth will likely see the migration of highly qualified scientists and technologists to exploit the opportunities for It will take astronauts between 7 to 9 months to reach Mars developing new space technologies and reap the advan- from Earth depending on the time of launch, the speed of tages [4]. the spacecraft, and Earth’s position from Mars at the launch date. During this journey, the astronauts will be subjected to 2 SELECTION OF ASTRONAUTS TO TRAVEL TO MARS a multitude of hazards ranging from exposure to deadly radiation to potential poisoning by toxic chemicals. So why would The selection of astronauts to journey to Mars is a complex humans want to travel to the Red Planet. There are several process because those chosen will need to be able to withstand main reasons why and these are interlinked with the how in living and working in the hostile conditions of the Red Planet. particular on the resources provided to control exposure to In recent years the use of exposome technology [5] together the major hazards: [1]. with biological screening has been used to select those astronauts that are most likely to survive the health effects from ex- 1. Interstate competition to be the first to reach Mars and posure to radiation and microbial infection [6]. the associated national pride in particular between Chi- na, USA, European Union including the United Kingdom Travelling to Mars will require stability in the crew chosen. and India. There will, therefore, need to be a balance in the number of sexes chosen and their ages. Those chosen will also need to be 2. Advances in space technology such as rocket propulsion resilient, adaptable in dangerous situations, curious and crea- systems and the development of sophisticated rocketry tive especially when establishing the Martian settlements. Fur- that make it easier and not as costly to travel to Mars for thermore, they will need to be well educated in particular in the both the public and private sectors. space sciences, astronautical hygiene [7], engineering and the medical sciences. But there will be exceptions if those applying 3. The long-term financial and economic advantages by have a background in the arts. Psychometric testing will be re- being the first to land on Mars and establishing colonies quired to establish whether the astronauts chosen will be able with associated rare-earth mining rights [2]. to withstand long periods of isolation, sleep deprivation and sexual tension [8] [9]. 4. Human curiosity is a major impetus for exploration on Earth and will be so on Mars [3]. 3 GENERAL HAZARDS DURING THE JOURNEY TO MARS

5. The first to establishment space settlements on Mars The journey to Mars will be fraught with dangers and there with regular communication between the Red Planet and will be a high risk of health effects if exposure to the various hazards is not contained [10]. The hazards likely to be encountered by the astronauts in space and also on Mars fall into three This paper was delivered to the “Mars in the Age of New Space categories. They include those due to the nature of space itself, Launchers Symposium”, London, 28 February – 1 March 2018. those due to the internal working environment of the space-

178 Vol 71 No.5 May 2018 JBIS MARS COLONISATION The health hazards and exposure control craft, those caused by the psychological make-up of the astro- the Martian pole-caps chosen because of the geology, glaciolo- nauts and those once settlements have been established includ- gy, climatology and potential biology [16]. Martian exploration ing extravehicular activity (EVA) [11]. will be one of the major objectives of EVA. The spacesuits of the astronaut explorers will become contaminated with exces- The hazards are physical (e.g. weightlessness, radiation such sive dust. The dust will need to be removed prior to entering as galactic cosmic radiation and intense solar particle events, and once inside a dedicated airlock by the use of a vacuum and light, noise, variations in spacecraft temperature/pressure, effective extraction respectively. Once the spacesuit has been pressure loss due to space debris impacts [12]). There are also cleaned and airborne dust levels are below safe levels, the suit chemical hazards including exposure to liquids, vapours, gas- will be removed [17]. es, fumes, solvents and dusts that could arise from off-gassing of equipment, from the life support systems (LSSs) and during 4.2 Martian regolith maintenance work. Dust exposure could arise when the spacesuit is removed following EVA. The Martian dust or regolith (soil) contains a number of toxic substances in varying concentrations, in differing particle There will be exposure to microbes including bacteria, vi- sizes and compositions. The characteristics of the dust will ruses and fungi arising from the astronauts themselves, from also be influenced by the geography of the area. The chemical microbes growing on contaminated surfaces and equipment substances found in the dust include perchlorates, hexavalent and from biofilms. Exposure to radiation and imbalances in chromium, silicates, arsenic and beryllium. All of these sub- the commensal flora may alter the genetic make-up of the or- stances are hazardous if inhaled at a specific concentration and ganisms making them more virulent and able to cause disease over a particular period of time [18]. Perchlorates are a major [13]. persistent component of the Martian regolith and the dust may contain the chemical up to a concentration of 1%. Because per- Psychological health hazards are likely to be a major health chlorates are oxidative, they could be used as a source of oxygen issue for the astronauts undertaking the long journey to Mars. and to fuel surface EVA [19]. However, if inhaled, the perchlo- This could be due to a lack of communication with family rates would cause the severest health effects. A few milligrams members on Earth, a lack of sleep due to spacecraft distur- of the dust within the airlock would be quickly absorbed into bances and equipment noise and heavy workloads resulting in the exposed body [20]. stress. During EVA there is the potential for musculoskeletal problems because of the spacesuit design and work activities in 4.3 Life support systems low gravity [14]. Once established, the settlement will require a regular supply Table 1 shows the major hazards and where they are likely of oxygen, water and food together with effective measures to to be encountered during a Mars mission. Uncontrolled expo- remove and re-cycle the waste material. During these activities, sure to one or more of the hazards could result in acute and/or there will be a release of volatile organic compounds (VOCs) chronic health effects. and other toxic chemicals such as ammonia, formaldehyde and polycyclic hydrocarbons (PAHs). The airborne levels of such 4 SPECIFIC HAZARDS RELATING TO MARS chemicals will need to be effectively controlled otherwise there could be astronaut high health risks from exposure [21]. 4.1 Initial landing site 4.4 3D printing and mining The initial landing site chosen by the voyagers will be in an area chosen for the best environmental conditions to establish a set- To survive on Mars long-term there will be the need for new tlement e.g. access to sub-surface water. This could be at one of technologies for example, the use of 3D printing to produce robotic devices, large mining equipment and plastic structural components for use by the settlement and by individuals [22]. TABLE 1 Major hazards encountered on a mission to Mars The scale of the use of 3D printing will vary according to the equipment size but it is likely to be large scale. Those directly involved with using 3D techniques will be potentially exposed Due to the nature of the space environment e.g. low gravity, 1 radiation, micrometeorites, extremes of temperature, humidity to a number of chemical hazards including aluminium, nick- and pressure. el, gold and silver and to plastic components released during heating [23]. Due to the spacecraft/settlement internal working environment e.g. chemical release from equipment off-gassing, life support There will also be developments in new mining and quarry- 2 systems, maintenance tasks, microbes in the air and on ing techniques on the Martian surface. These techniques will surfaces, astronaut commensal microbes, excessive light and generate large quantities of dust that will contain rare-earth noise from machinery and equipment. metals such as palladium and platinum both of which if inhaled following the removal of the spacesuit could cause severe From the psychological make up of the astronauts e.g. lack health effects [24]. 3 of sleep, from feelings of isolation, from stress due to work patterns [15]. 4.5 Radiation

From Extravehicular Activity e.g. Martian dust exposure when Exposure to radiation will be constant on Mars and in par- remove spacesuit in airlock, musculoskeletal/ergonomic ticular during EVA where the only protection will be from the 4 problems when carrying out surface tasks and spacesuit not wearing of a spacesuit. But will the radiation levels on Mars well designed. be sufficient to cause serious health effects? On the journey to Mars, the astronauts will be protected from radiation by the

JBIS Vol 71 No.5 May 2018 179 JOHN R. CAIN spacecrafts physical shielding and radiation storm shelters [24] light glare. Poor treatment of these issues could lead to con- [25]. Exposure to particle radiation carries the greatest risks flict and inter-group rivalry amongst sections of the settlement because the radiation can penetrate the skin and cause in the population unless they were addressed. Regular psychological short-term radiation sickness or cancer over a long latency and psychiatric monitoring of staff (as with Mars 500 isolation period. Cucinotta et al. [26] in a cancer risk projection have experiments [35]) would be one effective means to tackle these calculated that a journey of two hundred and ten days to Mars problems [36] [37]. will result in astronaut radiation exposure of 386 +/- 61mSv. On the surface of Mars, the astronauts will be exposed to about Astronaut musculoskeletal and related ergonomic issues 11 mSv per year, so the settlers should be able to spend about will arise on Mars due to working in low gravity conditions 60 years on Mars before reaching their career limit of between and with spacesuits that may not be specifically designed for 600 – 1200 mSv depending on sex and age. the tasks in hand. Such conditions could be treated with a combination of analgesics, rest and physiotherapy [38]. On 4.6 Microbes Mir and the International Space Station, exercise and food supplements have been used to reduce musculoskeletal deg- Only the hardiest of astronauts in terms of their immune status radation [39]. would be selected to journey to Mars. If the commensal flora of the astronauts (e.g. Staphylococcus aureas, Escherichia coli, 5 HAZARD EXPOSURE HEALTH EFFECTS viruses and fungi) and those growing on equipment surfaces mutate at a faster rate than normal because of genetic damage 5.1 Acute and chronic health effects caused by radiation or by changes in the microflora, then there is the possibility that the damaged organisms will become vir- High exposure to the hazards during the overall Mars mission ulent and cause infection. Those pathogenic microbes growing could cause acute and/or chronic health effects. Acute exposure in biofilm especially on equipment such as circuit boards may to the hazards will produce symptoms of ill health after a short infect the skin of astronauts and contaminate other surfaces time-period e.g. headache and breathlessness from chemical thereby increasing the risks of infection [27] [28]. exposure, tinnitus from noise exposure. Chronic exposure to a hazard that could result in health effects will be over a much Furthermore, if there are organisms growing on the Martian longer time-period e.g. exposure to Martian dust containing surface, then it is likely that they will have a similar biochemis- silicates could cause lung cancer, exposure to radiation could try to those organisms growing in extreme conditions on Earth cause skin cancer [40]. i.e. the Archaea [29]. The Archaea will differ biochemically from that of the Bacteria and Eukaryota domains [30]. During 5.2 Respiratory exposure EVA at selected sites, to collect soil samples, the astronauts will need to be extremely careful to prevent heavy contamination The most common health effects will be due to respiratory of their spacesuits with dust and potential exposure with Mar- exposure to hazardous substances in particular toxic chemi- tian organisms that could cause health effects [31]. The risks of cals. This is because inhalation via the lung is the main route exposure to microbes could be reduced by establishing Zones of exposure for toxic substances [41] [42] [43]. The nature of of Minimal Biological Risks around the settlements. Further- the health effects will mainly relate to the characteristics of the more, the astronauts would need to ensure that there was no chemical, its toxicity, particle size and where it will be deposit- possibility of cross - contamination with terrestrial microbes ed in the lungs by either sedimentation, impaction or deposi- from their spacesuits to the Martian surface. tion. The smaller the particle size, the deeper the lung penetra- tion and the potential for both acute and chronic health effects 4.7 Synthetic biology [44]. In the settlement, where microbes may thrive, astronauts may develop upper and lower respiratory disease that could be Whilst on Mars, the astronauts and technologists will use syn- fatal to susceptible individuals for example, legionellosis from thetic biology to design and engineer novel biologically based contaminated water in the LSSs. systems and the re-design of existing biological systems using DNA/RNA recombinant technology [32]. By using synthetic 5.3 Dermal problems biology techniques, it will be possible to bio-engineer microbes to produce a range of chemical substances for use in the main- Because of the high humidity conditions to be found inside tenance of LSSs. However, some of the chemicals generated the surface settlement modules, the skin will be susceptible from synthetic biology use will include arsenic and cyanide, to damage from itching and scratching. Such irritation of the both highly toxic chemicals, together with other hazardous skin dermal layers could result in dermatitis if not treated. Air- substances [33]. The use of synthetic biology techniques will borne microbes or those from surface biofilm could settle on therefore require legislation to ensure that exposure is prevent- the damaged skin and cause infection. Furthermore, dermal ed or effectively controlled [34]. exposure to a range of chemicals handled by astronauts and others such as acrylates and solvents could cause sensitisation 4.8 Psychological and psychiatric issues and dermatitis respectively. Such conditions could be difficult to treat and put the goals of the mission at risk [45]. Management of psychological and psychiatric issues by good habitability design, regular work patterns and the provision of 5.4 Eye damage leisure will need to be sustained at all levels otherwise there will be distress amongst the settlement workers. The isolation of be- If the eyes are in contact with chemical contaminated skin ing so far away from family members on Earth together with a there may be eye irritation resulting in redness. Prolonged eye heavy workload could cause stress and a sense of isolation lead- contact may result in conjunctivitis and eye infection. Artificial ing to sleeplessness. This lack of sleep could result from distur- light (e.g. light-emitting diode systems – LED) will be neces- bances at night from equipment and machinery e.g. noise and sary during all stages of the Mars mission [46]. The light pro-

180 Vol 71 No.5 May 2018 JBIS MARS COLONISATION The health hazards and exposure control duced will cause eye strain unless the lighting systems are well systems and who may be exposed to virulent organisms and maintained and spare parts are replaced frequently. In addi- toxic chemicals unless they are provided with suitable control tion, radiation exposure may result in cataracts and damage to measure as determined by the risk assessment. the retina. Recently, weightless conditions have been associated with optic nerve damage and retinal detachment that could 6.2 Steps to risk assessment have long-term implications for the astronauts in particular if the damage is not reversible and blindness occurs [47]. NASA has developed a risk management system based on five risk identification and management strategies (see Table 2). It 5.5 Ingestion and systemic health effects utilises five main steps to ensure that significant risks during a particular task are appropriately managed and the exposure is As on Earth, ingestion of microbes i.e. surface to mouth con- effectively mitigated [52]. Because there are so few exposure tact and swallowing may cause food poisoning resulting in studies of astronauts in general to the various hazards expe- stomach pains and diarrhoea. The ingestion of chemicals such rienced in space e.g. in the International Space Station (ISS), as xylene or toluene or the skin absorption and/or inhalation there is a need to use models to provide an accurate estimate of of these chemicals may result in systemic disease where more the likely exposures. A competent person such as an astronau- than one organ is affected and there are a number of bodi- tical hygienist will be integral in the design and use of concep- ly health effects for example, fever, nausea, muscular pains, tual models for assessing the health risks from chemical inha- headache and unconsciousness. Systemic disease can also be lation and skin exposure as well as assessing the health effects caused by weightlessness with widespread affects on the body related to radiation and noise exposure [53]. such as a loss of bone mass, renal stones, decreased red blood cell mass, muscle atrophy and decreased bloody volume [48]. 6.3 Web-based system Unprotected exposure to high levels of radiation may result in system health effects for example, radiation poisoning, cellular The results of any risk assessment will need to be communi- damage, hair loss, low blood pressure, stomach cramps and cated to all relevant parties so that they can take appropriate vomiting [49]. action to protect themselves during EVA for example. A web- based database has been developed by NASA that is used to 5.6 Noise issues identify, plan, track, control and communicate the health risks and associated risk data. However, there are problems with The noise levels encountered inside the settlement modules such a web-based system in particular in the interpretation of will be noticeable because they will be generated by necessary the results that will need people with a sound knowledge base equipment such as the airlock depressurisation pumps and of the issues involved to interpret them e.g. interpreting the heat exchangers etc. The nose levels could exceed 100 dB (i.e. concentrations of chemicals in Martian dust and assessing the the sound of a subway train) in the airlock due to the operating exposure health risks [54]. pumps. Both long and short-term exposure to high noise levels i.e. above 80 dB may cause permanent or temporary hearing loss and tinnitus (i.e. continuous noise in the ears). If tinnitus TABLE 2 A five-step approach to risk assessment is permanent it may result in health problems such as stress and during a Mars mission depression due to the incessant noise [50]. Step to risk Actions carried out 5.7 Psychological health effects and musculoskeletal assessment problems Identify the potential hazard(s) on Mars e.g. 1 radiation, chemical, microbial from recent data. Astronauts and other workers will at some stage experience psychological health effects. The risks of psychological disease developing and the associated health effects will increase with Determine the type of hazard, the routes of the length of the Mission and how well the crew interact with exposure, the health effects, the job tasks, the size of astronaut population exposed, time period 2 each other and address emergency situations. In a long-term of exposure e.g. two astronauts and one - hour mission to Mars, the initial human factor designs in the space- vapour exposure causing irritation via inhalation/ craft may become less user-friendly leading to boredom, com- skin exposure. placency and eventual stress issues. There may also be related musculoskeletal problems with some staff members as equipment builds-up making certain areas inaccessible and certain Monitor the exposure and assess whether they tasks become more painstaking [51]. comply with standards where applicable e.g. 3 Spacecraft Maximum Allowable Concentrations 6 RISK ASSESSMENT (SMACs) to determine if control is being achieved following chemical exposure. 6.1 Definition of risk

The Mars mission will need to address the health issues that Determine the exposure control strategies to the astronauts may face. This will require an on-going risk as- 4 mitigate exposure e.g. microbe cleaning regimes, sessment of all the potential hazards that may cause exposure radiation shelters, type of spacesuit. health effects. Risk can be defined as a measure of the probability of developing health effects following exposure to one Consider other factors that could contribute or more hazards during the Mars mission. The risk assessment 5 to exposure. Record results, communicate the will identify those astronauts and others that are working on findings/actions and review regularly. high risk tasks for example, changing filters in the extraction

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6.4 Monitoring strategies TABLE 3 Time Periods for SMAC Allocation and the Rationale The continuous monitoring of hazard exposure levels in both the spacecraft and in settlement modules will be a major part SMAC times Rationale for time SMACs of the risk assessment to ensure that safe limits are not exceed- allocation ed. The monitoring will be a combination of personal sampling (inhalation and skin) and fixed-point sampling to: Emergency situations, temporary discomfort (mild skin or eye irritation may occur but if the SMACs – measure airborne concentrations of toxic chemicals 1-24 hours are not exceeded there should be no marked released from equipment and LSSs; affect on the judgement, performance or ability to respond to emergencies. – measure background radiation levels;

– measure background noise and light levels; and Continuous SMACs, guideline concentrations to prevent adverse health effects, either 7, 30 and 180 intermediate or delayed (over the course – measure airborne and surface microbial concentra- days tion levels [55]. of a lifetime) and to avoid impairing crew performance. The monitoring of chemicals will be necessary to check compliance with Spacecraft Maximum Allowable Concentra- tions (SMACs) as well as Permissible Exposure Levels (PELs) in the airlock for example, during the removal of dusty space- 1000 days or For longer space missions beyond low Earth orbits suits [56] [57]. At low concentrations the chemical pollutants more and to other planets such as Mars. will cause little risks to health. However, if the concentrations of specific toxic substances such as aldehydes, hydrazine, dichlo- romethane, carbon monoxide and methanol increase above a certain level, then the exposure health risks will increase. particle sizes and distribution will be determined as well as 6.5 Spacecraft Maximum Allowable Concentrations the potential exposure risks to health. The smallest particles released inside the airlock following EVA will be inhaled. The Several hundred chemicals have been identified in the ISS but smallest particles (0.1µm) will be inhaled into the deep-seat- there is likely to be more within the settlement modules be- ed parts of the lung whereas the larger particles of over 10µm cause of the contained environments. SMACs are set for acute will be deposited in the upper respiratory tract. The dust will short-term exposure of 1-2 hours and intermediate exposure of contain toxic perchlorates, hexavalent chromium, arsenic and 7, 30 and 180 days. SMACs are also set for chronic long-term cadmium so therefore its chemical and biological activity will exposure of up to 1000 days. The determination of the SMACs need to be assessed in particular for the perchlorates which in a space-station, a spacecraft or within a colony are all based are oxidative in nature. The high oxidation of the soil will sig- on the toxicity of the hazardous substances, on their chemical nificantly increase the exposure health risks [60]. Appropriate and physical characteristics, from real-time exposures meas- monitoring and analytical techniques will be used to identify ured within the ISS, from the results of animal testing and from the exact composition of the dust. exposure modelling [58]. During the surface exploration of Mars, violent dust storms and high wind speeds will electrically charge dust particles re- If the SMACs and PELs are exceeded then the reasons why sulting in increased adhesion to the spacesuit. This would im- will need to be investigated and remedial action carried out pede the extent of the exploration time and place a limitation promptly. on the areas chosen. If the dust is not retained by the spacesuit, then more dust will become airborne in the airlock with the Once the risk assessment has been completed and the mon- high risks of respiratory, ingestion and dermal exposure and itoring data has been statistically analysed, then effective meas- potential contact with the eye. Any soil samples examined by ures to mitigate hazard exposure will be determined (e.g. noise the analysts from drill heads and robot digger components and mapping and assessment of noise abatement measures such as examined inside a glove box could be a high risk to health espe- the use of mufflers for the airlock pumps) [59]. In all instances cially if the glove box is not well maintained and the filters are of hazard control, the principles of good astronautical hygiene not changed frequently. will need to apply. 7.2 Risk assessment 7 EXAMPLE OF A RISK ASSESSMENT FOR MARTIAN DUST The overall risk assessment will need to include a monitoring 7.1 Excess Martian dust strategy to determine whether there has been compliance with relevant SMACs/PELs during the handling of the dust. Table 3 There will be excess dust on the Martian surface that the ex- gives the time periods for SMAC allocation and the rationale. plorers will need to assess in particular the dust that is retained It has been estimated by NASA that the quantity of dust inside on the spacesuit and will be released during removal in the air- the airlock should not exceed a maximum acceptable particu- lock. Prior to the EVA by the astronauts, the exploration site late concentration of between 0.05mg/m³ -1mg/m³ at all times will have been mapped using high-resolution stereoscopic im- as measured by a continuous air monitor [61]. aging to check the levels and types of Martian regolith. The completed risk assessment including an assessment of the The characteristics of the dust including its composition, its monitoring data will then determine the measures to mitigate

182 Vol 71 No.5 May 2018 JBIS MARS COLONISATION The health hazards and exposure control exposure for example, the provision of high recirculation rate TABLE 4 Astronautical hygiene measures to mitigate air removal with high speed fans and high efficiency particulate Martian dust exposure air filters (HEPA) in the airlock, providing vacuum cleaners with fans and HEPA fillers to remove dust from surfaces, pro- Only carry out Extravehicular Activity in a particular area if it vision of dust protection on depressurisation/re-pressurisation 1 is necessary; where necessary limit the time on the Martian valves [62]. surface and the number of astronauts to be involved. 8 MEASURES TO MITIGATE EXPOSURE TO MARTIAN HAZARDS Reduce or eliminate the dust in the airlock by for example, the 2 wearing of a suitable spacesuit with high dust retention or a The measures taken to prevent or control exposure to the range “Double Shell Spacesuit”. of Martian hazards will reflect the findings of the risk assessments and be regularly reviewed by an expert for example, an astronautical hygienist. Any significant changes in the control Prevent the spread of dust from the airlock by removing excess 3 measures being used will be implemented to reduce the expo- dust from spacesuits by the use of an effective vacuum. sure health risks. Where appropriate, the design of the spacecraft and settlements should incorporate measures to reduce exposure to the hazards e.g. shelters for radiation, sophisticated Reduce the levels of airborne dust in the airlock to below LSS to ensure homeostasis. appropriate Permissible Exposure Levels by the use of air 4 showers and local exhaust ventilation with effective and 8.1 Simple and sophisticated mitigation measures efficient filtration systems.

The control measures taken to mitigate exposure will be simple such as the wearing of a disposable dust mask respirator during Reduce dust surface contamination by the use of effective equipment maintenance work to the more sophisticated meas- 5 clean-up methods e.g. a vacuum with a high efficiency ures such as the use of local exhaust ventilation systems with particulate (HEPA) filter. effective and efficient particle, gas, vapour filtration systems or the use of revitalisation systems to recover, re-cycle and dis- tribute atmospheric gases [63] [64]. However, the main means Wear suitable disposable gloves and respiratory protective of protection against the exposure hazards during EVA will be 6 equipment when cleaning surfaces and where skin and the spacesuit. Table 4 lists astronautical hygiene measures to respiratory exposure may be significant. mitigate exposure to Martian dust. Design and use robust equipment that can withstand the 8.2 Spacesuits main means of control during EVA 7 affects of dust during EVA and when in use on the spacecraft in high risk areas such as the airlock. A spacesuit is a self-contained life support system. It will need to be specifically and individually designed to ensure that it is reliable and flexible in use. A poorly designed and inadequate- Ensure all extraction equipment (e.g. the glove box used for ly maintained spacesuit could lead to serious problems for the 8 dust analysis) is well maintained so that it remains effective at astronaut in particular a failure to protect the astronaut from all times. the harsh environment of Mars. The Martian spacesuits will need to be made of advanced composite fibre materials that are stronger and lighter than Kevlar and other materials [65] [66]. – t he introduction of quarantine laws to restrict astronauts/colonists and to isolate those with infection; Prior to exploration of the Martian surface, computational simulations will be needed to determine the expected work- – the need for health and safety legislation to prevent loads of the spacesuit including the mobility and the likely per- exposure to toxic chemicals in particular Martian formance as part of the risk assessment in choosing the correct dusts during mining and EVA; design for EVA. A “double shell spacesuit (DSS)” may suffice for some tasks where versatility is required and where excess – the need to introduce strict and severe punishments contamination with dust may be an issue; the contaminated for non-compliance of SMACs and other exposure part of the DSS will remain outside the airlock and the astro- levels; and naut will leave his suit through a bulkhead [67]. This procedure will prevent excess airborne dust within the airlock. – t he need for space science training and the education of colonists distinct from those of Earth to prevent 9 CONCLUSIONS conflict due to lack of resources in particular as the settlements expand. Once a settlement has been established on Mars it will be necessary to ensure its sustainability in such a hostile environment Cain has stated that [68]: in particular where the astronauts and others will need to live and work and where they will be exposed to a number of haz- “ Any social organisation will require health and safety ards. Measures to sustain a colony will include; provisions for its astronauts and other workers. The need to ensure a healthy astronaut population that opens the – t he improved development and use of exposome tech- frontiers of space will place a limitation on the freedom to nology including bio-markers to screen Martian colo- choose including how they live and work in the extreme nists for their susceptibility to specific hazards; environments of space”.

JBIS Vol 71 No.5 May 2018 183 JOHN R. CAIN

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Received 1 March 2018 Approved 15 September 2018

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IMPLICATIONS FOR RESOURCE UTILIZATION ON MARS: Recent Discoveries and Hypotheses FABRIZIO BERNARDINI1, NATHANIEL PUTZIG2, ERIC PETERSEN3, ANGEL ABBUD-MADRID4 and VALENTINA GIACINTI5 1Affiliate Engineer and2 Senior Scientist, Planetary Science Institute, 1546 Cole Blvd #120, Lakewood, CO 80401, USA; 3Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Blvd., P.O. Box 210092, Tucson, AZ 85721-0092 USA; 4Director, Center for Space Resources, Colorado School of Mines, 1310 Maple St., GRL 234, Golden, CO 80401, USA; 5University Campus Bio-Medico di Roma, Via Álvaro del Portillo, 21. 00128 Rome, Italy email [email protected]

Mars keeps proving to be the best candidate for the next step in human exploration: it is a complex frozen planet that offers innumerable research opportunities as well as all the raw materials to sustain a permanent presence on its surface. In addition, pictures obtained from orbiting spacecraft, as well as those from robotic surface explorers, show places worth seeing with human eyes, with a beauty and a complexity that needs to be appreciated by an inquiring and appreciative mind. While plans for exploring Mars have been postponed for years, we are now living in a very fortunate moment of human history in which we can look seriously at a celestial body as a place in which to live using local resources, both to sustain life and to produce energy, propellants and tools. The enabling ingredient in this scenario is the availability of water, and recent discoveries have provided new options that are defining a new paradigm for human exploration. After years of scientific exploration, it is indeed now time for prospecting and the first extractions of precious resources on which to base the future of human exploration of Mars: it is no longer merely visionary thinking, but a true practical possibility that is changing the rules of the game dictated so long ago.

Keywords: Water ice, ISRU (in situ resource utilization), Human landing site, Propellant production, Debris -overed glaciers

1 INTRODUCTION

Just as here on Earth, water and energy are indispensable to sustain life and machinery on another planet. Generating fuel and oxygen from water and the Martian atmosphere has been demonstrated, but uncertainties about the extraction of water ice from soil have complicated the evaluation of the efforts required to establish a first exploration campaign [1].

Papers published in 2008 [2] and 2009 [3] brought evidence of buried glaciers from the analysis of radar data obtained from SHARAD, the Mars Reconnaissance Orbiter’s Shallow Radar instrument. First seen in imagery decades ago and exhibiting intriguing flow-like features, structures previously known as Lobate Debris Aprons have been demonstrated to be glaciers, vast amounts of nearly pure water ice hundreds of meters thick extending many kilometers across the Martian surface. Processes that began sublimating the ice, accumulated during a previous climate regime as atmospheric precipitation, have been stopped by a layer of debris over the glaciers. The debris layer has been estimated to be less than ten meters thick, with a more precise estimate difficult to obtain with SHARAD per- formances (Fig.1).

The areas investigated are all at mid-latitudes, supporting a

This paper was delivered to the “Mars in the Age of New Space Fig.1 Findings from Mars Reconnaissance Orbiter's Launchers Symposium”, London, 28 February – 1 March 2018. Shallow Radar Instrument (SHARAD).

186 Vol 71 No.5 May 2018 JBIS IMPLICATIONS FOR RESOURCE UTILIZATION ON MARS: Recent Discoveries and Hypotheses

Fig.2 Mapping of glacier debris based on findings from Mars Reconnaissance Orbiter. climate-related deposition of precipitation in zones in which southern hemisphere. the topography facilitated both the deposition of the ice and its preservation by eroding debris. An extensive observing Radar studies, spectrometry and optical evidence from campaign and a first mapping of these debris-covered glaciers fresh meteoroid impacts all show that abundant sources of wa- (DCGs) have produced striking results (Fig.2). ter ice are available in the Martian soil, even in areas outside of the DCGs. The volume percentage of water ice within the Buried ice detections occur in multiple places, a great soil ranges from 1% to about 20% with various degrees of dif- quantity of them concentrated in Deuteronilus Mensae, a re- ficulties for extraction [1]. On the other hand, the DCGs have gion likely carved by ancient water and extremely interest- been estimated to contain at least 90% pure water ice well con- ing for human exploration both for its accessible location at centrated in areas adjacent to potential landing sites (Fig.3). mid-latitudes and its geologic characteristics. Other observing campaigns have identified similar glacial deposits, always A survey completed in 2014 determined that the average in the same bands of latitude, such as in Eastern Hellas in the ice thickness in the buried ice deposits is 420m +/- 170m and

Fig.3 Mapping of water resources based on findings from Mars Reconnaissance Orbiter.

JBIS Vol 71 No.5 May 2018 187 FABRIZIO BERNARDINI ET AL that the total amount of ice is up to 3.74 × 105 km3, represent- For these and other reasons, we think that a paradigm shift ing 13% of the volume of the Greenland Ice Sheet [4]. These is indeed in progress. There are no more excuses to keep Mars results have also been recently updated [5]. The discovery of exploration plans solely as a visionary project for the distant DCGs therefore presents a new way for implementing explo- future: it is now possible to implement new plans because the ration plans that need local resources for survival and for re- enabling technologies are now complemented with the ena- turn to Earth. Not surprisingly, the discovery paper [2] con- bling knowledge of resources. Therefore, the next step is to re- cluded with this statement: “This ice survives from climatic fine this enabling knowledge and select the best places for the conditions markedly different from today’s and is potentially mining hub that will drive the human exploration of Mars. accessible to future landed missions, not only for scientific Small resource-driven missions can be quickly assembled and study but as a resource to support exploration.” placed into Martian orbit to complete this knowledge. At the same time, a redoubled effort toward readying technologies What is surprising is that it has taken ten years for the im- such as drilling, excavating and refining for use on Mars will plications of this discovery to be fully recognized by the com- complete this game-changing scheme. While that effort will munity of people pursuing the human exploration of Mars. certainly have its challenges, there is no need to “re-invent the wheel”, since processes already used on Earth should be 2 A NEW PARADIGM readily adaptable for Mars.

Difficulties in extraction of water from ground sources have 3 A TANTALIZING HYPOTHESIS been one of the excuses that delayed the planning of a possible mission to Mars. However, the game-changing effect of One other area that has been largely overlooked after the 2008 the availability of huge quantities of surface ice has far-reach- and 2009 articles on the buried glaciers is their possible im- ing implications. plications in the search for life on Mars.

Removing the overburden that protects the ice buried in Recent results showed that conditions at the Martian sur- a DCG is a complex task, but in principle it does not require face (including areas containing water ice) are highly delete- anything beyond an excavator able to operate in Martian con- rious to living cells due to a components in the soil [6]. The ditions. Once the ice is made accessible, it is possible to start bactericidal effect of the soil has been tested both in the pres- extracting it in a horizontal mine: stocking the ice in blocks ence and in the absence of UVC radiation. However, it must will actually be made easier by the frigid conditions on Mars, be noted that the ice deposits originated hundreds of millions although the blocks must be protected from sublimation, of years before the surface deteriorated to such extent, at least such as by use of an inflatable shelter. preserving it in a different state.

Given the presence of easily stocked ice, the processing The presence of buried ice deposits has therefore implica- can be simplified perhaps using humans instead of complex tions for the possible presence of microbial life on Mars, since robotics to accomplish part of it. Production of propellants the ice may have preserved the Martian soil from the damag- can probably be accomplished with humans in the loop, and ing action of radiation. In addition, wet conditions may exist the overall ground operations will be simplified by the vast (or have existed) under the glaciers, and the fact that they are amounts of water available. For instance, complex closed-loop composed of nearly pure ice, likely with very low concentra- schemes to save water will not be required, simplifying life tions of salts, may make these subglacial terrains ideal envi- support systems: dirty water can be discarded or re-used for ronments for microbes and for their preservation. farming test purposes. Even the mitigation of Martian dust after an EVA becomes an easier task when plenty of water is Some might raise a concern that the possibility of finding available. In contrast, none of these options will be available traces of life in proximity to the first water ice-mine would be in a water-constrained Moon settlement. a show-stopper for extraction. In fact, it is the extraction of the ice that would enable such a discovery. Even if a particular More far-reaching implications stem from the realization site were to be set aside for scientific study, the large size and that a Mars Direct-like plan, in which subsequent automated abundant occurrence of glaciers will allow for side-by-side re- landers begins processing of local resources to build reserves source production and scientific analysis. for a follow-on human landing at different locations, is not so efficient when concentrated amounts of resources are avail- 4 CONCLUSIONS able in a single place. A water-ice mine and propellant production facility can be the hub for subsequent exploration via The discovery of large quantities of nearly pure water ice at light rocket-based vehicles to bring exploration parties else- the surface of Mars that is concentrated in huge debris-cov- where on the planet. The first settlement would thus be con- ered glaciers is a critical factor for Mars exploration and is the centrated in the new mining town in a pattern familiar from driver behind a new paradigm shift that is now in progress. human history. In the immediate area of the mining facilities, Different options exist to transport humans and equipment it may be necessary to relax planetary contamination restric- to Mars, and this has always been a major topic of discussion. tions while maintaining them where scientific explorations Starting today, technologies to excavate, stockpile and utilize are conducted at a distance from the central hub. resources are taking a central role in the exploration plans while providing new challenges for engineers. Local minerals in the soil, already partially prospected from orbit, will also be available as a secondary resource for While it is now well established that these vast ice re- other uses, like building structures and simple locally made sources are present, more detailed knowledge of their loca- tools. The combination of accessible water-ice and mineral tion, particularly the depth of the debris cover, is needed. resources may well be the primary drivers in the selection of This prospecting effort can be carried out quickly using a low the first landing sites. cost, short-term, orbiting mission with high-resolution radar

188 Vol 71 No.5 May 2018 JBIS IMPLICATIONS FOR RESOURCE UTILIZATION ON MARS: Recent Discoveries and Hypotheses sounding capability. Such a mission will enable the next step Acknowledgements in a new game-changing scheme for Mars exploration: setting up an ice mine in a new approach for a safe, efficient, and eco- The help and contribution of Roger Phillips is gratefully ac- nomic means to establish a settlement on Mars. knowledged both for this paper and in general for the advance- ment of Mars science.

REFERENCES 1. Abbud-Madrid, A., D.W. Beaty, D. Boucher, B. Bussey, R. Davis, L. 4. Levy, J. S., Fassett, C. I., Head, J. W., Schwartz, C., and Watters, J. L.,. Gertsch, L.E. Hays, J. Kleinhenz, M.A. Meyer, M. Moats, R. Mueller, A. Sequestered glacial ice contribution to the global Martian water budget: Paz, N. Suzuki, P. van Susante, C. Whetsel, E. Zbinden, 2016, Report of Geometric constraints on the volume of remnant, midlatitude debris- the Mars Water In-Situ Resource Utilization (ISRU) Planning (M-WIP) covered glaciers. Journal of Geophysical Research: Planets, 119, 2188- Study; 90 p, posted April 2016 at https://mepag.jpl.nasa.gov/reports/ 2196, doi:10.1002/2014JE004685, 2014 Mars_Water_ISRU_Study.pdf. 5. Petersen, E. I., Holt, J. W., and Levy, J. S., High Ice Purity of Martian 2 Holt, J.W., Safaeinili, A., Plaut, J.J., Head, J.W., Phillips, R.J., Seu, R., Lobate Debris Aprons at the Regional Scale: Evidence from an Orbital Kempf, S.D., Choudhary, P., Young, D.A., Putzig, N.E., Biccari, D., Radar Sounding Survey in Deuteronilus and Protonilus Mensae. and Gim, Y.,. Radar sounding evidence for buried glaciers in the Geophysical Research Letters, In Press, doi:10.1029/2018GL079759. southern mid-latitudes of Mars. Science 322, 1235–1238, doi:10.1126/ 2018. science.1164246, 2008 6. Wadsworth, J., Cockell, C. S., Perchlorates on Mars enhance the 3. Plaut, J.J., Safaeinili, A., Holt, J.W., Phillips, R.J., Head III, J.W., Seu, R., bacteriocidal effects of UV light. Nature Scientific Reports, doi:10.1038/ Putzig, N.E., and Frigeri, A.,. Radar evidence for ice in lobate debris s41598-017-04910-3, 2017. aprons in the mid-northern latitudes of Mars. Geophys. Res. Lett. 36, L02203, doi:10.1029/2008GL036379. 2009

Received 26 October 2018 Approved 7 November 2018

JBIS Vol 71 No.5 May 2018 189 JBIS VOLUME 71 2018 PAGES 190-196

THE LAWS OF MARS COLONISATION – a legal analysis RAPHAËL COSTA Executive Secretary, Institute for Space and Telecommunication Law email [email protected]

Space colonisation is almost exclusively approached from a scientific perspective, focusing its technical feasibility. Although since 1967 (the year of adoption of the Outer Space Treaty), human activities in outer space have been regulated by international law, the legal feasibility of colonising celestial bodies is still a new topic. This paper aims to consider the law as it already applies to Mars colonisation by analysing the legal conditions relating to a human colony on Mars and the legal problems that will arise through long-term occupancy of the Red Planet’s surface. It follows work on the same topic (including space colonisation by space stations) that comprehensively examines the subject and is to be published (in French) by The Hague Academy for International Law in a book entitled 50 Years of Space Law – Space Law in 50 Years.

Keywords: Mars, Colonisation, Law, Space Law, Legal

1 INTRODUCTION ticle V on the rescue of astronauts was detailed in the “Res- cue Agreement”. Article VII concerning the liability of States 1.1 International space law as it applies to the colonisation was detailed in the “Liability Convention”. Article VIII on the of Mars registration of space objects was detailed in the “Registration Convention”. And finally, the “Moon Agreement” setting the In 1967, space became the final frontier of international law. basis for the exploitation of natural resources of celestial bod- In the geopolitical context of the Cold War, the international ies was adopted in 1979. This would be insignificant if those community felt the need to regulate future space activities in treaties were ratified by an equivalent number of States, be- order to prevent an extension of the Cold War to outer space cause a treaty only applies to the States that have ratified it. [1]. After a short drafting process, in October 1967 the United But the OST has been ratified by 104 States, including the Nations adopted the Treaty on Principles Governing the Activi- spacefaring nations. The “Rescue Agreement” and the “Liabil- ties of States in the Exploration and Use of Outer Space, includ- ity Convention” respectively received 94 and 92 ratifications. ing the Moon and Other Celestial Bodies, called (for obvious The “Registration Convention”, less successful, was ratified by reasons) the Outer Space Treaty, or OST. 62 States. And finally, as evidence of its failure [2], the “Moon Agreement” received only 16 ratifications. This Treaty is considered to be the “Magna Carta” for human activities in outer space, including space colonisation. It This demonstrates the importance of The Outer Space Trea- contains the fundamental principles of positive space law: the ty but it also shows its weakness. Some States ratified major freedom of exploration and use of outer space carried out for principles but not their contents. Space law is not unified. the benefit of all mankind (Art. I), the prohibition of State ap- The OST is not self-sufficient, and some would say it is- un propriation of outer space (Art. II), the application of general finished [3]; it needs other treaties to complete it. We will use international law to space activities (Art. III), the total demil- all of these international agreements to express space law as it itarization of celestial bodies and the partial demilitarization applies to Mars colonisation, and our conclusions will apply of Earth orbits (Art. IV), the assistance due to astronauts in equally to all States and their nationals. It should be pointed distress (Art. V), the precondition for private entities to ob- out that even if colonisation of Mars is carried out by private tain authorization before engaging in activities in outer space companies, such as SpaceX, we will be talking here about State and to submit to their State's supervision (Art. VI), the liability colonisation. This is because, according to the OST’s Article of States for private and public activities in outer space (Art. VI, private entities conducting space activities need to obtain VII), the registration of space objects (Art. VIII), and mutual authorization before conducting their activities and must sub- respect and co-operation procedures (Art. IX to XIII). mit to their State's supervision. That is why no Martian colonisation will occur without (at the very least passive) connivance As its title says, the OST is a Principles Treaty. That is why of the State. Moreover, all States bear international responsi- some of its provisions, broadly drafted, had to be detailed bility to ensure that their nationals respect the provisions of in subsequent treaties adopted between 1968 and 1979. Ar- international space law as it applies to their State.

The Moon Agreement introduces the concept of “common This paper was delivered to the “Mars in the Age of New Space heritage of mankind” applied to outer space and its natural re- Launchers Symposium”, London, 28 February – 1 March 2018. sources. They are both held in trust for future generations and

190 Vol 71 No.5 May 2018 JBIS THE LAWS OF MARS COLONISATION – a legal analysis protected from self-interested exploitation by a State or com- 2.1.1 The legality of the definitive human occupation of Mars pany. Unfortunately, as the Moon Agreement was only ratified by 16 States, none of them spacefaring nations, we will not The Outer Space Treaty’s Article I establishes the fundamental discuss this concept further as it is not accepted that it applies principle that States parties to the Treaty shall be free to ex- to outer space. plore and use outer space, including the emptiness between celestial bodies. Back in the 1960s, this principle was a con- To summarise our introduction, the status of international sequence of the necessity to adopt a legal regime that distin- law as it applies to space is that it is applicable to space col- guished between outer space and airspace, over which each onisation. But not all treaties and concepts of international State is sovereign. According to the freedom of use recognized space law are applicable to space colonisation as a space ac- by the adoption of the OST in 1967, freedom to occupy Mars tivity. Moreover, even though there is no relevant Treaty, in- is implicit in the use of planet Mars. Indeed, “outer space oc- ternational customary law remains useful. For space law, this cupation” is a legal use that is recognized, allowed for and oc- concerns just a few principles we will detail bellow. casionally encouraged by various provisions of the Treaty. It therefore follows that Mars colonisation is legal. According to Article 3 of the Moon Agreement: “1. The provisions of this Agreement relating to the Moon shall also apply However, freedom of use is granted to all States without to other celestial bodies within the solar system […] 2. For the discrimination. To ensure proper use by each State, freedom purposes of this Agreement reference to the Moon shall include of use cannot be absolute. The first limit is in Article II of the orbits around or other trajectories to or around it.” All provi- OST: “[…] celestial bodies [are] not subject to national appro- sions of space law also apply to life on Mars and life to Mars. priation by claim of sovereignty, by means of use or occupation, or by any other means”. The first outcome of this provi- 1.2 The definition of Mars colonisation sion of the Treaty is that the colonising States cannot use the fact they are occupying a part of Mars to declare sovereignty Along with several other notions in space law, ‘colonisation’ over it, or over any other part of Mars. is not internationally and legally defined [4]. We should then try to define it ourselves. Colonisation is usually defined as a Article II also prevents States from claiming any title of process by which an organized group of human beings extends property or sovereignty over the occupied Martian territory. its territory to new places – in our case, the Martian surface During the 18th century, unoccupied territories, and some- or subsoil. To colonise Mars means its final occupation. This times occupied territories, were considered as Terra Nullius human establishment must exceed and outrun its founders. by European empires in their desire for territorial expansion When they die or return to Earth, the Martian colony will still and to annex newly discovered lands. In our introduction, we exist. Thenceforth, colonisation as an organized and planned gave a sociological and political definition of colonisation. But process must be distinguished from immigration, which is an classically, a legal definition would be the “territorial appropri- individual or familial act, and from occupation. The Interna- ation of a land”. This newly occupied region would automati- tional Space Station (ISS) is for the moment the only perma- cally become part of the sovereign territory of the colonising nent human occupation of outer space. Yet, it is not considered State, which would exercise sovereign rights over it and apply as part of a process of space colonisation because the ISS will its laws to the people living there. soon come to an end, and participating States do not intend to populate space by means of it. The OST’s Article II forbids any State from annexing Mars. Therefore, outer space colonisation cannot hold the same le- In our legal journey to Mars colonisation we can distinguish gal definition as classical terrestrial colonisation. Both com- two phases. The first is the installation of the colony, which we mon and science fiction uses of the word “colonisation” have call the legal Foundation of a Martian colony (in tribute to resulted in it being applied to human expansion in outer Isaac Asimov, and our teenage years reading his stories). It is space. But outer space colonisation implies a change in the discussed in Section 2. Once that stage is reached, other prob- legal meaning of “colonisation” itself. lems will arise due to the colony having a longer duration. This is discussed in Section 3. The meaning of Article II forbids the sovereign appropriation of Martian territory by any means. But does the word- 2 THE LEGAL FOUNDATION OF A MARTIAN COLONY ing of the Article imply that occupation always constitutes a national appropriation and is therefore forbidden? Article II In order to legally establish a human colony on Mars, we must mentions several instances of illegal national appropriation, first analyse the lawfulness of such a project before going on to one of which is “use”. But “use” cannot always be seen in the define its legal conditions. context of national appropriation, since its freedom is guaranteed by Article I of the OST. The question therefore remains 2.1 The legality of Mars colonisation as to what constitutes “occupation”. Additionally, other provisions of the OST allow States to establish bases and habitats Determining the legality, the international lawfulness, of Mars on, and below, the surface of Mars. Therefore, we can argue colonisation requires two levels of assessment. First, we must that definitive occupation of Mars is internationally legal (al- establish the legality of colonisation stricto sensu – that is, the beit with conditions) in order to guarantee the same possibili- legality of the permanent and definitive occupation of celestial ties of use to all States. bodies [5]. This is the compelling function of Martian colonisation. Once a colony is established, however, settlers may Even though we have established the international legali- engage in other tasks besides occupation, which means that ty of space colonisation, occupation of Mars may still be per- the legality of each of these tasks must be studied as well. In ceived as form of appropriation that can be made without the this paper we will focus on two of them: prospecting/mining prior consent of the international community. In this respect and military colonisation. States are not bound by international consent, as American

JBIS Vol 71 No.5 May 2018 191 RAPHAËL COSTA law on the exploitation of space resources has already illus- 2.2 The legal conditions for Mars colonisation trated. States conducting space exploitation projects can find interpretations in the Treaty authorizing them to colonise. 2.2.1 Respect for international space law provisions However, the OST authorizes States “to humanly occupy celestial body surfaces”. Colonisation is therefore a form of ap- States that wish to colonise Mars are bound by all internation- propriation that is authorized. al space law provisions applicable to them and to any human activity conducted in outer space. States are only bound by the The legal availability of celestial bodies for commercial ex- treaties they have ratified, or which are deemed law by inter- ploitation is more questionable. national custom. So far as space law is concerned, this last element concerns, for example, the freedom of use and non-ap- 2.1.2 The legality of Mars mining propriation principles, which apply to all States – even those that have not ratified the OST. Space mining constitutes the commercial use of space resources by some entity that is technically able to collect those Ideally, a State colonising Mars will follow the “common resources in situ. Such a complex task could be assigned heritage of mankind” principle enshrined in the Moon Agree- to Martian settlers. Once again, the freedom of use of out- ment. Unfortunately, none of the spacefaring nations have rati- er space implies commercial exploitation of it, as is the case fied this Agreement, and are therefore not bound by this highly with commercial satellite services. And here again, standing desirable principle. against this freedom is the non-appropriation principle. Con- cerning space resources, two interpretations of the treaties 2.2.2 The exclusive use of personal jurisdiction can be found among legal scholars. The first [6] considers resource exploitation as an appropriation, and therefore ex- Traditionally, jurisdiction is the tool by which a State applies pressly forbidden by the OST. The second [7], the majority its law. It is territorial, and at the exclusive will of the State. But one, regards the wording of Article II as imprecise and does a State extending its jurisdiction over a Martian colony on a not expressly prohibit space resource exploitation. territorial basis would violate the non-appropriation principle by claiming sovereignty over the land itself. That is why Article 11.1 of the Moon Agreement recognizes that space colonising States must exercise only personal jurisdiction over resources are the common heritage of mankind and can be their Martian colonies. Personal jurisdiction derives from the exploited. Therefore, States parties to the treaty shall imple- principle of space objects registration (OST Article VIII). States ment an international regime of exploitation that guarantees parties to the Treaty must register all space objects they in- the regulated exploitation of resources and distribution of tend to send to Mars, including bases, habitat modules, rovers their benefits to developing nations. This provision resulted and also the astronauts themselves. Over those objects alone, in the failure of the Moon Agreement, since both the United the Registering State maintains its (personal only) jurisdiction States and Luxembourg have adopted national laws allowing and applies its laws to them. their citizens and companies to wholly own space resources that they have extracted and brought back to Earth. 2.2.3 Protecting settlers

In conclusion, Mars mining is theoretically allowed ac- Article V of the OST recognizes that all astronauts are consid- cording to international space law by the Moon Agreement. ered to be envoys of mankind and require a protective regime in If the colonising State is party to the Moon Agreement, it situations of distress. But the provisions of the Treaty have little should adopt and respect the expected international regime. or nothing to say about what constitutes an astronaut. For sure, If, on the other hand, the colonising State follows its own na- we can apply the astronaut principle to all humans who travel tional legislation, its nationals may exploit Mars – although into space for professional reasons, on trips of a non-commer- there are questions over the international legality of such laws cial and State-sponsored nature – and this will apply to the per- as they stand against the provisions of the OST. If the colonis- sonnel involved in the early days of Mars occupation. But will ing State does neither of these things, they remain in the grey the same principles apply once a colony on Mars becomes es- zone arising from the OST’s Article II. tablished and begins to welcome settlers? Those settlers might be there to conduct private or commercial activities, not nec- 2.1.3 The legality of Mars military colonisation essarily for professional reasons [9]. Here again, two doctrinal interpretations exist. We will not expand on them here because Mars military colonisation is defined as the deployment of both [10] conclude that, whether astronauts or not, all settlers military personnel charged with occupying its territory for must all benefit from the protective regime offered to them a defence-related mission. This definition is realistic in the by the Outer Space Treaty in situations of distress, no matter sense that astronauts are, for now, officials in the service of whether the situation occurs during launch, during their time their States (and indeed, some hold a military rank). Further- on Mars, or during their return. more, military objectives were at the heart of the development of space activities during the Cold War [8]. To prevent 2.2.4 Environmental obligations concerning terraforming an extension of the Cold War to outer space, States parties to the Outer Space Treaty partially demilitarized it. Accord- In the preface of his Mars Trilogy [11], Kim Stanley Robin- ing to Article IV of the OST: “[…] celestial bodies shall be son defines Mars terraforming as “the process of substantially used by all States parties to the Treaty exclusively for peaceful modifying its surface in order to make it suitable for equip- purposes”. This means that States cannot send personnel to ment-free human life”. Article IX of the OST states that “States Mars to conduct military activities even if such activities are parties (sic) to the Treaty shall pursue studies of […] celestial non-aggressive. To conclude, although the OST allows mili- bodies and conduct exploration of them so as to avoid their tary personnel to carry out scientific activities on Mars, mili- harmful contamination.” Thus, States cannot engage in Mars tary colonisation of the Red Planet is forbidden. terraforming because it would constitute a harmful contam-

192 Vol 71 No.5 May 2018 JBIS THE LAWS OF MARS COLONISATION – a legal analysis ination of a celestial body and is internationally prohibited. property over the module that it provides and registers. When Moreover, as celestial bodies are not subject to appropriation sliding from module to module, an astronaut aboard the ISS and are free to use by all states, terraforming Mars would de- actually slides from one jurisdiction to another. The law of the prive other states of the natural state of the planet. Neverthe- State of Registry of each module applies inside it. But the hu- less, this obstacle can be overcome. The environmental protec- man element remains the most hazardous one. Article 11 of the tion established by Article IX aims to regulate the conduct of ISS IGA foresees the Crew Code of Conduct. Once inside the scientific studies and exploration. This means that once such space station, all crew members, irrespective of their nation- scientific studies of Mars are completed, Article IX would ality, must respect its provisions as agreed by all participating cease to be an obstruction. Furthermore, a terraforming plan States. Crew members must take into account the multicultural agreed at an international level, either by all States or by as and international nature of the entire crew in their personal many as possible, would be a good way to endorse the unilat- conduct. Authority inside the space station rests with the chief eral terraforming of Mars. But there is currently no recognized crew member, who is himself/herself under the authority of authority that could declare Mars to be no longer of scientific those on the ground. interest, and there is no international space agency leading international space exploration on behalf of all States. In cases of misconduct, various sanctions are allowed for – from an oral or written warning, to expulsion from the space 2.2.5 Obligations of co-operation station. The most interesting part concerns penal jurisdiction, about which the authors of the IGA have been creative given According to the provisions of the OST, co-operation, collabo- the framework of jurisdiction provided by the Registration ration and mutual assistance between States must drive all space Agreement. In the case of a crime involving two crew members activities. Whether concerning colonisation or not: “the use of of different nationalities, only the State of nationality of the al- […] celestial bodies shall be carried out for the benefit and the leged offender has jurisdiction to judge the affair. (This was to interests of all countries, irrespective of their degree of econom- prevent any Russian or American astronaut being judged by his ic or scientific development”. Moreover, when colonising Mars, or her rival State.) However, in cases where there is disagree- States are obliged by Article XII to inform the Secretary General ment, or where there is a lack of sufficient guarantees that the of the United Nations and the scientific community as to the case will be judged fairly, the State of nationality of the victim location(s) and nature of the colony, and the results of activi- recovers its jurisdiction to judge itself. ties carried out there. We note that the principles and spirit of co-operation governing space activities are in danger of being The International Space Station could be a good starting overlooked at a time of increasing private space activity. point for the drafting of a legal code for a Martian colony that would accommodate both the co-operation and common in- 3 THE LEGAL PROBLEMS OF A LONG-DURATION MARTIAN terest principles that are at the heart of international space law. COLONY 3.1.2 Legal regimes of habitats 3.1 Legal issues within the Martian colony itself Because of the inherent risk of national appropriation, the per- 3.1.1 Legal organization of the colony manent occupation of celestial bodies is strictly constrained by the provisions of the OST and the Moon Agreement. Ac- The law of each Martian colony depends of its instigators. If cording to the freedom of use expressed in OST Article I, and the entity conducting the colonisation is a single State or a na- in Article 8 of the Moon Agreement, colonising States are free tional of that State (for example, NASA as a representative of to choose where to establish their colony above or below the the U.S, or SpaceX as a national of the U.S.), the organization surface of Mars. Article 11.3 of the Moon Agreement, permits of the colony and the applicable law will be entirely under the a wide choice of architecture for a colony by which settlers jurisdiction of that State. This is a direct consequence of the can install themselves, their vehicles, their materials, their sta- personal jurisdiction granted by Article VIII to the State of tions, their installations or their equipment, including separate Registry of the colony, its equipment and its people. The only structures connected on or below the surface. However, once limit on the organizational freedom of the colonising State is several States colonise Mars, some will be unable to install that the legal arrangements of its colony must respect the OST their equipment wherever they want because of the presence provisions. This is also applicable if a private company is doing of earlier colonies. Therefore these earlier installations must the colonising. For all these reasons, in the case of unilater- be arranged in such a way as not to prevent others accessing al colonisation, the organization of the colony rests with the parts of Mars or pursuing their own activities. For this reason colonising State. But if the colonisation of Mars is conducted colonies cannot be over-large or appropriate entire regions by several States co-operating internationally, the organization of the planet. To conclude, the habitats themselves must be of the colony must be studied and negotiated between those accessible to other States. According to the Article XII of the States in order to preserve not only their own interests but OST: “All stations, installations, equipment and space vehicles hopefully the international interests of space, too. on […] celestial bodies shall be open to representatives of other States parties to the Treaty on a basis of reciprocity”. Such is the case with the International Space Station (ISS). In January 1998, the United States, Japan, Russia, Canada 3.1.3 Local use of Martian resources and the European Space Agency (representing all its member states) adopted the International Space Station Intergovern- “Local use” refers to the direct use of Martian resources for the mental Agreement (ISS IGA). From its first Article, the ISS day to day needs of its settlers, as opposed to commercial ex- IGA expresses the objectives of the ISS to develop an interna- ploitation of those resources. As long as such resources are re- tional peaceful program of permanent manned occupation of newable or endless, freedom to exploit them is enshrined in the outer space. According to the provisions of the Agreement and freedom of use provisions of OST Article I. This includes solar the Outer Space Treaty, each State preserves its jurisdiction and or cosmic rays, abundant minerals or anything else without

JBIS Vol 71 No.5 May 2018 193 RAPHAËL COSTA scientific value. Article 9.2 of the Moon Agreement confirms law and political history on Earth. that only resources needed to sustain the colony can be used. The possibility of building bases beneath the surface of Mars 3.2.1 The legal status of the colony solely in the hands of the implies that Martian resources may also be mined in order to Earth State protect the colony itself from cosmic rays. As we have explained, the State of Registry keeps its jurisdic- 3.1.4 The progressive development of institutions and of a tion over a Martian colony. As long as terrestrial space law complex legal system remains in force, this creates an asymmetrical link between Earth and the colony, in which the Earth State is empowered At first, a colony must be materially and technically established to choose the nature of its relationship with the colony. Given by a small and professional astronaut crew. The beginnings of the history of colonisation on Earth, several options exist – all the colony will be inorganic. This means that no legal authori- of which might be applied to a colony on Mars. ty except that of the chief crew member holds good. However, once the establishment phase is completed, colonisation will The first option is the subjugation regime, maintained, for proceed with the regular arrival of individuals, groups and example, in the former colonies France, Spain and Portugal, families, all of whom carry with them legal needs as in any where representatives of the colonies were only admitted to the developed society. Humans need a framework of organization, parliaments of their mother countries during the 19th century. adminstration, law and order to function, and to resolve dis- The chief characteristic of the subjugation regime is that colo- putes and conflicts. But a colonising State cannot decree that nists are excluded from participating in the elaboration of the the same law will apply to its colony as applies on Earth. To do laws that apply to them. On Mars, the principle of the State’s so would imply that it has property rights and/or sovereignty eternal jurisdiction over its colony would predispose the colo- over Martian territory. Instead, the State will have to gradually ny to such a regime: space law only prevents the subjugation of evolve political and legal institutions that apply specifically to outer space, not the humans living there. the colony, as has already happened with terrestrial colonisation in the past. The second option is the assimilation regime, in which the same legislation applies to all parts of territory, whether on The incremental addition of institutions will progressively Earth or Mars; once adopted by the State, a law applies equally develop the legal consistency of the colony in the same way that to the colony. As already explained, on the face of it this is im- human cells develop into an embryo. The difficulty arises when possible without a recognition of sovereignty, even an implicit predicting or prescribing in what the order such institutions one, over the Martian surface. However, it is still possible to are added. Factors such as distance, climate and the nature of proceed to a state of near-assimilation by including in each and the colony itself prevent us from automatically applying the every law a mutatis mutandis provision – for example, exclud- same governance to a Martian colony as we would to territories ing land rights on Mars. on Earth. In other words, the legal development of a colony is by definition both random and opportunistic. Even so, we can The final option is the self-governing regime, as preferred by identify some general principles – for example, the establish- the United Kingdom in the administration of its colonies. In ment of a civil administration and a judiciary, with each new this, colonies have their own representative and legislative in- institution assuming some of the powers of the previous ones stitutions that pass laws themselves while respecting the funda- in order to ensure consistent separation of power. mental legal principles of the mother country. On Mars, these principles could be the Outer Space Treaty provisions. 3.1.5 The legal relationship between Martian “foreigners” 3.2.2 The idea of a colony's “Independence Day” As long as all Martians belong to the same State of Registry, the legal relationships between them are unaffected by a lack Whatever the political regime, or the attitude of the mother of territorial jurisdiction. Disputes will be regulated according country, the gap between the head and the body may widen to to the laws of their State of Registry in the case of a unilateral the point where the colonists desire legal independence. The colonisation, or according to rules agreed by the participating risk of a unilateral declaration of independence is intrinsic to States in the event of international colonisation. But once sev- a colony that perceives itself to be separate from the State that eral States or entities colonise Mars, whose law will be used to founded it. This is not only a matter of law. Turgot compared resolve disputes or conflicts? When a legal dispute arises be- colonies to fruits: once they reach maturity, they no longer hold tween two foreigners on Earth, in the vast majority of cases on to the tree. After successive generations, the people of Mars the law of the State in which the dispute occurred applies. But will become the Martian people. What of this people’s right to on Mars, there is no such territorial jurisdiction and space law self-determination? does not provide for it. At best, States can choose to consult with one another in a spirit of co-operation as provided for in This right is guaranteed to people by the first Article of the the Outer Space Treaty. At worst, minor disputes can escalate International Covenant on Civil and Political Rights: “By virtue into international incidents, involving not only settlers them- of that right they freely determine their political status and free- selves but their respective States. For now, the only answer to ly pursue their economic, social and cultural development.” But this question under space law would be for a Martian colony to this principle does not enshrine the right to independence – it be under the unilateral control of a single State, or for it to be only protects a State from foreign interference in its domestic controlled by prior international agreement. affairs, and the right of an already existing State to autonomy. Some resolutions of the United Nations General Assembly have 3.2 The legal relationship between Mars and Earth implied a right to independence in the case of colonisation by a foreign State. But settlers on Mars may not be occupied by The following issues may be perceived as bold and speculative, a foreign nation, having chosen voluntarily to be within their but they are based on observations made regarding colonial State. Moreover, resolutions of the UN General Assembly are

194 Vol 71 No.5 May 2018 JBIS THE LAWS OF MARS COLONISATION – a legal analysis non-binding. Over the years, this question is bound to arise. In would apply according to the nationalities of the people living the words of de Tocqueville, “each generation is a new people”. there. It would have territory to develop, but it would not own it. The jurisdiction of such a State would be total. The Martian 3.2.3 The relevance of an unequal link with the colony State would have no territory and no borders, and its nationals would be unable to escape its jurisdiction unless they fled to a One problematic question that follows from the preceding classical State back on Earth. The only geographical border of point is whether it is relevant to maintain a link between Earth the Martian State would be the borders of other classical States. and a Martian colony. In the author's opinion, it is inappro- priate in the long term to maintain unequal relations with a 3.2.5 The end of actual space law? colony not bounded by our home planet. This is based on the gravitational relationships between colonies and their mother The abandonment of subordination to Earth will probably be countries. It is logical for a space station orbiting the Earth to accompanied by the abandonment of the application of posi- be subject to terrestrial authority because it relies on Earth for tive space law because it was drafted on Earth, by Earthling, in its position in space, the frequency with which it is visited, and order to assure them the legal control of the Martian colony. certainly for its supplies. However, it is to be hoped that the principles of space law on Earth will leave their mark on any new laws that are drafted. On the other hand, a wandering space station should not be subject to terrestrial authority, especially once it leaves our Let us dream bigger. Once the solar system, or even the solar system. Similarly, in a colonised solar system, authority entire galaxy, is colonised by humans, what legal framework should come from a central gravitational point – for example might then apply? Can we imagine, as has been the case on Mars should exert authority over all space stations orbiting it. Earth, States acquiring their independence from the State that Maybe then a single organization could govern all occupied colonised them and going on to join some international or in- planets of the solar system on the basis of equal participation terplanetary organization? Might we at some point see an in- according to common rules. The necessity of (and preference terplanetary federation, or even an interstellar one? for) such a central authority is coincidentally described by Shakespeare in Troilus and Cressida: In spite of its high-minded ambitions, positive space law will have to cope with the practical issues raised by the expansion of “And therefore is the glorious planet Sol mankind. Even so, as currently configured, such law embraces in noble eminence enthroned and sphered principles that will be essential for the peaceful and co-opera- Amidst the other; whose medicinable eye tive colonisation of the cosmos. Right now, space law is under Corrects the ill aspects of planets evil, attack by some authors [13] who justify the settlement of outer And posts, like the commandment of a king, space by the ancient doctrine of “first come, first served.” -Ac Sans cheque to good and bad: but when the planets cording to them, the non-appropriation principle is an impedi- In evil mixture to disorder wander, ment to the exponential growth of commercial space activities. What plagues and what portents! what mutiny!”. 4 CONCLUSION 3.2.4 The opportunity to create a State free of territory Through the interpretation of space law, we have a chance to If, in the longer term, subordination leads to a unilateral dec- learn from the past, to reinvigorate international law, and to pave laration of independence by the colony, it will give rise to the the way for greater international co-operation [13]. It is to be existence of a new State – a Martian State. In the past, decol- hoped that the humanist, pacifist and internationalist principles onisation often ended in the succession of States. For now, a on which space law is based will survive, and will continue to State is composed of three elements: a people, a territory and contribute to the development of general international law [14]. sovereignty over both. If the non-appropriation principle enshrined in space law remains in force, will the Martian peo- The French essayist Carl Siger wrote that [15]: “colonies ple be able to constitute themselves as a State without having could, at some point, be the safety valves of modern society. sovereignty over their territory? Such a State will be different Even if this characteristic were the only point of colonisation, it from one on Earth, maintaining sovereignty over its people by would be huge.” For now, space colonisation remains a dream – personal jurisdiction rather than territorial jurisdiction. Its law but its impact will be no less huge.

REFERENCES

1. For more details about the drafting history between the first UNGA 5. Space law does not define what constitutes a celestial body. So this notion resolution and the adoption of the Outer Space Treaty, see S. Hobe includes both planets and asteroids. See : V. Pop “A celestial body is a “Historical Background” in Cologne commentary on Space Law Volume celestial body is a celestial body...”, IISL Proceedings, 2001, p. 100-110. I – Outer Space Treaty, Hobe, Schmidt-Tedd, Schrogl (ed.), Goh (assist. Ed.), Carl Heymanns Verlag 2009, p.12 to p.17. 6. W. Jenks, Space Law, Stevens & Sons Ltd., London, 1965, p. 201 and following; M. Lachs in C. Q. Christol, “Article 2 of the 1967 Principles 2. N. Mateesco-Matte, “The Moon Agreement: What Future?”, inAnnuaire Treaty Revisited”, Annals of Air and Space Law, 1984, p. 217 and de droit maritime et aéro-spatial – Mélanges en l’honneur du Professeur following; P. De Man, Exclusive Use in an Inclusive Environment: Mircea Mateesco-Matte, Pedone, Paris, 1993, pp. 346 – 359. The Meaning of the Non-Appropriation Principle for Space Resource Exploitation, Springer, 2016, p. 305. 3. J. Combacau and S. Sur, Droit international public, Montchrestien, 8th edition, 2008, p. 477. 7. S. Hobe, P. De Man, “National Appropriation of Outer Space and State Jurisdiction to Regulate the Exploitation, Exploration and Utilization of 4. P. Martin, “Les definitions absentes du droit de l’espace”,Revue française Space Resources”, in Zeitschrift für Luft- und Weltraumrecht, ZLW 66. Jg. de droit aérien et spatial, Vol. 182, no 2 – 1992, p. 106. 3/2017, p. 462.

JBIS Vol 71 No.5 May 2018 195 RAPHAËL COSTA

8. P. Achilleas, “La guerre des étoiles – de la science fiction à la science 12. B. C. Gruner, “A New Hope for International Space Law: Incorporating juridique” in Actes du colloque Les lois de la guerre, 2015, Mare Nineteenth Century First Possession Principles Into the 1967 Space et martin, p. 57 to 80 ; M. I Nicui, “Considérations sur le droit Treaty for the Colonisation of Outer Space in the Twenty-first Century”, international spatial”, Annuaire de droit maritime et aéro-spatial – Etudes Seton Hall Law Review, Volume 35, pp. 299 – 357. en homage au Prof. Mircea Mateesco-Matte, Pedone, 1993, p. 401. 13. C. Schmitt, The Nomos of the Earth in the International Law of Jus 9. E. Gibbon Wakefield, A view of the Art of Colonisation, John W. Parker, Publicum Europaeum, 1950, Cologn. London, 1849. 14. B. Cheng, “The Contribution of Air and Space Law to the Development 10. F. von der Dunk, G. M. Goh, “The Article V of the Outer Space Treaty”, of International Law”, in Current Legal Problems, Volume 39, 1, 1986, p. in Cologne Commentary on Space Law. Volume I – Outer Space Treaty, 181 – 186. Or B. Cheng, Studies in International Space Law, Clarendon Op. Cit., p. 97 ; P. Achilleas,“L’astronaute et le droit international”, in Press Oxford, Oxford, 1997 L’adaptation du droit de l’espace à ses nouveaux défis – Mélanges en l’honneur de Simone Courteix, Pedone, Paris, 2007, p. 145. 15. C. Siger, Essai sur la colonisation, Paris, 1907. Quoted by Aimé Césaire, Discours sur le colonialisme, Paris/Dakar, Présence africaine, 1955, p. 18 11. K. S. Robinson, La trilogie martienne, Omnibus, 2012, preface.

Received 8 May 2018 Approved 29 October 2018

196 Vol 71 No.5 May 2018 JBIS DIARY FORTHCOMING LECTURES & MEETINGS OF THE BIS

APOLLOMOON,Call for Papers MARS 8 – MEN AND TO BEYOND THE MOON INTERNATIONAL1817 DecemberJuly 2018, 7 2018, pm 7.00pm SPACE STATION FORUM 14VENUE:VENUE November: TheBIS, Royal 27/29 2018, Institution,South 9.30 am Lambeth to 215pm Albermarle Road,(tbc) London, Street, SW8 London, 1SZ W1S 4BS JerryVENUE:Where Stone should BIS, takes 27/29 humans usSouth on inhabit the Lambeth next next? step Road, Apollo in hisLondon Astronautseries SW8 of 50th 1SZAl Worden anniversary and BIStalks Council covering Members, every Apollo Dr Stuart mission Eves up to Aand forum includingProf to Chris celebrate Apollo Welch 17the will by 20th argue looking anniversary their back case at of Apollofor operations settling 8's historic on aboard the journeyMoon, the ISS. Mars into Please lunaror travelling orbitemail – [email protected] abeyond. triumphant Who end will towin anwith anyotherwiseyour ISS-related vote? turbulent papers. and tragic year. RD APOLLOWEST73 ANNUAL MIDLANDS MISSIONS: GENERAL BRANCH: THE MEETINGMECHANICS OF RENDEZVOUS & DOCKING BYSTARSHIP28 July DAVID 2018, 1 pmBAKERENGINEERING & PROJECT CHEVALINE 2017VENUE FebruaryNovember: Royal 2019, 2018,Gunpowder 7.00pm 1,45pm Mills, Beaulieu Drive, Waltham Abbey, Essex, EN9 1JY VENUE:Admission TheBIS, to Gardeners27/29 the AGM South is Arms, Lambethopen Vines to Fellows Road, Lane, London, only Droitwich, but SW8 all MembersWR9 1SZ 8LU. are(We welcome regret there to join is no the disabled discussion access after to the this venue.)Startingformalities with conclude Apollo 9 around launched 1.15 on pm. 3 March Please 1969, advise a key in advance feature ofif youthe wishApollo to missions attend (attendance was the ability to this to part of the afternoon is free). Robrendezvous Swinney and of www.i4is.orgdock in orbit – talks a capability about how that to NASA design had a starship.evolved over the preceding four years. 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VENUE:8 November BIS, 2018,27/29 6pmSouth Lambeth Road, LondonLondon, SW8 SW8 1SZ 1SZ TheJerryVENUE: BIS Stone BIS,has takes now27/29 scheduled usSouth on the Lambeth next its 39th step Road, annual in hisLondon seriesRussian-Sino SW8 of 50th 1SZ Forumanniversary – one talksof the covering most popular every andApollo longest mission running up to eventsandNatalie including in Starkey, the Society's Apollo a geologist 17 history. by looking and Papers cosmochemist, back are at Apolloinvited. joins 8's Watch historicus to this discuss journey space her for into book further lunar ‘Catching orbitdetails. – aStardust’, triumphant telling end theto an otherwisestory of comets turbulent and andasteroids. tragic year. APOLLO MISSIONS: LANDING ON THE MOON BY DAVID BAKER 12 June 2019, 7.00pm VENUE: BIS, 27/29 South Lambeth Road, London, SW8 1SZ SpaceFlight's editor looks at the systems evolved by NASA for calculating optimum lunar landing trajectories, and at the descent procedures needed to achieve the maximum chance of success while preserving emergency abort and safety considerations. Journal of the British Interplanetary Society

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ISSN 0007-084X PUBLICATION DATE: 30 NOVEMBER 2018