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Home , Beagle 2, Mars Polar Lander, Peter Smith (scientist)

Makeshift to The red planet has claimed many a plucky spacecraft. Richard Corfield discovers how Nasa’s latest attempt hopes to overcome the odds with a different approach

It is easy to forget in these heady Gas Analyser) is a mass spectrometer, days of the Mars exploration rovers In short able to identify organic molecules and – which have  Nasa’s latest mission that could prove to be evidence of exceeded their design lifetime by a to Mars, , will be on Mars. factor of ten – that Mars has a long launched this month history of claiming spacecraft. In fact  It will attempt to land It’s on America’s tortured brow only half of the missions ever sent to near the north pole of Phoenix is well named – it is an the red planet have been successful. the planet to search for attempt to rise from the ashes of one The rest, for one reason or another, evidence of water of the controversial periods have failed.  Phoenix’s mass of Nasa’s chequered history. In the This month a new spacecraft will spectrometer will also spring of 1992 Dan Goldin took over once again test the odds test the Martian dust as the Chief Administrator of Nasa when the Phoenix launches for compounds that may declaring that the era of ‘big space’ from Cape Canaveral Air Force be hazardous for future was over and that, in future, the Base in Florida, US, and tries to land astronauts biggest space agency in the world close to the red planet’s north pole.  The extreme would explore the planets with If successful, it will be the first craft conditions at the Martian what he dubbed the ‘faster, better, to reach either of the Martian poles. north pole will eventually cheaper’ approach. For much of the Its mission is twofold: to search entomb Phoenix in ice 1990s it seemed to be working, with for environments suitable for past low-budget missions such as the 1997 or present microbial life and to Pathfinder mission and its miniature investigate the history of water in the rover a spectacular high latitudes of Mars. success that paved the way for the The probe carries a piece of hugely successful Mars Exploration equipment that should raise the Rovers still trundling the sands of arm hairs of any red-blooded Mars today. Englishman – it is the instrument This 35-kilometre-wide Then, in 1998, Nasa launched Mars that we tried and failed to land on Martian crater, snapped Surveyor 98 consisting of the Mars Mars aboard the Marie Celeste of lost by the orbiting and the Mars Polar Martian landers, 2. The Tega Express probe, contains Lander. Their joint mission was to instrument (Thermal and Evolved residual water ice explore the and also 44 | Chemistry World | August 2007 www.chemistryworld.org

CW.08.07.MARS.indd 44 24/07/2007 11:54:40 ESA / DLR / FU BERLIN (G NEUKUM) (G BERLIN FU / DLR / ESA

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CW.08.07.MARS.indd 45 24/07/2007 09:43:27 Planetary science

will be transferred to the lander’s instruments by a which NASA JPL NASA can extend 2.35 metres and which can dig a trench up to half a metre deep. The aluminium and titanium arm is equipped with tines and a back-hoe to cut through icy soil as well as a scoop camera to provide close-up, high resolution images of the . Researchers on can search within the radius of the arm for prospective samples as well as examine the rocky layers or stratigraphy of the walls of the trench as it is dug.

Space-age technology This spacecraft also has eyes. Positioned at about the height of human eyes, these twin cameras – stereoscopic imagers similar to those that have proved so successful on the MERs – provide three dimensional imaging out to the horizon. Another camera was due to take photographs during the probe’s descent to the martian surface, although a wiring problem has recently nixed that plan. Alongside the latest technology, Phoenix also has features from a previous age of space exploration, such as landing thrusters rather than air bags. And without wheels, it is stuck wherever it lands. From the scientists’ perspective one recognisable old-timer is the Meca instrument. As Phoenix principal investigator of the points the potential of the poles as oases of was to close down the next lander Nasa scientists put the out, this instrument was originally liquid water and, possibly, life. But mission in the Mars pipeline, the finishing touches to the envisaged to support the human the Climate Orbiter was lost when Mars Surveyor Lander of 2001. Its Phoenix lander exploration of the red planet by it entered the sister mission Mars Surveyor Orbiter analysing Martian dust for toxicity at too low an altitude and the lander 2001 was rapidly renamed Mars and abrasive properties. Such was lost when the engine cut out too Odyssey and, since its arrival in Mars concerns are a direct result of the early. orbit in 2001, has proved to be a Apollo missions of the late 1960s and In the first case the failure was spectacular success, mapping Mars early 1970s. As the Apollo astronauts caused by an embarrassing mismatch and acting as the communications climbed back aboard their lunar of imperial and metric units between relay for the most successful modules they were liberally caked the spacecraft manufacturer of all Mars landers, the Mars in black lunar dust and there was no Lockheed Martin and the project exploration rovers (MERs) Spirit and way of removing it in the confined manager, Nasa’s Jet Propulsion Opportunity. But the Mars Surveyor space of the lander. Inevitably some Laboratory (JPL). In the latter Lander has spent the last seven years of this dust was inhaled. case the deployment of the landing in a clean room facility in Colorado The same problem will be legs was so violent it triggered – a $100 million craft just waiting for unavoidable when the first human premature engine shutdown forty a mission. explorers land on Mars and so Nasa metres above the surface rather That mission has finally arrived. wants to know the composition of than at touchdown. In each case the Phoenix was selected from several the dust before they risk astronauts. problems were entirely avoidable. It competing tenders in 2003, and is There are specific concerns about became clear that faster and cheaper the first in a new series of ‘scout’ ‘So many the possibility that Martian dust may did not necessarily equate to better: missions designed to augment and contain heavy metals or tiny particles it could just as easily mean a quicker explore in detail crucial aspects of hopes have that might cause the inflammatory route to egg on the face of the world’s Nasa’s overarching Mars exploration been pinned on lung disease silicosis. most famous space agency. program. It is the first Mars mission The abrasion of space suit fabrics to be overseen by a university rather finding life on by these particles is also worrying. Waiting for a mission than a Nasa contractor and is the Mars – anyone By the time the Apollo program was The politically savvy Goldin knew largest single grant awarded in the drawing to its conclusion, one of the this as well as anybody and his first University of Arizona’s history. who goes there engineering findings of the extended action after this double whammy Samples of soil and water ice now is very coy’ ‘J’ missions – those with up to three 46 | Chemistry World | August 2007 www.chemistryworld.org

CW.08.07.MARS.indd 46 24/07/2007 09:44:02 Mars Science Lab (MSL) If the Phoenix mission is a curious will be the most comprehensively hybrid of old and new approaches equipped spacecraft ever to to exploring Mars, the mission rove across the red planet. It will planned for 2009 is the latest carry three camera systems and word. The six-wheeled MSL rover two sets of radiation detectors is about ten times the size of and a comprehensive suite of the 1997 Sojourner Rover – the environmental sensors. It will also size of a small car. Landing this carry four mass spectrometers kind of mass on the red planet including one, the Sample cannot be accomplished using Analysis at Mars Instrument either air bags or hydrazine Suite (Sam) that takes up more thrusters. The number of air than half the science payload. bags required to land on Mars Like the Viking GCMS Sam is a increases exponentially with both a mass spectrometer and mass and the MSL weighs almost a gas chromatograph so that 800 kg. Hydrazine thrusters compounds can be separated mounted on the lander – despite before isotopic analysis. However, their successes in delivering the most important innovation Viking and Pathfinder – are a risk of the Sam instrument is its NASA / JPL / NASA because of the extreme reactivity MSL is an extensive laboratory on wheels on–board laser for vapourising of the fuel. Nasa thinks that it rock and soil samples whereupon can minimise that risk using the separation, the lander will actively the hovering skycrane for a soft the captured gas will be fed to the so-called ‘Skycrane’ approach manoeuvre close to its landing landing on its wheels. GC and the mass spectrometer for whereby, following parachute site and then lower the rover from The analysis.

EVAs (extravehicular activity) and pure science is hinted at in the way ‘Phoenix will presence of sulfates, oxidants and, use of lunar rovers – was that the the instrument package’s name has crucially, biogenic carbonates in the astronauts’ space suits, despite evolved. Where once Meca stood for test . being made of supertough Teflon- ‘Mars Environmental Compatibility dust for heavy The second half of the Meca coated glass fibre beta cloth, were Assessment’ it now stands for device is an atomic force . being abraded almost to the point of the more prosaic ‘Microscopy, metals or tiny Complementing the wet chemistry unusability. Such a situation cannot Electrochemistry and Conductivity particles that laboratory aboard the spacecraft, this be allowed for Mars exploration Analyser’. instrument will use a combination where missions, by definition, will could pose of coloured and UV LEDs to create have to be long-term rather than the Searching for life health risks a small-scale topographic map of three or four day affairs of the lunar The Meca instrument package soil and water-ice grains retrieved landings. consists of two parts. One is a for future by the robotic arm. Detection of The Meca instrument is miniaturised wet chemistry astronauts’ any hydrous or clay minerals in designed to address science as laboratory – an ‘electronic tongue’ the soil will be strong evidence for well as health and engineering of four 35 millilitre cells that will the presence of liquid water at the concerns and the Phoenix team receive samples returned by the Martian poles. Particles from will use it to investigate the geology, scoop and analyse their composition 1 millimetre down to 10 microns can , palaeoclimatology using conventional wet chemistry be imaged, making this the most and exobiology of the Martian north in water brought from Earth. Each powerful microscope ever sent to pole. The subtle change in emphasis experiment takes up to 24 hours Mars. from manned exploration back to and includes reagents to test for the Tega is the other main analytical instrument. It is a combination of eight tiny ovens (each about the size of a ballpoint pen) hooked up to a mass spectrometer that will look for a variety of isotopes including carbon, oxygen, nitrogen and hydrogen. The ability to look for carbon isotopes NASA / UNIVERSITY OF ARIZONA OF UNIVERSITY / NASA is central to the search for life – be it extant or extinct – because photosynthesis splits carbon into its isotopes. On Earth, the light carbon isotope 12C is preferentially incorporated into organic material leaving the surrounding crystalline matrix enriched in the heavy carbon isotope, 13C. If Tega detects material isotopically depleted in 12C (with high levels of 13C) it will be strong Tega – Phoenix’s mass evidence of the presence of life on spectrometer Mars.

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CW.08.07.MARS.indd 47 24/07/2007 09:45:08 Planetary science NASA / JPL / NASA Of course, the whole concept Phoenix mission will look for water Rocky layers on the Is this too cautious? What centres on the idea that life on in the most likely places – the poles. Martian surface carry if Phoenix’s miniscule mass Mars will be based around the No matter that Mars is an arid, desert evidence of the planet’s spectrometer does find depleted chemistry of carbon, a concept planet with a temperature profile watery history carbon? Will that evidence be that has underpinned Nasa’s life that makes the Antarctic look like definitive, or only suggestive? Any exploration policy since the 1950s. Biarritz; there is the very strong discoveries will probably be closer to Although the two legendary Viking suspicion that if water exists it is the latter, which explains why more landers of the 1970s also carried at the poles, probably as water ice sophisticated life-hunting missions mass spectrometers, they found no but possibly sublimating to vapour are currently in the pipeline (see box, evidence for any organic material during the Martian summer. But p47). on Mars. With the other three that simply was not known at the experiments producing highly time the Viking landers were sent An icy tomb equivocal results the Viking landers to Mars, and so, as Smith says, they For all the sophistication of Phoenix – despite a price tag of over a billion landed in the wrong place. Extending it will be no match for the prevailing dollars – added almost nothing to the that reasoning to the more modern environmental conditions at the question of whether there was ever era of Mars exploration suggests north pole of Mars. Eventually the . that even if had set down solar panels that will unfurl like Peter Smith points to two flaws safely in her own mass Chinese fans will be unable to power of the Viking missions – one in spectrometer may well have drawn the back-hoe that will yank chunks design and the other in their mission a blank. out of the Martian permafrost. Then profile. ‘The Viking ovens did the craft’s other instruments will not get hot enough,’ he observes, Cautious new mission take precedence – most particularly ‘the kerogens [matter within And so Phoenix is going to Mars with the meteorological station that has sedimentary rocks] that are the the latest kit to investigate life. But been contributed by the Canadian most likely repositories of organic it is not going to search for life – the Space Agency to give us our first material will not vapourise below real emphasis is subtly different. view of the weather at Mars’ north 500oC, and that was the maximum As Smith points out, it is going to pole. rated temperature of the Viking Mars to find out if life could exist, But eventually this too will fail ovens.’ By contrast the ovens that rather than if it is there. This slight when the planet slides back into Phoenix carries will reach 1000oC, reluctance to grasp the biological the iron grip of the Martian winter. easily hot enough to vapourise any nettle is probably related to the many Soon after that, plucky Phoenix will hidebound hydrocarbons that the failures that have accompanied the find herself entombed in six metres Phoenix scoop feeds into the mass search for life on Mars. So many of ice, the first ice-maiden of Mars, spectrometer’s maw. The other hopes and expectations have been ‘Even if beyond even the rescue of the clever problem Smith identifies was simply pinned on finding life on Mars, Beagle 2 had set engineers of JPL. After that she will that the Vikings ‘landed in the wrong from the canals of Schiaparelli and become dormant, like her Viking place.’ Lowell to the Viking landers, the down safely in and Pathfinder predecessors; her job It’s a fair point: data from the and the ill-fated Isidis Planitia, done but waiting for the day when orbiting voyage of Beagle 2, that anyone who the astronauts she blazed the trail and the ’s goes to Mars now is very coy. The her own mass for come to dig her from the sands of (ESA’s) tell us that best that can be expected these days spectrometer Mars. Mars almost certainly had water is the mission profile that Phoenix billions of years ago, as well as in its is following – to find out if life could may well have Richard Corfield is a science more recent geological past. So the exist on Mars. drawn a blank’ writer based in Oxford, UK 48 | Chemistry World | August 2007 www.chemistryworld.org

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