JBIS,Refereed Vol. 64, pp.Correspondence92-95, 2011 REFEREED CORRESPONDENCE Comments on “Rationale for Flexible Path – A Space Exploration Strategy for the 21st Century” by Schmidt, Landis and Oleson, JBIS, 63, pp.42-52, 2010 Dear Editor, perhaps preferable to get some hardware off the ground (both literally and figuratively) in pursuit of a clearly defined objec- Schmidt et al. [1] are to be congratulated for their thoughtful tive, than risk getting bogged down in a directionless technol- and comprehensive analysis of the so-called ‘Flexible Path’ ogy development programme which never actually goes any- approach to future space exploration – one of the alternatives where. identified by the Augustine Commission’s inquiry into the fu- ture of US human spaceflight activities [2]. There is little doubt 2. Possible Exaggeration of the Efficacy that such an approach would, if steadily and systematically of Tele-robotic Exploration pursued over the coming decades, result in the development of a human spaceflight infrastructure which would facilitate both Although the Flexible Path approach will not enable near-term the scientific exploration, and the economic utilization, of the human landings on the Moon or Mars, it is designed to trans- st Solar System later in the 21 century. The authors make a port human crews to the vicinity of these planets, in addition to compelling case that Flexible Path is the most realistic route to near-Earth objects (NEOs). This raises the possibility that tele- achieving this desirable objective, and I found myself in agree- robotic operations on the surfaces of these bodies will be ment with much of what they had to say. possible, controlled by human operators from orbit. This could be an important contribution to exploration, as tele-robotic That said, I do have a number of residual concerns about the operations conducted with a minimal time-delay are likely to be Flexible Path approach. In the spirit of developing the policy much more efficient and capable than exploration conducted debate, I outline these concerns below and would be interested by autonomous robotic vehicles [4]. It also raises the exciting to know the authors’ responses to them. longer-term possibility of tele-robotic operations on (and be- low) the surfaces of bodies such as Venus and Europa where 1. Lack of Clearly Defined Objectives for Exploration human exploration may never be possible. There is perhaps a risk that, by lacking a specific destination However, I believe the authors exaggerate the capabilities of and well-defined timescale, the Flexible Path approach may be tele-robotic exploration when they describe it as “human-equiva- unable to sustain political and public support. Without such lent” [1; p. 44], and imply [1; Fig. 11] that it will be as efficient support there must be a risk that budgets initially allocated for and versatile as in situ human exploration. This conclusion is at developing Flexible Path will be whittled away by on-going odds with actual field studies (e.g. Snooks et al., [5]) which deficit reduction measures before there is anything substantive have found that space-suited astronauts are significantly more to show for them. Indeed, exactly this view has been reiterated efficient in pursuing field geological activities than tele-oper- by the recent US House of Representative’s Commerce Justice ated robotic vehicles. Garvin [6] reached the same conclusion, and Science Committee’s Report [3] which accompanies the and produced a more detailed comparison of human, robotic, 2012 NASA Appropriations Bill, viz: and tele-robotic capabilities, which indicated that humans on “Exploration destinations. - NASA’s stated intention is site would be expected to out perform tele-operated robots in to pursue a capabilities-based approach to human 18 out of 23 surface tasks considered [6; Fig. 2]. One area exploration, which means that the direction of the program where Garvin’s analysis indicated that a human presence in situ will be driven by what technologies are available at a would out perform tele-robotic operations was in establishing particular time. While this approach may offer some drilling operations (e.g. to depths >100m) in planetary crusts, advantages in terms of flexibility, it also lacks the clearly and in handing and analysing the extracted drill cores. This is defined goals that have historically driven space likely to be an especially important aspect of future geological exploration achievements. Specific, aggressive goals are and biological exploration on both the Moon and Mars, and it necessary both to focus the program and to provide a very likely will require a human presence on the surface. common vision around which public and political support can be rallied. Consequently, the Committee urges NASA An additional point concerns sample return capacity. While to adopt a destination-based approach to exploration tele-presence may enable geologists to interact remotely with a that would designate a specific target location, such as surface planetary environment, much of the scientific benefit of the Moon, to drive development decisions and timelines human planetary surface exploration (as demonstrated by Apollo) going forward.” lies in the quantity and diversity of rock and soil samples which may be returned to Earth for more detailed analysis. Although tele- It must be a cause of concern for the Flexible Path approach robots will be useful in examining and caching samples on the if, at this early stage, the congressional committee responsible surface, transporting them to Earth will require planetary ascent for authorising NASA’s funding identifies the lack of specific stages, and the sample return capacity is therefore likely to be objectives as a political weakness. Of course, merely identify- larger in the context of human surface missions. ing a specific target does not guarantee success, and there is the obvious risk that predicating a programme on a single objective The above points do not detract from some of the very may cause everything to grind to a halt if and when that objec- exciting possibilities which would be facilitated by tele-robotic tive is successfully accomplished; the history of the Apollo operations on planetary surfaces, as enabled by a Flexible Path- programme clearly illustrates this danger. Nevertheless, it is like architecture. However, they do indicate that there are 92 Refereed Correspondence important aspects of planetary exploration for which tele-ro- term focus for exploration activity and help address the important bots alone are unlikely to be sufficient, and where a human lunar science issues discussed above. presence on the surface will also be desirable. Near-term lunar surface exploration will help facilitate Mars 3. Marginalisation of Lunar Exploration surface exploration later in the century as a result of knowledge gained in at least the following areas: My final, and most serious, concern about the Flexible Path approach is the extent to which it downplays the status of the (i) Human physiology in low (but non-zero) gravity environments; Moon (which, interestingly enough, was the only target actually identified by name in the congressional report cited above [3]) (ii) Radiation protection; as an important destination in Solar System exploration. It is (iii) Dust mitigation; true that the lunar surface is relatively expensive to get to in energy terms, and that a dedicated lunar lander would have to (iv) Aspects of precision planetary landing capability (but be developed. However, it seems to me that this additional not all aspects, obviously, as the Moon lacks an investment would be justified for at least three reasons: atmosphere which greatly alters the requirements for a lander compared to what would be required for Mars); • The provision of a near-term space exploration objective to excite and maintain public and political interest; (v) Aspects of In Situ Resource Utilisation (ISRU); and • The scientific importance of the Moon itself (which is (vi) Safe and efficient human operations on hostile planetary almost invariably overlooked by Flexible Path advocates); surfaces. and Note that, in addition to paving the way for future explora- • Operational experience gained on the Moon which would tion of Mars, the biological aspects of lunar exploration are help facilitate later human missions to the surfaces of also of scientific interest in their own right [10, 11], and these Mars and other planetary bodies. cannot be pursued tele-robotically because astronauts actually on the surface will be required as experimental subjects. The first of these bullet points has already been addressed (Section 1); I briefly expand on the remaining two points 4. Conclusion below. I have highlighted a number of scientific and technical benefits 3.1 Lunar Science resulting from human planetary surface exploration which would not occur, or at least which would be postponed indefinitely, in the The primary scientific importance of the Moon arises from the fact context of a Flexible Path architecture unable to support human that it has an extremely ancient surface (mostly older than 3.5 landings on planetary surfaces. This might be a price worth paying billion years, with some areas extending almost all the way back to if it could be demonstrated that the cost of adding this additional the origin of the Moon 4.5 billion years ago). It therefore preserves capability would jeopardize the development of a future human a record of the early geological evolution of a