Abstract
As noted in the previous issue of New Space, 1 the current Administration is pursuing a human space flight policy of returning to the Moon with commercial and international partners. Then, so goes the stated plan, technologies and mission architectures developed for lunar exploration will facilitate the human journey to Mars.
There are profound differences between the environment of the Moon and Mars. Those differences (atmosphere, gravity, distance, surface composition, and so on) severely constrain any claim of broad applicability. Nevertheless, a group of advocates for the human exploration of Mars gathered in August 2018 in Washington, DC, to discuss the potential for lunar exploration to “feed forward” for the journey to Mars. 2
The workshop, dubbed Achieving Mars workshop number 6 (AM VI), was attended by 70 self-selected members of the human spaceflight community with a smattering of planetary scientists, related technologists, and some industrial/commercial providers. Many of the participants were from NASA, a not-unexpected outcome, since the domain of human exploration has traditionally been almost exclusively NASA and other governments. In addition to technical issues, there is almost always an economic subtext to this type of meeting. Having participated in many such conferences over the past 40+ years, I can say without hesitation that NASA staff are fully aware that any redirection of NASA's ∼$8 billion/year human spaceflight programs involves thousands of jobs and huge amounts of funding. If you work for NASA or the industry, it is in your best interests to attend such a workshop—and attempt to influence the outcome.
As a consequence of the underlying factors described above, one cannot regard the AM VI recommendations as free of bias or self-interest. However, as a participant in both the workshop and subsequent report writing, I can say that in general the attendees and conference leadership made a sincere effort to achieve balance and consensus. The outcome of the efforts resulted in a document that identifies a relatively small number of technologies and engineering developments that if utilized for the Moon may assist in the future human exploration of Mars. 3
From the recommendations put forward, one, in my view, stands out as absolutely critical to creating a sustainable future of human exploration on the Moon or Mars: that technology is, in the inimitable parlance of NASA, in situ resource utilization or ISRU. In simple terms, ISRU means living off the land. There is no believable mission architecture that plans for astronauts to take all possible supplies with them for exploration lasting months or years. Using regolith (soil), atmosphere (if one exists), and all-important water ice deposits to create water, oxygen, building materials, and rocket fuel is a critical element of long-term exploration and settlement.
The latest novel by Andy Weir (of The Martian fame), Artemis, speculates on the business case that might emerge if a private lunar settlement were to be established. Oxygen production would be pivotal (and very lucrative) in any such enterprise. Without being a spoiler, let's say that key plot elements hinge on who controls the ISRU of the Moon.
Science fiction aside, in recognition of the long-term importance of ISRU, AM VI called for a National Academy of Science (NAS) study of ISRU for the Moon and Mars. Beyond the fundamental importance of living off the land for sustainability, there are several reasons why I believe such a study is required:
NAS studies are the gold standard for advice to the nation. Exquisite care is given to selecting a panel with the correct expertise, balancing perspectives, and achieving consensus. Sufficient time (usually three to five multi-day meetings, plus months of writing and editing) is devoted to hearing from advocates/experts in a public setting, as well as opportunities for deliberation and (often) intense debate internal to the panel. An ISRU study would serve as a practical bridge between the robotic science and human spaceflight (HSF) communities—a collaboration that has long been sought by some, including me. The science community would learn about the special constraints that accompany human exploration, and the HSF groups would be confronted with what scientists and mission data say (and do not say) about the composition of the Moon and Mars. Finally, all consensus reports of the NAS go through a peer-review process by a completely separate panel of experts, just as is done for top-quality journal articles.
To highlight reason (3) above, let me cite one example. Administration officials have recently touted water on the Moon as the exciting finding that would lead to long-term lunar exploration. 4 While the paper cited does indicate there may be some water ice deposits where the water ice mass fraction approaches 30% 1 (as opposed to a few percent), all the inferences were drawn from remote-sensing measurements by previous missions such as the U.S. built M3 (Moon Mineralogical Mapper) aboard the Indian Chandrayyan-1 spacecraft. To date, there has been no in situ confirmation that such deposits exist or a dispassionate evaluation of the difficulty of mining in a shadowed region where the temperature is near absolute zero (40 K).
By comparison, the near-surface water ice on Mars with a mass fraction up to 80% at the poles has not only been detected by remote-sensing instruments on multiple spacecraft but also validated by the landed Phoenix mission. Buried glaciers the size of New Mexico have been identified on Mars, and recently there was the announcement of the detection of a “lake” perhaps half a mile beneath the surface. 5 Add to these data the existence of an atmosphere on Mars (unlike the airless Moon) plus surface soil that can be processed, and it is clear that we currently have better ISRU data on the Red Planet than the Moon.
To me, that one example of science-based analysis with significant engineering implications is more than enough reason to ask the Academy to evaluate ISRU. But if the outcome is a positive one, the potential for some entrepreneur to step in and process the lunar and Martian resources for future explorers (or settlers) represents the promise of New Space. The basic premise of Andy Weir's latest book may not be so fantastical after all.