The workshop’s first session, moderated by planning committee members Dava Newman and Robert Ferl, provided information on NASA’s planned return to the Moon. The session included examples of biological and physical sciences research questions of interest related to studies carried out on the lunar surface or in lunar orbit. The purpose of the session was to lay a foundation for the remainder of the workshop. There were three presenters from NASA.
First, Kevin Sato, program scientist for exploration in NASA’s Biological and Physical Sciences (BPS) division of the Science Mission Directorate, offered a broad overview of the sorts of biological and physical science experiments that NASA is planning to carry out or fund in its lunar program. Next, Sharmila Bhattacharya, a senior scientist at NASA’s Space Biosciences Research Branch, offered more detail about the biological research that NASA is planning to carry out on the Moon. Then, in a complementary presentation, Fran Chiaramonte, program scientist for physical sciences in NASA’s BPS division, described several physical science experiments that NASA is planning to carry out on its lunar missions.
ADVANCING SPACE BIOLOGY AND PHYSICAL SCIENCES TO THE MOON
“We’re going back to the Moon,” Sato began, noting that it has been almost 50 years since humans last walked on the lunar surface. He gave a quick rundown on the phases of Artemis, the NASA-led program to return to the Moon, from initial flybys to the establishment of the Gateway station in orbit around the Moon and, eventually, astronauts traveling to Gateway and from there to the Moon’s surface. Preceding much of this work and then proceeding in parallel with it will be the Commercial Lunar Payload Services (CLPS) landers that will conduct automated research and also put down rovers that will travel around on the lunar surface.
With the first human landing, there will be two humans on the Moon, with two staying back on the Gateway. Over time, the Gateway will be expanded with the addition of various modules, and there will be a significant amount of space for carrying out scientific experiments inside the Gateway. A habitat will be established at the Moon’s south pole and then expanded, and with the establishment of this habitat, NASA will increase the number of astronauts who will be on the lunar surface and increase the length of time that they stay on the surface and carry out research there.
One of the exciting things about this program, Sato said, is the way scientific considerations have been at the forefront. In the past, the typical practice was to focus on designing the rocket vehicles first, after which scientists were brought in to describe the research they would like to do. This time, he said, there was a concerted effort to work with scientists from the beginning and to take scientific needs into account in the design and manufacture of the vehicles. NASA sees the Artemis program as far more than simply getting humans to the Moon; being on the lunar surface offers opportunities to do various types of scientific exploration. Some of the cornerstone research will consist of solar system science and exoplanet studies, but there will be many other areas of research. The Moon is a natural laboratory in which to study planetary processes and evolution, for instance. It offers a training ground for learning how to conduct scientific exploration from a planetary surface using both crew members and robotic explorers. It offers
the chance to use infrastructure and resources associated with human exploration to leverage support for autonomous scientific investigations.
Sato listed a number of areas in which NASA expects to do fundamental science on the Moon. In the life sciences, a key goal will be to study the combined effects of fractional gravity and deep-space radiation on organisms. Areas of study in the physical sciences include combustion, fluid dynamics, dust, and materials science. This is only a partial list, he said. In fundamental physics, research areas would include general relativity, gravitational physics, and quantum information science. Various studies could be done on food and drug degradation. There will be many opportunities for scientists outside NASA to develop collaborations with NASA researchers for work on the Moon, Sato said. He encouraged those involved in the workshop to consider the ways in which access to the Moon would allow them to expand or extend their research. NASA is interested in hearing ideas from outside, as there are certainly many worthwhile studies that NASA researchers have not yet considered.
The research carried out on the Moon will be broad-based, both institutionally and in terms of its objectives. Institutionally, multiple NASA directorates—the Science Mission Directorate, the Human Explorations and Operations Directorate, and the Space Technology Mission Directorate—have been engaged equally in the plans. There is also international collaboration. In addition to NASA, the European Space Agency, the Japan Aerospace Exploration Agency, and the Canadian Space Agency are involved. The research itself will be focused not only on fundamental science but also on space technologies, human exploration, and Earth benefits.
There will be multiple ways to conduct science in the lunar environment, Sato said. Off the Moon’s surface, research can be done on the Gateway or in the Orion, which can be brought into lunar orbit. On the surface, research can be done with the human landing system or the base camp, as well as with CLPS landers. NASA’s Biological and Physical Sciences division will have its activities integrated into all these different areas he said.
To provide a sense of NASA’s scientific objectives in traveling to the Moon, Sato showed a list of objectives from the 2011 Decadal Survey on Life and Physical Sciences,1 which was the source of many of NASA’s current objectives. These included the following:
- Investigate and characterize the fundamental interactions of combustion and buoyant convection in lunar gravity.
- Investigate interactions of multi-phase combustion processes and convection in lunar gravity.
- Study behavior of granular media in the lunar environment.
- Investigate precipitation behavior in supercritical water in lunar gravity.
- Investigate the production of oxygen from lunar regolith in lunar gravity.
- Study the fundamental biological and physical effects of the integrated lunar environment on human health and the fundamental biological processes and subsystems upon which health depends.
- Study the key physiological effects of the combined lunar environment on living systems and the effect of pharmacological and other countermeasures.
“What I encourage everyone to do,” Sato said, “is to please download and read through the Artemis III Science Definition Team report,” which carries a full list of all the current objectives. “This will give you a good feel for what lunar exploration is and what . . . NASA is going to be doing there and possibly provide you some inspiration . . . for other areas and other groups that we can also work with.”
Not only is NASA working to develop its objectives for lunar research, Sato said, but it is also focused on making sure that the capabilities will exist to do the types of research necessary to support
1 National Research Council, 2011, Recapturing a Future for Space Exploration: Life and Physical Sciences Research for a New Era, The National Academies Press, Washington, D.C.
those objectives. In the biological sciences, these capabilities will range from small to large—from work with Arabidopsis and microbiology to research on invertebrates, larger plant habitats, and vertebrates—and the same will be true for the physical sciences. In short, NASA is looking not only at the small, easily transported experiments, but is also interested in which studies, small or large, will provide the most interesting science.
Noting that different places on the Moon may be more or less suitable for different types of research and other activities, Sato said that NASA has a process for identifying which factors are important and then developing criteria to recommend landing sites. If, for instance, the regolith—the loose layer of material on the Moon’s surface—in one area is more suitable for growing plants than the regolith in another area, that could influence where the base camp will be, because that is where the majority of the growing of plants is likely to take place.
Summing up, Sato emphasized that NASA is interested in getting comments and input from the broader scientific community. This input plays an important role in advancing space biological and physical sciences beyond Earth orbit, he said. He urged workshop attendees to mark their calendars for a physical sciences lunar surface science workshop run by NASA on August 18–19, 2021.
Last, he showed a list of funding opportunities for lunar research (Figure 2.1). Sato urged anyone interested in pursuing such funding to sign up with the NASA Solicitation and Proposal Integrated Review and Evaluation System (NSPIRES) in order to receive notifications of solicitation releases. “If you don’t, you’re not going to get it.”
THE FUTURE OF SPACE BIOLOGY RESEARCH BEYOND LOW-EARTH ORBIT
Next, Bhattacharya spoke about space biology research in the context of lunar exploration and beyond. The driver for this research, she said, is that NASA is planning to return humans to the Moon’s surface and establish a sustained presence there. They will then use the Moon to prepare for future missions to Mars, so it is important to understand the challenges that biological systems face in these
environments. These challenges include, she said, radiation, reduced gravity, large temperature ranges, altered day/night circadian cycles, and social isolation, both singly and in combination.
To carry out experiments to study the effects of these factors, Bhattacharya said, it will be necessary to deal with a number of logistics, engineering, and operational challenges. NASA will need to design and build “enclosed habitats that can support life in this otherwise hostile environment,” she said, as well as autonomous systems that can reduce the amount of crew intervention that the experiments will need. Radiation shielding will be needed to protect not only the biological organisms but also the electronics and other components in the habitat. It will also be necessary to maintain suitable temperatures within the habitat and to deal with the extensive amounts of data the experiments will generate—collecting it automatically on the lunar surface or in cis-lunar orbit, storing it, and then transmitting it back to Earth for analysis.
Much of NASA’s focus with its biological research on the Moon, she said, is tied in with the goal of learning how to “thrive in deep space”—in essence, to prepare for the planned much longer journey to Mars. For instance, the plan is to use a combination of lunar/cis-lunar platforms, small satellites, the International Space Station (ISS), and ground-based experiments (e.g., with particle accelerators) to study the effects of combined spaceflight stressors in preparation for deep-space exploration. Lunar and cis-lunar experiments will be used to look at the effects of deep space radiation, such as highly ionizing particles, and altered gravity; both are difficult to accurately replicate on the ground, she said. It will likely be necessary to start with smaller, simpler, more robust organisms in experiments on the lunar surface and then progress to the larger, more complex organisms as the technology and the resources available on the Moon evolve and mature. It may also be necessary to start with experiments of relatively short duration—those on the ISS are currently about a month or two long—but the goal is to do longer-duration experiments in order to study the effects of, for example, a 2- to 3-year mission to Mars. The emphasis in carrying out these experiments will be on understanding the important underlying mechanisms of change and the genetic, physiological, and metabolic susceptibilities of biological systems to the deep space environment.
In addition to the science, Bhattacharya added, NASA will also be exploring the technological advances that will be required to sustain long-duration science experiments in deep space.
On January 20–21, 2021, NASA held the Space Biology Lunar Surface Science Workshop to educate the science, engineering, and commercial space communities about the agency’s life science and exploration goals on the Moon and to obtain community input on key questions pertaining to deep space exploration, including issues in life science research. Bhattacharya spent much of the rest of her presentation summarizing the presentations, discussions, and results of that workshop.
At the workshop’s breakout sessions, members of the community were asked to address three basic questions:
- What are the top-priority space biology research topics that must be conducted on the Moon or in cis-lunar orbit (in order of priority) to facilitate sustained lunar habitation and future Mars missions? Which need to be initiated in the near term (5–10 years) in order of priority?
- How can we begin to separate the biological effects of multiple spaceflight stressors (e.g., ionizing radiation, partial gravity, social isolation, altered gas compositions, etc.) that will enable countermeasure development?
- What are key technologies, technical capabilities, and resources needed to conduct research on the Gateway and the Moon (e.g., CLPS landers, Artemis vehicles, lunar base camp)?
One of the key points that came out of the workshop discussions, Bhattacharya said, was that ground-based and low-Earth-orbit research serves as a complement to deep space research and that having the combination of the different types of research is important. The ground-based and low-Earth-orbit research provides additional reference frames for the lunar research. For example, she said. “When you do an experiment with a centrifuge on the ISS, you can mimic one-sixth g or one-third g for Moon or Mars, and then you have a slightly more benign radiation environment compared to beyond the Van Allen
belts.” This provides a useful reference point for experiments carried out on the lunar surface or in lunar orbit.
The workshop attendees discussed various priorities for biological research involving vertebrates, invertebrates, microorganisms, cells, and plants. The mentioned priorities included, for instance, studies of the effects of radiation on rodent models, Drosophila (fruit flies), C. elegans, and cell systems. There was also discussion about growing various plants on the Moon and understanding how they are affected by the radiation and partial gravity found on the lunar surface. Also, Bhattacharya said, workshop attendees thought that omics and systems biology approaches will be important in examining the underlying changes in organisms’ quantitative genetics, and thus developing an understanding of susceptibilities to the deep space environment. Her presentation slides2 contained additional relevant topics that Bhattacharya noted that she did not have time to describe.
PHYSICAL SCIENCES EXPERIMENT CONCEPTS ON THE MOON
Next, Chiaramonte transitioned from the biological to the physical sciences and spoke about some of the physical science experiments that NASA is considering for its lunar missions. “The point here is to inspire you to develop your own ideas,” he told the audience.
The first research area Chiaramonte discussed was dust remediation. A team at NASA is laying out some of the technical and scientific challenges related to dust, he said. In the Apollo era dust was found to be a serious problem, and the astronauts who visited the Moon said that if they had stayed more than three or four days, the dust could have gotten into the instruments, the machinery, the air revitalization systems, and all over the suits. “This problem not only has to be addressed, but has to be solved,” Chiaramonte said.
The NASA team in charge of examining the dust problem is looking at various approaches to ameliorating it, including electrostatic dust clearing, the use of attractive surfaces or wands to collect the dust, and lofting induced either by an ultraviolet or electron beam or by tribocharging, or using friction to create a charge on a surface. So the team is approaching the issue in a very fundamental way, examining the physics behind the issue, “which is exactly how we want them to do it,” he said. Meanwhile, other groups at NASA are coming at the problem from an engineering problem, maximizing the chances of finding a good solution.
To support the scientific approach, NASA has identified a number of objectives for lunar studies: measuring plasma properties near the lunar surface, determining if electrostatic lofting occurs naturally, determining if electrostatic levitation occurs, measuring the cohesion and adhesion of the regolith, evaluating the hazard posed by electrostatically lofted or levitated dust, characterizing the size and shape of regolith particles from relevant lunar sites, and so on.
It is not clear, Chiaramonte said, if the experimental apparatus necessary to do some of these studies would fit on a CLPS mission. “It is possible if you come in small with some kind of charging device and some lunar simulant, you might fit something in there”—in which case, another way of getting the apparatus to the lunar surface will be needed.
Another priority set of experiments involves the study of cement solidification in the Moon’s gravity. The regolith offers a convenient source of materials that might be used in making cement, but there is an issue concerning the strength of concrete solidified on the Moon. The lesser gravity is likely to lead to larger crystalline particles and more air trapped within the material, decreasing its overall strength. Experiments on the ISS in a centrifuge that mimicked the gravity at the Moon’s surface have indicated that this is likely the case.
Thus, NASA wants to test an alternative—a cement-free binder made with the lunar regolith. There are three different experiments being considered in this area. The first would use a lunar simulant with a
2 Slides available at Committee on Biological and Physical Sciences in Space, Space Science Week Spring Meeting 2021, National Academies.
small amount of water and a polymer-based binder that would cause the solidification of the material. This experiment could be done on the lunar surface on a CLPS lander by having small mixers to put together various compositions under lunar gravity, which could then be returned to Earth for analysis.
A second experiment, which would be too large and involved for a CLPS lander, would involve using the actual regolith, rather than a simulant, to create the concrete. The regolith would be activated by alkalis and, along with a small amount of water, would form a geopolymer concrete. Again, the samples would later be returned to Earth for analysis.
A third type of experiment would be exposure studies. Both the simulant concrete and the lunar concrete could be left on the lunar surface for, say, a year or two to see how the materials aged under lunar conditions.
Another topic area, Chiaramonte said, is fire safety. Because the lunar habitat will likely have an air pressure lower than the air pressure on Earth’s surface, the percentage of oxygen will be kept higher so that breathing is not difficult. However, this will make the habitat environment very flammable. Thus, it is important to understand how flames behave in a lunar environment. Chapter 5 contains a detailed description of CLPS experiments designed to study this behavior.
The final experiment Chiaramonte described involved testing a system for taking icy regolith from the Moon’s surface, extracting the water, using electrolysis to separate the water into oxygen and hydrogen, and then liquefying the oxygen and hydrogen. This would provide both oxygen to breathe and hydrogen and oxygen for fuel. However, there are many tests to perform and gravity-related engineering challenges to overcome.