NASA’s lunar Gateway, part of the agency’s Artemis program, could also be used to support Mars exploration through long-duration crewed missions there. (credit: NASA)
For decades, it seems, space exploration advocates have done battle over the long-term goals of human spaceflight, even as humans remained stuck in low Earth orbit. Some have argued for a return to the Moon, both for its own sake as well as a proving ground for missions beyond. Others, though, have pushed for going to Mars, often as soon as possible, fearing that a lunar return could be a costly, lengthy detour.
There were plenty of shades of gray—or, perhaps, reddish gray—between those two viewpoints, but that nuance was often lost in policy debates, particularly as administrations changed direction from one president to the next. It even had partisan overtones, given that pushes to return to the Moon had typically come from Republican administrations (the two President Bush and, now, President Trump,)
“When I was in the House of Representatives, it was shocking to me that Republicans were for the Moon and Democrats were for Mars,” recalled Jim Bridenstine, former congressman and current NASA administrator, during a recent meeting of the Lunar Exploration Analysis Group (LEAG). “I was so stunned by this artificial division, which made no sense.”
Bridenstine has worked to emphasize both destinations are important: “It’s Moon and Mars, not Moon or Mars,” he said at the meeting.
NASA’s near-term emphasis, of course, has been on the Artemis program to return humans to the Moon, using a combination of the Space Launch System, Orion, the lunar Gateway, and commercially developed landers. But NASA has emphasized they’re looking beyond a human return in 2024 to “sustainable” lunar exploration and eventual human missions to Mars. (With some prodding, perhaps, from President Trump, who complained in a tweet in June 2019 that NASA should be focused more on Mars; after that, NASA placed a greater emphasis on the “Moon to Mars” concept.)
The logic is straightforward: going back to the Moon offers an opportunity to test both technologies and techniques required for future missions to Mars, albeit in a different environment. But do Mars advocates, particularly those who have been skeptical about going back to the Moon, approve of it?
The answer, based on a recent study, appears to be yes. Last month, the advocacy group Explore Mars released the final report of its “Affording Mars” workshop last November. That meeting brought together both lunar and Martian exploration efforts to study if the Artemis program, in something like its current form, could truly benefit future human missions to Mars.
The study looked at 85 activities or technologies needed for a human mission to Mars, from life support to landing systems. It concluded a “significant” number of them would, in fact, benefit from either the Artemis program or research on the International Space Station.
“The group concluded that planned Artemis and ISS activities either naturally contribute directly to progress towards sending humans to Mars or could be easily modified to do so,” the report stated. “While some technology or process maturation would remain to address Mars-specific requirements, it is clear that he path to Mars is facilitated by certain activities at the Moon and in LEO.”
For example, for landing on Mars, the Moon doesn’t help with some Mars-specific technologies needed to decelerate through the planet’s thin atmosphere, like supersonic retropropulsion. But lunar landing missions can offer what the report described as “substantial benefit” in testing technologies for precision landing, sensors, landing legs, and the interaction between the rocket engine’s plume and the surface.
Similarly, lunar missions offer benefits for learning about surface operations, including conducting EVAs on the surface. It also provides experience working a partial gravity environment, as well as a way of studying the health effects of extended exposure to reduced gravity, something that has hardly been studied on humans.
“We don’t know what we don’t know about being in partial gravity,” said Michelle Rucker, Mars architecture lead at the Johnson Space Center, during a panel discussion about the report at the Humans to Mars Summit earlier this month. “One data point between zero and one would be good for us.”
Some Mars-specific technologies will need to be developed, something the study participants said should be done in parallel with the Artemis program. “We should be looking at retiring risks, proving technologies and living and working on the Moon in parallel with developing those specific, unique technologies,” said Lisa May, chief technologist for civil and commercial space at Lockheed Martin, during the panel.
A specific area of interest in the study was in situ resource utilization. Both Mars and the Moon have water ice that, depending on its abundance and ability to be extracted, could become a key resource for future human missions.
While there are big differences between the water ice on the Moon and Mars, studying how much is there, and how it can be extracted, is critical for human exploration of both worlds. “In terms of going to the Moon and Mars in a sustainable way, we need to understand how we can use the local environment,” said Brett Denevi, a planetary scientist at the Johns Hopkins University Applied Physics Lab. “We especially need to know if the resources on the Moon and Mars are, in fact, reserves that can be used to enable humans to survive and thrive at both locations.”
That’s been done at both worlds from orbit, with more missions, like NASA’s proposed Mars Ice Mapper, being contemplated to study water ice for both science and exploration purposes. That’s not enough, though, she said. “The next step is to stop being in orbit, get down on the ground, start digging in the dirt and understanding what is actually there in the surface.”
Clive Neal, a professor at the University of Notre Dame, agreed. “We’ve got to get to the surface and understand the local detail of what is there: what form is it in, can we actually extract it, can we process it and store it?” he said. That’s essential, he said, since the amount of accessible water ice “is going to dictate the architecture of what we put together to go to the Moon and then Mars.
While the report sees Artemis as a good step towards Mars, it’s not a perfect one. The report argued that those plans, if “slightly modified,” could better support human Mars exploration.
One example is the lunar Gateway, which will be visited by astronauts for relatively short stays supporting missions on the lunar surface. Having longer missions, to simulate a transit from the Earth to Mars or back, could help planning for a Mars mission (and bring it back to the “Deep Space Gateway” concept proposed before Artemis, when NASA foresaw using a cislunar facility to conduct Mars mission tests.)
“We could emulate Mars missions, Mars transit durations, by having crews stay for longer times on the Gateway,” said May. It could also test getting down to the surface and back again. “Those are operations we have not yet practiced,” she said. “Practicing those activities, and learning about what technologies and tools are needed in order to accomplish them, is an important precursor.”
Neal also argued that those efforts ensure sustainability for both lunar and Martian exploration. “Developing sustainability at the Moon gives us a template for developing sustainability on Mars,” he said, and avoid “another 50-year gap before we send humans beyond Earth orbit.”
Sustainability also has a political dimension. Bridenstine often notes, as he did at the LEAG meeting, that the technical risks associated with Artemis was overshadowed by the political risks. That’s a major reason, he argued, for trying to go back to the Moon as soon as possible.
That rush could be affected if the Democratic presidential nominee, Joe Biden, wins in November. Space policy has, understandably, been even more minimized in the general election campaign than usual.
However, the Democratic Party platform for 2020 does endorse a return to the Moon, although not necessarily on the current, accelerated timescale. “We support NASA’s work to return Americans to the moon and go beyond to Mars, taking the next step in exploring our solar system,” it states.
Bridenstine emphasized at the LEAG meeting what he saw as bipartisan support for Artemis, including funding for NASA’s Human Landing System program in the Democratic-led House’s fiscal year 2021 spending bill. (He did mention that the bill provided only about a fifth of the requested $3.3 billion for the program, a funding shortfall that would likely place a 2024 landing in jeopardy regardless of who wins in November.)
“People are ready to go back to the Moon,” he said. “The time is now to put aside differences and just go get it done.” Especially, it seems, if it is also on the path to Mars.