While NASA is focusing upon sending astronauts to Mars in the 2030s, the European Space Agency (ESA) is setting its sights a bit closer.
At a recent ESA-sponsored symposium in the Netherlands, scientists, engineers and space policy makers discussed the agency's vision for what's been called a "moon village" — a permanent outpost on the lunar surface that would be used both for research and for harvesting raw materials that could be used in missions to deeper space. While the plan and the budget needed still haven't been finalized, the Europeans are gauging international interest and looking at what technologies would be needed to make it a reality. One idea is to use robots and massive 3D printers to erect the base more efficiently.
News headline writers had fun with ESA's use of the term "village," but as ESA Director General Jan Woerner explained at a recent press conference, the Europeans aren't envisioning some quaint town with a square full of cafes and cottages. "I already got mails, asking for position of mayor of that village," he said with a bemused look.
"A village, from my understanding, is a place where people come together with different ideas and create something that is more than just an individual," said Woerner. "A moon village is a single place, with multiple users. Maybe one is a country more interested in science. Another may be a private company interested in mining. Another may be interested in putting to use the moon as a stepping stone for further exploration."
The project wouldn't necessarily compete with the United States, which has opted to bypass revisiting the moon in favor of concentrating on Mars, but instead might complement NASA's efforts. University of Notre Dame planetary geologist Clive Neal says that a lunar base would be invaluable for studying the effects of reduced gravity on astronauts' health. While the International Space Station has provided an opportunity to study the longer-term effects of zero gravity, the Moon, which has one-sixth the gravity of Earth, might provide a better indication of how humans would fare on Mars.
"We know that zero gravity has certain effects," says Neal, "but we don't know if there is a linear relationship between zero gravity and Earth gravity."
Neal also says a base might provide an opportunity to harvest resources such as hydrogen, oxygen and other substances that could be used to make rocket fuel for longer space missions. That would enable spacecraft headed to Mars or beyond to refuel in space, rather than having to weight themselves down with fuel before lifting off from Earth.
The lunar surface might also provide an even more potent fuel as well. The Earth's satellite has an abundant supply of Helium-3, which could be used if we're able to develop a practical nuclear fusion reactor. (Learn more about Helium-3 and lunar mining by listening to this podcast.)
"We don't yet have the technology to be able to do that, so it's all theoretical right now," Neal emphasizes.
It's not clear yet how much building a lunar base might cost, or the extent to which resource extraction might help to cover the expense. "How much a lunar return costs depends very strongly on how you go about doing it, and on what scale, so there is no single answer to this question," Paul D. Spudis, a senior staff scientist for the Lunar and Planetary Institute, says via email.
When Spudis published a cost-benefit study for a NASA lunar base in 2011, he estimated that such a project would cost $87 billion over a 10-year-period. After that, however, he envisioned that such a base might pay for itself, if it were able to extract enough hydrogen and oxygen from lunar soil to create 165 tons (150 metric tons) of water per year.
"If you got to that point, your sunk costs to establish the outpost would be spent, but future missions would be of minimal cost," he said.