The International Space Station has been occupied for nearly 15 years, but the astronauts' lower-Earth orbit home away from home won't be around forever—or even that much longer.
So while NASA is all about reaching for Mars, the European Space Agency has its sights set a little closer to our home planet.
"Mars is a nice place, maybe—not so much for us, but it's a nice place—but for me it's a little bit far away from the point of view of direct vision," new ESA Director General Johann-Dietrich Woerner told me in an interview. "And therefore now what I'm putting on the table is something that can happen after the International Space Station."
That something? A "moon village."
Woerner's moon village would be located on the dark side of the Moon. It could house a huge telescope that would be shaded from the radiation absorbed by the Earth's atmosphere and so able to look deep into the Universe. A satellite stationed at the Lagrange Point L2—a spot where the gravitational forces from the Sun and Earth are balanced enough to keep a satellite in a fixed position—could enable communication direct from Earth to the Moon's shadowy side. The Americans could use the base to test out their Mars-bound tech.
The moon village would not be "some houses, a church, and a town hall," but a place where different ideas could cohabit. "This moon village should be a location where multiple users can act with multiple activities, be it robotic or human space activities," said the ESA head.
He proposes a separate spacecraft for microgravity research, which could be used for medical research into conditions like osteoporosis, ageing, and blood pressure, and which can't easily be done on Earth. Currently, microgravity research is conducted on the ISS but is limited owing to the difficulty of getting equipment up and down easily.
"For microgravity I see a smaller spacecraft, maybe in bilateral cooperation between United States and Europe, to fly in the low Earth orbit and then have experiments onboard, either robotic or human driven," Woerner explained.
At present, the International Space Station holds the record for the longest-inhabited satellite, but talks are turning to its replacement. Funding of the ISS beyond 2020 hasn't been confirmed by several partners in the project (including Europe), while others such as Russia have agreed to keep it going until 2024.
International collaboration is a key part of ESA's vision for the future. I spoke to Woerner, who took on his new role on July 1, at an event to mark the inauguration of the first ESA facilities in the UK last week. At that point he celebrated the UK's role in ESA, but a project like the moon village would go beyond European agency and require international partnerships that Woerner thinks should go even further than the current ISS model and offer access to any and all spacefaring nations.
"You know in the ISS we have Russia, the US, Japan, Canada, and Europe, but some spacefaring countries are out," he said. "[With] moon village, I would be happy if they are in."
Pressed on the potential difficulties of this kind of collaboration given strained relations between some of those international collaborators—specifically regarding Russia and the Ukraine crisis—Woerner was unfazed.
At the moment, astronauts rely on Russia's Soyuz capsule to get to and from the ISS, but while Woerner said that his background as an engineer meant he liked having redundant systems just in case, he thought the ongoing collaboration around the Soyuz was "proof of international relations in space beyond earthly problems."
"I believe that this is the future of our planet; that we should work together across borders, and space—and science in general—can be a frontrunner in this direction," he said.
And it's not just other countries that he thinks should have a say in the future of space exploration; Woerner is keen for regular citizens to have more of a say in ESA's work. After all, it's fuelled by taxpayers' money. As he describes it, they (along with scientists, politicians, and other partners) should be part of the "jam session" that takes an idea—his moon village, say—and riffs on it to produce the final mission.
"This is exactly what I would like to do: to open the space sector to the public in both directions," he said.
So far, ESA seems to be doing all right on the public satisfaction front: the Rosetta mission, which has been in the works for decades but reached its pinnacle last year with the landing of a spacecraft on a comet, has met with particular popularity.
Before we set our sights on colonising the dark side of the Moon, there are other, non-human space missions in the works: The Copernicus Earth observation mission will continue to launch satellites to monitor the globe closer than ever before, while 30-satellite constellation Galileo will provide a navigation system to rival GPS.
But the new ESA head has bigger ambitions too, and while he might think Mars missions are a little far-off, he's not restricting his vision for future. I brought up NASA's plans to get man into Mars's orbit by the 2030s.
"Yes, and they call it the 'ultimate goal,' which is strange, to be very blunt," he said. "An 'ultimate goal' is a final goal. Do you believe that Mars is the real final goal? I don't believe. If we can maintain the Earth as a living planet for humans—if—then humans will go even further than Mars. They will not stay just at Mars."