Right now, it's only possible to fill up the gas tank of a spaceship down here on Earth. But MIT scientists have a new plan for refueling stations in space. Space.com reports that a research team has come up with two ways to create refueling stations for missions to the moon, or points further. Both involve the use of contingency propellant—the fuel that missions (in particular the Apollo missions) took up in case of emergency, and either left on the moon or destroyed during re-entry.
Instead, the MIT team proposes using contingency propellant from past missions to fuel future spacecraft. For instance, as a mission heads back to Earth, it may drop a tank of contingency propellant at a depot before heading home. The next mission can pick up the fuel tank on its way to the moon as its own emergency supply. If it ends up not needing the extra propellant, it can also drop it at the depot for the next mission...
The depots would potentially be located at Lagrange points, or areas in space where the gravitational forces of the moon, Earth and sun balance out. That’s where many space telescopes and observatories are sent, to keep them stable. And stability would be a good thing for this type of project—having to chase a gas station through space wouldn’t be much fun. That being said, the Lagrange points aren’t perfect.
Keeping depots "stationary" at Lagrange points may be tricky, though. Another challenge is preventing cryogenic fuels, such as liquid hydrogen and oxygen, from warming up and boiling off while being stored, said Ian Crawford, professor of planetary science and astrobiology at Birkbeck College, University of London, who was not involved in the research.
"This may require challenging thermal control for the depots, but if it can be mastered, this will have wide applications for future space exploration," Crawford told Space.com. "Anything which increases the efficiency of space exploration is to be welcomed."
But even with the technological challenges that the plan faces, it’s not just a pipe dream, and MIT isn’t the only one working on the idea. Plans for refueling stations for satellites are already in the works. In addition, companies are working on ways to create fuel from resources available in space, either by mining water from the moon or asteroids, which can then be converted into oxygen for air, and hydrogen to be used as fuel.