Future lunar missions may be fueled by gas stations in space, according to MIT engineers: A spacecraft might dock at a propellant depot, somewhere between the Earth and the moon, and pick up extra rocket fuel before making its way to the lunar surface.
Orbiting way stations could reduce the fuel a spacecraft needs to carry from Earth — and with less fuel onboard, a rocket could launch heavier payloads, such as large scientific experiments.
Over the last few decades, scientists have proposed various designs, such as building a fuel-manufacturing station on the moon and sending tankers to refill floating depots. But most ideas have come with hefty price tags, requiring long-term investment.
The MIT team has come up with two cost-efficient depot designs that do not require such long-term commitment. Both designs take advantage of the fact that each lunar mission carries a supply of “contingency propellant” — fuel that’s meant to be used only in emergencies. In most cases, this backup fuel goes unused, and is either left on the moon or burned up as the crew re-enters the Earth’s atmosphere.
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 — an arrangement that the team refers to as a “steady-state” approach.