A spaceship isn't much use if it doesn't have the juice to go somewhere. And if you're an astronaut bouncing around destinations like the moon, random asteroids, Lagrange points, and Mars, you'll probably need an interstellar gas station.
NASA has launched an "In-Space Cryogenic Propellant Storage and Transfer Demonstration Mission Concept (PDF)" study, which is essentially a call for scientific institutions around the globe to help create a space gas station. Those wishing to build a fueling stop in the sky have until May 23 to submit their proposals.
Cryogenic propellants used in rocket engines are usually made of liquid hydrogen and liquid oxygen. Both liquids reside in enormous insulated containers and are pumped through an expansion chamber, then mixed and ignited in the combustion chamber. The result is an incredible amount of power per gallon of cryogenic proellant, up to 40 percent higher than other rocket fuels.
However, there are many challenges to creating a gas station in the stars. The primary objectives of the study are to address key elements including a fail-safe way to transfer the propellants from a storage container to a ship. The difficulty is high since hydrogen tends to leak (it's the smallest element), and can eventually deteriorate the container it's stored in. … Read more