Space scientists are set to compete to build the first gas stations in orbit. Nasa plan to offer a $5 million dollar prize for private enterprise to develop pit stops around the Earth and Moon.

The orbiting garages could supply liquid hydrogen and oxygen to spacecraft on interplanetary missions. Fuel would be made from any water found in craters near the Moon’s poles plus oxygen extracted from the lunar soil.

Scientists say it will be much easier to lift fuel from the Moon than Earth because of its weaker gravity. But they need to overcome a number of problems to produce a fuel depot in space. For example, you could not use a dipstick to measure liquid levels in a zero gravity environment.
Fuel tanks would also need special insulation to keep their contents cold (-253C for hydrogen and -183C for oxygen) in the glare of sunlight, New Scientist reports online.

Nasa also need the gas stations to operate automatically with no human attendant to fill a spaceship’s tank. The prize money will go to the first team to build, launch and test a working fuel station in low-Earth orbit by 2012. The tanks must hold at least 20kg of liquid hydrogen and 120kg of liquid oxygen for 120 days.