NASA collects proposals for space fueling stations

Sometimes rocket science is actually, you know, rocket science. Getting to the moon was tough enough, but deep space exploration poses all manner of additional concerns -- like getting back home alive, for one thing. And then there's the issue of fuel, something long distance trips require a lot of -- but stocking up on here on Earth means potential weight problems at launch. One proposal offered up in the past is space-based fueling stations conveniently located in key spots on the way to a distant destinations like the Moon, Mars, and asteroids. NASA is collecting proposals that can demonstrate the validity of such a plan, including the ability to store liquid oxygen and hydrogen, transfer it, and have a ship approach for fueling. If you think you've got your bases covered -- and can keep it under $200 million -- you've got until May 31st at 11:59 PM EST to hand over a proposal.