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
