game dev software for space games?

Ok, first of all you have to realize that graphics and models you use have no effect on game play. Any engine that you may use doesn't give a shit whether or not you're a spaceship or a teapot, there is no magical engine that will make everything easy and straight forward. If you have no experience with making games I really advise against wasting any time on something over your head. However Its wonderful that you want to start imagining and creating your own worlds instead of living in worlds imagined by others. If you want to start programming try and make an exact copy of a mario level even down to the physics, if you're a beginner it will definitely teach you far more than you think it will, putting your current ideas into perspective. People always want to start off creating the next world of warcraft or Call of duty, but creating a much smaller piece of art like Braid or Limbo is just as much of an accomplishment.

download eclipse
download gimp
pick up a good book(Java is a good language to start with)
create

My advice, start with a game you -don't- want to make, if you can manage that then you may have what it takes. The hardest part of making games isn't neccesarily learning, it's keeping at it. If you really want to program you're going to hit a -lot- of brick walls, and when I mean brick walls I mean solid slippery concrete you'll have to run halfway up and jump to the ledge to get over.