There's a reason not everybody is building spaceships. They cost lots of money, take a long time to build, and people often get hurt in the process.

If you have the resources to build your own ship, have a blast (no pun intended). I believe that you will find that as you build your own ship, you will inevitably come across the same tough problems as has the people that came before you. You'll have the choice of learning from them, or learning the hard way.

Food for thought.. if all of the resources that went into the space race were actually combined into one project instead of several different projects, we might be walking on Mars by now.

My point.. take advantage of open source programming by improving somebody else's space ship, not building your own. Replace a wheel or two if you have to, thats far better than having to come up with a few thousand wheels on your own.