Hitting Alt-O will open a screen that allows you to test
out the ships Capabilties without much fear of destruction.
Unlimited ammo, joystick calibration, invulnerabilty (GOD MODE)
are a few of the options that are available.
Be careful when using this "cheat" though, if you are either
flying a mission (cargo or plot) and you go into this option
screen to save yourself, the mission is considered a failure
and if you are on a plot mission, you are basically screwed.
You'll need to go back to a saved game (hopefully you remembered
to save!) and start from there. Bounty missions are different,
apparently they are unaffected by this option (sometimes getting
rid of a mission is good, you can only "hold" three missions...not
including plot missions).
You can get into this mode at any time, even while flying.