one thing about time travel i thought, is if it did work, and a vehicle was made that could travel through time, but not space it would be risky. assuming you travel back, say 10 years, then the earth wouldnt be where you left it, it would be in a different area of space, either by the earths rotation around the sun or by overall 'solar movement' (as a phrase i just made up), so if you took your souped up delorian through time you would end up in space, or maybe in the middle of another planet so the best option would be to create a vehicle wihich either could trvle through time and space, or launch the time machine from space and hope for the best
all of this theory is probobly bullshit tho.