Stole this from another board...Good question to ponder.

[harshman]

Maybe I’m missing something here. Space is a vacuum. Once desired velocity is reached there is no need to use the engines. No friction, no air, nothing to slow it down. The only thing that will impede progress is the gravity of a planet. So if this is true, the fuel is not an issue. “Continue present course and speed number one.”

and

i should have read the rest of the posts!!!