I've been trying to remember the title of a sci fi movie I rented in the late 90's about a former NASA rocket scientist and three or so other talented friends or co-workers that built a space ship from discarded military rocket parts. The scientist left NASA because they wouldn't try his ingenious economical propulsion system, so he decided to do it himself to prove his theory. Their plan was to travel to the moon and collect as many items as they could that were left behind by the Apollo missions, return them safely and efficiently to Earth, and sell them to museums or the highest bidders. They hacked into a NASA or similar main frame super computer during off hours to provide guidance for propulsion and re-entry. The mission was going well until a computer tech shut down the main frame for scheduled maintenance. They had to come clean with the authorities to get the computer re-started to safely complete the mission, which, I believe, ended in New York's Central Park.

Does this synopsis ring a bell with anybody? I've followed a few leads and searched the sci fi, fantasy, and adventure movie lists from 1970 to 2000 and no luck. The closest I came was The Astronaut Farmer, which is similar, but too new and not it.

That sounds a lot like an old TV series (1979) with Andy Griffith called "Salvage 1".

That must be it. Isaac Asimov himself consulted on the show.