Figured the ending out?

Yes...this movie was terrible - but slightly entertaining.
I think the reason the ship blew up is because the 'old captain' set the ship to destruct, but then at that stage he lost control of all the ships functions (Dracula has some freaky engineering skills). Zoom into the year'3000' and the professor guy (with better skills) managed to get the systems all up and running (which is why they could fly towards the sun). Because everything was up and running as per normal, the self destruct command was up and running again and subsequently worked as well.

I noticed they made a lot of reference to time through the movie...ie. 13 hours etc...cant be bothered watching it again, but maybe it matches up with the start and the 'old captains' reference to the time remaining til the ship blows up. Man, I have thought through this way to much.