Note that this post is not affilated with the Mostly Harmless mod, which only simulates camera gravity. Thank you.
I think a cool addition to Celestia would be a Gravity Sandbox mode, where you could see how gravity affects stuff. Example - what if a large comet passed by Jupiter? Would it fall into orbit around it? Would its orbit get perturbed? Would it smash into Io?
The way it'd work would be that you set up a comet in the normal way, with a eccentric orbit that brings it close to Jupiter. Then we'd set a "gravity true" tag, which means its orbit can change according to the gravity. Then we'd switch gravity on in Celestia, sit back and watch...
It'd be interesting to go forward and watch the Moon and Earth become locked, or Phobos spiral down towards the surface of Mars. Or maybe even a Rogue Star simulation...
The only problems are... 1. Do we need a supercomputer to simulate gravity, or can a modern desktop PC do it accurately enough?
And 2... Would a gravity sandbox "corrupt" Celestia's space simulation goal, making it into a mere astronomical tool?
Planetary Gravity
Planetary Gravity
"I have been asked, 'Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?' I am not able to rightly apprehend the kind of confusion of ideas that could provoke such a question."