An answer in the following mentions a free online calculator for long-distance space travel. https://worldbuilding.stackexchange.com/questions/33757/software-to-ease-my-interstellar-travel-calculations I'm looking for a 3d simulator that accurately and visually shows transition from orbit and other aspects of interplanetary (rather than interstellar) travel. I don't care about trading between planets or social interactions or wars - just the travel aspect. I'm thinking of purchasing Kerbal Space Program, which although it has cartoon green aliens as an extra, does, I've heard, have accurate physics. Does anyone have experience of this software? Will it serve my purpose? Does anyone have other recommendations? NOTE: There is a tag especially for software-recommendations so I don't believe this question should be closed as 'opinion based')