>>1454451 (last)

Rockets and jets operate on the principle of conservation of momentum, not energy. Energy isn't particularly conserved because a lot of it is wasted as heat.

For conservation of momentum to work, there is no need for something for the molecules to "push against". Rockets work best in space where there are no such molecules, no friction. This idea that rockets have to push against something is probably being pushed by the "flat earth" people i.e. it's a wrong idea. There, I've just offended more people, but let's face facts. Anyway …

Jets don't work in space because they need to take molecules in, then accelerate them out the back. Rockets store all the molecules internally, calling them "rocket fuel".

If shuttle is a jet rather than a rocket, that would make sense. I wondered about that years ago when they were saying it's a rocket. Since it glides until it gets into the atmosphere, why not just use a jet engine rather than a rocket.