How to travel through space without modern technology
So. A looong time ago, I asked how to remove most technology in a hundred years. However, I just realized that for my plot to work, I still need my characters to move from one planet to another. I have decided to leave a few (4-5/planet) space-elevators in place, but I got stuck there.
The question:
How do I move my characters from Mars' orbit to Mercury safely, without using anything space-age other than the elevator already mentioned?
Life support is not a problem.
Edit:
* Since I have an ex-mining colony on Mercury, I will have some sort of shielding system in place to keep my colonists safe. Hopefully, that is still there. I might add a subplot about something threatening this shield.
* Mercury and Mars are just examples. I am not necessarily talking about those particular planets, just a pair that are a comparable distance away from each other.
* there are probably a bunch of old spaceships around without engines, so life support should not be a problem. Also, see the next point.
* In my universe, somehow I have some people who have energy-manipulating (as in: moving and/or absorbing heat, cold, kinetic energy, etc.) powers, so they could theoretically provide life support.
EDIT 2:
* the space elevators are in perfect working order, with nanotech repair crews and power beamed from a Dyson cloud.
* One idea (not mine) is to use maybe a large pot of water and boil that away. Basically a steam-powered spaceship. Would that work? Just an Idea.
Edit 3:
For those who want to know about the magic system:
Your "other" strength starts at the level of your normal strength, and drops off linearly(~1 n/m ), but can be boosted by absorbed energy. When absorbing, you can absorb 10 J before you have to dump it somewhere (say, [lifting] a nice, big, rock [for kinetic powers]). 199
Some people can make forcefields, but need to have anchor points. Basically a thin, flat, unbreakable, [inflexible,] air-proof, waterproof, transparent cloth of arbitrary size.
Something I just thought of: when absorbing energy the drop-off is same as when projecting. Forcefields basically absorb the kinetic energy of something colliding with it, and almost instantly projects it back into the same object.
Something else: the loss of power is turned into heat.
Edit 4: in reply to a comment by @sphennings
The transfer speed of the energy is the speed of light. In theory you could move yourself, but only as far as you could lift something as heavy as you are. Teleportation is impossible for this class of Gifted, though I might add more classes that don't need these spacecraft so are irrelevant to the question. Long distance communication isn't really relevant, but I guess that you could make a pair if tiny plasma-spheres and use them to make semaphore-signals. When projecting into something, you can't chose what to project into more selectively than "that rock" or in the case of fluids "this area of fluid", so you can't filter air by molecule-type. For movement I guess I am basing my system on the system from Mistborn, more specifically the steel and iron powered allomatic powers. You push against something, it pushes back. You pull, and get pulled. Basically, <PERSON>'s laws still hold. 580