Also, assuming a lot of electricity, some form of ion engines would likely be (much) more efficient than heating. Also, nuclear reactors aren't the ideal way t

Also, assuming a lot of electricity, some form of ion engines would likely be (much) more efficient than heating. Also, nuclear reactors aren't the ideal way to make electricity in space. Proper nuclear reactors work as heaters for a heat engine, and heat sinks are proportionally much more expensive in space than on earth. However, solar power is much more efficient. You get 100% efficiency all the time, and it's 30% better in space (near Earth) than it is down here at best. Also, since no structure has to carry any significant weight, you can build things like a flexible paper-thin sheet of solar cells printed on plastic that is spun about it's axis to keep it deployed and spread out.