Mini reactors are useless on Mars. The power they generate is waaay to low compared to the money that is needed to bring them there. Also putting nuclear reactors on sattelites almost never happens and is VERY DANGEROUS. It's what the Soviet Union did in the 70s-90s. The last sattelite launched with a nuclear reactor was in 1988.

You have to be pretty insane to launch large amounts of nuclear material from earth in a rocket that can randomly explode in our atmosphere.