I'm guessing you don't know anything about orbital mechanics. While a satellite can be shifted to a new orbit, this "space mines" idea would be terribly inefficient.
A nuclear powered satellite would not have such a problem. When the space mine uses it's nuclear power supply to increase the effect of the explosion, that explosion would have a large radius. Even if it does not physically cause the destruction of the enemy satellite, it could still fry the electronic circuits of the target to make it dysfunctional.