Q) How much transmitter power should be used on the uplink frequency of an amateur satellite or space station?
A) The minimum amount of power needed to complete the contact
QRP (low power) operators already understand the meaning of this rule. They accomplish DX (long distance) contact with just a few watts or sometimes even miliwatts. It is rather fun to turn down the power during a contact to see "how low you can go".
This rule becomes even more critical with a space station since transmitting on the uplink at greater power than necessary increases the chances you will cause harmful interference.