Then you're going to be disappointed by all satellites I'm afraid. They all need to do station-keeping, and have a way to maintain orientation when they spin-down their reaction wheels. "Solar-powered" thrusters use fuel too but use an electric field to accelerate it.
20 years is still a rather long time. Expect something else fragile to fail before then. And that's still double the target life time! (And unless they've made it almost maliciously difficult to add fuel, I'm sure there will be some Space Bro who'll offer to refuel it for likes / tax reasons.)
20 years is still a rather long time. Expect something else fragile to fail before then. And that's still double the target life time! (And unless they've made it almost maliciously difficult to add fuel, I'm sure there will be some Space Bro who'll offer to refuel it for likes / tax reasons.)