(01-01-2019 03:58 AM)Almadenmike Wrote:  

(12-31-2018 06:23 PM)I45owl Wrote:  

(12-29-2018 02:50 PM)sts60 Wrote:  I had an almost vanishingly small role supporting the radioisotope thermoelectric generator (RTG) powering this spacecraft. Trivia note: it was actually a flight spare for Cassini, and was refurbished with a mix of re-refined American and Russian plutonium (we used to buy Pu-238 from the Russians).
ETA: it’s the black finned double cylinder projecting to the lower left.

I used to try to argue with a friend that these probes did not actually have nuclear reactors sent into space, but were you aware of the (one, and I believe it was only one) actual reactor that was sent into space?

The SNAP-10A was the first -- and only -- reactor that the U.S. sent into space. But more than a dozen of the USSR's Cosmos launches included a reactor.

Even I find the latter a bit scary... the Soviets didn't have or earn the reputation for safety or sustainability planning. RTGs seem pretty foolproof, though there are various overblown concerns about what may happen if a rocket were to fail on launch and/or if it were to descend back to earth. I believe the US uses RTGs for probes... I'm unsure about whether they are used for satellites.

The timeframe of operation to descent into orbit should be such that the most dangerous elements (among them Cesium-137) that result from fission reactors should be minimal or gone by the time you have to worry about them.