After reading If the reactor on a nuclear sub were breached, what would happen? and Could a year’s waste from a nuclear power plant be stored under a desk?, I’m wondering what happens to the nuclear waste output from a orbiting satellite? Does it hold it all inside and then at end of its lifespan the whole thing burns up on re-entry? Or does the satellite produce a constant stream of the stuff, either burning up or ending up wafting out into space? Whats the dope here? S.Butler. Melbourne, Australia
Space probes that utilize nuclear power for energy use Radioisotope Thermoelectric Generators (RTG) that produce electricity from the decay heat of non-weapons grade plutonium-238. Like all nuclear energy sources, including nuclear reactors, there is no constant stream of nuclear waste released. All of the waste products are sealed up.
Orbiting satellites do not use RTGs for power, for exactly the reason you bring up. Burnup during reentry would spread radioactive contaminants into the atmosphere.
RTGs are only used for interplanetary space probes. They’re only really necessary where solar cells are impractical, such as for space probes on missions far from the sun.
While reactors in orbit are now uncommon, the USSR launched over 30 of them. Perhaps the most famous was Cosmos 954, which spewed its fuel over northern Canada in 1978.
Actually there have been many reactors and RTGs flown in earth orbit. They are usually designed to survive reentry or launch failure without scattering radioactive material. A few have failed and did release small amounts of radioactive material into the atmosphere.
More detailed information here, including a complete (I think) list of nuclear-powered spacecraft in section 3.
:smack:
I guess I took the furor over the Cassini RTGs as evidence that RTGs have not been used for orbiting satellites.
While I shouldn’t be surprised that they were used years ago, I don’t believe they are commonly used for satellites today, especially those in low Earth orbit.