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Near-earth space has an abundance of solar energy convertible to electrical energy. Deep space is an interesting potential use case for fusion, but fission-powe
by notahacker 2y ago
Near-earth space has an abundance of solar energy convertible to electrical energy. Deep space is an interesting potential use case for fusion, but fission-powered electric space propulsion via RTGs has the virtue of having demonstrated nearly half a century of continuous operation
(and after it leaves the earth's atmosphere, radioactivity ceases to be a concern)
- pfdietz 2y agoAs far as I know there has never been an RTG powered electric rocket engine. RTGs are extremely expensive per unit of power output. Spacecraft like that ion engine propelled one that was sent to Ceres use solar power.
- notahacker 2y agoVoyager and Pioneer used RTGs, as well as some more recent longer range missions and the planned Dragonfly to Titan. Agree that solar has much better unit economics, but I don't see any reason why the same wouldn't be true of fusion too.
- pfdietz 2y agoAnd none of those use RTGs to power electric rocket engines. (EDIT: thrusters are rocket engines, just very small ones. All those missions used small chemical rockets for maneuvering, using storable propellants like hydrazine.)
- notahacker 2y agoEdit: I stand corrected on Voyager/Pioneer exclusively using hydrazine, though you could get similar thrust from a modern HET without needing insane amounts of RTG power, and run other electrical equipment off that extra power when you've reached target velocity and aren't firing the thrusters for attitude control. The higher Isp of the EP system is an advantage too...