What powers those thrusters? Never really thought about it.
Re:SpaceX Punched a Hole in the Ionosphere
by panick21_ on Friday July 28, 2023 @10:50PM
(#36916331)
They are powered by solar electricity that is saved in batteries. But to actually move you need something to throw out. That can be many things, anything from normal water, metal or noble gases.
Starlink initially used Krypton for its thrusters. But they have now switched to Argon since its incredibly cheap and available. Xenon for a long time was the standard, but its to expensive and rare.
Some sats also have chemical power, often a Hypergolic propellant, like dinitrogen tetroxide plus hydrazine. Specially for larger sats this is the case.
- https://en.wikipedia.org/wiki/Ion_thruster
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Collision avoidance in LEO is quite elegant. When two satellites are predicted to pass uncomfortably close to one another, one satellite will fire its station keeping thrusters to raise its orbit above the other. No brakes or swerving needed, just a slight push well ahead of time. Starlink sats do this over 1000 times per week.
Even better, energy used for avoidance reduces energy needed for station keeping on a 1:1 basis. Avoidance maneuvers are effectively free.