[the8472]

> while the satellite itself needs to increase this to ~12,000 km (I'm rounding these numbers). The sat has to carry enough on-board propellant to raise it's orbit that much which necessarily increases it's wet-weight due to the rocket equation.

Looks like they use a liquid fuel thruster lift it to its final orbit[0]. Some other missions have used ion engines for orbit raising[1]. I wonder why that wasn't incorporated into the GPS design.

[0] https://en.wikipedia.org/wiki/Lockheed_Martin_A2100 [1] https://space.skyrocket.de/doc_sdat/ses-12.htm

[pilsetnieks]

Ion engines still need propellant, you might be thinking of the so far unproven EM drive.

[elihu]

Ion engines need propellant, but they need a lot less of it to achieve a similar result as a traditional rocket engine.