As RCS (Reaction Control System) mainly required less thrust than regular rocket engine can ion Thrusters be used for attitude determination in spacecraft(Orion, Dragon), satellites or even during propulsive landing of booster/first stages ?
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3$\begingroup$ For stationkeeping and orientation of a satellite, sure. For active control of a capsule in space, no. Too weak by two orders of magnitude. For in-atmosphere orientation control of booster, no. Too weak by SEVEN orders of magnitude. $\endgroup$– CuteKItty_pleaseStopBArkingJul 17, 2021 at 15:03
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Reaction Control System Thrusters typically have a thrust on the order of Newtons to tens of Newtons – hundreds of Newtons for atmospheric control (e.g. the RCS thrusters on Falcon 9 have about 400 N). Ion Thrusters in current use have a thrust on the order tens to hundreds of Millinewtons. There are experimental thrusters that have achieved 5 N in lab settings.
So, even the most powerful Ion Thrusters that aren't even in use yet are barely able to keep up with the least powerful RCS thrusters. If we are talking about typical thrusters that are actually flying right now, Ion Thrusters are off by a factor of 100×–1000×.
And that's only talking about RCS thrusters for low-mass vehicles in space. For sensible control authority within an atmosphere, as needed for e.g. Falcon 9, you need another couple of orders of magnitude.
answered Jul 17, 2021 at 15:16
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$\begingroup$ And remember that ion thrusters are weaker, to the point of almost not working at all, in atmosphere. Even 50km up atmosphere. $\endgroup$ Jul 17, 2021 at 16:29
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$\begingroup$ so an Ion thruster is too weak by a factor of 1000. A RCS maneuver would take too long time by a factor of 1000. From 0,5 seconds as an example to 8 mintues and 20 seconds. $\endgroup$– UweJul 17, 2021 at 16:43
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$\begingroup$ Different but related: Are the (relatively) new “all electric” satellite buses like the Boeing 702SP really all-electric? Are RCS and momentum unloading done with ions? $\endgroup$– uhohJul 19, 2021 at 0:25