3 ms·

> Maybe you could program the software to notice that it hasn't gotten commands for a while and deliberately rotate itself into an orientation that causes a pow

> Maybe you could program the software to notice that it hasn't gotten commands for a while and deliberately rotate itself into an orientation that causes a power loss and reset? heh, some spacecraft buses are designed to do the opposite. they'll go into a spin during emergencies just to guarantee that their solar panels are hit at least occasionally. > I'm guessing that the solar panels are arranged in such a way that it wouldn't work, plenty of spacecraft have solar panel arrangements where it is possible for them to not receive any light. > and the attitude control fuel consumption might be excessive. spacecraft can (if designed to include them, which is common AFAIK) control their orientation with reaction wheels, no propellent required. (the reaction wheels will become saturated sooner or later, though. when orbiting bodies with significant magnetic fields they can be desaturated through the use of magnetic torquer bars. otherwise they have to use propellent to do it.)

quotemstr 9y ago
Right. I was imagining the reaction wheel unloading using the propellant. But I don't know anything about this particular design, so the concern may or may not apply.
Armisael16 9y ago
Simply turning around won’t put any long-term load on the reaction wheels though - you spin up to start reorient the satellite and then spin back down once you’re in the desired orientation. It’d be slow - reaction wheels aren’t really designed for gross maneuvers like this - but this is hardly an urgent situation.
- naikrovek 9y ago
  It's the spin up and spin down that actually make the orientation changes, though. You can't spin up infinitely, so once a reaction wheel is spinning as fast as it can, you can't accelerate it further, and you can't rotate the spacecraft in the opposite direction on that axis any longer. (I don't think reaction wheels are capable of gross orientation changes at all -- only very minor alignment corrections.)
  - sigstoat 9y ago
    > It's the spin up and spin down that actually make the orientation changes, though. You can't spin up infinitely, so once a reaction wheel is spinning as fast as it can, you can't accelerate it further, and you can't rotate the spacecraft in the opposite direction on that axis any longer. precisely. angular momentum. > I don't think reaction wheels are capable of gross orientation changes at all -- only very minor alignment corrections. nah. as an example, SORCE has nothing but wheels and a torquer bar (or two?), and aims all over the sky.

quotemstr 9y ago

Right. I was imagining the reaction wheel unloading using the propellant. But I don't know anything about this particular design, so the concern may or may not apply.

Armisael16 9y ago

Simply turning around won’t put any long-term load on the reaction wheels though - you spin up to start reorient the satellite and then spin back down once you’re in the desired orientation. It’d be slow - reaction wheels aren’t really designed for gross maneuvers like this - but this is hardly an urgent situation.

naikrovek 9y ago
It's the spin up and spin down that actually make the orientation changes, though. You can't spin up infinitely, so once a reaction wheel is spinning as fast as it can, you can't accelerate it further, and you can't rotate the spacecraft in the opposite direction on that axis any longer. (I don't think reaction wheels are capable of gross orientation changes at all -- only very minor alignment corrections.)
- sigstoat 9y ago
  > It's the spin up and spin down that actually make the orientation changes, though. You can't spin up infinitely, so once a reaction wheel is spinning as fast as it can, you can't accelerate it further, and you can't rotate the spacecraft in the opposite direction on that axis any longer. precisely. angular momentum. > I don't think reaction wheels are capable of gross orientation changes at all -- only very minor alignment corrections. nah. as an example, SORCE has nothing but wheels and a torquer bar (or two?), and aims all over the sky.