A story from Engadget reports:
Satellites often rely on reaction wheels, or constantly spinning flywheels, to tweak their attitudes without using precious fuel. However, they tend to be very delicate -- since they use ball bearings, they spin relatively slowly (under 6,000RPM), take up a lot of space, need tightly controlled environments and aren't very precise. Thankfully, researchers at Celeroton have a better way. They've created a magnetically levitated motor that achieves the effect of a regular reaction wheel with virtually none of the drawbacks. Since its rotor floats in a magnetic field, it can spin much faster (up to 150,000RPM) without wearing out, creating vibrations or requiring a special, lubricated environment. And given that it produces the same angular momentum as a much larger reaction wheel, it's perfect for CubeSats and any other tiny satellite where internal space is at a premium.
The motor is only a prototype at the moment, and it'll take a while before there's something commercially viable. However, multiple potential partners (including the European Space Agency) are reportedly interested. You may well see production satellites that can always adjust their positions, which might keep them useful well after conventional orbiters break down and become space junk.
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @03:09AM
You may well see production satellites that can always adjust their positions, which might keep them useful well after conventional orbiters break down and become space junk.
I think you'd need stuff like the emdrive for that. I'm quite sure barring malfunctions and defects the bearings would last within the same magnitude of duration as the fuel for maintaining the correct orbital position. If the bearings are wearing out, the satellite is probably running out of fuel too.
See: https://en.wikipedia.org/wiki/Orbital_station-keeping [wikipedia.org]
(Score: 2) by Immerman on Thursday July 28 2016, @06:58AM
Indeed. Gyros only allow you to adjust your orientation, NOT your position.
Still, even without an EMdrive, ion drives are beginning to gain traction now that they've been proven practical, and they can get orders of magnitude more total impulse from the same mass of "fuel". And there are at least a few groups looking to commercialize satellite refueling as well, so these are probably a good long-term technology investment.
They probably also allow for much lower "idling" power draw, and potentially more precise attitude adjustment (no chaotic drag from imperfect bearings), not to mention that having much less size (and presumably mass) for the same angular momentum translates to both cheaper launches and better acceleration for the same thrust.
And of course that "less vibration" also means clearer images from space based telescopes, whether they're pointed towards Earth or away.
(Score: -1, Troll) by Anonymous Coward on Thursday July 28 2016, @03:29AM
East Germany solved this problem ages ago. Neighbors spy on each other. It's a self-perpetuating solution that exploits the social animal tendency to gossip.
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @04:51AM
from the book Diamond Age
http://www.technovelgy.com/ct/content.asp?Bnum=233 [technovelgy.com]
(Score: 3, Disagree) by korger on Thursday July 28 2016, @06:29AM
It's altitudes, not attitudes. Unless satellites have grown sentient while I wasn't looking.
(Score: 5, Informative) by Immerman on Thursday July 28 2016, @07:03AM
No, they have it right. Altitude is positional, and thus not something a gyroscope can modify at all.
Attitude control is controlling the orientation of an object with respect to an inertial frame of reference or another entity
https://en.wikipedia.org/wiki/Attitude_control [wikipedia.org]
(Score: 3, Touché) by korger on Thursday July 28 2016, @07:57AM
OK, thanks. Now I can be a smartass and tell people "Is your gyroscope broken or what?! Cause you have a serious attitude problem!"
(Score: 2) by Bot on Thursday July 28 2016, @02:40PM
I was going to express my reaction to your attitude about the reaction at your attitude joke on reaction wheels, but I'd like to avoid stack overflows.
Account abandoned.
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @09:16AM
I'm kinda surprised this is new. Magnetically levitated turbo-molecular vacuum pumps and energy-storage flywheels have been a thing for decades. So applying it to a reaction wheel where there's a relatively easy source of vacuum and electricity just seems obvious.
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @02:59PM
Maybe I'm misunderstanding how this works but wouldn't something like this require a constant input of power?
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @02:06PM
I don't know how to explain this *sigh*
if you turn one thing in one direction then the other thing it is connected to needs to spin into the other direction.
this is called impulse conservation, i think.
this magnetic bearing and motor is news because it might allow to "sail" the gravitation field of earth/sun (and maybe moon).
since there's not mechanical fixed "shaft" (think steel-shaft) that instantly transfers this impulse from one rotating body to another but it is rather magnetic/electrical,
it might be possible to "store" a "impulse debt" in the magnetic field generated by the motor on the far-away-from the sun (less gravitation pull) side of earth
and "pay it back" on the "near-to-the-sun" side of earth (thus allowing to gradually climb out of the gravity well)?
i don't think there's a physical law violated. nothing says that you have to equalize impulse conservation instantly.
however with a mechanical shaft it will be equalized instantly. with a electric/magnetic bearing it can also be instantaneous but it might not have to be ^_^
note: sail ships use wind (pressure differences) to move around without violating impulse conservation. in outer space there ARE gravitational gradients?
(Score: 2) by pkrasimirov on Thursday July 28 2016, @05:00PM
> nothing says that you have to equalize impulse conservation instantly
Ah, so that's how the world debt was accumulated! Someone had this idea but for Economics...
(Score: 1, Informative) by Anonymous Coward on Thursday July 28 2016, @06:31PM
No, this is not whatever conservation-law-breaking magic you think it is.
This is just replacing ball bearings with magnetic bearings. There's still a shaft, there's still the same force couples between the rotating shaft and the body of the satellite, it's just that those forces through the bearings are now mediated by electromagnetic forces instead of normal forces between balls and races. (The force couple of the motor itself doesn't change at all, as that's already electromagnetic.) Benefits include higher RPM, and perhaps more importantly dramatically lower wear, which means longer service life, especially important for ion-propulsion missions.
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @06:49PM
A large ring (1 to 4 meters) would get more capability. By going with a ring, the space usage isn't bad -- you can fill the inside with random satellite odds and ends.
(Score: 0) by Anonymous Coward on Thursday July 28 2016, @08:48PM
What would a momentary power outage or other electromagnet disruption produce if it let a 150,000 RPM flywheel loose inside of... well, pretty much anything?