Solar Pressure May Help Kepler Return To Planet-Hunting Duties 46
Zothecula writes "Last August, it looked as if NASA's Kepler space telescope was as good as scrap due to the failure of its attitude control system. Now the space agency proposes what it calls the K2 mission concept, which may fix the problem by using the Sun to regain attitude control and allow Kepler to resume its search for extrasolar planets."
Attitude Control? (Score:1)
Re: (Score:1)
I believe they are mostly inquisitive.
Re:Attitude Control? (Score:5, Informative)
Re:Attitude Control? (Score:5, Funny)
Oh, no, they have an attitude all right. If you point them in the wrong direction they won't even talk to you. God forbid you give one a command it doesn't like or understand; you may never hear from it again. Fussy, high-maintenance, only responding to what it wants to hear; if that's not attitude I don't know what is...
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Attitude Control (Score:4, Informative)
Attitude control [wikipedia.org]
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Attitude adjustment [youtube.com]
Why would much budget be needed, I wonder (Score:1)
"Whether or not K2 goes ahead depends on the results of NASA's 2014 Senior Review and the acceptance of a budget for the mission."
One would think the cost of keeping it going would be absolutely minimal, manufactured and launched as it is... did they cut funding when the 2nd wheel failed?
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Actually they did. Ceasar cut all funding on wheels and called them a failure. Luckily private chariot companies picked up where they left off and created the booming chariot industry that carried Rome from it's beginning, to burning and beyond.
forget the sun (Score:4, Funny)
Solar pressure? The only thing that works for attitude control is peer pressure (for lack of a timeout corner in orbit).
Tell Grandpa Hubble to shame Kepler into behaving.
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Correct, they are BETTER than your peers and you should listen to them instead of the morons you call friends.
Now get back to mowing the lawn!
Rocket Scientists? (Score:1)
Wow, these guys are smart. What are they, rocket scientists or something?
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Rocket brain surgeons.
As in the disparaging remark: "this isn't rocket surgery, you know. Hell, it ain't even sociology." (Best used before anthropologists.)
Light Sail (Score:4)
This is fascinating, but what I find even more interesting is why they couldn't use a similar technique to make the need for the attitude control wheels obsolete? It would require a spacecraft much different than Kepler, but would it not be possible to use sails to orient a similar craft no matter what area of the sky it wanted to point to?
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Maybe they will next time.
Re:Light Sail (Score:4, Insightful)
Variability and unpredictability of the solar wind?
It could work, but it would be like reverting from steamships to sail power, and in the billion dollar satellite business, answering the question "when will our gizmo be working?" with something like "well, between 10 and 40 days, depending on what kind of winds we get..." might not be as satisfying for the businessmen as "27 days, 13 hours and 6 minutes, +/- 30 seconds, depending on interference from the solar wind."
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Solar wind isn't what solar sails use, despite the name. A solar sail works by photon pressure, and the Sun is pretty stable when it comes to that.
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the Sun is pretty stable when it comes to that
Then how do you explain global warming?
(I keed, I keed...)
Re:Light Sail (Score:5, Informative)
This is fascinating, but what I find even more interesting is why they couldn't use a similar technique to make the need for the attitude control wheels obsolete?
Wouldn't work very well near Earth, because you're in darkness much of the time and there's enough atmosphere left that drag might be larger than any force you could create from light pressure.
But I seem to remember that Mariner Mercury used light pressure on its solar sails for attitude control when it could, to miminize fuel use by the thrusters.
Re:Light Sail (Score:5, Informative)
Mod parent up. In Earth orbit, aerodynamic wind is very tiny but so is solar wind, and solar steering as a primary attitude-control system would be very complex. Acceptable as a last-ditch fallback, but you wouldn't want to base a mission on it.
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This works, but provides verrry small torques or forces.
FWIW, a couple of years ago, with my (european space industry) employer and a neighbor astronomy lab we designed a device involving a large and rough telescope concentrating light on mobile smaller mirrors, so as to provide torques or even forces, but very low, to light and very slowly moving spacecrafts. We wanted to deploy a flock of these, coordinating them to form a very large, multipart space telescope. Then, well, money went on missing. This will
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This is fascinating, but what I find even more interesting is why they couldn't use a similar technique to make the need for the attitude control wheels obsolete? It would require a spacecraft much different than Kepler, but would it not be possible to use sails to orient a similar craft no matter what area of the sky it wanted to point to?
The advantages are obvious, but there are disadvantages:
1. It doesn't work near the Earth, because atmospheric drag, magnetic torque, and gravity gradient torque are all considerably larger than radiation pressure.
2. The forces are tiny, so your spacecraft won't be very agile. If you need to reorient to change targets or point an antenna at Earth to send your downlink, it'll take awhile.
3. While as an exercise in applied physics radiation pressure may be the simplest attitude control method, it doesn
just gotta say... (Score:4, Funny)
Re:just gotta say... (Score:4, Funny)
Such mercurial joviality mars this saturnine thread. Something about venereal disease...
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Venereal disease? Oh good. I had feared a plutonian Uranus was the butt of the joke.
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Can't you be Ceres for just one minute? I think we should Nix this now before I have to come over there and Makemake you apologise.
Good as scrap? Hah! (Score:3)
The whole point of scrapping a ship is that the steel can be reused for other purposes. The Kepler space telescope can't be scrapped-- it's in the wrong sort of orbit to be returned to earth. From that perspective, it's actually worse than scrap.
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Indeed. "As good as scrap" could be corrected by deleting one of the S's.
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scrap /skrap/
noun
1. discarded metal for reprocessing
2. any waste articles or discarded material
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You should write up that idea and send it into Analog