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Solar Pressure May Help Kepler Return To Planet-Hunting Duties

samzenpus posted about a year ago | from the back-to-the-search dept.

NASA 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."

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Attitude Control? (0)

suman28 (558822) | about a year ago | (#45575997)

I did not know that telescopes had an attitude to begin with. How does adjusting attitude allow a telescope to search for planets?

Re:Attitude Control? (1)

Anonymous Coward | about a year ago | (#45576023)

I believe they are mostly inquisitive.

Re:Attitude Control? (4, Informative)

gmclapp (2834681) | about a year ago | (#45576095)

Attitude describes position in a rotational sense. TFS is correct.

Re:Attitude Control? (5, Funny)

Anonymous Coward | about a year ago | (#45576843)

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...

Re:Attitude Control? (0)

ganjadude (952775) | about a year ago | (#45577191)

+1 - best comment of the day

Re:Attitude Control? (0)

Anonymous Coward | about a year ago | (#45578299)

Yeah, I know what you mean.

It's like, take my ex-wife... Please!

((badaboom))

Attitude Control (3, Informative)

Thanshin (1188877) | about a year ago | (#45576007)

Attitude control [wikipedia.org]

Why would much budget be needed, I wonder (1)

Anonymous Coward | about a year ago | (#45576029)

"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?

Re:Why would much budget be needed, I wonder (1, Offtopic)

Lumpy (12016) | about a year ago | (#45577165)

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.

Re:Why would much budget be needed, I wonder (0)

Anonymous Coward | about a year ago | (#45584267)

off topic? what dipshit did that? some no brain idiot moderating without READING the threads again?

That's weird (0)

Anonymous Coward | about a year ago | (#45576067)

Did NASA forget to pack a 3D printer with the telescope? So it can print out spare parts as needed?

forget the sun (3, Funny)

bob_super (3391281) | about a year ago | (#45576097)

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.

Re:forget the sun (0)

Anonymous Coward | about a year ago | (#45576259)

Your elders are not your peers.

Re:forget the sun (1)

Lumpy (12016) | about a year ago | (#45577177)

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!

Re:forget the sun (0)

Anonymous Coward | about a year ago | (#45578083)

Yes, I know you loved slavery, Gramps, I know sex before marriage was a deeply shameful thing back then, I know that Gramma told all her daughters to not bother with education in favor of seducing a wealthy husband.... but I don't think it's just childish rebelliousness to have serious moral qualms about those things now....

Re:forget the sun (0)

Anonymous Coward | about a year ago | (#45578125)

But your friends are still morons, Like the one there with you, really a Sponge-bob tattoo on his forehead... and the redbull tattoo on his neck, He's a special kind of stupid, yet you still take his advice.

Rocket Scientists? (1)

Anonymous Coward | about a year ago | (#45576115)

Wow, these guys are smart. What are they, rocket scientists or something?

Re:Rocket Scientists? (0)

Anonymous Coward | about a year ago | (#45576895)

Rocket surgeons.

Re:Rocket Scientists? (1)

Will.Woodhull (1038600) | about a year ago | (#45578355)

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 (3)

lazarus (2879) | about a year ago | (#45576135)

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?

Re:Light Sail (1)

beschra (1424727) | about a year ago | (#45576209)

Maybe they will next time.

Re:Light Sail (3, Insightful)

JoeMerchant (803320) | about a year ago | (#45576213)

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."

Re:Light Sail (2, Interesting)

Anonymous Coward | about a year ago | (#45576927)

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.

Re:Light Sail (1, Funny)

MightyYar (622222) | about a year ago | (#45577095)

the Sun is pretty stable when it comes to that

Then how do you explain global warming?

(I keed, I keed...)

Re:Light Sail (0)

Anonymous Coward | about a year ago | (#45578783)

The solar wind (proton impact) and photon pressures are approximately equal for a solar sail...did this problem in Jackson Electrodynamics....LOL

Re:Light Sail (0)

Anonymous Coward | about a year ago | (#45579489)

You can't have gotten a very good grade, because photon pressure is about a thousand times stronger than the solar wind.

Re:Light Sail (4, Informative)

0123456 (636235) | about a year ago | (#45576445)

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 (4, Informative)

Deadstick (535032) | about a year ago | (#45576773)

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.

Re:Light Sail (2)

Herve5 (879674) | about a year ago | (#45577523)

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 certainly come back some day.
Also, as mentioned around here, when in low earth orbit the multiple eclipses per day raise a situation where you lose control too often : this is really for when you're quite far from Earth.

Re:Light Sail (1)

yesterdaystomorrow (1766850) | about a year ago | (#45577741)

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't fit NASA's engineering approach, where teams of specialists make cautious, incremental changes to what their predecessors did. Here, there are few precedents, and the specialists usually don't understand them.

Note that we are not talking about the pressure of the solar wind. That's much smaller that the pressure of solar radiation.

Re:Light Sail (0)

Anonymous Coward | about a year ago | (#45579813)

"Reaction wheels" are used with the law of conservation of momentum, so that they turn in the opposite direction that you want the satellite to turn. Usually there's three of them (cubic arrangement) or four of them (tetrahedral arrangement). I'd guess NASA are using the two working ones to make the satellite turn such that the solar panels face the Sun and act as sails. Maybe they could use the electromagnetic fields generated by the power cables as well.

The solar wind or photon pressure only comes from one direction, so it would be like yacht sailing. then you would have to orient the sail (or solar panels) so that the wind direction pushed the satellite in the direction you wanted it to go.

just gotta say... (3, Funny)

BenSchuarmer (922752) | about a year ago | (#45576139)

Don't make me get my asteroid belt!

Re:just gotta say... (3, Funny)

wonkey_monkey (2592601) | about a year ago | (#45576869)

Such mercurial joviality mars this saturnine thread. Something about venereal disease...

Re:just gotta say... (2)

VortexCortex (1117377) | about a year ago | (#45579815)

Venereal disease? Oh good. I had feared a plutonian Uranus was the butt of the joke.

Re:just gotta say... (2)

wonkey_monkey (2592601) | about a year ago | (#45581751)

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.

Re:just gotta say... (0)

Anonymous Coward | about a year ago | (#45577387)

James Van Allen you get back in that orbit and you clean up that spacejunk, right now mister! No Lagrangian excuses either!

Good as scrap? Hah! (2)

Jeremy Erwin (2054) | about a year ago | (#45576183)

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.

Re:Good as scrap? Hah! (2)

Deadstick (535032) | about a year ago | (#45576783)

Indeed. "As good as scrap" could be corrected by deleting one of the S's.

Re:Good as scrap? Hah! (1)

wonkey_monkey (2592601) | about a year ago | (#45576899)

scrap /skrap/

noun
1. discarded metal for reprocessing
2. any waste articles or discarded material

Re:Good as scrap? Hah! (0)

Anonymous Coward | about a year ago | (#45577013)

Who is to say it won't be salvaged by spacers a few decades from now since the cost of getting that mass into orbit has already been covered?

Re:Good as scrap? Hah! (1)

Jeremy Erwin (2054) | about a year ago | (#45580511)

You should write up that idea and send it into Analog

Solaire of Astoria (0)

Anonymous Coward | about a year ago | (#45576625)

Praise the sun!

Re:Solaire of Astoria (0)

Anonymous Coward | about a year ago | (#45576853)

Hooray for the sun god! He sure is a fun god! Ra! Ra! Ra!

Not good enough (0)

Anonymous Coward | about a year ago | (#45580065)

If they really want to get it right, they need a K-9 mission. With help from the Doctor and Romana, he'll make it good as new.

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