The thread for space cadets!
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PlutonianEmpire
King of the Plutonian Empire
I didn't know Chris Hadfield could sing!
I couldn't resist...
Who made those gyros? Were they delivered on time?
PlutonianEmpire
King of the Plutonian Empire
Why? Is there something I missed?
I'm curious, since they didn't last 15x the mission life, like most of the stuff NASA contracts. Granted something has to fail first… but I just wonder if these were the proverbial low bid components.
Yarg, I was really looking forwards to more Kepler data. I don't know why they don't do everything in duplicate anymore.... it was such a good idea.
That said, the google lunar x-prize quest is still getting new teams signing up.
That said, the google lunar x-prize quest is still getting new teams signing up.
warpus
Sommerswerd asked me to change this
I think the system did work with one of those components not working. I seem to remember reading somewhere that the spacecraft was already running without one of them working.
tokala
Emperor
Because it was launched with 4 instead of the necessary 3 for redundancy.
One has to wonder, why not 5 or 6 from the get go?
If I remember correctly, some other space telescope (Hubble?) had issues with the gyros, too.
I think 5 or 6 would got past the point of diminishing returns - that's more mass, they take up more real estate in the launch vehicle, and there could be an engineering constraint. With 4 gyroscopes you have 2 different tetrahedra formed by the axes. I'm not sure that 5 or 6 would gain you enough to justify the extra mass.
For that matter, i wonder if mass is a zero-sum element of the design. More kg in gyroscopes removes kg from another system?
hobbsyoyo
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In many cases, yes, mass is absolutely a zero sum design constraint. Sometimes you can add a strap on booster or change to a larger rocket, but that could throw off your launch window (which may or may not be critical). If you are adding extra components, then you are going to have to redesign whole sections of the spacecraft such as the electrical subsystems and so on. All that takes (a lot of) money, which takes away from the pool of money you could use to buy a bigger launcher or strap on boosters. So, long story short, you are spot on.
hobbsyoyo
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Even if there is money for a bigger rocket and extra stuff on the spacecraft, there are other considerations to uh, consider, as well. For example, your spacecraft may be built to tolerate a 3g max launch profile but the bigger booster may max out at 4.5g's.
It's a pity we don't have some sort of, oh, I don't know, space shuttle or something so we could send up some astronauts to fix it.
hobbsyoyo
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Yeah, Bush really screwed up in cancelling the shuttle whilst not providing enough funds to make sure the replacement program (Aries I and V rockets) were completed on schedule. Then Obama came and axed Aries altogether and then immediately reinstated basically half of the old Aries program under a different name. He gets blame for part of that debacle, but he has at least tried to make lemonade out of the lemons whereas Bush more or less ignored it all after the Vision for Space Exploration was announced.
Glassfan, have you followed Obama's free-market privatization initiatives wrt NASA and the COTS program? It's pretty interesting stuff and will (hopefully) lead to less government control of space activities and more private sector endeavors.
Glassfan, have you followed Obama's free-market privatization initiatives wrt NASA and the COTS program? It's pretty interesting stuff and will (hopefully) lead to less government control of space activities and more private sector endeavors.
It's a pity we don't have some sort of, oh, I don't know, space shuttle or something so we could send up some astronauts to fix it.
Well, given that Hubbles orbit is on the outer edge of the Shuttle capabilities I doubt it would be much help fixing a spacecraft never meant to be serviced.
I honestly don't know the technical specifics. Yet Shuttle astronauts visited the Hubble repeatedly to repair it and extend it's lifetime by decades.
It's a pity we don't have some sort of, oh, I don't know, space shuttle or something so we could send up some astronauts to fix it.
Servicing Kepler is far beyond the capabilities of the Shuttle. Rendesvouing [sp??}with Kepler is more like a lunar mission. But even if you could get to it, I really doubt it could be repaired. For something to be repaired in orbit, it has to be *designed* to be repaired. Bolts, not welds; hand-holds, zero-G friendly tool interfaces, wide access ports; and a host of less-obvious things that I can't even imagine.
Exactly. Kepler doesn't orbit the Earth, like Hubble - it orbits the Sun:
http://kepler.nasa.gov/multimedia/animations/?ImageID=39
Hubble was specifically designed to be a compatible with the Shuttle program. It's sort of like how semi-trailers are specifically designed to be pulled and maneuvered by a semi tractor. In this case, Kepler is more like a container that washed off the deck of a freighter, and you want to send a semi-tractor out into the ocean to go and retrieve it. That's not going to work.
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