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#560
by
ZANL188
on 06 Sep, 2009 21:36
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Which TDRS spacecraft are being used as TDRS-East & TDRS-West Now? I had assumed it was TDRS-4 (Norad: 19883) & TDRS-7 (Norad:23613) however it appears TDRS-7 has been moved quite a bit west of its old location. This put the ZOE over mid Pacific which I don't think is correct..
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#561
by
klausd
on 07 Sep, 2009 05:11
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What is this on the discovery
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#562
by
DaveS
on 07 Sep, 2009 05:13
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What is this on the discovery
Vents 1 and 2.
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#563
by
Hungry4info3
on 07 Sep, 2009 12:56
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I never noticed those. What do they do?
They're close to the RCS system, do they vent out the remaining RCS fuel once the shuttle is in the atmosphere and RCS is useless?
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#564
by
Jim
on 07 Sep, 2009 13:52
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I never noticed those. What do they do?
They're close to the RCS system, do they vent out the remaining RCS fuel once the shuttle is in the atmosphere and RCS is useless?
No, they vent the internal compartments of the orbiter during ascent and descent. They line the orbiter going from the nose to the aft. They are more visible on the payload bay sides. The payload bay is not air tight and all the air must go in and out.
The forward RCS "dumped" right before entry and it is done through the thrusters.
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#565
by
arkaska
on 09 Sep, 2009 16:10
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During the STS-125 mission they attached a soft docking mechanism to Hubble to de-orbit it safely. I understand that this is because they don't want it there when the gyroscopes fail and they loose control of it. But what about the KH-12 spy satellite (or the other KHs) which are about the same size and mass as Hubble, what will happen to them when there gyroscopes fail?
Or is the safe de-orbiting of Hubble just because of the big public awareness of Hubbe compare to KH-12?
(sorry if this is the wrong section, couldn't find a good one)
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#566
by
Jorge
on 09 Sep, 2009 16:26
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During the STS-125 mission they attached a soft docking mechanism to Hubble to de-orbit it safely. I understand that this is because they don't want it there when the gyroscopes fail and they loose control of it. But what about the KH-12 spy satellite (or the other KHs) which are about the same size and mass as Hubble, what will happen to them when there gyroscopes fail?
Or is the safe de-orbiting of Hubble just because of the big public awareness of Hubbe compare to KH-12?
(sorry if this is the wrong section, couldn't find a good one)
KH-12 has propulsion systems. Hubble doesn't.
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#567
by
Danny Dot
on 09 Sep, 2009 16:29
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During the STS-125 mission they attached a soft docking mechanism to Hubble to de-orbit it safely. I understand that this is because they don't want it there when the gyroscopes fail and they loose control of it. But what about the KH-12 spy satellite (or the other KHs) which are about the same size and mass as Hubble, what will happen to them when there gyroscopes fail?
Or is the safe de-orbiting of Hubble just because of the big public awareness of Hubbe compare to KH-12?
(sorry if this is the wrong section, couldn't find a good one)
It is because Hubble is NASA and KH-12 is DOD. DOD follows the international rules on satellite and upperstage disposal, and NASA makes up its own and any engineer that brings the international rules into a NASA meeting for discussion on the matter is considered a trouble maker and is labeled a "loose cannon" by his boss. I have first hand experience in this matter.
I am sure Hubble could just be allowed to enter own its own and all would be well. This happens all the time to space assets. Station, however, could not be allowed to have a natural decay. It is too big and there would be too much risk to people on the ground. The ET is also too big and it must be disposed of in a controlled manner.
Danny Deger
Edit: Come to think about it. Upperstage disposal hurt EELV performance a lot, even though it is clearly not needed.
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#568
by
DaveS
on 09 Sep, 2009 16:56
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In which checklist are the PL Cams B/C tilt/pan angles listed for the FCS C/O?
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#569
by
billshap
on 09 Sep, 2009 22:29
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Why are there quindar tones on UHF comm, but not on A/G1 and A/G 2?
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#570
by
ChrisGebhardt
on 09 Sep, 2009 22:40
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Why are there quindar tones on UHF comm, but not on A/G1 and A/G 2?
Bill, this has been answered many, many, many times. Use the search function to search the Q&A forums.
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#571
by
arkaska
on 09 Sep, 2009 22:46
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During the STS-125 mission they attached a soft docking mechanism to Hubble to de-orbit it safely. I understand that this is because they don't want it there when the gyroscopes fail and they loose control of it. But what about the KH-12 spy satellite (or the other KHs) which are about the same size and mass as Hubble, what will happen to them when there gyroscopes fail?
Or is the safe de-orbiting of Hubble just because of the big public awareness of Hubbe compare to KH-12?
(sorry if this is the wrong section, couldn't find a good one)
KH-12 has propulsion systems. Hubble doesn't.
That's something I didn't know. So the question that pops up in my head is why don't Hubble have propulsion? Is it unnecessary for it's mission or would it be to heavy to launch on shuttle? What kind of propulsion does KH-12 have and how long does it last? I know this is classified but a qualified guess?
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#572
by
billshap
on 09 Sep, 2009 22:48
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Chris, I searched and couldn't find it. I searched again, and was directed to this current thread. I'll keep trying, will throw out another question. C.J. just requested a tag-up with Entry Flight on Air/Ground 3. What is A/G3?
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#573
by
Jorge
on 09 Sep, 2009 22:48
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During the STS-125 mission they attached a soft docking mechanism to Hubble to de-orbit it safely. I understand that this is because they don't want it there when the gyroscopes fail and they loose control of it. But what about the KH-12 spy satellite (or the other KHs) which are about the same size and mass as Hubble, what will happen to them when there gyroscopes fail?
Or is the safe de-orbiting of Hubble just because of the big public awareness of Hubbe compare to KH-12?
(sorry if this is the wrong section, couldn't find a good one)
KH-12 has propulsion systems. Hubble doesn't.
That's something I didn't know. So the question that pops up in my head is why don't Hubble have propulsion?
Concerns over contamination of the optics.
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#574
by
Jim
on 09 Sep, 2009 23:41
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What kind of propulsion does KH-12 have and how long does it last? I know this is classified but a qualified guess?
Define a qualified guess. There are many types of low orbiting NRO spacecraft, and the propulsion systems would be just varied as NASA's spacecraft.
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#575
by
Jim
on 09 Sep, 2009 23:44
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It is because Hubble is NASA and KH-12 is DOD. DOD follows the international rules on satellite and upperstage disposal, and NASA makes up its own.
Danny, you are painting NASA with a too broad of brush. NASA follows the proper protocols for orbital debris and its requirements are more stringent than the FAA's or international laws.
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#576
by
Danny Dot
on 10 Sep, 2009 00:08
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It is because Hubble is NASA and KH-12 is DOD. DOD follows the international rules on satellite and upperstage disposal, and NASA makes up its own.
Danny, you are painting NASA with a too broad of brush. NASA follows the proper protocols for orbital debris and its requirements are more stringent than the FAA's or international laws.
I plead guilty as charged. I can only speak toward making the Delta and Atlas do a "guided" disposal of their upperstages for Exploration missions. I know that this is not done for commercial satellite missions where they end up in Geo Transfer Orbit. Does the Atlas and Delta upperstages do a deorbit burn when they go low earth orbit? I do recall being repermanded for being a loose cannon just because I asked the question to help get the performance up. I really did my best to save us many billions of dollars.
And Hubble has no propulsion at all. The gyros and some type of control wheels control attitude. I don't know about the NRO telescopes. I could make a guess, but I know too much to do it here.
Danny Deger
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#577
by
yinzer
on 10 Sep, 2009 00:52
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During the STS-125 mission they attached a soft docking mechanism to Hubble to de-orbit it safely. I understand that this is because they don't want it there when the gyroscopes fail and they loose control of it. But what about the KH-12 spy satellite (or the other KHs) which are about the same size and mass as Hubble, what will happen to them when there gyroscopes fail?
Or is the safe de-orbiting of Hubble just because of the big public awareness of Hubbe compare to KH-12?
(sorry if this is the wrong section, couldn't find a good one)
KH-12 has propulsion systems. Hubble doesn't.
That's something I didn't know. So the question that pops up in my head is why don't Hubble have propulsion?
Concerns over contamination of the optics.
Hubble doesn't have to be in any particular orbit, as it looks at stuff that is distributed all over the sky and that generally doesn't change. So they put it up as high as possible, and reboost it when they service it.
The KH-12 likes to be in a particular orbit, since it looks at certain things on the ground and wants to see them at certain times. Staying in that orbit requires propulsion. It also sometimes wants to be in a different particular orbit from the one it happens to be in, which also requires propulsion.
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#578
by
Antares
on 10 Sep, 2009 04:05
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Re: disposal orbits. Mostly they just have to get out of the orbit of whatever they're dropping off. Usually it's perigee lowering to facilitate entry, but it can also be an out-of-plane burn. Once in a long while they can even do earth escape.
In any case, the key is inerting, blowing down all fluids and leaving the valves open (which makes me wonder about wet cell batteries, come to think of it). There was a spent Ariane stage that exploded in the 90s that led to the international agreements on this.
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#579
by
rlloyd1
on 10 Sep, 2009 15:35
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I was wondering, while shuttle is orbitting in space how long does it take to revolve around the earth?
