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#1040
by
Danderman
on 04 Apr, 2010 13:52
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What are the internal factors that limit Shuttle visit times at ISS? Yes, I know there are constraints due to visiting vehicles not docking with ISS while Shuttle is attached, but I am trying to figure out why otherwise the Shuttle could not stay attached for 30 days, now that ISS can provide power and other consumables to Shuttle.
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#1041
by
arkaska
on 04 Apr, 2010 14:00
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If a LON during STS-131 is required the shuttle is planned to stay attached for close to 30 days (don't remember exact number of days) so there is nothing that stops the shuttle from staying longer. I would guess the reason it isn't staying longer is because the crew would need to use ISS consumables and that's not something the program want.
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#1042
by
psloss
on 04 Apr, 2010 14:17
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If a LON during STS-131 is required the shuttle is planned to stay attached for close to 30 days (don't remember exact number of days) so there is nothing that stops the shuttle from staying longer.
For this mission it was estimated at ~FD27, so a couple of days less than that on docked time. That would probably have different cryo margins for the power necessary to do a post-undocking disposal re-entry (in that hypothetical) vs. a normal post-undocking timeline that has a significant power load prior to re-entry.
Not sure cryos are the only limiting factor.
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#1043
by
Jim
on 04 Apr, 2010 14:18
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What are the internal factors that limit Shuttle visit times at ISS? Yes, I know there are constraints due to visiting vehicles not docking with ISS while Shuttle is attached, but I am trying to figure out why otherwise the Shuttle could not stay attached for 30 days, now that ISS can provide power and other consumables to Shuttle.
The fuel cell H2 boils off (the boiloff is still used to produce electrical power). The shuttle needs the fuel cells to provide power post undocking, no H2, no electricity.
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#1044
by
mmeijeri
on 04 Apr, 2010 14:27
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The fuel cell H2 boils off (the boiloff is still used to produce electrical power). The shuttle needs the fuel cells to provide power post undocking, no H2, no electricity.
It's too late for that now, but had such a requirement been in place earlier in the program, could the Shuttle have been relatively easily designed/modified to support this? Say by using active cooling with power supplied by the ISS or by using differently designed APUs for electrical power as well as hydraulics during deorbit and descent?
Edit: or using noncryogenic fuel cells...
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#1045
by
grakenverb
on 04 Apr, 2010 14:28
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OK, I know this is not going to happen, but...........
Would it be possible, and if it was, would it be a good idea to leave a shuttle (with a spacehab in the payload bay) attached to the ISS as an improvised new module? If it wasn't going to return to earth you wouldn't have to worry about post undocking fuel reserves. As a bonus, the station looks much cooler with a shuttle docked to it.
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#1046
by
psloss
on 04 Apr, 2010 14:30
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OK, I know this is not going to happen, but...........
Would it be possible, and if it was, would it be a good idea to leave a shuttle (with a spacehab in the payload bay) attached to the ISS as an improvised new module?
Frequently asked question...short answer is no. I'll see if I can find the thread again...
Edit -- here:
http://forum.nasaspaceflight.com/index.php?topic=13950.0
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#1047
by
10W29
on 04 Apr, 2010 15:34
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What are the internal factors that limit Shuttle visit times at ISS? Yes, I know there are constraints due to visiting vehicles not docking with ISS while Shuttle is attached, but I am trying to figure out why otherwise the Shuttle could not stay attached for 30 days, now that ISS can provide power and other consumables to Shuttle.
Real limiting factor is the crew.
LDO
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#1048
by
grakenverb
on 04 Apr, 2010 20:00
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OK, I know this is not going to happen, but...........
Would it be possible, and if it was, would it be a good idea to leave a shuttle (with a spacehab in the payload bay) attached to the ISS as an improvised new module?
Frequently asked question...short answer is no. I'll see if I can find the thread again...
Edit -- here:
http://forum.nasaspaceflight.com/index.php?topic=13950.0
Thanks for the link.... I had done a search before posting but didn't find it!
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#1049
by
mogso
on 04 Apr, 2010 20:27
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2 rocketguy101
I have no such access, unfortunately. It is possible to see this page somehow?
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#1050
by
Martin FL
on 04 Apr, 2010 20:48
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#1051
by
Danny Dot
on 04 Apr, 2010 23:56
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What are the internal factors that limit Shuttle visit times at ISS? Yes, I know there are constraints due to visiting vehicles not docking with ISS while Shuttle is attached, but I am trying to figure out why otherwise the Shuttle could not stay attached for 30 days, now that ISS can provide power and other consumables to Shuttle.
The fuel cell H2 boils off (the boiloff is still used to produce electrical power). The shuttle needs the fuel cells to provide power post undocking, no H2, no electricity.
That would be really, really bad. My 1941 Taylorcraft "Putt-Putt" and my 15 foot john boat don't require electricity to work. My kind of space ship -- as y'all all know
Danny Deger
Attached are two pictures of "Putt-Putt". The one with the attack helos were taken in Texas at a refueling stop. She had to wait for her fuel, even though we were there first. She understood and was happy to stand guard of the the helos while the crew of the helos took a potty break. They were great guys -- and gals.
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#1052
by
Danny Dot
on 04 Apr, 2010 23:59
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#1053
by
Danny Dot
on 05 Apr, 2010 00:01
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Did my Entry Guidance Work Book get posted here??
Reply to
[email protected]Danny Deger
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#1054
by
jhf
on 05 Apr, 2010 01:03
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What are the internal factors that limit Shuttle visit times at ISS? Yes, I know there are constraints due to visiting vehicles not docking with ISS while Shuttle is attached, but I am trying to figure out why otherwise the Shuttle could not stay attached for 30 days, now that ISS can provide power and other consumables to Shuttle.
The fuel cell H2 boils off (the boiloff is still used to produce electrical power). The shuttle needs the fuel cells to provide power post undocking, no H2, no electricity.
It's my understanding, also, that it's possible to turn down the fuel cells only so far before they start choking on their own exhaust, so to speak -- there have been a couple of recent shuttle missions where there was a concern that it would be necessary to throttle the fuel cells up to keep them operational, which would have required cutting the mission short. I have no idea if the fuel cells can be shut down and restarted on orbit -- I know Apollo's couldn't, it required Ground Support Equipment. Or, perhaps NASA just isn't interested in experimenting with the Shuttle these days.
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#1055
by
elmarko
on 05 Apr, 2010 09:42
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Did my Entry Guidance Work Book get posted here??
Reply to [email protected]
Danny Deger
I'm sure you posted it months ago but if not I'll take any interesting documents you want to share
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#1056
by
racshot65
on 05 Apr, 2010 16:09
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Considering how important the Ku Band Attenna is for communicating video to the ground how come they don't have two on the shuttles ?
Are they really expensive ?
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#1057
by
psloss
on 05 Apr, 2010 16:13
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Considering how important the Ku Band Attenna is for communicating video to the ground how come they don't have two on the shuttles ?
It's important, but not mission critical (they still have S-band for data and communications). It's not like other systems where loss of the functionality might have more severe consequences to the mission (like a minimum duration, for example -- not the case for this). There have been multiple missions with loss of one or both modes of the Ku antenna and those all accomplished their mission objectives.
In this case, even assuming that both modes of the antenna have failed (which is not confirmed at this time), the question isn't so much whether or not the mission objectives can be accomplished, but how differently they might be accomplished than the plan going into the mission.
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#1058
by
arkaska
on 05 Apr, 2010 16:17
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It's important, but not necessarily mission critical (they still have S-band for data and communications). It's not like other systems where loss of the functionality might have more severe consequences to the mission (like a minimum duration, for example -- not the case for this). There have been multiple missions with loss of one or both modes of the Ku antenna and those all accomplished their mission objectives. In this case, even assuming that both modes of the antenna have failed, the question isn't so much whether or not the mission objectives can be accomplished, but how differently they might be accomplished than the plan going into the mission.
But since the Columbia disaster ku has been more important since it's crucial for the safety, with the OBSS inspection. In this case this is solved since they can use station ku but what would they have done if they lost ku during STS-125? Then they wouldn't have any chance at all to down-link the inspection video.
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#1059
by
psloss
on 05 Apr, 2010 16:20
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It's important, but not necessarily mission critical (they still have S-band for data and communications). It's not like other systems where loss of the functionality might have more severe consequences to the mission (like a minimum duration, for example -- not the case for this). There have been multiple missions with loss of one or both modes of the Ku antenna and those all accomplished their mission objectives. In this case, even assuming that both modes of the antenna have failed, the question isn't so much whether or not the mission objectives can be accomplished, but how differently they might be accomplished than the plan going into the mission.
But since the Columbia disaster ku has been more important since it's crucial for the safety, with the OBSS inspection. In this case this is solved since they can use station ku but what would they have done if they lost ku during STS-125? Then they wouldn't have any chance at all to down-link the inspection video.
The STS-125 case is the unique case. Would have to check, but it might have been handled differently for that mission.
Edit -- would not have been huge mission impact to 125. Flight rule for that is on L2. (One of the actions, as with STS-92, would have been to use MILA and Dryden to downlink data -- in that case, high-priority inspection data.)
