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#1660
by
ChrisGebhardt
on 16 Mar, 2009 20:13
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If STS-125 can do 5 back-to-back-to-back EVAs, why can't 119 do any, given the shortened docked mission?
It is a crew workload issue for ISS mission. Because you have more time with ISS missions you can space out your EVAs to give the crew some down time. On HST mission, the workload (in terms of EVAs) is heavier so you alternate EVA teams thereby allowing you to do back-to-back EVAs and get all 5 EVAs completed in the 11 mission days you have based on fuel consumable status.
Remember, before SSPTS ISS missions were limited to 3 EVAs (4 in a pinch) because of consumable status.
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#1661
by
NavySpaceFan
on 16 Mar, 2009 20:26
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Just read Chris's articles about the late release of the Tyvek RCS covers, and I was wondering how thick they are? Are they like the Tyvek housewrap you see on newer homes?
ETA: What is the electrical configuration of the shuttle? Current? Voltage? Alternating or Direct Current? Etc.
Tyvek used for the RCS covers is nominally 0.003" to 0.010" for a single ply, but due to problems with tearing they now select for covers with at least 0.007" thickness in those zones prone to tearing. Reinforced areas use three plys together. I think the total weight of a cover is about 30 grams, but I sure someone will be able to correct me if I'm wrong. I don't know how thick building grade Tyvek is.
Thanks AM! And for comparison, the Tyvek used on the orbiters is the same thickness (3 to 10 mils) that is used for industrial packaging.
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#1662
by
NavySpaceFan
on 16 Mar, 2009 20:27
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ETA: What is the electrical configuration of the shuttle? Current? Voltage? Alternating or Direct Current? Etc.
28 VDC*, with some inverters supplying 115 VAC 400 Hz to certain boxes
The standard for spacecraft
Thanks Jim! 3 phase or single phase?
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#1663
by
oxford750
on 16 Mar, 2009 20:59
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Thanks for the answers folks, those pictures are neat.
I will also look at the shuttle Q&A thread.
Still though in regards to question 1, it must be hard "climbing" a ladder that is now going from "left to right" instead of "up and down.
Thanks again
oxford750
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#1664
by
mkirk
on 16 Mar, 2009 21:23
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ETA: What is the electrical configuration of the shuttle? Current? Voltage? Alternating or Direct Current? Etc.
28 VDC*, with some inverters supplying 115 VAC 400 Hz to certain boxes
The standard for spacecraft
Thanks Jim! 3 phase or single phase?
It depends on the system/component - for instance most of the motors (such as freon pumps, water loop pumps, cabin fans, ET door motors etc...) operate on 3 phases.
Mark Kirkman
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#1665
by
NavySpaceFan
on 16 Mar, 2009 21:44
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ETA: What is the electrical configuration of the shuttle? Current? Voltage? Alternating or Direct Current? Etc.
28 VDC*, with some inverters supplying 115 VAC 400 Hz to certain boxes
The standard for spacecraft
Thanks Jim! 3 phase or single phase?
It depends on the system/component - for instance most of the motors (such as freon pumps, water loop pumps, cabin fans, ET door motors etc...) operate on 3 phases.
Mark Kirkman
Thanks Mark!
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#1666
by
Jim
on 16 Mar, 2009 21:50
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Still though in regards to question 1, it must be hard "climbing" a ladder that is now going from "left to right" instead of "up and down.
They don't use the ladder
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#1667
by
usn_skwerl
on 17 Mar, 2009 11:28
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Correct me if I'm wrong, but i think I heard that John Young stood during reentry during STS-1. Is this true?
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#1668
by
dmuench
on 17 Mar, 2009 11:32
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I believe that was Story Musgrave on STS-80 - I bet John Young was too busy during STS-1's reentry.
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#1669
by
psloss
on 17 Mar, 2009 12:26
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Correct me if I'm wrong, but i think I heard that John Young stood during reentry during STS-1. Is this true?
purple monkey dishwasher
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#1670
by
usn_skwerl
on 17 Mar, 2009 16:22
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So it was Musgrave? or no one?
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#1671
by
usn_skwerl
on 17 Mar, 2009 16:43
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ok, thank you kindly
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#1672
by
kimmern123
on 17 Mar, 2009 16:44
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It was Musgrave. It's documented in a book on either Columbia or Challenger - I think it's Challenger.
Tom Jones also writes about it in his book "Skywalking"
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#1673
by
DerekL
on 18 Mar, 2009 15:01
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What's the typical apogee for the ET of a Shuttle mission bound for ISS?
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#1674
by
Jorge
on 18 Mar, 2009 15:08
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What's the typical apogee for the ET of a Shuttle mission bound for ISS?
In general, ET apogee is close to the OMS-2 altitude. For ISS missions, that's 122 nmi.
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#1675
by
Jim
on 18 Mar, 2009 15:30
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What's the typical apogee for the ET of a Shuttle mission bound for ISS?
In general, ET apogee is close to the OMS-2 altitude. For ISS missions, that's 122 nmi.
The only difference is that the orbiter's orbit is slightly different due to the separation maneuvers
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#1676
by
Jorge
on 18 Mar, 2009 16:20
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What's the typical apogee for the ET of a Shuttle mission bound for ISS?
In general, ET apogee is close to the OMS-2 altitude. For ISS missions, that's 122 nmi.
The only difference is that the orbiter's orbit is slightly different due to the separation maneuvers
Right. The +X burn after ET sep, in particular, adds a couple of miles to the orbiter's apogee (since it's effectively posigrade, and is performed not long after perigee).
The -Z burn immediately after ET sep (and before the +X), on the other hand, is mostly radial. So it doesn't significantly alter the orbiter's apogee, though it does rotate the line of apsides a bit.
The pitch maneuver (on flights where it's performed; 119 did not) probably introduces some translational perturbations, since it's a relatively fast maneuver. Almost certainly less than the -Z burn induces.
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#1677
by
MarsMethanogen
on 18 Mar, 2009 19:12
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http://www.belmont.k12.ca.us/ralston/programs/itech/SpaceSettlement/teacher/course/merc.html
Why did NASA switched to a
Oxygen - 21.7% O2 / 78.3% N2 with cabin pressure at 14.7 psi atmosphere for the Shuttle ?
To be like the normal atmosphere
I'm not sure I understand the context of the response to this question (new joiner, just now getting this part of the Q&A and was in high school at the time of the AS-204/Apollo 1 fire), but was the orbiter ever designed to use a pure O2 atmosphere? Didn't NASA go to the mixed gas atmosphere (mimics earth's atmosphere) after the Apollo 1 fire, at least on ascent during the remainder of the Apollo flights? And when developing the orbiter, they used the mixed-gas approach for the entire mission from the beginning?
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#1678
by
ChrisGebhardt
on 18 Mar, 2009 19:28
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http://www.belmont.k12.ca.us/ralston/programs/itech/SpaceSettlement/teacher/course/merc.html
Why did NASA switched to a
Oxygen - 21.7% O2 / 78.3% N2 with cabin pressure at 14.7 psi atmosphere for the Shuttle ?
To be like the normal atmosphere
I'm not sure I understand the context of the response to this question (new joiner, just now getting this part of the Q&A and was in high school at the time of the AS-204/Apollo 1 fire), but was the orbiter ever designed to use a pure O2 atmosphere? Didn't NASA go to the mixed gas atmosphere (mimics earth's atmosphere) after the Apollo 1 fire, at least on ascent during the remainder of the Apollo flights? And when developing the orbiter, they used the mixed-gas approach for the entire mission from the beginning?
Welcome to the site!
Yes, the switch to a more earth-like atmosphere was made after the Apollo 1 fire since a pure oxygen environment is prone to combustibility. Shuttle was designed after the Apollo 1 fire and was never intended to have a pure oxygen atmosphere.
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#1679
by
Jim
on 18 Mar, 2009 21:22
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Yes, the switch to a more earth-like atmosphere was made after the Apollo 1 fire since a pure oxygen environment is prone to combustibility.
Only on the ground. It went to pure O2 at 5 PSIA on orbit. This always was intent for Apollo and Gemini and Mercury did the same thing. The issue was the pure O2 at sea level pressure
