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#1280
by
hyper_snyper
on 17 Sep, 2008 20:03
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I have a question...
What are the procedures if one, two, or all three SSMEs fail immediately after launch. Say within 10 or 20 seconds or so. So early in the launch I would imagine losing even one would be a problem. Or even anytime before SRB burnout.
I guess my question is... do the SRBs have enough control authority to keep the stack stable until sep so then the vehicle can go into some abort mode, if it is even possible at that point. Is there like a neat chart which summarizes all the abort scenarios and their limits?
Oh, apologies if this has been asked before I did a search and couldn't find it.
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#1281
by
psloss
on 17 Sep, 2008 20:17
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What are the procedures if one, two, or all three SSMEs fail immediately after launch. Say within 10 or 20 seconds or so. So early in the launch I would imagine losing even one would be a problem. Or even anytime before SRB burnout.
Single engine out would be a RTLS abort with the orbiter landing at the SLF. Two or three engines out that early in first stage, if they are lucky, it would be a contingency abort with the crew bailing out of the orbiter -- ride the boosters up to just before what would normally be SRB sep and then do a fast-sep from the ET/SRBs and get into a safe config for bailout, with the orbiter being ditched in the Atlantic (and thus lost).
Oh, apologies if this has been asked before I did a search and couldn't find it.
No worries; I'm having trouble finding it, too...it's definitely been discussed here.
Edit: found it; start here, and then read through the replies on the next few pages:
http://forum.nasaspaceflight.com/index.php?topic=10600.msg278427#msg278427
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#1282
by
Zoe
on 18 Sep, 2008 22:06
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There is an engine out RLTS simulation on youtube, search for RTLS Simulation. The video is not part of the simulation, only the commentary is.
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#1283
by
Danny Dot
on 19 Sep, 2008 14:38
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I have a question...
What are the procedures if one, two, or all three SSMEs fail immediately after launch. Say within 10 or 20 seconds or so. So early in the launch I would imagine losing even one would be a problem. Or even anytime before SRB burnout.
I guess my question is... do the SRBs have enough control authority to keep the stack stable until sep so then the vehicle can go into some abort mode, if it is even possible at that point. Is there like a neat chart which summarizes all the abort scenarios and their limits?
Oh, apologies if this has been asked before I did a search and couldn't find it.
For three engines out off of the pad, the air loads at max Q will rip the orbiter off of the ET.
Danny
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#1284
by
DMeader
on 19 Sep, 2008 14:59
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For three engines out off of the pad, the air loads at max Q will rip the orbiter off of the ET.
Danny
Without the main engines thrusting it seems like the stack would want to go over on its back almost immediately or at least fly significantly off the normal trajectory. I wonder if it would even clear the pad.
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#1285
by
Ford Mustang
on 20 Sep, 2008 20:57
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The Shuttle uses Ku-Band downlink for their video from on orbit. Does it go through a satellite and specific transponder to be played over NASA's airwave? If so, what are the coordinates / frequencies?
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#1286
by
bobthemonkey
on 20 Sep, 2008 21:06
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Surely it goes through the TDRSS network.
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#1287
by
Jim
on 20 Sep, 2008 21:08
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The Shuttle uses Ku-Band downlink for their video from on orbit. Does it go through a satellite and specific transponder to be played over NASA's airwave? If so, what are the coordinates / frequencies?
Actually, it is Ku-band uplink from the shuttle to the satellite and the satellite downlinks it. The satellite system is TDRSS and there are multiple spacecraft. You won't be able to get these signals, they are directed only to White Sand Ground station and they are encrypted.
The TV is sent to Houston and then included on NTV which uses a domestic comsat
Ford, I am surprised you didn't know this
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#1288
by
Ford Mustang
on 20 Sep, 2008 21:12
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The Shuttle uses Ku-Band downlink for their video from on orbit. Does it go through a satellite and specific transponder to be played over NASA's airwave? If so, what are the coordinates / frequencies?
Actually, it is Ku-band uplink from the shuttle to the satellite and the satellite downlinks it. The satellite system is TDRSS and there are multiple spacecraft. You won't be able to get these signals, they are directed only to White Sand Ground station and they are encrypted.
The TV is sent to Houston and then included on NTV which uses a domestic comsat
Ford, I am surprised you didn't know this
Perhaps I worded it wrong. I knew it went through TDRSS, as per the TDRS handovers on orbit, but was curious as to if you could get it from home without going through NASA TV. I figured it would be highly encrypted, but had a brainy (read: stupid) idea that you could somehow get the signal directly. I know you can do this through C-Band (get it directly in the raw without going through NASA TV), but was wondering on the Ku part.
Thanks anyways.
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#1289
by
Jim
on 20 Sep, 2008 21:16
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I knew it went through TDRSS, as per the TDRS handovers on orbit, but was curious as to if you could get it from home without going through NASA TV.
Direct TV has antennas that spread the signal all over the country. TDRSS focuses its link only at White Sands.
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#1290
by
Ford Mustang
on 20 Sep, 2008 21:21
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I knew it went through TDRSS, as per the TDRS handovers on orbit, but was curious as to if you could get it from home without going through NASA TV.
Direct TV has antennas that spread the signal all over the country. TDRSS focuses its link only at White Sands.
Alright. Just looking on the internet, found a document that has TDRSS information (downlink and uplink), as well as White Sands information, which perked my curiosity. Would be on the top of Page 8 if you are interested.
.PDF file located here.
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#1291
by
rdale
on 20 Sep, 2008 21:25
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I know you can do this through C-Band (get it directly in the raw without going through NASA TV)
No you cannot - there is no raw video on C-Band either. The only source of it not encrypted is NASA TV.
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#1292
by
Ford Mustang
on 20 Sep, 2008 21:45
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Thanks for the replies, guys. I'm good when there is a Shuttle on orbit, but not so good as to their downlinking system (as you can obviously see).
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#1293
by
Orbiter
on 21 Sep, 2008 01:30
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Got a question that is bugging me.
After the horrible and tragic loss of Challenger, because the cold weather was only just above freezing which help along with many other factor's for the O-Ring to burn through, do they now allow Shuttle's to launch in cold weather because of the modified O-Rings since Challenger?
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#1294
by
DaveS
on 21 Sep, 2008 01:55
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Got a question that is bugging me.
After the horrible and tragic loss of Challenger, because the cold weather was only just above freezing which help along with many other factor's for the O-Ring to burn through, do they now allow Shuttle's to launch in cold weather because of the modified O-Rings since Challenger?
Nope. Too cold and there's a scrub. STS-109/HST SM3B actually got scrubbed for 24 hrs when the forecast for Feb. 28 promised too cold weather. Warmer temperatures was expected 24 hrs later on March 1. And it was indeed too cold for a launch on Feb. 28.
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#1295
by
psloss
on 21 Sep, 2008 02:04
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After the horrible and tragic loss of Challenger, because the cold weather was only just above freezing which help along with many other factor's for the O-Ring to burn through, do they now allow Shuttle's to launch in cold weather because of the modified O-Rings since Challenger?
Here's a link to a press release that outlines launch weather criteria, including temperature constraints:
http://www-pao.ksc.nasa.gov/kscpao/release/1999/39-99.htm
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#1296
by
HelixSpiral
on 22 Sep, 2008 20:29
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#1297
by
mark147
on 22 Sep, 2008 20:32
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One just after midnight at the beginning of the day, one around midnight at the end of the day.
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#1298
by
psloss
on 22 Sep, 2008 20:39
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One just after midnight at the beginning of the day, one around midnight at the end of the day.
Right -- if I pick a different time zone, GMT, then those two windows work out to:
11 Oct: 4:03:54 to 5:09:13
12 Oct: 3:36:45 to 4:38:36
Same "double" window happens in GMT on October 19...
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#1299
by
HelixSpiral
on 22 Sep, 2008 20:49
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One just after midnight at the beginning of the day, one around midnight at the end of the day.
Right -- if I pick a different time zone, GMT, then those two windows work out to:
11 Oct: 4:03:54 to 5:09:13
12 Oct: 3:36:45 to 4:38:36
Same "double" window happens in GMT on October 19...
Haha, silly me.
Gotta love times that cross midnight.
Gotta love times that cross midnight.