Author Topic: Shuttle Questions Q & A (Part 4)  (Read 532112 times)

Offline AnalogMan

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2080 on: 06/11/2009 11:16 pm »
I have a question: where in the space shuttle is an APU power?

They in the aft fuselage, on the back side of the payload bay aft bulkhead.

This is what an APU looks like (from the KSC Media Gallery).

For the second photo:

CAPE CANAVERAL, Fla. In Orbiter Processing Facility bay No. 2, technicians  begin installation of an auxiliary power unit 3, or APU3, in space shuttle  Endeavour for the STS-126 mission. The auxiliary power unit is a  hydrazine-fueled, turbine-driven power unit that generates mechanical shaft  power to drive a hydraulic pump that produces pressure for the orbiter's  hydraulic system. There are three separate APUs, three hydraulic pumps and three  hydraulic systems, located in the aft fuselage of the orbiter.

Offline Antares

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2081 on: 06/12/2009 12:45 am »
Firstly, for the third time I'm hoping someone can answer my question about "spreading" - sometimes MCC will call the orbiter to let the crew know that there will be a loss of comm due to this spreading. What is spreading in this context?

At the time when I heard it, I remember thinking it was the plume obscuring the RF, but that doesn't make sense if it was going up through TDRSS.  Maybe multipath?  (I figured on the 3rd try, a non-RF guy was allowed to guess.)
If I like something on NSF, it's probably because I know it to be accurate.  Every once in a while, it's just something I agree with.  Facts generally receive the former.

Offline AnalogMan

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2082 on: 06/12/2009 02:26 am »
Firstly, for the third time I'm hoping someone can answer my question about "spreading" - sometimes MCC will call the orbiter to let the crew know that there will be a loss of comm due to this spreading. What is spreading in this context?

At the time when I heard it, I remember thinking it was the plume obscuring the RF, but that doesn't make sense if it was going up through TDRSS.  Maybe multipath?  (I figured on the 3rd try, a non-RF guy was allowed to guess.)

It may be related to the use of spread spectrum methods in the S-band (I think orbiters use 1.7- to 2.3 GHz).  As I understand it some channels optionally use this method which spreads the channel over a wider band of frequencies to reduce the effects of interference from other systems (ground or orbiter based).  The technique involves modulating the RF carriers with a pseudo-random sequence to spread the RF energy over a wider bandwidth.

The receivers (ground and orbiter based) must be able to lock onto these transmitted signals and synchronise their own local version of the pseudo-random sequence in order to reconstruct the original data content.

So maybe the comment refers to predictable difficulties with receiving such signals - two possibilities that spring to mind are reduced signal-to-noise ratios, or variable signal loss across the RF signal band.

Offline MarsMethanogen

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2083 on: 06/12/2009 01:48 pm »
Appreciate your research AnalogMan, in Reply 2106 above, but that's not what I'm referring to.  It actually looks like steam, it comes out in pulses, there is a sound that accompanies it, and it's coming out right at the location where the outlets for the water spray boilers are on either side of the tail after the Orbiter has come to a stop at the SLF, but has yet to shut off its APUs.  Venting from the water spray boilers is the only thing that makes sense.  I just wanted to make sure that it wasn't APU, expended hypergol "exhaust", because these vents are very close to the water spray boiler vents.  Not a big deal, it's just that this looks so incongruous ("locomotive breath") coming out of a relatively high-tech Orbiter.

Offline psloss

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2084 on: 06/12/2009 02:10 pm »
Appreciate your research AnalogMan, in Reply 2106 above, but that's not what I'm referring to.  It actually looks like steam, it comes out in pulses, there is a sound that accompanies it, and it's coming out right at the location where the outlets for the water spray boilers are on either side of the tail after the Orbiter has come to a stop at the SLF, but has yet to shut off its APUs.  Venting from the water spray boilers is the only thing that makes sense.  I just wanted to make sure that it wasn't APU, expended hypergol "exhaust", because these vents are very close to the water spray boiler vents.  Not a big deal, it's just that this looks so incongruous ("locomotive breath") coming out of a relatively high-tech Orbiter.
Can you point to an example mission?  Would probably help with responses.

Offline MarsMethanogen

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2085 on: 06/12/2009 02:34 pm »
Appreciate your research AnalogMan, in Reply 2106 above, but that's not what I'm referring to.  It actually looks like steam, it comes out in pulses, there is a sound that accompanies it, and it's coming out right at the location where the outlets for the water spray boilers are on either side of the tail after the Orbiter has come to a stop at the SLF, but has yet to shut off its APUs.  Venting from the water spray boilers is the only thing that makes sense.  I just wanted to make sure that it wasn't APU, expended hypergol "exhaust", because these vents are very close to the water spray boiler vents.  Not a big deal, it's just that this looks so incongruous ("locomotive breath") coming out of a relatively high-tech Orbiter.
Can you point to an example mission?  Would probably help with responses.

I never really made the time, or was too busy to watch the landings until the I found this site (and the time) to watch the last two SLF landings, and the last one would have been STS-119.  I recall that the NSF coverage on the landing day thread that someone made a comment on what a noisy beast she was exactly at the point that I'm describing.  This isn't the only time I've seen it, but can't recall any specific missions.  But my impression was that this was completely normal. Indeed, the PAO on NASA TV never made any mention of it, either.

Offline psloss

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2086 on: 06/12/2009 02:44 pm »
I never really made the time, or was too busy to watch the landings until the I found this site (and the time) to watch the last two SLF landings, and the last one would have been STS-119.  I recall that the NSF coverage on the landing day thread that someone made a comment on what a noisy beast she was exactly at the point that I'm describing.  This isn't the only time I've seen it, but can't recall any specific missions.  But my impression was that this was completely normal. Indeed, the PAO on NASA TV never made any mention of it, either.
Well, since the 119 landing was in daylight and no one mentioned seeing anything in the regular video, I'm assuming you're referring to the IR video...if that's the case, that's thermal signature of the normal APU exhaust.

The sound is also the APUs.  If those are running, it's something we get to hear when the orbiter is close enough to ground microphones-- both before liftoff and around/after wheels stop.

Offline MarsMethanogen

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2087 on: 06/12/2009 08:14 pm »
If there were to be a TAL abort, are there NASA TV cameras stationed at the abort sites, just in case?

No.
Perhaps it's buried in this or the three preceeding threads, but I had always been curious as to the nature of these TAL sites (primarily the two in Spain and the one in France.  Are they military bases, with the typical long runways that accompany a military base, are there NASA personnel there at the time of a launch, etc.  Recognizing that Google can be one's friend, I found this and so I thought I'd share it.

NASA PRESS RELEASE: 05-143

U.S. & FRANCE AGREE TO ESTABLISH NASA SHUTTLE LANDING SITE

The governments of the United States of America and the French Republic have agreed to establish a Transoceanic Abort Landing (TAL) site for NASA's Space Shuttle at Istres Air Base 125, in the South of France.

The agreement was signed in Washington today by NASA Administrator Michael Griffin and the Ambassador of France, His Excellency Jean-David Levitte. The agreement covers Space Shuttle missions supporting the International Space Station. It provides for landing at the French Air Force base for a Shuttle that encounters an emergency during launch. The TAL sites could be used if a Shuttle is unable to reach orbit or a landing site in the U.S.

This agreement permits the U.S. government to place equipment and personnel at the base in advance of Space Shuttle missions; to perform weather monitoring; to ensure NASA navigational facilities and landing aids are operational; to provide search and rescue capability and medical evacuation support.

"Today's agreement follows a long history of mutually beneficial space cooperation between France and the United States," Griffin said. "We also appreciate the assistance of the French Air Force, which has taken a leading role in this effort."

Istres Air Base 125 was selected because of its location near the nominal ascent ground track of the Space Shuttle. The base also has one of the longest airstrips in Europe, more than 3.1 miles long. The base will be the third active TAL site, supplementing NASA's two other sites in Zaragoza and Moron, Spain. For NASA to launch a Shuttle, weather conditions must be acceptable at least at one TAL site.

Offline psloss

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2088 on: 06/12/2009 08:50 pm »
If there were to be a TAL abort, are there NASA TV cameras stationed at the abort sites, just in case?

No.
There's only two landing sites that can provide live coverage right now: KSC and Dryden/Edwards.  (When there seemed to be a greater possibility of a Northrup/White Sands landing for STS-116, they were going to have to send TV equipment out to cover it.)

Offline rdale

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2089 on: 06/12/2009 09:03 pm »
Banjul, also no longer used, is Yundum International Airport. NASA built a dedicated building at each of those locations.

STS-125 was told "negative Moron, select Banjul." Wouldn't that imply it's still used?

Offline MarsMethanogen

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2090 on: 06/12/2009 09:04 pm »
Thanks, padrat, for the additional detail.  That's the kind of stuff I'd always been curious about.

Offline mmeijeri

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2091 on: 06/12/2009 09:05 pm »
"negative Moron, select Banjul."

What a memorable and hilarious turn of phrase! :)
We will be vic-toooooo-ri-ous!!!

Offline MarsMethanogen

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2092 on: 06/12/2009 09:14 pm »
"negative Moron, select Banjul."

What a memorable and hilarious turn of phrase! :)
I didn't pick up on that the first time around, but that could be right out of the movie, 'Airplane'.  Proof that it all depends on which syllable one places the accent on!

Offline psloss

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2093 on: 06/12/2009 09:35 pm »
Banjul, also no longer used, is Yundum International Airport. NASA built a dedicated building at each of those locations.

STS-125 was told "negative Moron, select Banjul." Wouldn't that imply it's still used?
In a big emergency they might land there (edit -- probably only considered for low-inclination flights, which are now concluded), but the execute packages for 125 noted that Banjul was "politically not recommended."
« Last Edit: 06/12/2009 09:38 pm by psloss »

Offline NSF Webmaster

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Re: Shuttle Questions Q & A (Part 4)
« Reply #2094 on: 06/12/2009 11:14 pm »

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