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#500
by
Jorge
on 09 Feb, 2008 13:17
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nacnud - 9/2/2008 8:15 AM
That was quick, thanks.
Jorge - 9/2/2008 2:07 PM
Speed is slowest at apogee so the orbiter is falling behind a bit.
Ok so the shuttle has a higher apogee than the station then I suppose to help manage the rate of approach. Is a (small) burn at perigee is needed to lower this?
No, if you look at the plot you see that apogee is actually a bit below the station altitude.
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#501
by
Jim
on 09 Feb, 2008 13:18
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Susan27 - 9/2/2008 7:13 AM
Hi,
when watching live coverage showing the shuttle cruising the orbit I recognized that the orbiter is situated Upside-down towards the earth nearly all the time...
Do you know the reason for that kind of positioning? Does that have something to do with the radiators, the TDRS-signal quality or why is it that way...?
Thanks!
Kind regards
it provides for a relatively benign thermal environment. The earth's thermal radiance is better than deep space or pointed at the sun. The TDRSS antenna has to actually stick out and look past the radiators
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#502
by
ZANL188
on 09 Feb, 2008 13:20
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Susan27 - 9/2/2008 6:13 AM
Hi,
when watching live coverage showing the shuttle cruising the orbit I recognized that the orbiter is situated Upside-down towards the earth nearly all the time...
Do you know the reason for that kind of positioning? Does that have something to do with the radiators, the TDRS-signal quality or why is it that way...?
Thanks!
Kind regards
Thermal control. The earth provides a moderating influence to the payload bay, providing a near constant temp. As opposed to the belly which is sometimes pointed at the sun, blazing hot, and sometimes pointed away from the sun, super cold.
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#503
by
Squid.erau
on 09 Feb, 2008 13:25
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Jorge is deffinately the authority on this, but I was actually just learning about this display in one of my classes the other day. It's a coordinate system based on the position of the ISS. The ISS is fixed in the upper left corner of the display, with down or the negative y direction being the negative R-bar. Right, or positive x direction is the negative V-bar. This looks like the shuttle is doing an approach along the negative V-bar, with the final location located like Jorge said on the negative R-bar, in place for the RPM.
Hope this helps some,
Matt
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#504
by
Jim
on 09 Feb, 2008 13:30
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elmarko - 9/2/2008 8:42 AM
1.Can someone give me some information on the "path" of the signal from the ET tank? And approximately how long after separation the signal can be picked up? Is it coming from the ET to the Orbiter to the ground? Or via a satellite? Or is it direct from the ET to it's destination.
2. Secondly, the SRB cameras, how do they work? I'm assuming it's solid state storage of some kind?
1. the signal is sent from the ET to a ground station. Either, the NASA Tracking Station at Ponce DeLeon Inlet 3\; JDMTA, the Air Force tracking station in south Florida at Jupiter Inlet; MILA, the NASA tracking station at Kennedy; or Wallops Flight Facility, Virginia Eastern Shore. the signal is lost when the ET goes below the hrizon
2. correct
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#505
by
psloss
on 09 Feb, 2008 13:33
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Jim - 9/2/2008 9:30 AM
1. the signal is sent from the ET to a ground station. Either, the NASA Tracking Station at Ponce DeLeon Inlet 3\; JDMTA, the Air Force tracking station in south Florida at Jupiter Inlet; MILA, the NASA tracking station at Kennedy; or Wallops Flight Facility, Virginia Eastern Shore. the signal is lost when the ET goes below the hrizon
While you're here, is there any difference in the ground station for due-east launches? Wondering if Wallops is in range in that case.
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#506
by
Jorge
on 09 Feb, 2008 14:03
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Squid.erau - 9/2/2008 8:25 AM
Jorge is deffinately the authority on this, but I was actually just learning about this display in one of my classes the other day. It's a coordinate system based on the position of the ISS. The ISS is fixed in the upper left corner of the display, with down or the negative y direction being the negative R-bar. Right, or positive x direction is the negative V-bar. This looks like the shuttle is doing an approach along the negative V-bar, with the final location located like Jorge said on the negative R-bar, in place for the RPM.
Hope this helps some,
Matt
NASA uses a coordinate system a little different from that. The +X axis is along the positive velocity vector (+Vbar) and the +Z axis is toward the center of the Earth (+Rbar). The +Y axis points "into the screen". This coordinate system is called Local Vertical - Local Horizontal (LVLH).
The system you're describing sounds more like the Orbital Coordinate System, which is used by the Russians and is also fairly common in academic texts.
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#507
by
Jim
on 09 Feb, 2008 14:30
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psloss - 9/2/2008 9:33 AM
Jim - 9/2/2008 9:30 AM
1. the signal is sent from the ET to a ground station. Either, the NASA Tracking Station at Ponce DeLeon Inlet 3\; JDMTA, the Air Force tracking station in south Florida at Jupiter Inlet; MILA, the NASA tracking station at Kennedy; or Wallops Flight Facility, Virginia Eastern Shore. the signal is lost when the ET goes below the hrizon
While you're here, is there any difference in the ground station for due-east launches? Wondering if Wallops is in range in that case.
Antigua
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#508
by
psloss
on 09 Feb, 2008 14:31
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Jim - 9/2/2008 10:30 AM
psloss - 9/2/2008 9:33 AM
Jim - 9/2/2008 9:30 AM
1. the signal is sent from the ET to a ground station. Either, the NASA Tracking Station at Ponce DeLeon Inlet 3\; JDMTA, the Air Force tracking station in south Florida at Jupiter Inlet; MILA, the NASA tracking station at Kennedy; or Wallops Flight Facility, Virginia Eastern Shore. the signal is lost when the ET goes below the hrizon
While you're here, is there any difference in the ground station for due-east launches? Wondering if Wallops is in range in that case.
Antigua
Thanks, Jim.
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#509
by
Susan27
on 09 Feb, 2008 14:50
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1) During the final part of the ISS-docking procedure the commander/pilot of course have to sit in their seats, but what about the other crew members...do they also have to sit in their seats for safety reasons? Or are they allowed to move freely through the orbiter?
2) What about safety (seat) belts, I mean the ones they wear at launch: Does the crew have to wear them due to possible impact-motions when going into port (with the docking ring) while docking or isnt it required at all?
Thanks very much!
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#510
by
Jorge
on 09 Feb, 2008 14:57
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Susan27 - 9/2/2008 9:50 AM
1) During the final part of the ISS-docking procedure the commander/pilot of course have to sit in their seats
No. The CDR is flying manually in the aft station, and is floating free.
The PLT sits in the CDR seat but that is only required so he can access the forward THC in the event of an aft THC failure.
but what about the other crew members...do they also have to sit in their seats for safety reasons? Or are they allowed to move freely through the orbiter?
There is typically one MS in the PLT seat to assist the PLT with any forward switch throws, but this is not required. Everyone else floats free.
2) What about safety (seat) belts, I mean the ones they wear at launch: Does the crew have to wear them due to possible impact-motions when going into port (with the docking ring) while docking or isnt it required at all?
Not required.
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#511
by
Jim
on 09 Feb, 2008 15:00
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Susan27 - 9/2/2008 10:50 AM
1) During the final part of the ISS-docking procedure the commander/pilot of course have to sit in their seats, but what about the other crew members...do they also have to sit in their seats for safety reasons? Or are they allowed to move freely through the orbiter?
2) What about safety (seat) belts, I mean the ones they wear at launch: Does the crew have to wear them due to possible impact-motions when going into port (with the docking ring) while docking or isnt it required at all?
Thanks very much!
1. the CDR doesn't sit in his seat, he is at the aft flight deck where the rendezvous and docking are performed. some other crew members are in the seats monitoring the shuttle systems. the remaining are free to move around
2. no restraints are required. the accels are low. BTW, the term is "to dock" vs "into port"
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#512
by
Susan27
on 09 Feb, 2008 15:44
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Jorge - 9/2/2008 9:57 AM
No. The CDR is flying manually in the aft station, and is floating free.
Oh, I see. But how does he "steer" the orbiter? Are there also RHC in the aft section etc. and what is the reason the CMD doesnt fly the docking from his seat in front of the shuttle?
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#513
by
Jorge
on 09 Feb, 2008 15:53
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Susan27 - 9/2/2008 10:44 AM
Jorge - 9/2/2008 9:57 AM
No. The CDR is flying manually in the aft station, and is floating free.
Oh, I see. But how does he "steer" the orbiter? Are there also RHC in the aft section etc. and what is the reason the CMD doesnt fly the docking from his seat in front of the shuttle?
There is a THC and an RHC in the aft station. The RHC is not used during ISS approach; the CDR allows the digital autopilot (DAP) to control attitude and the CDR controls translation manually with the THC.
The CDR flies from the aft station because he can't see the station from the forward station.
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#514
by
Jim
on 09 Feb, 2008 15:57
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Jorge - 9/2/2008 11:53 AM
Susan27 - 9/2/2008 10:44 AM
Jorge - 9/2/2008 9:57 AM
No. The CDR is flying manually in the aft station, and is floating free.
Oh, I see. But how does he "steer" the orbiter? Are there also RHC in the aft section etc. and what is the reason the CMD doesnt fly the docking from his seat in front of the shuttle?
There is a THC and an RHC in the aft station. The RHC is not used during ISS approach; the CDR allows the digital autopilot (DAP) to control attitude and the CDR controls translation manually with the THC.
The CDR flies from the aft station because he can't see the station from the forward station.
the station is visually tracked through the overhead windows
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#515
by
dcbecker
on 09 Feb, 2008 18:14
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here's a fun trivia question and answer.
What is the *root* cause/reason for the specification of the shuttle SRB diameters?
The SRBs are made by Thiokol at their factory at Utah. The engineers who designed the SRBs would have preferred to make them a bit fatter, but the SRBs had to be shipped by train from the factory to the launch site. The railroad line from the factory happens to run through a tunnel in the mountains. The SRBs had to fit through that tunnel.
So why was the tunnel that size? The tunnel is slightly wider than the railroad track.
So why are the railroad tracks that width? The US standard railroad gauge (distance between the rails) is 4 feet, 8.5 inches. That's an exceedingly odd number.
Why was that gauge used? Because that's the way they built them in England, and English expatriates built the US Railroads.
Why did the English build them like that? Because the first rail lines were built by the same people who built the pre-railroad tramways, and that's the gauge they used.
Why did "they" use that gauge then? Because the people who built the tramways used the same jigs and tools that they used for building wagons, which used that wheel spacing.
Okay! Why did the wagons have that particular odd wheel spacing? Well, if they tried to use any other spacing, the wagon wheels would break on some of the old, long distance roads in England, because that's the spacing of the wheel ruts.
So who built those old rutted roads? Imperial Rome built the first long distance roads in Europe (and England) for their legions. The roads have been used ever since.
So why were the the ruts in the roads that size? Roman war chariots formed the initial ruts, which everyone else had to match for fear of destroying their wagon wheels. Since the chariots were made for Imperial Rome, they were all alike in the matter of wheel spacing.
The United States standard railroad gauge of 4 feet, 8.5 inches is derived from the original specifications for an Imperial Roman war chariot. And bureaucracies live forever. So the next time you are handed a specification and wonder what horse's ass came up with it, you may be exactly right, because the Imperial Roman army chariots were made just wide enough to accommodate the back ends of two war horses!
So the answer is that one of the components of the most advanced space transportation system in the world was based on the width of a horse's ass.
:laugh:
Dan
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#516
by
Chris Bergin
on 09 Feb, 2008 18:22
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Actually, that's total nonsense, and has been heavily debunked as an urban myth. Sorry.
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#517
by
dcbecker
on 09 Feb, 2008 18:27
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I should'a known.
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#518
by
TJL
on 09 Feb, 2008 18:53
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Of the 9 Shuttle / MIR dockings and 24 Shuttle / ISS link-ups, have all of them occured on FD-3?
Thanks.
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#519
by
Squid.erau
on 09 Feb, 2008 19:02
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Jorge - 9/2/2008 10:03 AM
[
NASA uses a coordinate system a little different from that. The +X axis is along the positive velocity vector (+Vbar) and the +Z axis is toward the center of the Earth (+Rbar). The +Y axis points "into the screen". This coordinate system is called Local Vertical - Local Horizontal (LVLH).
The system you're describing sounds more like the Orbital Coordinate System, which is used by the Russians and is also fairly common in academic texts.
Thank you very much sir. I was a bit confused by some of the lables for ISS and shuttle attitudes on the timeline summeries on L2, but your explanation cleared up my confusion.
Matt
