Question Q/A's FOR STS - Page 24 - Orbiter-Forum

**Urwumpe** · 08-26-2011, 04:39 PM

Quote:

Originally Posted by Eagle1Division

I remember reading somewhere that the shuttle doesn't open it's bay doors soon after MECO, that it waits a good while first. I know it's vague, but if it's true, why? Wouldn't opening the payload bay doors be one of the first things done on-orbit, to get rid of the system heat of the hydraulics, EPS, APU, OMS and MPS from the climb to orbit and OMS burns?

...Maybe, is it because they want to ensure all systems are working before they open the doors?

Shuttle Reference Manual didn't even mention the opening of the Payload bay doors as one of the post-MECO ops.

The opening of the Payload bay doors happens during the Post-Insertion (PI) checklist. Nominally you begin that task one hour after lift-off, with "CONFIG FOR PLBD OPERATIONS" (PI 1-14) and actually opening the doors at about 01:25 MET.

The PI checklist starts at 00:50 MET and thus directly after OMS-2. before you configure the payload bay doors, you have the following major activities:

SPECIALIST SEAT EGRESS
CONFIG GPCS FOR OPS2 (important since the payload bay door control software is in SM OPS2, also this is a very complex task, since it involves 5 computers at once)
PL BUS ACTIVATION
PRELIM MIDDECK CONFIG
AFT STATION CONFIG (so you can also check that the payload bay doors open properly)

Between configuration for payload bay door operations and opening, you have:

WCS CONFIG/ACT (the toilet, you really need it)
SWITCH CONFIG/GALLEY ACT (If you get thirsty by now, you might like it)
DON/CONFIG COMM (It is a bit loud in the Shuttle, so you better get this done soon, so you know what the person right next to you is saying)
LOAD DAP A5 (configure the autopilot for the next maneuver)
MNVR TO PLBD OPENING ATT ("maneuver to payload bay door opening attitude"; you can't do this in every orientation, you use "BIASED -ZLV +YVV".*)
RAD ACT (the radiators are already activated before opening the doors - otherwise you could damage them)

*The exact attitude is defined in UNIV PTG as follows: Body vector is selected as 3 (-Z), Target is 2 (Center of Earth), Omicron angle is 280°. This means the shuttle Z axis is pointed as such that down (-Z) is towards the center of Earth, and Y is in the plane between -Z and orbit antinormal (-h) and then the shuttle is rotated clockwise around the target vector (towards center of Earth) by 280° (Defined in ORB OPS 7-33). Which in this case means: The shuttle flies wings level and with 80° slideslip to the left.

If +/- Y would be selected as reference body vector, the -Z axis of the Shuttle Coordinate System (down) would be used as second vector instead.

Zamzara · 10-04-2011, 04:15 PM

In Orbiter I can reach a Moron-TAL with one engine out from launch, and an ATO shortly after. This is with a payload set to 25 tonnes.

Clearly either the real life abort windows are rather conservative, or the simulated characteristics in Orbiter are a bit generous, does anyone know which?

**Urwumpe** · 10-04-2011, 04:21 PM

Quote:

Originally Posted by Zamzara

In Orbiter I can reach a Moron-TAL with one engine out from launch, and an ATO shortly after. This is with a payload set to 25 tonnes.

Clearly either the real life abort windows are rather conservative, or the simulated characteristics in Orbiter are a bit generous, does anyone know which?

Actually both. The Moron-TAL window is calculated with a lot of extra performance left so some damage to the Shuttle remains tolerable.

Also, the Orbiter Shuttle models have all some small and large variations to the real one, especially the default Shuttle.

Finally: The checklist TAL windows are no-communication TAL windows, which means, they have to be very conservative, as the crew has less means to calculate their ability to reach an abort site, than mission control with their radar tracking sites and special computer programs.

Zamzara · 10-05-2011, 12:00 PM

That makes sense, thanks.

Spaced · 10-05-2011, 03:06 PM

I've heard it said that before her accident Challenger was considered the workhorse of the fleet. I've also read that Columbia had more surface tiles and weighed more than the other orbiters. How different was each airframe?
Were there any capability specific reasons for an orbiter's selection for a mission? Or was it simply maintenance and turnaround that specified what shuttle would be available?

GoForPDI · 10-11-2011, 01:41 PM

All the Orbiters had different weights. Columbia was by far the heaviest, she was used mainly for science missions with a pressurised Hab module in the payload bay. All the Orbiters have small differences to each other. I believe either Endeavour or Atlantis (i'm not too sure) was not fitted with plumbing which could attach to the ISS' plumbing, which limited its usable time in Orbit.

Scav · 10-11-2011, 03:06 PM

Quote:

Originally Posted by GoForPDI

I believe either Endeavour or Atlantis (i'm not too sure) was not fitted with plumbing which could attach to the ISS' plumbing, which limited its usable time in Orbit.

It was Atlantis, yes.

**garyw** · 10-11-2011, 03:24 PM

By 'plumbing' do you mean SSPTS?

If so only Endeavour and Discovery had that modification. Atlantis was supposed to be retired first.

MattBaker · 01-06-2012, 10:20 PM

I asked myself how high the Shuttle could fly, so:

A Shuttle with the configuration of 2011, Super Leightweight ET etc, with nothing in the cargo bay.
The orbit should be circular, as an example 600x600.
There should be enough fuel left for an deorbit burn of course.

So, what's possible for the Shuttle? The Hubble missions were, compared to the ISS, missions with a quite high orbit.

**Urwumpe** · 01-06-2012, 10:24 PM

Quote:

Originally Posted by MattBaker

So, what's possible for the Shuttle? The Hubble missions were, compared to the ISS, missions with a quite high orbit.

Hard maximum is about 700 km circular. That is not only getting at the limits of the propellant resources, but also at the limits of the heat shield.

**IronRain** · 01-15-2012, 05:55 PM

Not entirely a STS question but it gets close to it.

I was watching the post-flight video of STS-37 and the Gamma Ray Observatory was lifted out of the cargo bay, then one solar panel was deployed, when that was completed the other solar was deployed and then the Hi-gain antenna should have deployed.

Now is my question: Who issues the command to do this? Ground controllers or the shuttle crew? And if it's the shuttle crew do they do it wireless or is there some kind of data transfer possible through the RMS?

Thanks!

**Urwumpe** · 01-15-2012, 06:08 PM

Quote:

Originally Posted by IronRain

Not entirely a STS question but it gets close to it.

I was watching the post-flight video of STS-37 and the Gamma Ray Observatory was lifted out of the cargo bay, then one solar panel was deployed, when that was completed the other solar was deployed and then the Hi-gain antenna should have deployed.

Now is my question: Who issues the command to do this? Ground controllers or the shuttle crew? And if it's the shuttle crew do they do it wireless or is there some kind of data transfer possible through the RMS?

Thanks!

Usually, such tasks are done by the Payload Interrogator, an S-band radio system to transmit numeric command codes to a spacecraft.

**IronRain** · 06-20-2012, 10:59 AM

Was the APAS hatch in the ODS designed to be able to be opened from the outside? If yes, how?

**Urwumpe** · 06-20-2012, 11:24 AM

Quote:

Originally Posted by IronRain

Was the APAS hatch in the ODS designed to be able to be opened from the outside? If yes, how?

The ODS is just installed on-top of the external airlock and has no own hatch. You can actually even remove the ODS by EVA, by removing many, many screws.

All three hatches of the external airlock are essentially the same and all have a pressure equalization valve that can be operated from both sides of the hatch, to vent the pressure inside the external airlock. Once the pressure is equalized, you can open the hatch by the same bellcrank mechanism as you use for leaving the Shuttle.

There is no protection for not venting the whole crew cabin atmosphere into space, but the valve does not have such a high volume flow, that you can't just slam the inner door closed if somebody steals your air.

08-26-2011, 04:39 PM	#346
Urwumpe Donator	Quote: Originally Posted by Eagle1Division I remember reading somewhere that the shuttle doesn't open it's bay doors soon after MECO, that it waits a good while first. I know it's vague, but if it's true, why? Wouldn't opening the payload bay doors be one of the first things done on-orbit, to get rid of the system heat of the hydraulics, EPS, APU, OMS and MPS from the climb to orbit and OMS burns? ...Maybe, is it because they want to ensure all systems are working before they open the doors? Shuttle Reference Manual didn't even mention the opening of the Payload bay doors as one of the post-MECO ops. The opening of the Payload bay doors happens during the Post-Insertion (PI) checklist. Nominally you begin that task one hour after lift-off, with "CONFIG FOR PLBD OPERATIONS" (PI 1-14) and actually opening the doors at about 01:25 MET. The PI checklist starts at 00:50 MET and thus directly after OMS-2. before you configure the payload bay doors, you have the following major activities: SPECIALIST SEAT EGRESS CONFIG GPCS FOR OPS2 (important since the payload bay door control software is in SM OPS2, also this is a very complex task, since it involves 5 computers at once) PL BUS ACTIVATION PRELIM MIDDECK CONFIG AFT STATION CONFIG (so you can also check that the payload bay doors open properly) Between configuration for payload bay door operations and opening, you have: WCS CONFIG/ACT (the toilet, you really need it) SWITCH CONFIG/GALLEY ACT (If you get thirsty by now, you might like it) DON/CONFIG COMM (It is a bit loud in the Shuttle, so you better get this done soon, so you know what the person right next to you is saying) LOAD DAP A5 (configure the autopilot for the next maneuver) MNVR TO PLBD OPENING ATT ("maneuver to payload bay door opening attitude"; you can't do this in every orientation, you use "BIASED -ZLV +YVV".) RAD ACT (the radiators are already activated before* opening the doors - otherwise you could damage them) The exact attitude is defined in UNIV PTG as follows: Body vector is selected as 3 (-Z), Target is 2 (Center of Earth), Omicron angle is 280°. This means the shuttle Z axis is pointed as such that down (-Z) is towards the center of Earth, and Y is in the plane between -Z and orbit antinormal (-h) and then the shuttle is rotated clockwise around the target vector (towards center of Earth) by 280° (Defined in ORB OPS 7-33). Which in this case means: The shuttle flies wings level and with 80° slideslip to the left. If +/- Y would be selected as reference body vector, the -Z axis of the Shuttle Coordinate System (down) would be used as second vector instead. Last edited by Urwumpe; 08-26-2011 at 05:05 PM.*

10-04-2011, 04:21 PM	#348
Urwumpe Donator	Quote: Originally Posted by Zamzara In Orbiter I can reach a Moron-TAL with one engine out from launch, and an ATO shortly after. This is with a payload set to 25 tonnes. Clearly either the real life abort windows are rather conservative, or the simulated characteristics in Orbiter are a bit generous, does anyone know which? Actually both. The Moron-TAL window is calculated with a lot of extra performance left so some damage to the Shuttle remains tolerable. Also, the Orbiter Shuttle models have all some small and large variations to the real one, especially the default Shuttle. Finally: The checklist TAL windows are no-communication TAL windows, which means, they have to be very conservative, as the crew has less means to calculate their ability to reach an abort site, than mission control with their radar tracking sites and special computer programs. Last edited by Urwumpe; 10-04-2011 at 04:23 PM.

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10-04-2011, 04:15 PM	#347
Zamzara Orbinaut	In Orbiter I can reach a Moron-TAL with one engine out from launch, and an ATO shortly after. This is with a payload set to 25 tonnes. Clearly either the real life abort windows are rather conservative, or the simulated characteristics in Orbiter are a bit generous, does anyone know which?

10-05-2011, 12:00 PM	#349
Zamzara Orbinaut	That makes sense, thanks.

10-05-2011, 03:06 PM	#350
Spaced Orbinaut	I've heard it said that before her accident Challenger was considered the workhorse of the fleet. I've also read that Columbia had more surface tiles and weighed more than the other orbiters. How different was each airframe? Were there any capability specific reasons for an orbiter's selection for a mission? Or was it simply maintenance and turnaround that specified what shuttle would be available?

10-11-2011, 01:41 PM	#351
GoForPDI Good ol' Max Peck	All the Orbiters had different weights. Columbia was by far the heaviest, she was used mainly for science missions with a pressurised Hab module in the payload bay. All the Orbiters have small differences to each other. I believe either Endeavour or Atlantis (i'm not too sure) was not fitted with plumbing which could attach to the ISS' plumbing, which limited its usable time in Orbit.

10-11-2011, 03:06 PM	#352
Scav Mostly Harmless	Quote: Originally Posted by GoForPDI I believe either Endeavour or Atlantis (i'm not too sure) was not fitted with plumbing which could attach to the ISS' plumbing, which limited its usable time in Orbit. It was Atlantis, yes.

10-11-2011, 03:24 PM	#353
garyw O-F Administrator	By 'plumbing' do you mean SSPTS? If so only Endeavour and Discovery had that modification. Atlantis was supposed to be retired first.

01-06-2012, 10:20 PM	#354
MattBaker Orbinaut	I asked myself how high the Shuttle could fly, so: A Shuttle with the configuration of 2011, Super Leightweight ET etc, with nothing in the cargo bay. The orbit should be circular, as an example 600x600. There should be enough fuel left for an deorbit burn of course. So, what's possible for the Shuttle? The Hubble missions were, compared to the ISS, missions with a quite high orbit.

01-06-2012, 10:24 PM	#355
Urwumpe Donator	Quote: Originally Posted by MattBaker So, what's possible for the Shuttle? The Hubble missions were, compared to the ISS, missions with a quite high orbit. Hard maximum is about 700 km circular. That is not only getting at the limits of the propellant resources, but also at the limits of the heat shield.

01-15-2012, 05:55 PM	#356
IronRain Orbinaut	Not entirely a STS question but it gets close to it. I was watching the post-flight video of STS-37 and the Gamma Ray Observatory was lifted out of the cargo bay, then one solar panel was deployed, when that was completed the other solar was deployed and then the Hi-gain antenna should have deployed. Now is my question: Who issues the command to do this? Ground controllers or the shuttle crew? And if it's the shuttle crew do they do it wireless or is there some kind of data transfer possible through the RMS? Thanks!

01-15-2012, 06:08 PM	#357
Urwumpe Donator	Quote: Originally Posted by IronRain Not entirely a STS question but it gets close to it. I was watching the post-flight video of STS-37 and the Gamma Ray Observatory was lifted out of the cargo bay, then one solar panel was deployed, when that was completed the other solar was deployed and then the Hi-gain antenna should have deployed. Now is my question: Who issues the command to do this? Ground controllers or the shuttle crew? And if it's the shuttle crew do they do it wireless or is there some kind of data transfer possible through the RMS? Thanks! Usually, such tasks are done by the Payload Interrogator, an S-band radio system to transmit numeric command codes to a spacecraft.

06-20-2012, 10:59 AM	#358
IronRain Orbinaut	Was the APAS hatch in the ODS designed to be able to be opened from the outside? If yes, how?

06-20-2012, 11:24 AM	#359
Urwumpe Donator	Quote: Originally Posted by IronRain Was the APAS hatch in the ODS designed to be able to be opened from the outside? If yes, how? The ODS is just installed on-top of the external airlock and has no own hatch. You can actually even remove the ODS by EVA, by removing many, many screws. All three hatches of the external airlock are essentially the same and all have a pressure equalization valve that can be operated from both sides of the hatch, to vent the pressure inside the external airlock. Once the pressure is equalized, you can open the hatch by the same bellcrank mechanism as you use for leaving the Shuttle. There is no protection for not venting the whole crew cabin atmosphere into space, but the valve does not have such a high volume flow, that you can't just slam the inner door closed if somebody steals your air.