Author Topic: Shuttle Q&A Part 5  (Read 810409 times)

Offline psloss

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Re: Shuttle Q&A Part 5
« Reply #3440 on: 07/17/2016 02:17 PM »
It's only been 10 years, but someone posted video of the STS-31 post-launch press conference on YouTube, which covers the LO2 outboard F/D valve issue (sounds more like a software/process issue) that stopped the terminal count at T-31 seconds for a short time. 


Aside from John's help with this way back when (quoted below), the only other description of the issue was in Harry Kolcum's contemporary story in AW&ST.  There's a little extra background in the opening remarks from Bob Sieck and George Sasseen and the Q&A.  The briefing stars at about 2 hours and 30 minutes into the video.

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Orbiter Obvious - 7/11/2006  8:37 PM

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jcopella - 25/7/2006  1:50 PM

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psloss - 25/7/2006  6:20 AM

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jcopella - 25/7/2006  12:44 AM

P.S.  Prerequisite Control Logic (PCL) is a little GOAL subroutine that console engineers could associate with a particular command.  The idea was you would put safety checks inside the PCL sequence to ensure that the command never resulted in an unsafe situation.  In this case, MPS apparently made some kind of procedural change which caused the PCL (which would normally allow the command to go thru) to block the command.  I remember a little bit of a fire drill after this incident to hunt down all the GLS-issued commands that had PCL sequences associated with them so we wouldn't be quite so surprised if it ever happened to us again.
Thanks, John.  On the comm loop that was broadcast on NASA Select, SPE says it was PCL sequence 18 (if I'm hearing right).  Also sounds like Ms. Pape's voice at the GLS console.

Yep.  GCL18.  That's the PCL sequence for V41K1515XL, the LO2 outboard f/d valve close command (I still have my GLS "brain book" here in the office, which I keep around for sentimental reasons.  Never thought I'd have to use it to look up a PCL sequence again!  LOL)

How long does it take someone to train up and know all these sequences like this?

The short answer is, years.  But you should keep in mind a couple of things.  Not everyone in a given system knows every single PCL sequence for that system cold.  Usually only the system specialists (very small number of very senior people) had that sort of in-depth knowledge, and even they relied on source code listings and other reference material to supplement their grey matter.

I was a GLS engineer, and we executed a lot of commands on behalf of the subsystems, and we were software weenies anyway, so we were sort of expected to have that sort of knowledge.  But even we realied on our "brain books" for this sort of thing, and of course that knowledge is supplemented by messages and displays that we saw in real-time on launch day.

On my first tour thru KSC, I worked with GLS for about 4 years, and at the end of that 4 years I felt like I was just starting to really know what I was doing.  At that time (early 90s), we had a training and certification program for new engineers that generally took about a year to complete, depending on what the launch schedule was like -- you had to complete X number of S0044s, X number of S0017s and X number of S0007s (both as early shift support, backup operator, and primary operator).  There were also classes you were required to attend, and we had some assignments and tests as well.  That was on top of your daily job assignments which would've included software development & maintenance, data review, paperwork, attending meetings (yay!!), etc.  After your training was complete, you really needed a few (3 or 4 years) of hard experience before things really settle in and you get confident in the role.

Maybe some of the other Shuttle vets who worked on the hardware can chime in on what sort of training they received and how long it took them to get comfortable with the job.  And if they worked console for any length of time, and dealt with high energy systems, I'll be they even remember some of their PCL sequences!  LOL
« Last Edit: 07/17/2016 02:18 PM by psloss »

Online DaveS

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Re: Shuttle Q&A Part 5
« Reply #3441 on: 09/10/2016 05:36 PM »
Is anyone here familiar with the changes to the Orbiter Docking System from the Shuttle-Mir missions to the ISS missions if any?
"For Sardines, space is no problem!"
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Offline Zoe

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Re: Shuttle Q&A Part 5
« Reply #3442 on: 11/08/2016 02:23 PM »
GLS is go for main engine start at T-10 seconds but I note that unlike at other points in the GLS sequence below T-9 minutes this was not marked as auto in S0007.  Was an action required by CGLS to allow the RSLS to start the engines?
« Last Edit: 11/08/2016 02:25 PM by Zoe »

Offline psloss

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Re: Shuttle Q&A Part 5
« Reply #3443 on: 11/08/2016 02:39 PM »
GLS is go for main engine start at T-10 seconds but I note that unlike at other points in the GLS sequence below T-9 minutes this was not marked as auto in S0007.  Was an action required by CGLS to allow the RSLS to start the engines?
It was a software command, see the chart that Mark posted here:
https://forum.nasaspaceflight.com/index.php?topic=10600.msg263210#msg263210

(The conversation around that post is relevant, too.)

Belated edit to highlight this specific post from former GLS jcopella in that conversation:
https://forum.nasaspaceflight.com/index.php?topic=10600.msg263266#msg263266
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At this point GLS & RSLS run in parallel, interacting directly only when there's a countdown clock hold/resume (e.g., the T-9m built-in hold), and at T-31 sec and T-10 sec when the two LPS "go" flags (auto sequence start & SSME start, respectively) are sent.
« Last Edit: 11/08/2016 03:53 PM by psloss »

Offline Zoe

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Re: Shuttle Q&A Part 5
« Reply #3444 on: 11/08/2016 04:08 PM »
Thanks, I'm still curious though as to why the RSLS auto sequence start at T-31 seconds is marked as auto whereas the main engine start at T-10 seconds is not if both commands were sent automatically from the GLS to the RSLS.
« Last Edit: 11/08/2016 04:09 PM by Zoe »

Offline e of pi

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Re: Shuttle Q&A Part 5
« Reply #3445 on: 12/09/2016 03:04 AM »
Does anyone know what the upmass used on a Hubble Servicing Mission was?

Offline Hog

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Re: Shuttle Q&A Part 5
« Reply #3446 on: 12/12/2016 01:37 PM »
Does anyone know what the upmass used on a Hubble Servicing Mission was?
Which one?
Paul

Offline e of pi

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Re: Shuttle Q&A Part 5
« Reply #3447 on: 12/24/2016 02:56 PM »
Which one?
Any generic one (a rough total mass for a generic Hubble servicing), but all if possible. I looked in L2, but the documentation I found is very in depth on the systems carried up while not actually mentioning total mass.

Offline Hog

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Re: Shuttle Q&A Part 5
« Reply #3448 on: 01/02/2017 07:02 PM »
Which one?
Any generic one (a rough total mass for a generic Hubble servicing), but all if possible. I looked in L2, but the documentation I found is very in depth on the systems carried up while not actually mentioning total mass.
This is all stuff from Wikipedia and isn't consistent in format.  Some is detailed payload breakdown, while some is simply launch mass and landing mass of the Orbiter.  I think there was some very detailed documentation on payloads earlier on in this very thread.  Perhaps a quick read in this thread may reveal some answers.  Perhaps this will pique some others input?

STS-31-Discovery Launch mass 11,110 kg (24,490 lb)

STS-61 Endeavour had a payload mass of 10,949 kg (24,138 lb)

STS-82-Discovery-Servicing Mission 2

STS-103-Discovery-Servicing Mission 3A

Launch mass
112,493 kilograms (248,005 lb)
Landing mass
95,768 kilograms (211,132 lb)

STS-109-Columbia-Service Mission 3B

Launch mass
116,989 kg (257,917 lb)
Landing mass
100,564 kg (221,706 lb)

STS-125-Atlantis-Servicing Mission 4  https://en.wikipedia.org/wiki/STS-125
As per Wikipedia, the total upmass of payload for STS-125, the last Hubble Service Mission, was 13,104 kilograms (28,889 lb).

Bays 12 Orbiter Docking System
EMUs 3006, 3004, 3015, 3017 1,800 kilograms (4,000 lb)
 ~480 kilograms (1,060 lb)

Bay 3P Shuttle Power
 Distribution Unit (SPDU) ~17 kilograms (37 lb)

Bays 45 SLIC /COPE with
 Wide Field Camera 3 2,990 kilograms (6,590 lb)

Bays 78 ORUC COS/RSU/FGS
 Cosmic Origins Spectrograph
 Fine Guidance Sensor, Gyros 3,339 kilograms (7,361 lb)

Bay 10P GABA/MFR ~50 kilograms (110 lb)

Bay 10P GABA/PFR ~50 kilograms (110 lb)

Bay 11 HST-FSS/BAPS/SCM
 Berthing and Positioning Sys
 Soft Capture Mechanism 2,177 kilograms (4,799 lb)

Bay 12 MULE
 RNS, NOBL blankets 1,409 kilograms (3,106 lb)

Starboard Sill Orbiter Boom Sensor System ~382 kilograms (842 lb)
Port Sill Canadarm 301 410 kilograms (900 lb)
 
Total: 13,104 kilograms (28,889 lb)


Paul

Offline smn

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Re: Shuttle Q&A Part 5
« Reply #3449 on: 05/21/2017 04:17 PM »
Hi there,

I'm new to this site and hope this question hasn't been asked before:

What are the hinges of the Payloadbay Doors and the surroundings of the FRCS thrusters made of? It looks like a metallic material, is it Inconnel?
I miss the Shuttle

Offline billshap

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Re: Shuttle Q&A Part 5
« Reply #3450 on: 05/22/2017 04:12 AM »
Can anyone provide links to audio/video/transcript/articles of instances when an orbiter burn was not responded to with "no trim required"...and needed to be trimmed?  Curious as to what instructions were given, what corrections were made to meet the targets, and any other information.

Offline mkirk

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Re: Shuttle Q&A Part 5
« Reply #3451 on: 05/28/2017 06:02 PM »
Can anyone provide links to audio/video/transcript/articles of instances when an orbiter burn was not responded to with "no trim required"...and needed to be trimmed?  Curious as to what instructions were given, what corrections were made to meet the targets, and any other information.


I can’t think of any examples from a real mission off the top of my head, but hearing something different certainly wouldn’t be nominal.  It would mean the crew missed a step in the procedure or the resulting burn didn’t go as planned (e.g. flight control problems, premature cutoff, etc.).
“trimming out the residuals" is the last step of the burn procedure.

Burn Procedure 101:
Any burn (OMS or RCS) is obviously monitored very closely by the crew.  For a typical OMS burn the workload is divided as follows:

PLT (Pilot) will monitor the health of the burn (i.e. the engines)
-   Engine chamber pressure (Pc)
-   Helium and Propellant tank pressures
-   Position of the engine ball valves
-   Oxidizer and fuel engine inlet pressures
-   Fuel injector temperature

CDR (Commander) will monitor where the orbiter is going
-   Burn attitude (are we pointed in the right direction and is the attitude stable).  This is done primary by looking at the error and guidance steering needles on the ADI (attitude direction indicator or “8 ball”)
-   Shape of the current orbit versus the new targeted orbit - this is done by tracking the Perigee and Apogee altitudes, HP and HA, they should be changing as the burn progresses.  For a de-orbit burn the HP would be a value well within the atmosphere
-   Duration of the burn and remaining Delta V to go.

Let’s say you are conducting a deorbit burn with a target Delta V of 321 feet per second and an OMS burn duration of 3 minutes 18 seconds.  The crew would see the TGO (time to go) counting down to zero from 3:18 and the Delta VTOT (total delta v required) counting down.  Ideally both values will get to zero at the same time and the engine burn will stop.  Any “residual” velocity components along any of the orbiter’s axis (X, Y and Z) would be indicative of the sloppiness of the burn.  This information was displayed to the crew as VGOs (velocity to go) for each axis.  In reality the guidance and flight control systems were very good and these values were quite small - within 10ths of a foot per second.

The last step of the burn card/procedure was to trim out the residuals to within defined limits (based on the type of burn) this was done by manually moving the THC (translational hand controller) in the direction needed to reduce these velocity components.  Which direction to move the controller for a given axis (ex: push in versus pull out for the x-axis) was based on the sign (plus or minus) of the VGO.

I have attached an image of the Maneuver Display where this information was provided to the crew (in the box at the top right corner) and a copy of an OMS 2 Burn Card.  At the bottom of the card you will see that 2 seconds after cutoff (this allowed time for a purge) the crew would take the OMS engine switches to off and then trim out any residuals to within the limits specified.


Mark Kirkman
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« Last Edit: 05/28/2017 06:15 PM by mkirk »
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Offline billshap

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Re: Shuttle Q&A Part 5
« Reply #3452 on: 05/29/2017 06:02 AM »
Mark,
Thank for the info and the burn card.  I know the guidance and flight control systems were exceptionally good and accurate.  I couldn't remember any burn that wasn't responded to with "no trim required."  Would still like to hear audio or read a transcript of what happened if trim was required.  Would the ground communicate residuals to be trimmed and give some type of PAD?  Would the CDR and PLT just trim it on their own, without direction?

Offline billshap

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Re: Shuttle Q&A Part 5
« Reply #3453 on: 07/21/2017 04:13 AM »
Listening to some old Shuttle audio, before the full TDRSS network was operational.  The Orbiter was instructed to "Configure LOS" and "Configure AOS" as its orbital path moved from ground station to ground station...and TDRSS.  What did these procedures entail?

Offline mkirk

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Re: Shuttle Q&A Part 5
« Reply #3454 on: 07/23/2017 02:32 PM »
Listening to some old Shuttle audio, before the full TDRSS network was operational.  The Orbiter was instructed to "Configure LOS" and "Configure AOS" as its orbital path moved from ground station to ground station...and TDRSS.  What did these procedures entail?


As you probably already know, Mission Control can uplink commands from the ground to the orbiter.  These commands are received onboard via the communication system (S-band or Ku) and forwarded to the shuttle's general purpose computers (GPCs).  To protect against the possibility of receiving so called "spurious" commands while the orbiter was crossing a gap between tracking stations, the crew would "configure for LOS" (loss of signal) by blocking the GPCs from accepting commands from the comm system.  When acquisition of signal occurred (AOS) as the orbiter came into range of the next tracking station, the crew would "configure AOS" by enabling the GPCs to accept commands thru the comm system again.

This blocking and enabling can be done either with a switch located near the aft portion of the center console (C-3) or by selecting the appropriate item entry with a GPC Data Processing System Utility Display known as SPEC 1.


Mark Kirkman

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Offline billshap

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Re: Shuttle Q&A Part 5
« Reply #3455 on: 07/23/2017 03:23 PM »
Mark,
Thanks for the info, and the enlightenment.  Was trying to figure out what would have to be configured comm-wise, and why; overlooked the GPC aspect.

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