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Author
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Topic: Plan for Apollo 14 if LM docking failed
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Scottvirgil
New Member Posts: 8
From: London UK
Registered: Aug 2019
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posted 05-22-2020 01:18 AM
   
I was wondering what the back up plan was had Apollo 14 command module pilot Stuart Roosa been unable to dock the command module with the lunar module after numerous attempts.Would the mission have continued to the Moon? Was there a back up lunar orbital mission, or would the craft simply come back on a free return? This also got me asking why transposition and docking took place on Apollo missions after trans-lunar injection (TLI).It seemed to me to make sense to carry out this manoeuvre in Earth orbit, so that if it failed the crew did not make a pointless, hazardous, half million mile round trip. I'd appreciate any thoughts on this. |
Mike Dixon
Member Posts: 1455
From: Kew, Victoria, Australia
Registered: May 2003
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posted 05-22-2020 03:22 AM
And leaving Earth orbit? |
Scottvirgil
New Member Posts: 8
From: London UK
Registered: Aug 2019
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posted 05-22-2020 06:29 AM
What I mean is docked to the lunar module without retracting it from the S-IVB. |
David C
Member Posts: 1083
From: Lausanne
Registered: Apr 2012
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posted 05-22-2020 07:22 AM
For transposition and docking (T&D) to take place the spacecraft-lunar module adapter (SLA) panels had to be jettisoned. Once that happened you could not re-connect the CSM to the S-IVB. The LM was extremely delicate and not stressed to "carry" the fully laden CSM on top of it through a TLI burn. So T&D had to take place after TLI. |
oly
Member Posts: 1049
From: Perth, Western Australia
Registered: Apr 2015
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posted 05-22-2020 07:45 AM
The CSM attached to the S-IVB is structurally mounted to handle the acceleration loads imposed during all mission phases up to and including TLI. The guidance and navigation control (GNC) platform was programmed using the calculated mass of the configured spacecraft, and the time constraints during the parking orbit/s of approximately 118.8 miles (191.2 km) prohibited transposition and docking.Conducting the transposition and docking maneuvers after TLI allowed more time to do the sequence and the GNC could be realigned from the orbital program into the TLI phase using star alignments. The vehicle was structurally sound and the crew orientated forward, keeping the GNC reference plane aligned with the stack axis. Conducting the transposition and docking maneuvers pre TLI would orient the crew and CSM rearward, changing the GNC reference plane, place all structural acceleration loads through the docking hatch structure of the LM and also through the LM/S-IVB attach points, and add time to the task list of items to be performed in LEO. What if the docking latch issue occurred in LEO, how many revolutions would be required to achieve docking and how does the extended time in orbit change the mission profile? All of these issues are calculatable but also add to the workload and programming of the GNC because burning propellant for docking changes vehicle mass. Also, if the docking in LEO fails, the only option would be mission termination, whereas a failure on the way to the moon gives additional time to troubleshoot or plan another mission profile. The CSM had reserves to make a free return or use the SM SPS capacity for direct return/abort capability. |
Scottvirgil
New Member Posts: 8
From: London UK
Registered: Aug 2019
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posted 05-22-2020 08:23 AM
Thanks for that. It makes perfect sense.So, if they hadn't docked, did they come straight home, or go to the Moon and keep trying? Would they stay at the Moon and complete the tasks assigned to the CMP? |
LM-12
Member Posts: 3396
From: Ontario, Canada
Registered: Oct 2010
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posted 05-22-2020 08:53 AM
If the transposition and docking had failed on Apollo 14, an alternate mission (2C) under consideration would have been a CSM-only lunar orbit mission. The tasks in lunar orbit would have included radar tests and low-altitude landmark tracking photography, and a TEI burn on REV 20.
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Scottvirgil
New Member Posts: 8
From: London UK
Registered: Aug 2019
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posted 05-22-2020 08:57 AM
A CSM only mission in the immediate aftermath of 13? That shows some chutzpah! |
LM-12
Member Posts: 3396
From: Ontario, Canada
Registered: Oct 2010
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posted 05-22-2020 08:58 AM
Alternate mission 2C was in the final flight plan. |
Philip
Member Posts: 6036
From: Brussels, Belgium
Registered: Jan 2001
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posted 05-22-2020 09:24 AM
There are some great photos of Eugene Cernan and a pipe smoking John Young discussing the docking issue. |
Jim Behling
Member Posts: 1518
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 05-22-2020 09:24 AM
Performing T&D in LEO would disconnect the communications between the CSM and S-IVB. The crew would not have have any insight into the stage nor the ability to shutdown the stage.The main reason is that the LM was not designed to handle the loads from CSM during TLI. |
LM-12
Member Posts: 3396
From: Ontario, Canada
Registered: Oct 2010
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posted 05-22-2020 10:00 AM
After the fourth failed docking attempt, Shepard mentioned the possibility of doing an EVA to try and fix the problem:
CDR: Houston, 14. I'm sure you're thinking about the possibility of going hard suit and bringing the probe inside to look at, as we are. |
Jim Behling
Member Posts: 1518
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 05-22-2020 12:49 PM
It is not an EVA. They do not open the side hatch and go outside. They would have just vented the cabin, opened the tunnel hatch and pulled the probe in. |
Paul78zephyr
Member Posts: 686
From: Hudson, MA
Registered: Jul 2005
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posted 05-28-2020 11:33 AM
quote:
Originally posted by LM-12:
...an alternate mission (2C) under consideration would have been a CSM-only lunar orbit mission.
Was this the planned contingency for all missions Apollo to Apollo 17? |
Jim Behling
Member Posts: 1518
From: Cape Canaveral, FL
Registered: Mar 2010
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posted 05-28-2020 12:49 PM
Yes. |
Fra Mauro
Member Posts: 1650
From: Bethpage, N.Y.
Registered: Jul 2002
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posted 05-28-2020 07:54 PM
The Apogee books on the Apollo missions mention the alternative flight plans. |
jklier
Member Posts: 57
From: Austin, Texas
Registered: Aug 2007
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posted 05-29-2020 09:35 AM
As I recall the time counted for an EVA starts as soon as the cabin is depressurized. Would this have counted as an EVA since they would have been suited up in a depressurized cabin? Or does someone have to physically leave the vehicle as well? |
Delta7
Member Posts: 1551
From: Bluffton IN USA
Registered: Oct 2007
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posted 05-29-2020 10:07 AM
IVA (Intra-Vehicular Activity)? |
David C
Member Posts: 1083
From: Lausanne
Registered: Apr 2012
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posted 05-29-2020 11:54 AM
This may be a good time to muddy the waters by pointing out that the tally of the world EVA record holder - Anatoly Solovyev, includes one "internal spacewalk" inside the damaged and depressurized Spektr module. Wouldn't this hypothetical Apollo 14 case be basically the same and so arguably count as an EVA also, regardless of the technicalities?Then again I guess it’s up to NASA. I mean I don’t think they counted any of the final lunar surface LM equipment jettisons as EVAs. It would be nice to have some consistency. |
Robert Pearlman
Editor Posts: 43998
From: Houston, TX
Registered: Nov 1999
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posted 05-29-2020 01:24 PM
From Walking to Olympus, NASA's EVA chronology: Russia and the U.S. define EVA differently. Russian cosmonauts are said to perform EVA any time they are in vacuum in a space suit. A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. The difference is based in differing spacecraft design philosophies. Russian and Soviet spacecraft have always had a specialized airlock through which the EVA cosmonaut egressed, leaving the main habitable volume of the spacecraft pressurized. The U.S. Gemini and Apollo vehicles, on the other hand, depressurized their entire habitable volume for egress. |
jklier
Member Posts: 57
From: Austin, Texas
Registered: Aug 2007
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posted 05-29-2020 01:25 PM
From what I remember reading when on the moon the clock for the EVA started when the cabin was depressurized. So I was assuming it doesn't matter if you are in a cabin. Being exposed to the vacuum of space was what was determined that they were performing an EVA. I don't have this in print in front of me, just going from memory. |
jklier
Member Posts: 57
From: Austin, Texas
Registered: Aug 2007
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posted 05-29-2020 02:33 PM
A U.S. astronaut must have at least his head outside his spacecraft before he is said to perform an EVA. So then putting this together with what I mentioned. The EVA clock starts at depressurization but it isn't recorded as an EVA until someone pokes their head through a hole in the cabin. Would that be correct? |
David C
Member Posts: 1083
From: Lausanne
Registered: Apr 2012
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posted 05-30-2020 02:09 AM
The difference is based in differing spacecraft design philosophies. So logically we should have adopted the Russian definition after Apollo? |
moorouge
Member Posts: 2474
From: U.K.
Registered: Jul 2009
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posted 05-30-2020 04:41 AM
Just to confuse matters, back in 1975 I had to add this note to the table of timings in my publication "Manned Spaceflight" for those with EVA experience - The above table is not accurate. This is because some times are given in reports as PLSS timings, some as hatch to hatch and some as the time actually spent outside the spacecraft. It does give, however, a crude guide to the achievements of those concerned. |
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