|
Author
|
Topic: Why did the Apollo CMP stay in lunar orbit?
|
BBlatcher
Member Posts: 57
From: Savannah, GA, USA
Registered: Aug 2011
|
posted 10-18-2011 06:39 PM
  
I've always figured the command module stayed in lunar orbit because the technology wasn't that great the time. Thus a human pilot was needed to keep the Command/Service Module operating and perform the docking.Is this so? If not, could you explain what the real reason was or go into more detail? Thanks! |
Fezman92
Member Posts: 1031
From: New Jersey, USA
Registered: Mar 2010
|
posted 10-18-2011 06:52 PM
The CMP was there for various reasons, the most morbid one being that if something went wrong there would be at least one crew member who could get home alive. |
APG85
Member Posts: 307
From:
Registered: Jan 2008
|
posted 10-18-2011 07:29 PM
The Lunar Module was designed for two. It would have taken a complete redesign for it to carry three not to mention the increase in power/fuel for lunar-lift-off and a myriad of other things... |
BBlatcher
Member Posts: 57
From: Savannah, GA, USA
Registered: Aug 2011
|
posted 10-18-2011 07:29 PM
Also, if anyone could point me towards documents that explain how NASA decided on the Apollo CMP staying behind, that would be helpful, thanks. |
Paul78zephyr
Member Posts: 678
From: Hudson, MA
Registered: Jul 2005
|
posted 10-18-2011 08:28 PM
The key reason for the CMP to remain in the CM in lunar orbit was to FLY the CM and assure that it rendezvoused and docked with the LM. That's the 'P' in CMP. This was especially critical if the LM had problems attaining a good orbit during its ascent from the moon. The CMP would FLY the CM to what ever orbit was needed to link up with the LM to assure that the two guys in the LM got back OK. |
Paul78zephyr
Member Posts: 678
From: Hudson, MA
Registered: Jul 2005
|
posted 10-18-2011 08:30 PM
Also as far as 'technology that wasn't that great', we landed on the Moon. I think the technology was pretty damn good. |
MCroft04
Member Posts: 1647
From: Smithfield, Me, USA
Registered: Mar 2005
|
posted 10-18-2011 08:44 PM
I'm re-reading Apollo by Murray and Cox. Page 106 discusses the size of the Apollo crew. While they acknowledge that a three man crew "turned out to be perfect", two men to land and one in orbit, early on when NASA was making the decision for the size of the crew, "the designers hadn't thought about such things as lunar modules. They just figured that they would run the duty shifts as the Navy did, four hours on, eight off, which meant they needed three astronauts to ensure that an astronaut would be on duty all the time." |
MikeSpace
unregistered
|
posted 12-03-2011 05:35 PM
But did the technology exist for the Command Module to keep itself working and in orbit for the longer times of the later missions without a human to throw some switches? Were orbital adjustments necesary all the time or could the CSM just 'drift'? Plus, as Mike Collins has written extensively about and mentioned above, there were scenarios they trained for where the ascent didn't go as planned and the CMP had to essentially go and get and LM, if possible. |
randy
Member Posts: 2231
From: West Jordan, Utah USA
Registered: Dec 1999
|
posted 12-03-2011 08:10 PM
If memory serves, when John Houbolt first proposed the LOR method of going to the moon, the LM design he came up with (as well as subsequent designs) were for two men. It seems that the third man, the CMP staying in the CM, was almost a foregone conclusion. |
Jay Chladek
Member Posts: 2272
From: Bellevue, NE, USA
Registered: Aug 2007
|
posted 12-05-2011 03:38 PM
Even if a CM could fly unmanned for the docking, Apollo 9 showed that docking with the LM as the primary vehicle was indeed possible, but also very difficult due to the heads up orientation the pilot of the LM had to maintain during the docking. So, from that point on, the CMP and the CSM became the prime vehicle for initiating the docking manuever.Besides, there is something to be said about having a man "holding the fort" down in orbit while the rest of the crew were on the moon. Should something have happened to an unmanned CSM in lunar orbit, they would have had NO WAY for the lander crew to get home. As such, no matter how sophisticated the equipment might have been, man was still the ultimate backup on those missions. |
Space Cadet Carl
Member Posts: 225
From: Lake Orion, Michigan
Registered: Feb 2006
|
posted 12-06-2011 05:31 AM
I believe the concept of totally atonomous control of spacecraft was still in it's infancy or dreaming stages in the 1960's. A 1960's engineer could not yet fathom leaving a machine as complicated as the Apollo CM unattended to take care of itself. Small, simple Mariner and Surveyor probes, yes. |
SpaceAholic
Member Posts: 4494
From: Sierra Vista, Arizona
Registered: Nov 1999
|
posted 12-06-2011 07:18 AM
quote:
Originally posted by MikeSpace:
But did the technology exist for the Command Module to keep itself working and in orbit for the longer times of the later missions without a human to throw some switches?
Possibly but at a significant premium in mass to orbit and lengthy program delays to effect implementation. Some elements of autonomous control (with backup manual override) were embedded within the CSM - the Autonetics (Rocketdyne) relay based Sequential Events Control System (SECS). These were relatively large bulky boxes (there are several examples on my site), individually apportioned to performed specialized functions such as jettisoning of key components, undocking, staging, parachute deployment. Autonetics used a similar system onboard the unmanned Block I test flights to simulate actions the crew would take if they were actually embarked. Timed relays however do not have the ability to anticipate situational/environmental changes – for that additional sensors, controls and the analytical processing capability to evaluate and react are necessary. Lots more code to write and test, more power to run a larger computer generating more heat and taking up greater space and expanded engineering/integration challenges that would have made man rating the CSM a nightmare. |
Blackarrow
Member Posts: 3160
From: Belfast, United Kingdom
Registered: Feb 2002
|
posted 12-06-2011 05:35 PM
Imagine if all three crew members could have descended to the surface of the Moon in the Apollo lunar module. On Apollo 15, what would have been the outcome of the water leak in the command module if it had occurred when there was no human hand to wield the tool to shut off the flow? Three dead astronauts. The most sophisticated computer in the world, even today, can't tighten a loose nut and bolt assembly. It's true that simpler spacecraft like Mariner, Viking, Voyager, etc could operate without direct human supervision, but they didn't require a large, heavy and sophisticated life-support system complete with heavy tanks of air and liquid water. |
Dave Clow
Member Posts: 236
From: South Pasadena, CA 91030
Registered: Nov 2003
|
posted 12-16-2011 11:12 AM
You can't discuss the LM without mentioning the word "weight." To carry two it was pared and peeled gram by gram from the blueprints to the flight item. Redesigning it for three would have been impossible under the time constraints and with the weight constraint. Also, everything I've read indicates that Paul is correct--the CMP was there to do what the machine couldn't do automatically. Finally, as the J missions showed, the CMP's orbital perspective has as much scientific importance as that of the surface explorers. |
Jeff
Member Posts: 483
From: Fayetteville, NC, USA
Registered: May 2009
|
posted 12-16-2011 11:35 AM
quote:
Originally posted by Blackarrow:
On Apollo 15, what would have been the outcome of the water leak in the command module if it had occurred when there was no human hand to wield the tool to shut off the flow?
I may be misunderstanding what you're saying but the water leak was in the LM not the CM. In the Apollo Surface Journal under Apollo 15 EVA 2 prep at the 138:04:15 mark... you can pick up the conversation with Dave Scott and the CAPCOM. |
Glint
Member Posts: 1044
From: New Windsor, Maryland USA
Registered: Jan 2004
|
posted 12-16-2011 01:02 PM
quote:
Originally posted by Jeff:
I may be misunderstanding what you're saying but the water leak was in the LM not the CM.
He's thinking of one inside the CM on day 3. Al Worden discussed it sometime this year (I don't remember if I read it in his book or heard him talking about it in person -- or both). He mentioned cleaning up the mess by surrounding the water ball with a towel or towels and soaking it up rather easily.The fact that the water's surface tension was strong enough to permit its forming a large globular ball also discounts the likelihood it had occurred in the 1/6 G environment on the lunar surface. Guess there was more than one leak on the mission. See this NASA history page for details. |
Jeff
Member Posts: 483
From: Fayetteville, NC, USA
Registered: May 2009
|
posted 12-16-2011 03:49 PM
Thanks for the clarification. Guess I'll read his book next. |
Apollo Redux
Member Posts: 346
From: Montreal, Quebec, Canada
Registered: Sep 2006
|
posted 12-17-2011 07:51 PM
quote:
Originally posted by BBlatcher:
I've always figured the command module stayed in lunar orbit because the technology wasn't that great the time
12 American's walked on the moon, a feat no other nation has matched yet. I think that technology is great by any measure. |
Lou Chinal
Member Posts: 1332
From: Staten Island, NY
Registered: Jun 2007
|
posted 12-19-2011 06:27 PM
This post got me thinking (always dangerous).On display at the National Air and Space Museum in Washington D.C. is a crescent wrench which was carried aboard the CM. It's up on the second floor underneath Aldrin's biological insulation garment (BIG). What was it used for? I think (notice I say think) I know the answer. Was it for the CMP to disassemble the docking probe? Mike Collins describes in his book (Carrying The Fire) that he HAD to know how to it. Anyone out there know for sure? |
ilbasso
Member Posts: 1522
From: Greensboro, NC USA
Registered: Feb 2006
|
posted 12-19-2011 06:50 PM
Keeping unruly LMP's in line? |
schnappsicle
Member Posts: 396
From: Houston, TX, USA
Registered: Jan 2012
|
posted 01-19-2012 04:20 AM
As stated previously, the CMP was onboard to rescue the lunar crew should they fail to achieve orbital altitude, but there were many other reasons for him being there. Probably the best way to think of the CMP is as a bus driver. He was responsible for delivering the crew to the moon and "returning them safely to the earth". It would have taken many more years of training to bring the surface crew up to speed on the CSM. Learning to fly two vehicles at the same time was not within the timeframe we had to reach the moon. The CMP was also responsible for the many experiments onboard the CSM, none of which were automatic. He also took photographs of future possible landing sites. I believe it was Worden who observed the orange soil in the Tarus Littrow area that finally convinced NASA to send Apollo 17 to that landing site. It was so subtle that no photograph at the time was able to show it. |
MCroft04
Member Posts: 1647
From: Smithfield, Me, USA
Registered: Mar 2005
|
posted 01-19-2012 07:15 AM
I'll need to do some more research, but I believe Worden observed features at Taurus-Littrow that looked like evidence of recent volcanic activity, not orange soil. Ron Evans on A17 did observe the orange soil from lunar orbit, but only after Jack Schmitt found it on the lunar surface and then Farouk El-Baz advised Evans to look for it. See pages 316 and 321 in Footprints in the Dust. |
TLI
Member Posts: 31
From: London, UK
Registered: Mar 2005
|
posted 01-19-2012 09:34 AM
Wouldn't the mascons perturb a CSM in an unmanned free drifting orbit? |
schnappsicle
Member Posts: 396
From: Houston, TX, USA
Registered: Jan 2012
|
posted 01-20-2012 02:49 PM
quote:
Originally posted by MCroft04:
I believe Worden observed features at Taurus-Littrow that looked like evidence of recent volcanic activity, not orange soil.
You are correct. I overstated the facts a little. I've read so many books that I've forgotten exactly what I read. While I don't have the book you mention, I do have a copy of "To A Rocky Moon" which I downloaded here. It greatly details the selection process for the Apollo landing sites. The real truth of which I speak is on page 313: But the real reasons for the victory of Taurus-Littrow lay in what happened on Apollo 15. Al Worden had seen dark-halo craters that looked like cones scattered all over the region's brighter surfaces. The same paragraph mentions Shorty Crater in particular, the site of the orange soil.Even though it wasn't orange soil that Worden saw, my point remains that his direct observations from lunar orbit finalized the landing site for Apollo 17; something that would have have been nearly impossible with a two man crew. |
MCroft04
Member Posts: 1647
From: Smithfield, Me, USA
Registered: Mar 2005
|
posted 01-20-2012 06:31 PM
I agree with you on Worden's contributions to Apollo 17. And I too get facts and books mixed up. That's another reason I like cS so much; keeps us honest. By the way, you really should read Footprints in the Dust! |
advertisement