ddavey@grits.ctt.bellcore.com (Doug Davey) (07/19/89)
In article <1989Jul19.005449.3163@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: > orbit, Apollo 10 flew a dress rehearsal of the landing (including LM > descent to 10 miles above the Moon), and Apollo 11 was the big one. The line that sticks in my mind from Apollo 10 was: "We're really down among 'em!" It must have been quite a sight to be in orbit, but be only 10 miles above the surface. Does anybody remember whether the ascent or descent engine was used during Apollo 10's return from low orbit to rendezvous with the CSM? Either option seems difficult. On the one hand, I would not expect the descent engine to be restartable. On the other, firing the ascent engine and getting the ascent stage cleanly separated from the descent stage would be tricky since the descent stage was deigned to be firmly on the lunar surface during this operation. | ___ ___ ___ ___ __ ___ Doug Davey | /__/ /__ / / / / / /__) /__ bellcore!rruxi!ddavey | /__/ /__ /__ /__ /__ /__/ / \ /__ |
kluksdah@enuxha.eas.asu.edu (Norman C. Kluksdahl) (07/19/89)
In article <17231@bellcore.bellcore.com>, ddavey@grits.ctt.bellcore.com (Doug Davey) writes: > Does anybody remember whether the ascent or descent engine was used > during Apollo 10's return from low orbit to rendezvous with the CSM? > Either option seems difficult. On the one hand, I would not expect > the descent engine to be restartable. On the other, firing the > ascent engine and getting the ascent stage cleanly separated from the > descent stage would be tricky since the descent stage was deigned to > be firmly on the lunar surface during this operation. > The LM used nitrogen tetraoxide and hydrazine (was it UDMH or some other chemical variant???) as oxidizer and propellant. These are hypergolic propellants, which means that you don't need an igniter--the chemicals hate each other so much that they ignite on contact (paraphrased from "Chariots for Apollo"). So, if you can control the fuel and oxidizer valves (simple, since the engines had to have thrust control, so valves were there), you can re-start the engine repeatedly, until you run out of fuel. My memory indicates that the descent stage was cut free, and the ascent stage was used for the rendezvouz. Again, the book "Chariots for Apollo" gives some very human-oriented insight into this process. Some of the engineers at Grumman who were responsible for the separation never did watch or listen to a take-off from the moon. There were many pyrotechnic charges for the separation, each of which powered a guilliotine to sever electrical, water, air, etc, lines between the ascent and descent stages. Failure of one of the guilliotines would have been catastrophic. If you haven't read this book, find it. It is very good, IMHO. ********************************************************************** Norman Kluksdahl Arizona State University ..ncar!noao!asuvax!enuxha!kluksdah alternate: kluksdah@enuxc1.eas.asu.edu standard disclaimer implied
boley@ingr.com (Kirk Boley) (07/20/89)
In article <1989Jul19.005449.3163@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: > There was some discussion about whether Apollo 10 was really needed; why > get to within 10 miles of the lunar surface and then go home? But a lot > of people felt that an all-up test, including a real lunar-orbit rendezvous, > was a good idea before landing. What finally settled the matter was that > Apollo 10's LM was overweight and could not have flown a complete landing > mission. > -- > $10 million equals 18 PM | Henry Spencer at U of Toronto Zoology > (Pentagon-Minutes). -Tom Neff | uunet!attcan!utzoo!henry henry@zoo.toronto.edu I always wondered about that, after reading about the descent. (I was too young to remember much about the space program, even though my dad was working on the Saturn V Instrument Unit for IBM.) I remember thinking, "Hey if it was me, I'd made up some sort of excuse for going ahead and landing!" I mean really, it's like Christopher Columbus coming to within 30 feet of the American shoreline and saying, "Nah, this is too dangerous, let's go back." It's nice to know the real reason after all these years. Thanks, Henry. -- ******************************************************************************* Standard disclaimer. | Kirk Boley, Intergraph Huntsville, UAH Witty .sig message. | 61 hours to go and counting... ...!uucp!ingr!boley *******************************************************************************
ralf@b.gp.cs.cmu.edu (Ralf Brown) (07/20/89)
In article <17231@bellcore.bellcore.com> ddavey@grits.UUCP (Doug Davey) writes: }Does anybody remember whether the ascent or descent engine was used }during Apollo 10's return from low orbit to rendezvous with the CSM? }Either option seems difficult. On the one hand, I would not expect }the descent engine to be restartable. On the other, firing the }ascent engine and getting the ascent stage cleanly separated from the }descent stage would be tricky since the descent stage was deigned to }be firmly on the lunar surface during this operation. As I recall, one contingency plan was in fact such a separation while not on the surface, in case they ran out of fuel trying to land. They would then separate immediately and use the ascent stage to abort back to the CSM. -- {backbone}!cs.cmu.edu!ralf ARPA: RALF@CS.CMU.EDU FIDO: Ralf Brown 1:129/46 BITnet: RALF%CS.CMU.EDU@CMUCCVMA AT&Tnet: (412)268-3053 (school) FAX: ask DISCLAIMER? Did |"Let both sides invoke the wonders of science instead of I claim something?| the terrors." --John F. Kennedy
mike@ames.arc.nasa.gov (Mike Smithwick) (07/20/89)
In article <4481acbf.b097@shadow.engin.umich.edu> tyg@caen.engin.umich.edu (Tom Galloway) writes: >In article <1989Jul19.005449.3163@utzoo.uucp>, henry@utzoo.uucp (Henry Spencer) writes: <> There was some discussion about whether Apollo 10 was really needed; why <> get to within 10 miles of the lunar surface and then go home? But a lot <> of people felt that an all-up test, including a real lunar-orbit rendezvous, <> was a good idea before landing. What finally settled the matter was that <> Apollo 10's LM was overweight and could not have flown a complete landing <> mission. < <The last was probably a good thing. I remember as a kid thinking that if I was <on 10's flight, I would have gotten some printouts before leaving of what <information would be needed to land and revendevous later, and gone ahead and <landed. So what if I would've been court-martialed....Just imagine what the <temptation would have been like if a landing and return had been possible. < >tyg tyg@caen.engin.umich.edu Problem is, what would you have done once you reached the surface? Apollo 10 carried no proper EVA equipment, no scientific packages. All the crew could have done was to land, lookaround and leave (assuming they could have taken off). They probably had some emergency portable oxygen system in the case they had to perform an EVA in order to get back to the CM due to a docking malfunction. As I remember, Tom Stafford was himself asked if Apollo 10 should have been the landing, and he said no, the LM needed further testing. *** mike (still looking for a publisher) smithwick *** "Los Angeles : Where neon goes to die" [disclaimer : nope, I don't work for NASA, I take full blame for my ideas]
mike@ames.arc.nasa.gov (Mike Smithwick) (07/20/89)
In article <17231@bellcore.bellcore.com> ddavey@grits.UUCP (Doug Davey) writes: >In article <1989Jul19.005449.3163@utzoo.uucp> henry@utzoo.uucp (Henry Spencer) writes: >> orbit, Apollo 10 flew a dress rehearsal of the landing (including LM >> descent to 10 miles above the Moon), and Apollo 11 was the big one. > >Does anybody remember whether the ascent or descent engine was used >during Apollo 10's return from low orbit to rendezvous with the CSM? >Either option seems difficult. On the one hand, I would not expect >the descent engine to be restartable. On the other, firing the >ascent engine and getting the ascent stage cleanly separated from the >descent stage would be tricky since the descent stage was deigned to >be firmly on the lunar surface during this operation. Since the Apollo 10 was a full dress-rehersal for Apollo 11 it did everything 11 would do, except land. This flying under the same lighting conditions as 11 to take landing site pictures, establish landmarks, etc. This included staging and returning to high-orbit using the ascent stage, much as was done on Apollo 9 two months before. So they were doing nothing really new, just verifying the LMs capabilities in the Lunar environment. The notable thing that happened on Apollo 10 was at the point of staging when one of the crew accedentally switched the computer from "attitude hold", over to a mode that told it to start hunting for the CM. Since the CM was nowhere to be found the LM went into a wild dance. Stafford hit the abort button (what Armstrong would've done if the 1202 and 1201 alarms were too serious to ignore), staged and everything calmed down. They were at an altitude of about 8 1/2 NM (at least according to the Flight Plan), and were coming up to a mountain that was 3 miles high. Pretty dramatic stuff. *** mike (still looking for a publisher) smithwick *** "Los Angeles : Where neon goes to die" [disclaimer : nope, I don't work for NASA, I take full blame for my ideas]
henry@utzoo.uucp (Henry Spencer) (07/20/89)
In article <17231@bellcore.bellcore.com> ddavey@grits.UUCP (Doug Davey) writes: >... On the other, firing the >ascent engine and getting the ascent stage cleanly separated from the >descent stage would be tricky since the descent stage was deigned to >be firmly on the lunar surface during this operation. No, there were various abort possibilities (including running out of descent-stage fuel while trying to find a smooth spot to land) that required in-flight separation. I *think* Apollo 10 tested it. -- $10 million equals 18 PM | Henry Spencer at U of Toronto Zoology (Pentagon-Minutes). -Tom Neff | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
vail@tegra.UUCP (Johnathan Vail) (07/20/89)
In article <4481acbf.b097@shadow.engin.umich.edu> tyg@caen.engin.umich.edu (Tom Galloway) writes: The last was probably a good thing. I remember as a kid thinking that if I was on 10's flight, I would have gotten some printouts before leaving of what information would be needed to land and revendevous later, and gone ahead and landed. So what if I would've been court-martialed....Just imagine what the temptation would have been like if a landing and return had been possible. I remember a documentary about the X-15. There was one pilot that with just a little more pressure on the stick could have been the first into space. He followed the mission and didn't do it. Of course on later a mission a pilot died when his plane re-entered backwards... ____//| O \\| _____ | | Johnathan Vail | tegra!N1DXG@ulowell.edu |Tegra| (508) 663-7435 | N1DXG@145.110-,145.270-,444.2+,448.625- -----
rodman@mfci.UUCP (Paul Rodman) (07/20/89)
In article <199@enuxha.eas.asu.edu> kluksdah@enuxha.eas.asu.edu (Norman C. Kluksdahl) writes: > >My memory indicates that the descent stage was cut free, and the ascent >stage was used for the rendezvouz. Again, the book "Chariots for Apollo" Mine too. And I also recall the the LEM underwent some very scary gyrations when the ascent stage was fired.....which were not worried about afterward, as this was the only time anyone planned to fire the ascent stage/jettision the descent stage in flight. pkr