Tuesday, July 01, 2003

Apollo LM mad science:

Asked by a non-science university graduate:

What happened to the Apollo LEMs after docking with the CSMs? (I Suppose the crashed back onto the Moon's surface. At what velocity did they crash?)

Yes, they crashed back on to the Moon, and it was done on purpose, to provide noise for the seismometers to be able to get data on the Moon's deep interior.

You got me curious, so I went and found out what happened to all the Lunar Modules.

Grumman Aerospace built 16 LMs of human-flight-ratable quality, and several additional modules (also known as "lunar test articles," or LTAs) that were used for unmanned flights and ground testing (including test-to-failure).

By the way, the early name for this spacecraft was Lunar Excursion Module (LEM), but NASA felt that the word "Excursion" gave it a frivolous feel, so they got rid of it, and the official name for the spacecraft became Lunar Module (LM) -- but by that point the pronunciation was fixed, and LM was pronounced "lem" and that has confused everybody ever since (including you and me!). (Reference: http://www.hq.nasa.gov/office/pao/History/SP-4205/ch14-6.html).

I'm sure you know, but for completeness I should state that the LM was actually composed of two stages; the descent stage, which carried the motor that slowed the LM on its landing (basically the lower part with the legs), and the ascent stage which was the strange looking upper part in which the astronauts actually stayed, and which carried them back to the CSM in lunar orbit. Your question refers specifically to the fate of the ascent stages of the LMs except in the cases of Apollo 10 and 13 (see below).

In chronological order of LTA and LM flights (or scheduled flights), this is what I found for you:

1. Apollo 4 - launched 9 November 1967. The first all-up launch of Saturn V rocket (unmanned) carried LTA-10R into orbit, which was completely destroyed on re-entry into the Earth's atmosphere.

2. Apollo 5 - launched 22 January 1968. First test of LM1 in space (unmanned). This LM had no legs. The LM's orbit later decayed and LM1 re-entered atmosphere several hundred kilometers SW of Guam on February 12 1968. (http://www.hq.nasa.gov/office/pao/History/SP-4205/ch10-3.html)

3. Apollo 6 - launched 4 April 1968. LTA-2R carried into orbit, and was destroyed on re-entry into the atmosphere. This flight was to have carried LM2, but due to the success of Apollo 5 LM testing, LM2 was never flown, and LM2 now sits in the National Air and Space Museum in Washington DC.

Apollo 7 and Apollo 8 did not carry LMs, despite having LM Pilots along in their crews.

4. Apollo 9 - launched March 3, 1969. Extensive manned flight-testing of LM3 "Spider" in Earth orbit, carrying out in-space engine tests and maneuvers equivalent to those that would be needed for lunar orbit rendezvous. LM3 becomes the first non-re-entry capable spacecraft to carry humans (i.e. if something went wrong with the CSM, there was no way home). The LM was jettisoned into a highly elliptical orbit (237 km perigee, 6900+ km apogee) that later decayed. LM destroyed on re-entry into atmosphere.

OK, now I finally get to answering your exact question...

5. Apollo 10 - launched May 18 1969. LM4 "Snoopy" goes to the Moon, and descends to within 14,447 meters altitude of the lunar surface, where the descent stage was jettisoned. The descent stage simply fell to the surface, so it impacted at approximately lunar free-fall from this height, 152 m/s or 547 km/hr. The ascent module, on the other hand, was jettisoned after re-docking with the CSM in lunar orbit, and then its engines were fired, injecting it into a solar orbit where it still exists! People often ask if this crew was tempted to land, but it should be pointed out that the ascent module was incapable of climbing back all the way from the surface (insufficient fuel), so the crew knew it would have been stranded had they actually landed.

6. Apollo 11 - launched July 16 1969 LM5 "Eagle" left the descent stage on the Sea of Tranquillity, and the ascent stage was jettisoned 2 hours after docking with the CSM. This orbit decayed, and it crashed onto Moon, but we are unsure where. This impact velocity was much much greater, not only because it was in free-fall from a much higher altitude (the CSM orbited at about 111 km above the surface), but because the forward velocity was at least 600 km/hr as well. My estimate for a minimum speed at impact is 1,600 km/hr. The seismometers left on the Moon by the crew registered the impact of the ascent module. (But note also that all the Saturn IV-B translunar injection stages also crashed onto the Moon before their respective LM's arrival -- this velocity had to be staggering, since the stage was basically accelerating all the way from the Lagrange point inwards!)

http://www.hq.nasa.gov/office/pao/History/SP-4205/ch14-6.html for mission details

http://nssdc.gsfc.nasa.gov/planetary/lunar/images/a11lmreturn.jpg for a photo of Eagle after being jettisoned.

http://www.hq.nasa.gov/office/pao/History/ap15fj/loressay.htm for a GREAT page on the physics of getting the LM to get back to the CSM, which was actually more difficult than getting to the Moon itself!

7. Apollo 12 - launched November 14, 1969 LM6 "Intrepid" also left the descent stage on the Moon, on the Sea of Storms. The ascent stage was jettisoned and crashed at the lunar coordinates 3.94 S, 21.21 W, probably at a very similar velocity to LM5.

8. Apollo 13 - launched April 11, 1970 LM7 "Aquarius" was the famous lifeboat that saved Lovell, Swigert and Haise after an explosion on the SM. The LM descent stage was used to insert the LM-CSM into a trans-Earth injection orbit, a task for which it was never designed. LM7 burned up in Earth's atmosphere after it was jettisoned just prior to CM re-entry procedures began.

For great info on the orbit used by the Apollo program, go to http://www.christa.org/lunar.htm, and especially the diagram at http://www.christa.org/lor.htm which shows the various orbits very clearly.

9. Apollo 14 - launched January 31, 1971. LM8 "Antares" also left the descent stage on the Moon, on the Fra Mauro highlands. The ascent stage was jettisoned and crashed at the lunar coordinates 3.42 S, 19.67 W, probably at a very similar velocity to LM5.

10. LM9 was originally scheduled to fly on Apollo 15, but the J-series redesign of the LM to include the rover and extended stay capability made it obsolete. It now sits at the Kennedy Space Center Visitor's Center.

11. Apollo 15 - launched July 26 1971. LM10 "Falcon" was the first of the J-series, heavier LMs. The descent stage was also left on the Moon, in the Hadley Rille area of the Apennines. The ascent stage was jettisoned and crashed at the lunar coordinates 26.36 N, 0.25 E, probably at a very similar velocity to LM5, despite a much higher orbital inclination.

12. Apollo 16 - launched April 16 1972. LM11 "Orion" - descent stage was also left on the Moon, in the Descartes highlands. The ascent stage began to tumble immediately after being jettisoned, so the lunar impact site is unknown.

13. Apollo 17 - launched December 7 1972. LM12 "Challenger" was the final LM to reach the Moon. . The descent stage was also left on the Moon, in the Taurus-Littrow area of the Sea of Serenity. The ascent stage was jettisoned and crashed at the lunar coordinates 19.96 N, 30.50 E, probably at a very similar velocity to LM5

14. Apollo 18 - this mission to Copernicus Crater was cancelled in September of 1970, so LM13 was not used. It now belongs to the Cradle of Aviation Museum on Long Island, and was used by HBO for filming "From the Earth to the Moon"

15. Apollo 19 was also cancelled in September of 1970, so LM 14 was not used. It now belongs to the Franklin Institute in Philadelphia.

16. Apollo 20 was cancelled earlier, on January 4, 1970, along with the manned mission to Mars. LM15 was scrapped by Grumman before making it off the assembly line.

A final module, MSC-16, now sits at the Museum of Science and Industry in Chicago, IL. -- this is a LTA, and served only as a training vehicle.

If you want to find out where many components of the American program are now housed, a great resource is the following page: http://aesp.nasa.okstate.edu/fieldguide/frames.html -- you will probably find some piece of American space history is housed nearby.

James McDivitt (Commander, Apollo 9) to Grumman Aerospace workers: "Thanks for the funny-looking spacecraft - It sure flies better than it looks!"

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