- April 16th, 2012
- Write comment
“For the wise man looks into space and he knows there is no limited dimension.”
*Writer’s Note: There’s a lot more on this topic which I will cover in my upcoming blogs. I just wanted to share this part of history with you. I have always been fascinated with space exploration. Hope you enjoy it. JP
On April 17, 1970, Apollo 13 successfully splashed down in the South Pacific Ocean, after what Commander James Lovell called a “successful failure,” that is “the safe return of the crew, but the failure to make the lunar landing”. Accompanying Commander Lovell on this mission was John Swigert (Command Module pilot) and Fred Haise (Lunar Module pilot).
Apollo 13 was to be the third manned space mission to land on the moon. However, 56 hours into the mission, an explosion involving oxygen tank #2 in the Service/Command Module occurred at 173,790 nautical miles (almost 200,000 miles) away from earth. The lunar landing was aborted, and the crew was forced to return to earth using the Lunar Excursion Module (LEM) “Aquarius” as a lifeboat because of the damage done to the Service Module. The Command Module “Odyssey” was the reentry vehicle used.
The following is from the “Apollo 13 Technical Air–to-Ground Voice Transcript, April, 1970.” The time column is day, hour, minute, and second. CDR is Commander Lovell, CMP-John Swigert, LMP-Fred Haise, and CC is Capsule Communicator.
02 07 52 58: CC-13, we’ve got one more item for you, when you get a chance. We’d like you to stir up your cryo tanks. In addition, I have shaft and trunnion…
02 07 53 06: CMP-Okay.
02 07 53 07: CC-for looking at the Comet Bennett, if you need it.
02 07 53 12: CMP-Okay. Stand by.
02 07 55 19: LMP-Okay, Houston
02 07 55 20: CDR-I believe we’ve had a problem here.
02 07 55 28: CC-This is Houston. Say again, please.
02 07 55 35: CDR-Houston, we’ve had a problem. We’ve had a MAIN B BUS UNDERVOLT.
Three days later, the extent of the damage was discovered with the jettison of the Service Module:
05 18 04 46: CDR-And there’s one whole side of that spacecraft missing.
05 18 04 50: CC-Is that right?
05 18 04 57: CDR-Right by the – Look out there, will you? Right by the high gain antenna, the whole panel is blown out, almost from the base to the engine.
05 18 05 09: CC-Copy that.
Three hours later came the LEM jettison and subsequent discussions of its location:
05 21 29 56: CDR-Five. LM jettison.
05 21 30 05: CC-Okay, copy that. Farewell, Aquarius, and we thank you.
05 22 0l 12: CDR-Okay. Fine; thank you Joe. How does the LM look? Are you still tracking it?
05 22 01 17: CC-All I’ve heard was that it’s-that the cabin was holding pressure. I haven’t heard anything more.
05 22 30 50: CC-Okay. At 10 minutes to 400 K, you’re looking good; we’re real happy with the trajectory, and a minute ago, we just lost contact with your friend Aquarius.
05 22 3] 03: CMP-Okay. Where did she go?
05 22 31 07: CC-Oh, I don’t know. She’s up there somewhere.
05 22 31 13: CMP-She sure was a good ship.
05 22 31 16: CC-Hey, just as I said that, we got another burst of LM data, so I guess it’s still ticking.
Apollo 13 Technical Air–to-Ground Voice Transcript, April, 1970
Aquarius reentered the Earth’s atmospheric and landed in the South Pacific, in the Tonga Trench south of Fiji. The Tonga Trench has an average depth of 20,000 feet. The Command Module splashed down 201 miles south of Johnston Atoll in the South Pacific, with all three crew members safe.
Apollo 13 Home Page-NASA
Stowed away on the Lunar Module was a SNAP-27 (Systems Nuclear Auxiliary Power), a Radioisotope Thermoelectric Generator (RTG). It was designed to be left on the lunar surface to power experiments left by the crew.
The SNAP-27 contained 3.79 kilograms (8.36 pounds) of Plutonium 238, one of the 15 isotopes of Plutonium, atomic number 94 on the element chart.
The SNAP-27 is designed to operate off of power produced by the natural decay of Plutonium 238. The Pu 238 produces heat, which in turn produces electricity, around 63 watts. Plutonium 238 has a half life of 87.74 years. A half life is the amount of time it takes for half of the atoms of the element to decay.*
On page 8 of the Department of Energy’s publication “Nuclear Power in Space”, there’s a picture of astronaut Gordon Bean of the Apollo 12 mission preparing a RTG.
Nuclear Power in Space
*Physical, Nuclear, and Chemical Properties of Plutonium
Institute for Energy and Environmental Research (IEER)
Apollo 13 Lunar Module/ALSEP
To give you a good explanation of the lunar experiment (Passive Seismic Experiment) and a description of the SNAP-27 unit, I have gathered the following information from the Apollo 13 Press Kit, April 2, 1970:**
Passive Seismic Experiment
The ALSEP (Apollo Lunar Surface Experiments Package) Passive Seismic Experiment (PSE) will measure seismic activity of the Moon and obtain information on the physical properties of the lunar crust and interior. The PSE will detect surface tilt produced by tidal deformations, moonquakes and meteorite impacts. The passive seismometer design and subsequent experiment analysis are the responsibility of Dr. Gary Latham of the Lamont-Doherty Geological Observatory.
A similar passive seismic experiment was deployed as part of Apollo 12 ALSEP station at Surveyor crater last November and has transmitted earthward lunar surface seismic activities since that time. The Apollo 12 and 13 seismometers differ from the seismometer left at Tranquility Base in July 1969 by the Apollo 11 crew in that they are continuously powered by a SNAP-27 radioisotope electric generator, while the Apollo 11 seismometer was powered by solar energy and could output data only during the lunar day at its location.
SNAP-27 is one of a series of radioisotope thermoelectric generators, or atomic batteries, developed by the U.S. Atomic Energy Commission under its SNAP Program. The SNAP (Systems for Nuclear Auxiliary Power) Program is directed at development of generators and reactors for use in space, on land, and in the sea.
SNAP-27 was first used in the Apollo 12 mission to provide electricity for the Apollo Lunar Surface Experiments Package (ALSEP). A duplicate of the Apollo 12 SNAP-27 will power the Apollo 13 ALSEP.
The basic SNAP-27 unit is designed to produce at least 63 electrical watts of power. It is a cylindrical generator fueled with the radioisotope plutonium 238. It is about 18 inches high and 16 inches in diameter, including the heat radiating fins. The generator, making maximum use of the lightweight material beryllium, weighs about 28 pounds unfueled.
The fuel capsule, made of a superalloy material, is 16.5 inches long and 2.5 inches in diameter. It weighs about 15.5 pounds, of which 8.36 pounds represent fuel. The plutonium 238 fuel is fully oxidized and is chemically and biologically inert.
The rugged fuel capsule is contained within a graphite fuel cask from launch through lunar landing. The cask is designed to provide reentry heating protection and added containment for the fuel capsule in the unlikely event of an aborted mission. The cylindrical cask with hemispherical ends includes a primary graphite heat shield, a secondary beryllium thermal shield, and a fuel capsule support structure made of titanium and Inconel materials.
The cask is 23 inches long and eight inches in diameter and weighs about 24.5 pounds. With the fuel capsule installed, it weighs about 40 pounds. It is mounted on the lunar module descent stage by a titanium support structure.
Once the lunar module is on the Moon, the lunar module pilot will remove the fuel capsule from the cask and insert it into the SNAP-27 generator which will be placed on the lunar surface near the module.
The spontaneous radioactive decay of the plutonium 238 within the fuel capsule generates heat into the generator. An assembly of 442 lead telluride thermoelectric elements converts this heat-1480 thermal watts-directly into electrical energy-at least 63 watts. There are no moving parts.
Plutonium 238 is an excellent isotope for the use in space nuclear generator. At the end of almost 90 years, plutonium 238 will still supply half of its original heat. In the decay process, plutonium 238 emits mainly the nuclei of helium (alpha radiation) a very mild type of radiation with a short emission range.
Before the use of the SNAP-27 system in the Apollo program was authorized, a thorough review was conducted to assure the health and safety of personnel involved in the mission and the general public. Extensive safety analyses and tests were conducted which demonstrated that the fuel would be safely contained under almost all creditable accident conditions.
Contractors for the SNAP-27
General Electric Co., Missile and Space Division, Philadelphia, PA, designed, developed, and fabricated the SNAP-27 generator for the ALSEP.
The 3M Co., St. Paul, MN, fabricated the thermoelectric elements and assembled the SNAP-27 generator.
Solar Division of International Harvester, San Diego, CA, fabricated the generator’s beryllium structure.
HITCO, Gardena, CA, fabricated the graphite structure for the SNAP-27 Graphite LM Fuel Cask.
Sandia Corp., a subsidiary of Western Electric, operator of AEC’s Sandal Laboratory, Albuquerque, NM, provided technical direction for the SNAP-27 program.
Savannah River Laboratory, Aiken, SC, operated by DuPont Co. for the AEC, prepared the raw plutonium fuel.
Mound Laboratory, Miamisburg, OH, operated by Monsanto Research Corp. for the AEC, fabricated the raw fuel into final fuel form and encapsulated the fuel.
I will provide additional information about several sites listed above (Sandia Corp., Savannah River, and the Mound Laboratory) in upcoming blogs.
**NASA-Apollo 13 Press Kit, April 2, 1970
Nuclear Power on the Moon-Apollo 12
Will NASA ever recover Apollo 13’s Plutonium from the Sea?
Matthew Van Dusen, November 28, 2011