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Saturday, January 06, 2024

Performing Science on The Moon with Radioisotopes | NASA Apollo Missions

Performing Science on The Moon with Radioisotopes | NASA Apollo Missions

Apollo 12 Mission: NASA astronaut Alan Bean unloads Apollo Lunar Surface Experiments Package (ALSEP) Radioisotope Thermoelectric Generator (RTG) fuel element.
Astronaut Alan L. Bean, lunar module pilot, is photographed at quadrant II of the Lunar Module (LM) during the first Apollo 12 extravehicular activity (EVA) on the Moon. This picture was taken by astronaut Charles Conrad Jr., commander. Here, Bean is using a fuel transfer tool to remove the fuel element from the fuel cask mounted on the LM's descent stage. The fuel element was then placed in the RTG, the power source for the ALSEP that was deployed on the moon by the two astronauts. The RTG is next to Bean's right leg. While astronauts Conrad and Bean descended in the LM "Intrepid" to explore the Ocean of Storms region of the moon, astronaut Richard F. Gordon Jr., command module pilot, remained with the Command and Service Modules (CSM) "Yankee Clipper" in lunar orbit.
Image Date: 11-19-1969

Alan Bean has just offloaded Apollo 12 ALSEP package No. 2 from the Scientific Equipment (SEQ) Bay using a retractable boom, pulleys, and cables. Cooling fins on the RTG can be seen just to the right of Alan's right knee.
Image Date: 11-19-1969


 Apollo 16 Mission: This shows the dark grey doors of the Scientific Equipment (SEQ) Bay to the left of center, with a silver-colored, cosmic ray detector panel to the right of the doors and the protective cask for the RTG plutonium fuel element beyond the doors on the far left.  A lanyard was used to pull the  main door up and out of the way, revealing side doors which could be opened by hand.
Image Date: 04-21-1972

 Apollo 16 Mission: Astronaut John Young stands at ALSEP deployment site during first EVA 
Astronaut John W. Young, commander of the Apollo 16 lunar landing mission, stands at the Apollo Lunar Surface Experiments Package (ALSEP) deployment site during the first Apollo 16 extravehicular activity (EVA) at the Descartes landing site. The components of the ALSEP are in the background. The lunar surface drill is just behind and to the right of astronaut Young. The drill's rack and bore stems are to the left. The three-sensor Lunar Surface Magnetometer is beyond the rack. The dark object in the right background is the Radioisotope Thermoelectric Generator (RTG). Between the RTG and the drill is the Heat Flow Experiment. A part of the Central Station is at the right center edge of the picture. This photograph was taken by astronaut Charles M. Duke Jr., lunar module pilot.
Image Date: 04-21-1972

A partial view of the Apollo 16 Apollo Lunar Surface Experiments Package (ALSEP) in deployed configuration on the lunar surface as photographed during the mission's first extravehicular activity (EVA), on April 21, 1972. The Passive Seismic Experiment (PSE) is in the foreground center; Central Station (C/S) is in center background, with the Radioisotope Thermoelectric Generator (RTG) to the left. One of the anchor flags for the Active Seismic Experiment (ASE) is at right. While astronauts John W. Young, commander; and Charles M. Duke Jr., lunar module pilot; descended in the Apollo 16 Lunar Module (LM) "Orion" to explore the Descartes highlands landing site on the moon, astronaut Thomas K. Mattingly II, command module pilot, remained with the Command and Service Modules (CSM) "Casper" in lunar orbit.
Image Date: 04-21-1972

Apollo 14 Mission: View of the Central Station of the ALSEP deploy by Apollo 14 astronauts
A close-up view of the central station (CS) of the Apollo lunar surface experiments package (ALSEP), which was deployed on the moon by the Apollo 14 astronauts during their first extravehicular activity (EVA). While astronauts Alan B. Shepard Jr., commander, and Edgar D. Mitchell, lunar module pilot, descended in the Lunar Module (LM) to explore the moon, astronaut Stuart A. Roosa, command module pilot, remained with the Command and Service Modules (CSM) in lunar orbit.
Image Date: 02-05-1971

Apollo 11 Mission: A close-up view of the Apollo 11 Lunar Module as it rested on the surface of the Moon. This photograph was take with a 70mm lunar surface camera during the extravehicular activity of Astronauts Neil Armstrong and Edwin Aldrin on July 20, 1969. This photo shows Aldrin off-loading the Passive Seismometer package from the left-hand Scientific Equipment (SEQ) Bay compartment. The laser reflector is in the righthand compartment.
Image Date: 07-20-1969

 Apollo Radioactive Fuel Case: Cylindrical-shaped assembly with assorted wires and sockets mounted inside a metallic bar cradle. This artifact was transferred to the Smithsonian's National Air & Space Museum in 1974 from NASA's Johnson Space Center.

The Apollo Lunar Surface Experiments Package (ALSEP) was a set of experiments that were placed on the Moon by the Apollo astronauts. The ALSEP received electrical power from heat produced by a radioactive substance. The power generator is called an radioisotope thermal generator (RTG). The radioactive material used for fuel by the RTG was stored outside the Lunar Module, mounted in a casing prior to transfer to the RTG.

The LSEP contained a collection of geophysical instruments designed to continue to monitor the environment of each Apollo landing site for a period of at least a year after the astronauts had departed. Designed for a life of one year (Apollo 17 was for two), they ended up working for up to 8 years, the experiments permanently shut down by Mission Control on September 30, 1977. Due to the experimental nature of the first landing of Apollo 11, especially the mechanics of getting to the lunar surface and back, science took a lesser role, so Apollo 11 had a simpler version known as the Early Apollo Surface Experiments Package (EASEP), with only two experiments.

The ALSEP/EASEP packages were stowed in Scientific Equipment Bay (SEQ Bay)/Quad II during the flight from Earth. The height of the pallets was at the limit for easy manual deployment on level terrain. There were booms to help with off-loading, particularly if the Lunar Module was tilted in such a way that the Bay was higher than normal.  Lanyards were used to release the packages and allow them to swing free and then be lowered by pulley to the surface. On Apollo 15, the LM tilt put the package in easy reach and the off-loading was done entirely by hand. The pulleys were removed for Apollo 17 since the crew felt they were not needed.  The mission timelines show offloading as a coordinated activity and allowed 8 to 9 minutes for both crewmen.

Image Credit: NASA/JSC/Smithsonian
Apollo Image Dates: July 20, 1969- April 21, 1971

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