
I wrote in my last blog about the new images of the moon which show the Apollo landing sites and even the astronauts, footprints on the moon. The photos also show the scientific experiments that were placed there to monitor the geophysical makeup of the moon. These experiments were collectively called the
Apollo Lunar Surface Experiment Package (or ALSEP). Each Apollo mission carried a set of experiments but the mix of experiments was different on every flight. [The image to the left was from Apollo 16 and you can see the Lunar Rover in the background next to the Lunar Lander.]
I began working for Bendix Aerospace Systems Division in Ann Arbor, Michigan in 1970, right after graduating from the University of Michigan. Bendix was the prime contractor for the ALSEP experiments. The Apollo 11 and 12 missions had already successfully landed on the moon by the time I joined Bendix. Shortly after I started, the Apollo 13 disaster occurred (April, 1970) and it set back subsequent missions by more than a year. I was involved in engineering efforts on all the subsequent Apollo science packages (14 through 17).
A little background about the experiments: ALSEP was designed to be a package of experiments that shared a common communication and power source. The Central Station housed all of the communications electronics and telemetry systems. It is the tall, gold structure in the photo below. The antenna for transmitting data is the pole-like object on top of the Central Station. The gold is actually metal-coated mylar-plastic film and it was used to control the thermal environment inside the Central Station. Keep in mind that the moon in the daytime is over 200 degrees F and it is -200 degrees F at night. That is a tough environment and controlling the temperature in the electronics in all of the experiments was a major challenge.

The little gray, finned object to the left and behind the Central Station is the Radio Thermal Generator or RTG. It is the power source for all of the experiments. Electricity is generated by converting the heat from a Plutonium-238 fuel cartridge inside the RTG. As an aside, one of the Apollo 12 astronauts said that he could feel the heat from the Plutonium cartridge all the way inside his space suit when he was loading the cartridge into the RTG. That's hot (in more ways than one)!
The silver disk-like object in the foreground is actually a lunar seismometer, part of something called the Passive Seismic Experiment or PSE (the program just loved acronyms). It was designed to measure "moonquakes". Actually, you are not looking at the seismometer but at the thermal shroud (think blanket) which covered the seismometer. The instrument was so sensitive that if it had been directly exposed to the lunar day and night, it would have "creaked" due to thermal expansion and contraction. Even with the thermal shroud, it still creaked a little and buggered up the data.
All of the experiments (and there are three more that are out of the picture) were connected to the Central Station by cables. You can just make these out in the photo as copper/gold-colored ribbons in the lunar soil. They really
were ribbons, by the way, ribbons that were about three inches wide, each of which carried multiple wires.
By the time I got to Bendix, the system and the experiments had already been designed (the work started in 1966). Bendix was in the process of building the final instrument packages and testing them to make sure they were ready for their missions. As a young engineer, my job was to work on problems that came up from experiences on previous missions. One of those experiences happened on the Apollo 16 mission. Astronaut John Young was deploying some of the experiments when his boot became entangled in one of the flat-ribbon cables. With the bulk of his suit and the changed sensations of lunar gravity, he was completely unaware that he had snagged a cable. When he moved, he accidentally tore the cable out of the experiment (it was an experiment for measuring heat flow) and the experiment was wrecked. Several million dollars gone in an instant. You can see this happen in the movie below if you start watching around the 11:36 mark. (The whole movie tells the story of the Apollo 16 mission. It is worth watching.) [movie from Internet Archive]