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Are the ALSEP Transmitters on the Moon Still Functional?

-- Michael | June 7, 2020

Question:

The Apollo missions left several transmitters on the moon, powered by radioisotope generators. At the end of 1979, the experiments were commanded off, but the transmitters were left on (with no modulation).

They were subsequently used for some experiments in the next few years, utilizing VLBI to locate their positions with more precision, etc.

I’ve spent a few hours trying to find any documentation of their last observation… to no avail.

Are any of these transmitters still active? Who has the capability to detect them?
ALSEP 1 Apollo 12 2278.5 MHz
ALSEP 3 Apollo 14 2279.5 MHz
ALSEP 2 Apollo 15 2278.0 MHz
ALSEP 4 Apollo 16 2276.0 MHz
ALSEP 5 Apollo 17 2275.5 MHz

They are 1 watt crystal controlled transmitters with their antenna pointed at earth. It’s possible one or more are still alive, but unlikely.

Any info would be appreciated.

Mike Warot
KA9DGX
Munster, Indiana, USA

-- Michael

Answer:

You probably found the very thorough summary of the Apollo Lunar Surface Experiments (ALSEP) packages deployed on the surface of the Moon by the Apollo missions in the 1970s. As you noted, there were a number of Very Long Baseline Interferometry (VLBI) measurements of these transmitters in the 1970s, but I could not find any references to measurements of the ALSEP transmitters after the program’s termination in September 1977. It appears to me that the transmitters were turned-off when the program ended.

-- Jeff Mangum

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