Apollo 15 astronaut on the moon

Apollo astronauts changed the moon forever, but not in the ways you think

Contributed by
Sep 14, 2018, 9:51 AM EDT

Humans have doubtless had an effect on the Earth’s temperature, never mind what you might see on your Twitter feed. But the moon?

The Apollo 15 and Apollo 17 missions in 1971 and 1972 didn’t just leave behind boot prints in the moon dust. Astronauts conducted experiments measuring the flow of subsurface heat to the lunar surface in an effort to demystify at least some aspects of the moon’s geology — until some strange temperature increases had them rethinking everything. Temps would rise by 34.7 to 38.3 degrees Fahrenheit. All they could be certain of was that neither the sun nor the thermometers’ power generators were literally heating up the moon, but the culprit has remained a mystery until now.

Turned out the answer was buried in the data we were missing. As the probes transmitted temperature data to Earth, it was recorded on admittedly archaic 7-track magnetic tapes that were eventually archived in the Washington National Records Center. The 440 tapes recovered only accounted for 10 percent of the data collected, and none went past 1974. Even what remained had all but completely broken down, and extracting data from these tapes was a tedious process. Anything from 1975-77 was assumed lost until NASA investigated its archives of Apollo data in 2010.

Apollo 17 image of astronaut on the moon

The astronauts of Apollo 17 had no idea they were leaving behind more than just an experiment. Credit: NASA

At the Lunar and Planetary Institute in Houston, NASA unearthed weekly logs of the temperatures measured by the probes from those two years that were thought to have vanished. It took eight years of search and analysis before they finally figured it out.

What the probes had recorded were temperatures that would not stop rising through 1977. Probes closer to the surface heated up faster, indicating the soil had been heated from above, and also clueing in scientists that this was a man-made phenomenon. Images from the Lunar Reconnaissance Orbiter revealed exactly how this had happened. The moment a space boot shuffled the dust on the moon around, it revealed a deeper and darker layer of lunar soil. Anything darker absorbs more heat, which meant the darker soil inevitably absorbed more solar radiation.

Meaning, humans walking around on the moon were warming it up without even trying. Just installing the probes interfered with the experiment, so whatever data we were getting included whatever extra heat resulted from human activity. It obviously doesn’t take much to disturb the soil to the point of setting off a temperature increase, either.

Maybe we should think about this when we finally touch down on Mars.

(via Seeker)