Let’s go back in time to the Apollo 15 and Apollo 17 missions. During the 1971 and 1972 missions, the astronauts conducted an experiment of the lunar heat flow by drilling holes more than six-feet deep in the surface of our satellite to measure the moon’s surface and subsurface temperatures
If you’re wondering what happened with the Apollo 16 mission, they had a broken cable connection so they couldn’t finish setting up their experiment.
The experiment – dubbed the Heat Flow Experiment was an attempt to not only measure the moon’s surface and subsurface temperatures but to measure the rate at which the interior of the Moon loses heat. Sensors were put in the holes at varying levels and on the surface substrate.
And until 1977, data was collected and beamed back down to Earth where scientists were perplexed over the gradual warming of the moon’s surface. Strangely enough, the data monitoring was abandoned in 1977 because of a lack of funding and only a few of the tapes containing all that data were archived. It was assumed the rest of the tapes were lost.
What was lost was ultimately found
Well, fast forward about 30 years or so to 2010. Texas Tech researchers made an amazing discovery: 440 of the lost tapes, tucked away at the Washington National Records Center. The tapes represent the period April through June 1975 and account for less than 10 percent of all the tapes, and they were badly damaged.
For the past eight years, the researchers have spent a considerable amount of time using a number of data recovery techniques to try to restore the tapes, restoring most of the data. And while the remaining tapes were lost, researchers at the Lunar and Planetary Institute in Houston found hundreds of weekly logbooks that included temperature readings from the probes from 1973 through 1977. Now that was a truly lucky find, no?
So the last several years have been spent examining all that data. Interestingly, it showed the warming continued – all the way through to the end of observations in 1977. And that fact led to the question – What was causing the warming?
What the researchers surmised from their study of the data resulted in a research paper published last month in the journal AGU 100.
Study co-author Walter Kiefer, a senior staff scientist at the Lunar and Planetary Institute said the team spent years recovering and interpreting the data in order to pinpoint the source of the warming. And according to the study, the data showed the moon’s subsurface temperatures — in some areas as deep as three meters (9.84 feet) — increased from 1.6 C to 3.5 C over the roughly six-year period measurements were being taken.
A matter of bright versus dark
To understand what the scientists discovered, we need to have some information about the geological makeup of the moon. Basically, there are primarily two types of rocky material on the moon – anorthosite and basalt. Anorthosite is light in color and makes the moon bright, while basalt, which is common on Earth, is darker and appears as the maria, or “seas,” on the moon.
It’s well known that lighter colored surfaces reflect energy (or heat) outward while darker surfaces absorb energy. The research showed that closer to the surface, the warming was more pronounced; and the warmth reached the shallower depths sooner, suggesting that the warmth was occurring from the surface down, and not radiating out from the Moon’s interior.
And that bit of information was good to know, but it still didn’t fully explain the warming. The scientists then looked at the disturbances on the moon’s surfaces – places where the landings took place and the astronauts had walked around. So, could human activity have caused the warming?
“Recently acquired images of the Lunar Reconnaissance Orbiter Camera over the two landing sites show that the regolith (lunar soil), on the paths of the astronauts turned darker, lowering the albedo,” they wrote in their paper. “We suggest that, as a result of the astronauts’ activities, solar heat intake by the regolith increased slightly on average, and that resulted in the observed warming.”
“You can actually see the astronauts tracks, where they walked,” Kiefer said. “And we can see … where they scuffed dirt up — and what it leaves behind is a darker path. In other words, the astronauts walking on the moon changed the structure of the regolith … in such a way that made it a little bit darker.”
CBC Canada reports that Kiefer points out this research paper is a reminder of how human activity can disrupt an ecosystem that has been undisturbed for billions of years. The information gleaned from this research will also provide some information on future lunar and Mars missions.
“The overall effect on the moon of having even a few hundred people isn’t going to be that big of a deal,” Kiefer said. “The moon will be just fine if it’s two degrees hotter than it is right now.”
However, planetary scientist Catherine Neish says that while the moon being two degrees warmer may not pose a problem, it could affect our scientific understanding of the whole universe and not just the moon.
“Even on Earth, it’s this balance of making progress with science and technology but respecting the system that we were given as human beings,” said Neish, who works at Western University in London, Ontario. “We’re obviously changing Earth in significant ways, and I’m sure we would do that on other planets as well.”
Well, this is something to think about, isn’t it?
