Science & Technology

Humans Have Already Caused Global Warming on the Moon

We're all familiar with the doom-and-gloom headlines about how human activity is wreaking havoc on the climate of our world. Well, make that two worlds. It turns out that simply by visiting the moon, astronauts have warmed it up — and not by an insignificant amount, either.

Missing Moon Media

NASA has somewhat of a reputation for losing important videotapes. Seriously: We could be watching crisp, high-resolution clips of Neil Armstrong kicking up puffs of moon dust today if the original Apollo 11 tapes hadn't been lost and accidentally erased. So it's not so surprising that after a 1970s-era study of the moon's temperature was abandoned due to lack of funding, they only archived some of the tapes of their data. The rest — we're talking hundreds of reels of tape — were assumed to be lost.

At the time, NASA was puzzled by the data. It showed that the moon's temperature had risen by several degrees just a few years after the first astronauts had visited. Recently, Texas researchers who were looking into the strange temperature fluctuations made it their mission to find the missing tapes. It took them eight years, but they finally tracked down and restored more than 400 reels, which they used to delve into the mystery of the warming moon.

What the tapes showed was that up to 10 feet (3 meters) below the moon's surface, temperatures had risen from 1.6 degrees Celsius (34.9 degrees Fahrenheit) to 3.5 degrees Celsius (38.3 degrees Fahrenheit) over a period of only six years. The research team's hypothesis was intriguing, if a little depressing: What if the astronaut's footprints were warming the moon?

The moon's grayscale appearance comes from the fact that it's mostly made up of two types of rock. Anorthosite is the bright whitish stuff you see over most of its surface; basalt is the darker rock that forms the lunar maria: those big gray "seas" that mar its face. In the same way the sun feels hotter in a black T-shirt than a white one, the dark surfaces on the moon absorb more of the sun's heat than the light surfaces. The team combined their 40-year-old data with cutting-edge imagery from the Lunar Reconnaissance Orbiter (LRO) currently orbiting the moon to zoom in on the disturbances in the lunar soil, known as regolith, that our visits left there.

Hot Moon Rising

As you might expect, every astronaut activity — from Apollo 11's "small step for man" to the liftoff of the final Apollo mission — disturbed the surface regolith to expose the darker soil beneath. "You can actually see the astronauts tracks, where they walked," study co-author Walter Kiefer told the CBC. "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." 12 people have walked on the moon. The last time it happened was with Apollo 17 in 1972, which happened to be the mission that planted the temperature probes for this research.

In fact, the probes themselves probably contributed to the problem — an error we hopefully won't be repeating. "In the process of installing the instruments you may actually end up disturbing the surface thermal environment of the place where you want to make some measurements," lead author Seiichi Nagihara told the American Geophysical Union. "That kind of consideration certainly goes in to the designing of the next generation of instruments that will be someday deployed on the Moon."

This news might be shocking, but there are two things we can all take solace in. First, the researchers say the temperatures would have reached equilibrium at some point, and it's probably already happened. Second, while a temperature change this big would be devastating on Earth, it's not a big deal on the moon. "The moon will be just fine if it's two degrees hotter than it is right now," Kiefer told the CBC.

The bigger takeaway, though, is about just how easily our mere presence can impact extraterrestrial worlds. With sights set on Mars and beyond, our effects on the moon should be a wake-up call that reminds us to take extreme care with planets that aren't our own.

To learn more about humanity's early visits to the moon, check out "Apollo 8: The Thrilling Story of the First Mission to the Moon" by Jeffrey Kluger. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Apollo 11: From the Earth to the Moon

Written by Ashley Hamer July 11, 2018

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.