Why did the Moon’s surface warm slightly back in the 1970s? It’s been a mystery for decades, but now the discovery of long lost data from the Apollo missions has shown that astronauts were to blame.
Between 1971 and 1977 heat probes, placed by Apollo astronauts, recorded heat flow through a few metres of Moon crust, to try to establish how much heat moves from the Moon’s core to its surface. The data showed anomalous warming of the lunar surface over this period, but, because the last three years of data were mislaid, scientists remained baffled as to the cause of the warming. Potential explanations included changes in the Moon’s orbit, excess radiation from Earth and astronaut activity.
In 2010, Seiichi Nagihara, a planetary scientist at Texas Tech University, and colleagues found the lost data, languishing in the Washington National Records Center in Maryland. After extracting the numbers they’ve been able to show that disturbance of the surface, caused by astronauts driving around in their rover and clomping about in moon-boots, resulted in less sunlight being reflected, and raised the surface temperature in the disturbed regions by 1 to 2 degrees. Their findings are published in Journal of Geophysical Research: Planets.
