On August 27, the Indian Space Research Organisation (ISRO) released a graph of the temperature variation between the moon’s surface and a point around 8 cm below as measured by an instrument named ChaSTE on board the lander module of the Chandrayaan-3 mission.
According to ISRO, ChaSTE – short for ‘Chandra’s Surface Thermophysical Experiment’ – measured the temperature profile of the lunar topsoil around the south pole to understand its thermal behaviour.
ChaSTE is a temperature probe that can be driven into the moon’s surface using a motor to a depth of up to 10 cm. It has 10 sensors. The probe “… is mounted on the side of the lander,” according to a NASA catalogue entry.
ChaSTE was developed by a team led by the Space Physics Laboratory of ISRO’s Vikram Sarabhai Space Centre (VSSC), together with the Physical Research Laboratory (PRL), Ahmedabad.
ISRO said the data recorded by ChaSTE’s sensors after one insertion yielded the graph shown above.
Scientists have known from past studies and missions that the moon’s south pole hosts a variety of temperatures. The sides of some craters never receive any sunlight and can be as cold as just 40 degrees C above absolute zero.
Other parts, like the parts of some craters that frequently receive sunlight, can get up to more than 50 degrees C.
ChaSTE’s findings reflect this variation between the moon’s surface, which is covered by a patina of loose rocks and dust called the lunar regolith, and 10 cm under it.
Its data show that at the moon’s surface (where the lander is located, a point between the craters Manzinus C and Simpelius N), the temperature is 40-50 degrees C. But just under 80 mm under, it plunges to around -10 degrees C.
Given that Chandrayaan-3 is the first mission to have soft-landed a robotic instrument in the moon’s south pole area, ChaSTE’s data is also the first such from this place. “Detailed observations are underway,” ISRO said in a tweet.
The temperature variation indicates that the moon’s topsoil is a powerful thermal insulator, in keeping with previous findings, and adds credence to the idea that it can be used to build habitats for humans to shield them from frigid conditions and harmful radiation.
With agency inputs