ChaSTE payload onboard of Vikram Lander reveals Lunar South Pole Temperature Profile

Indian Space Research Organization(ISRO) has published the first temperature profile of the lunar south pole. The information was released just four days after the Vikram lander and Pragyaan rover landed at the location that Prime Minister Narendra Modi called the "Shiv Shakti" point [1].

The Chandra Surface Thermo-physical Experiment, or ChaSTE monitors the temperature profile of the lunar topsoil around the pole to better understand the thermal behaviour of the moon's surface. It has a temperature probe with a regulated penetration mechanism that can penetrate 10 cm below the surface. Ten separate temperature sensors are installed on the probe [2].

Fig : A design of the Vikram Lander on the Chandrayaan-3 mission [3].

The data was published on the official X page of the Indian Space Research Organization(ISRO). The graph displays the variations in surface and near-surface temperatures that were detected when the probe descended to various depths on the moon.

Fig: Variation of Lunar sure Temperature with respect to depth [2].

The moon surface temperature can reach 127°C when illuminated by the sun, but drops sharply to -232°C when the illuminated side goes into darkness which are also the coldest temperatures recorded in our solar system. There are certain craters at the poles of the moon that never receive sunlight. In 2018, NASA scientists confirmed the presence of ice in these dark and cratered regions using the Moon Mineralogy Mapper (M3) instrument aboard the Chandrayaan-1 mission launched in 2008 by ISRO [4]. Additionally, scientists found that some of these craters and shaded regions might reach temperatures as low as -272°C [5].

The image shows the distribution of surface ice at the Moon’s south pole (left) and north pole (right), detected by NASA’s Moon Mineralogy Mapper instrument. Blue represents the ice locations, plotted over an image of the lunar surface, where the gray scale corresponds to surface temperature (darker representing colder areas and lighter shades indicating warmer zones). The ice is concentrated at the darkest and coldest locations, in the shadows of craters. This is the first time scientists have directly observed definitive evidence of water ice on the Moon’s surface.

Credits: NASA [4]

ISRO scientists anticipated that the surface temperature in the vicinity would range from 20°C to 30°C as Chandrayaan-3's Vikram Lander touched down close to the south pole of the moon [8]. However, data from the ChaSTE payload indicated temperatures as high as 70°C. This is especially intriguing given that when we go a few centimetres beneath the surface of the Earth, a temperature variation of not more than 2–3 degrees is typically noticed. The Moon’s south pole, however, displays a 50 degree variation between the surface and 8 cm deep reaching upto -10°C [6] and 5-10°C at 6 cm (60 mm) depth [7].

The first two of Chandrayaan-3's three main goals—to soft land on the south pole of the moon, demonstrate the rover's capabilities, and conduct in-situ experiments at the landing site—have been successfully met [9]. All of the instruments, according to ISRO, are working. While the discovery of the temperature profile of lunar soil is remarkable, we continue to be excited for further incredible discoveries.