ISRO to revive Vikram lander, Pragyan rover after cold lunar night

Waking up the rover, the lander

The Chandrayaan-3 mission was initially planned to last one lunar day, equivalent to 14 days on Earth. The landing point of Vikram has been dubbed Shivshakti Point by ISRO, and the rover spent the next few Earth days carrying out multiple experiments using its onboard sensors.

Knowing that the Sun would set at Shivshakti point on September 4, the scientists began a phased shutdown of the two devices on September 2. The mission had already completed its objectives, but a revival at the next sunrise gives the researchers a bonus attempt to conduct more experiments on the lunar surface.

To maximize their chances, the scientists carried out three critical steps. I am recharging the onboard batteries completely and orienting the solar panels. Hence, they receive light as soon as the Sun rises, leaving the receiver on so the devices can be contacted again.

... ... and here is how the Chandrayaan-3 Rover ramped down from the Lander to the Lunar surface. pic.twitter.com/nEU8s1At0W

— ISRO (@isro) August 25, 2023

Hopeful not confident

On Thursday (September 21), as the Sun rises again on the south pole of the Moon, the team at ISRO Telemetry, Tracking and Command Network  (ISTRAC) will begin entering commands, which, if the instruments receive, will help them wake up from the 14-day slumber and ready to continue the mission for another 14 days.

This might sound like an easy feat for a space agency that has created a record, but the frigid temperatures during lunar nights stand in the way. Night temperatures on the Moon regularly dip to -328 Fahrenheit (-200 degrees Celsius). Near the lunar poles, these reach -418 Fahrenheit (-250 degrees Celsius).

For the rover and lander to successfully revive, their onboard instruments must survive these horrible temperatures. Previous missions, such as China's Chang'e 4 lander and rover, survived around -310 Fahrenheit (-190 degrees Celsius) but were equipped with radioisotope heating units (RHU).

A RHU is a radioactive device that decays heavy elements like Plutonium-238 to provide heat to instruments and help them keep warm, even if the ambient temperatures fall. Neither the rover nor the lander were equipped with RHUs, making ISRO more hopeful than confident that the instruments would awaken again.

ISRO chairman S Somnath hopes to achieve this feat on Friday, September 22.