Why ISRO put Chandrayaan-3's Rover to sleep on the Moon: A simple explanation

The Indian Space Research Organisation (ISRO) announced a significant milestone in the Chandrayaan-3 mission as its rover, named Pragyan, has successfully completed its designated tasks on the lunar surface. In a statement shared on social media platform X (formerly known as Twitter), ISRO confirmed that Pragyan has been safely parked and placed in sleep mode.

As per ISRO's update, the rover's current status is as follows:
- The rover's battery is fully charged.
- The solar panel has been oriented to capture light during the upcoming lunar sunrise, expected on September 22, 2023.
- The receiver remains active.

ISRO expressed its hopes for a successful awakening of the rover for future assignments. However, the space agency also noted that if the rover doesn't awaken, it will remain on the Moon as India's lunar ambassador.

Pragyan is powered by solar panels, like how your calculator or some watches are powered by sunlight. To keep it awake and working, it needs sunlight to charge its batteries. But the Moon has very long nights, lasting about two Earth weeks! During this time, Pragyan can't get any sunlight, so it can't work. So, the scientists at ISRO have put Pragyan to sleep until the next lunar sunrise, which is expected on September 22, 2023.

Pragyan, weighing 26 kilograms and equipped with six wheels, operates on solar power and is designed for scientific exploration. Its primary mission objective was to analyze the composition of lunar soil and rocks in the south polar region, where the Chandrayaan-3's lander, Vikram, made its historic touchdown.

ISRO shared that the APXS (Alpha Particle X-ray Spectrometer) and LIBS (Laser Induced Breakdown Spectroscope) payloads on the rover have been deactivated. Data collected by these instruments is transmitted back to Earth through the lander Vikram.

The APXS instrument is specialized for in-situ analysis of the elemental composition of soil and rocks on celestial bodies with minimal atmosphere, like the Moon. Notably, APXS observations have identified the presence of intriguing minor elements, including sulphur, alongside major elements such as aluminium, silicon, calcium, and iron.

Chandrayaan-3 Mission:
The Rover completed its assignments.

It is now safely parked and set into Sleep mode.
APXS and LIBS payloads are turned off.
Data from these payloads is transmitted to the Earth via the Lander.

Currently, the battery is fully charged.
The solar panel is…

— ISRO (@isro) September 2, 2023