Chandrayaan-3 instruments to be put to ‘sleep’ today

The primary objectives of the mission have been successfully completed, including recording the first seismic readings on the Moon.

The Indian Space Research Organisation (Isro) began putting the Chandrayaan-3’s lander, Vikram, and rover, Pragyan, to sleep on Saturday, confirming that the primary objectives of the country’s third lunar mission were successfully completed.

The Chandrayaan-3 mission was launched on July 14 from the Sriharikota spaceport (PTI)

The agency did not rule out the possibility of the robot and the scientific instruments being revived when the Sun rises again on the Moon around September 22, a period before which the devices will be in complete darkness and severely cold temperatures that are expected to be punishing for the batteries that store power.

“We have achieved all our primary mission objectives. From September 3, before the lunar sun set, the instruments will be turned off. The collected data will now be analysed by our teams,” Isro chairman S Somanath told HT.

Hours later, Isro confirmed in a tweet that Pragyan had been “safely parked and set into sleep mode”.

“Currently, the battery is fully charged. The solar panel is oriented to receive the light at the next sunrise expected on September 22, 2023. The receiver is kept on,” it added, after mentioning that two of Pragyan’s instruments had been turned off and data from them were being transmitted via Vikram to Earth.

“Hoping for a successful awakening for another set of assignments! Else, it will forever stay there as India’s lunar ambassador,” Isro added.

The Chandrayaan-3 mission was launched on July 14 from the Sriharikota spaceport. On August 23, at 6.03pm, Vikram made a successful soft-landing near the lunar south pole, making India the first country to achieve the feat. On August 24, the rover rolled out of Vikram’s belly.

The equipment, all of which is solar powered, spent a day charging batteries, and the experiments commenced late on August 24, giving the mission around nine days for collecting data.

While the lunar sunset is expected around September 6, scientists explained that the visibility in the area where the lander is parked has started reducing, necessitating a phased initiation of putting the equipment to sleep.

Speaking to HT, Anil Bhardwaj, director of the Physical Research Laboratory (PRL), said: “We do not have a set timeline for when which instrument will be put to sleep, but the process will start from tomorrow (September 3). The problem is that the light around the area has started getting dimmer.”

Isro’s PRL is closely involved in the mission and designed some of the instruments on-board the modules.

According to National Aeronautics and Space Administration’s (NASA) Moon Tracker, the lunar sunset will commence from September 4 — starting from the area where Chandrayaan-3’s lander is parked —and go on till September 6.

The next lunar sunrise is scheduled for September 20, according to the NASA tracker, but at the south pole, that could come slightly later.

Bhardwaj, however, reiterated that the Indian space agency has successfully completed its mission targets.

“We are still getting data and we are extremely happy with the quality and the quantity of it,” he said.

Bhardwaj said that there is a possibility of the instruments recharging after a fortnight if they are able to withstand the low temperatures during the lunar night.

“The lunar surface experiences major temperature variations and during lunar nights, the temperatures tend to drop to below 200 degrees Celsius. If instruments are able to withstand such temperatures, there is a possibility that it will recharge itself once the sun’s rays hit their solar panels again after a fortnight or so. That will be bonus data for us,” he said.

So far, Isro has revealed some crucial findings from the lunar experiments including recording the first seismic readings on the Moon, confirming the presence of sulphur, oxygen and other elements on the lunar surface, and recording the thermal variations beneath the surface.

The rover, which according to Isro scientists was supposed to have traversed a distance of around 200metres throughout its mission life, has successfully charted a distance of over 100metres from the landing point of Vikram.

The scientists attributed this gap in distance to the manoeuvres the rover had to undertake to avoid craters.

A follow-up mission to the 2019 Chandrayaan-2, the latest Moon programme had three objectives – to demonstrate a safe and soft landing on the moon surface, to demonstrate rover roving abilities on the moon surface, and to conduct in-situ scientific experiments.

With the successful landing on August 23, India became the fourth country to land on the surface of Moon after the US, the USSR and China.