HELSINKI — India’s Chandrayaan-3 lander and rover have been set to sleep for the onset of lunar night, days after the country successfully launched its Aditya L1 solar mission.
The historic Chandrayaan-3 mission lander Vikram set down near at 8:32 a.m. Eastern (1232 UTC) Aug. 23, making India only the fourth country to successfully land on the moon.
Vikram was set to sleep at 10:30 p.m. Eastern Sunday, Sept. 3 (0230 UTC; 8 a.m. IST, Sept. 4) the Indian Space Research Organisation (ISRO) announced on X, formerly known as Twitter. Local sunset will occur Sept. 5. Vikram’s payloads were turned off, but with receivers remaining on, with ISRO hoping the spacecraft may reactivate following sunrise over the landing site, at 69.373° South, 32.319° East near crater Manzinus C, after sunrise in late September.
The landing site—the first soft-landing in the vicinity of the lunar South Pole region—is now named Shiva Shakti Point. The site was spotted by the Chandrayaan-2 orbiter, part of the 2019 mission that included the failure of India’s first lunar landing attempt. Prime Minister Narendra Modi announced that the landing date of Aug. 23 will be celebrated as ‘National Space Day.’
The mission’s small, 26-kilogram rover, Pragyan, rolled out onto the moon from Vikram within hours of the landing. The first rover images were published Aug. 27 and in-situ measurements detected sulfur on the lunar surface. Images from the surface show long shadows near lunar noon, and the vertical solar array of the rover, indicative of operations at a high latitude on the moon. Pragyan was set to sleep after 10 days of activities, ISRO stated on Sept. 2.
The rover accumulated a drive distance of 101.4 meters, according to the agency. Nilesh M. Desai, Director of the Space Applications Centre (SAC) said Sept.1 that the rover had been expected to move 300 to 350 meters. “We have moved around 65-70 meters. Our initial expectation was that we would move it around 30 meters a day. It moves five meters in one go and we wanted to move it six times a day. We have not been able to do it.”
The spacecraft’s solar panel is oriented to receive the light at the next sunrise expected Sept. 22.
The mission completed and exceeded its primary missions. These were demonstration of a safe, soft lunar landing, demonstrating roving on the surface, and conducting in-situ scientific experiments. These include release of initial results from a lunar seismic activity payload on the Chandrayaan-3 lander.
ISRO is however hoping one or both spacecraft reawaken following the next sunrise.
Neither Vikram nor Pragyan carry radioisotope heater units often used on lunar missions to help keep spacecraft and their components warm to survive the deep cold of lunar night. China’s Chang’e-4 lunar far side mission recorded lunar nighttime temperatures of minus 190 degrees Celsius in 2019.
Second lunar landing
Vikram also performed a propulsive hop, on Sept. 2, ISRO tweeted. The lander was commanded to fire its engines and landed safely as expected around 30–40 centimeters away from its starting point, according to ISRO.
Footage shows lunar dust kicked up as the 710-kilogram dry mass lander lifts off from the surface and apparent movement to a new resting place. The test echoes the hop by the U.S. Surveyor 6 mission in 1967 which marked the first lift off from another planetary body.
First solar observatory
India followed up its lunar landing feat with the successful launch of its first dedicated solar observatory.
Aditya-L1 launched on Polar Satellite Launch Vehicle (PSLV-C57) from Satish Dhawan Space Centre (SDSC), Sriharikota, at 2:20 a.m. Eastern, (0620 UTC; 11.50 a.m. IST) Sept. 2. The spacecraft separated from the launch vehicle around 63 minutes into the flight.
“Aditya L1 spacecraft has been injected in an elliptical orbit of 235 by 19,500 km which is intended, very precisely by PSLV,” ISRO Chairman S. Somanath said.
Aditya-L1 is headed to its destination of Sun-Earth Lagrange point 1, around which it will enter a halo orbit. The journey will require four Earth-bound orbital maneuvers before entering a transfer orbit. The voyage will take around 125 days.
The 1480-kilogram spacecraft carries seven indigenously-developed scientific payloads to study the Sun while situated around 1.5 million kilometers from the Earth. These include an ultraviolet imaging telescope, soft and hard X-ray spectrometers, and a coronagraph for making observations of the Sun, and a pair of particle analyzers and a magnetometer for in-situ measurements.
Science objectives include studying coronal heating, solar wind acceleration, Coronal Mass Ejections, dynamics of solar atmosphere and temperature anisotropy.
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Edited Sept. 5 to correct dry mass of Vikram lander to 710 kg (previously stated as 626 kilograms (Chandrayaan-2 Vikram lander dry mass)).
