India's Rover Rolls Out Onto the Lunar Surface

On July 14th, 2023, the Indian Space Research Organization (ISRO) launched the third mission in its Chandrayaan (“Moon vehicle” in Hindi) lunar exploration program. Earlier this week (Wednesday, August 23rd), the Chandrayaan-3 mission’s Vikram lander touched down on the far side of the Moon, making India the fourth nation in the world to send missions to the lunar surface and the first to land one near the Moon’s south pole region. Shortly after that, the ISRO announced that they had deployed Pragyan, the rover element of the mission, to the surface.

The ISRO shared the news via its official Twitter account on the evening of August 23rd, stating, “Chandrayaan-3 ROVER: Made in India. Made for the MOON! The Ch-3 Rover ramped down from the Lander, and India took a walk on the Moon!” Multiple updates followed, including how communications were established between the lander and the ISRO’s Telemetry, Tracking, and Command center and the Mission Control /Mission Analysis Room (ISTRAC-MOX) in Bengaluru, India, and how the rover had completed its first maneuvers and systems’ checks:

wp:paragraph “All planned Rover movements have been verified. The Rover has successfully traversed a distance of about 8 meters. Rover payloads LIBS and APXS are turned ON. All payloads on the propulsion module, lander module, and rover are performing nominally.” /wp:paragraph

https://twitter.com/isro/status/1694945669721776263

They also shared images of the lunar surface taken by Vikram’s Lander Horizontal Velocity Camera (LHVC) as it slowly descended. These and other images were stitched together to create animations of the lander’s descent and the rover’s deployment onto the surface (see above). The lander and rover will conduct science experiments on the surface, including characterizing the local environment, atmosphere, and surface composition while also scouting for resources (the most important being water ice).

This research will enable future missions, which could include sending crews (vyomanauts) to the Moon. As noted, this mission is the first to land near the Moon’s South Pole-Aitken Basin, a highly significant accomplishment given that this is where multiple space agencies plan to establish habitats that will enable lunar research, exploration, and development. This includes NASA’s Artemis Program – which will lead to the Lunar Gateway and the Artemis Base Camp – and the Russian-Chinese International Lunar Research Station (ILRS).

Under the circumstances, this successful landing and deployment show that India will likely be a crucial partner in any future lunar settlement. This is all the more poignant given the current competition between India and its Russian counterparts. Chandrayaan-3 launched on July 14th and established orbit around the Moon by August 4th, almost three weeks before making its descent. Meanwhile, Roscosmos launched its comparatively smaller and lighter Luna-25 mission on August 10th, reaching lunar orbit on the 16th.

Roscosmos has reportedly scheduled a landing date for Monday, August 21st, but the mission controllers reported an “abnormal situation” that was later revealed to be due to an engine failure. This caused the mission to crash into the surface (in the southern Pontecoulant crater) two days before its scheduled landing. A day later, RussianSpaceWeb creator/publisher Anatoly Zak posted that according to rumors on Russian social media, “mission managers were pressured not to postpone the transfer to a lower orbit in order to beat an Indian lander to the lunar surface.”

The Vikram lander with its ramp deployed to show how the rover will roll onto the surface. Credit: ISRO

The fact that Chandrayaan-3 made it to the surface safely indicates that a slow and measured approach is better than a hasty one. It was also a welcome relief after the failure of Chandrayaan-2, which crashed on the lunar surface in September 2019 during an attempted landing. The lessons learned from that mission helped inform the design of Chandrayaan-3, which included improvements like autonomous attitude control, a Laser Doppler Velocimeter (LDV), greater systems redundancy, and stronger landing legs.

The Pragyan rover will spend the next two weeks studying the composition of the lunar surface, measuring the presence of water in the regolith, and gathering data on the history of impacts in the region and the evolution of the Moon’s tenuous atmosphere. Similarly, the Vikram lander will rely on its suite of instruments to measure the thermal conductivity and temperature of the lunar surface, search for seismic activity around the landing site, and estimate the near-surface plasma density over time.

Further Reading: ISRO