Chandrayaan 3: Vikram Lander's role, key objectives before descent on Moon

Chandrayaan-3 entered the final leg of its mission on August 17, following a meticulously-controlled separation of the lander and rover payloads from the propulsion module.

The lander named Vikram and the rover named Pragyan underwent a successful separation from the spacecraft's propulsion module at around 1:15 pm on August 17, the Indian Space Research Organisation (ISRO) informed via a post on microblogging platform X, formerly Twitter.

Also Read: Chandrayaan-3: Vikram lander inches closer to Moon after separating from module

The separation process marked the beginning of the most crucial stage of the Moon mission, which was launched from the Satish Dhawan Space Centre in Sriharikota on July 14. The key objectives of the mission, as outlined by the space agency are to demonstrate a safe and soft landing on the Moon, and a demonstration of the Pragyan rover collecting vital lunar data to conduct in-situ scientific experiments.

Vikram - The Lander

Vikram, the lander module, has three scientific payloads - RAMBHA-LP, ChaSTE and ILSA. The mission's next stage involves the activation and validation of the onboard instruments encompassing these three pivotal payloads. Vikram is also equipped with a passive Laser Retroreflector Array from NASA for lunar laser ranging studies.

The lander will maintain communication with the Pragyan rover and the Indian Deep Sea Network (IDSN).

Final descent

The first orbital manoeuvre will insert Vikram into a circular orbit at an altitude of 100x100 km above the Moon, followed by another manoeuvre, which will insert the lander in its ultimate orbit and closer to the Moon at a height of 100x30 km. This strategic orbital position will aid the lander in initiating its final descent on August 23.

Role of Vikram payloads

RAMBHA-LP or Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere (RAMBHA)-Langmuir probe (LP) will measure the near-surface plasma (ions and electrons) density and its changes over time, according to a document released by the space agency. Meanwhile, the ChaSTE or Chandra’s Surface Thermophysical Experiment will study and measure the thermal properties of the moon's surface near its poles.

The ILSA, or the Instrument for Lunar Seismic Activity, will measure the seismicity of the landing site and delineate the structure of the lunar crust and mantle. The LRA is a passive experiment to understand the dynamics of the Moon's system.

Vikram - Lost lander of Chandrayaan-2

ISRO's Chandrayaan-2, which took flight on July 22, 2019, failed to make a soft landing on the Moon after it lost communication with the Vikram lander when it was at a distance of barely 2.1 km from the lunar surface.

Also Read: Roadmap to lunar success: Chandrayaan-3 is key to India's long-term space exploration