Chandrayaan-3 mission’s Vikram lander’s successful landing on August 23, in close proximity to the prime landing site at 69.37° south latitude and 32.35° east longitude, near the Manzinus U crater marked the highest-ever latitude achieved by a spacecraft during a soft moon landing. The European Space Agency’s (ESA’s) ESTRACK deep-space tracking station in New Norcia, Australia, played a crucial role in supporting the descent.
Chandrayaan-3’s lander, Vikram, and rover, Pragyaan, conducted data and image collection in the region for approximately ten days before transmitting the gathered information back to Earth for analysis. Pragyan was put to sleep on September 2 and Vikram on September 4, while ISRO confirmed, “The rover has successfully fulfilled its designated tasks.”
ISRO had expressed the hope that the lander could be reactivated at the end of a two-week lunar night when the rover and lander’s location would have been bathed in sunlight. The lunar sunrise had occurred on September 20 and the most favourable opportunity for Vikram and Pragyan to reactivate extended until September 22, spanning the initial three days.
“Neither Vikram, nor Pragyan was equipped with systems to maintain warmth in temperatures that could drop to as low as -190°C. Sunlight started dissipating from the lunar surface again on September 30 even as ISRO scientists hoped to revive Vikram and Pragyan with the arrival of a new lunar day. Nevertheless, despite numerous attempts, Vikram and Pragyan remained dormant, with no signals received from Chandrayaan-3,” explained space expert Girish Linganna.
Shortly before the rover was deactivated on September 2, ISRO mentioned that Pragyan had covered a distance of more than 100 metres and was still in motion—a remarkable journey for the six-wheeled rover, considering its speed of only 1 cm/s. Pragyan also avoided descending into craters scattered throughout the moon’s south polar region as its specialized mechanism allowed individual wheels to move independently, facilitating travel over various terrains.
“The initial data set obtained from the lunar topsoil extending to a depth of 10 cm beneath the surface through a probe on the Vikram lander revealed a stark temperature contrast just above and below the surface. Surface temperatures were observed at nearly 60°C, while they sharply decreased below the surface, reaching -10°C at a depth of 80 mm,” remarked Linganna.
The moon is known for its extreme temperature variations, with daytime temperatures near the lunar equator soaring to a scorching 120°C and nighttime temperatures plummeting to a frigid -130°C. In perpetually shadowed craters, where sunlight never reaches, temperatures as low as -250°C have been recorded. The wide temperature range is significant as it indicates that the moon’s soil (lunar regolith) serves as a highly effective insulator and could potentially be harnessed for constructing space colonies to regulate temperature and shield against radiation, making it a natural choice for habitat construction.
“Pragyan’s laser detector that measured chemicals on the lunar surface traced various elements including aluminum, calcium, iron, chromium, titanium, manganese, silicon and oxygen. But the most significant element was sulphur, which typically originates from volcanoes, so contributing to our understanding of how the moon formed and evolved, besides its geographical features. Since sulphur serves as a valuable fertiliser, it is also promising news for potential plant growth if there is ever a lunar habitat,” said Lingana
The Vikram lander was equipped with an instrument, the Instrument for Lunar Seismic Activity (ILSA), which not only monitored vibrations arising from its own research and experiments but also those generated by the rover and its operations. While ILSA was listening closely to lunar activities, it also recorded an event that seemed to be of natural origin and was actively investigating its source. It might have resulted from space debris, such as a meteorite or an asteroid impacting the lunar surface, or it could have been a seismic event, potentially marking the first Moonquake recorded since the 1970s.
ISRO shared on X (formerly Twitter) that Vikram had conducted the “first-ever measurements of the near-surface lunar plasma environment” in the south polar region and determined it to be “relatively sparse”. Plasma denotes the existence of charged particles in the atmosphere, which could potentially interfere with the radio-wave communication employed by Chandrayaan-3. But the lunar plasma was found to be very thin, which implied that it would cause significantly less disruption to radio communication.
The last action performed by Vikram before it was deactivated was referred to as a “hop experiment”. The lander was instructed to activate its engines, lifting off by approximately 40 cm and landing at a distance of 30-40 cm. This successful experiment, testing the engine’s capability to restart after a lunar landing, signified that the spacecraft could potentially be utilized in the future for such tasks as returning samples to Earth or supporting human missions.