BENGALURU: Two days ahead of Chandrayaan 3’s lander module, Vikram, attempting a record by soft-landing near the lunar south pole, it has established a two-way communication link with its predecessor mission Chandrayaan 2, whose orbiter continues to orbit the Moon despite its lander failing to achieve that feat four years ago.
Indian Space Research Organisation (ISRO) on the X platform said, “Welcome, buddy! Ch-2 (Chandrayaan 2) orbiter formally welcomed Ch-3 (Chandrayaan 3) LM (lander module Vikram). Two-way communication between the two is established. MOX (Mission Operations Complex) now has more routes to reach the LM.”
ISRO had earlier said Chandrayaan 2 orbiter, Pradhan, would help facilitate communication between Chandrayaan 3 and ISRO’s earth-based stations to help scientists keep an eye on the well-being of Vikram lander and Pragyaan rover throughout their 14-day mission. The on-site lunar mission is expected to begin soon after Vikram lands near the lunar south pole and deploys Pragyaan rover on August 23 evening.
The two-way communication link between lander Vikram and Pradhan orbiter of Chandrayaan 2 would boost the process of obtaining and issuing commands from MOX at ISRO Telemetry, Tracking and Command Network (ISTRAC) in Bengaluru and the Deep Space Network at Byalalu near Bengaluru, which will receive data from the on-site lunar experiments conducted near the lunar south pole. The MOX provides tracking and orbit manoeuvring support for its satellites during space missions, including Chandrayaan 3.
A lunar dream dashed in 2019 when lander crashed
On September 7, 2019, MOX lost contact with the Chandrayaan 2 lander (also named Vikram) with just two km to descend and land near the lunar south pole. The lander crashed due to a software anomaly during the final moments of landing. However, the Pradhan orbiter of Chandrayaan 2 mission, launched on July 22, 2019, continues in its 100km x 100km to orbit around the Moon to this day.
In March 2022, Chandrayaan 2 orbiter’s Chandra’s Atmospheric Composition Explorer 2 (CHACE-2) payload provided first-time insights into the dynamics of the lunar exosphere and on activities of gases emerging through radioactive decay from the first few tens of metres below the lunar surface.
It discovered the Moon-wide spread of one of the noble gases Argon-40 (Ar-40) to study the lunar exosphere as well as the surface from where this gas is understood to have escaped. The importance of Chandrayaan 2’s CHACE-2 observations was that although NASA’s Apollo 17 (the last of the manned lunar missions in 1972) and a robotic mission, Lunar Atmosphere and Dust Environment Explorer (LADEE), in 2013-14 detected the presence of Ar-40 in the lunar exosphere, the measurements were confined to the near-equatorial region of the Moon. It had remained a gap area to study the pan-lunar dynamics of Moon’s exosphere — a temperature-driven process — which the Chandrayaan 2 orbiter filled.
Also, in October 2022, the Chandrayaan 2 Large Area Soft X-ray Spectrometer (CLASS) on board the orbiter provided clean signatures of sodium lines, thanks to its high sensitivity and performance. The study found that a part of the signal could be arising from a thin veneer of sodium atoms weakly bound to the lunar grains.
The rock and soil samples that Apollo 11 astronauts brought back to Earth in 1969 showed that regions on the lunar surface are mainly composed of silicate minerals, including sodium. But the findings from Chandrayaan 2 took the data forward by mapping the abundance of sodium on the lunar atmosphere and surface.