The Lunar Science Workshop 2021 has recently been held by the Indian Space Research Organisation (ISRO) to celebrate two years of operation for the Chandrayaan-2 orbiter in lunar orbit. According to ISRO, the insights gathered by the payloads on the Chandrayaan-2 orbiter have led to striking new discoveries. The next mission, Chandrayaan-3, is set to launch at the end of the following year.
About the Chandrayaan-2
Chandrayaan-2 is the second spacecraft in India’s series of Lunar exploration satellites, including an orbiter, a lander named Vikram, and a rover called Pragyan designed to explore the unchartered South Polar region of the Moon. This ambitious project was launched from the Sriharikota spaceport using GSLV Mk-III on 22nd July, 2019, successfully entering lunar orbit in August of that same year.
Fate of the Lander and the Rover
Although the lander’s descent was normal up to about 2.1 km from the lunar surface, communication was unfortunately lost thereafter and it crashed onto the lunar terrain. The six-wheeled Pragyan rover, housed within the Vikram lander, couldn’t carry on its mission as a result.
The Orbiter’s Role
The orbiter, which was correctly positioned in its orbit around the Moon, played a critical role in improving our understanding of lunar evolution and mapping minerals as well as water molecules in polar regions. It was equipped with eight advanced scientific instruments, and due to precise launch and mission management, its lifespan extended to nearly seven years, much more than the expected one-year duration.
Key Discoveries of the Chandrayaan-2 Orbiter
Several important findings were made by the orbiter. Its mass spectrometer, CHACE 2, carried out the first-ever in-situ study of lunar neutral exosphere composition from a polar orbital platform, identifying variability of Argon-40 at higher latitudes. This revealed radiogenic activities within the higher latitudes of the lunar interior.
The CLASS payload remotely detected minor elements of chromium and manganese. Along with this, observations of the microflares of the Sun, during quiet periods, were made by the Solar X-ray Monitor (XSM) payload. These observations provided crucial insights on the coronal heating problem of the Sun.
Hydration Features and Subsurface Water
Chandrayaan-2 had its Imaging Infra-Red Spectrometer (IIRS) payload unambiguously detect the Moon’s hydration features, revealing clear signatures of Hydroxyl and water-ice on the lunar surface. Signatures of subsurface water-ice were identified by the Dual Frequency Synthetic Aperture Radar (DFSAR) instrument, which also achieved high-resolution mapping of lunar morphological features in the polar regions.
Lunar Imaging and Geological Insights
Using the Orbiter High Resolution Camera (OHRC), the Moon was imaged from a 100 km lunar orbit with an unparalleled resolution of 25 cm. The Terrain Mapping Camera (TMC 2) discovered intriguing geologic signatures of lunar crustal shortening and identified volcanic domes.
Study of Moon’s Ionosphere
Through the Dual Frequency Radio Science (DFRS) experiment, Chandrayaan-2 studied the Moon’s ionosphere, generated by the solar photo-ionisation of the neutral species of the lunar exosphere.
The Chandrayaan-2 mission has significantly contributed to our understanding of the Moon. The data from the mission is now being shared with the wider public via the PRADAN portal, hosted by the Indian Space Science Data Centre (ISSDC), ISRO’s nodal centre for data archive.