ISRO Chief S Somanath Discusses Plan for Successful Landing of ‘Vikram’ Lander Despite Sensor and Engine Failure

According to ISRO chairman S Somanath, Vikram, the lander of India’s Chandrayaan-3 lunar mission, will still be capable of achieving a soft-landing on the Moon’s surface on August 23, even in the event of sensor and engine failures.

The entire design of the Vikram counter has been done in a way that ensures it can handle failures, Somanath said in a discussion at the Chandrayaan-3: Bharat’s Pride Space Mission event hosted by the non-profit organization. organization Disha Bharat.

“If everything fails, if all the sensors fail, nothing works, still it (Vikram) will make the landing. That’s how it’s designed – provided the propulsion system works well,” Somanath said.

Chandrayaan-3 blasted off into space on July 14 and entered lunar orbit on August 5. There are three more deorbits – exercises to bring it closer to the moon so that Vikram will land on the lunar surface on August 23.

These de-orbit maneuvers will be performed on August 9, August 14 and August 16 until its orbit shrinks to 100 km by 100 km from the Moon, Somanath said. The lander’s propulsion module separation exercise begins later, shortly after the lander “deboosts,” a process that slows the craft. It will be followed by a landing on the surface of the Moon on August 23, he explained.

“We have also ensured that if two of the engines (on Vikram) fail this time too, it can still land,” the ISRO chairman said. “So the whole design is done to ensure that it (Vikram) can handle many faults if the algorithms work properly,” he added.

The biggest challenge for the ISRO team, he said, is to make the horizontal ‘Vikram’ land vertically on the lunar surface. According to Somanath, after the lander leaves orbit, it moves horizontally. It will be brought into an upright position through several maneuvers to land safely on the Moon.

This exercise is crucial because ISRO failed to land its lander safely on the lunar surface during the Chandrayaan-2 mission. “The ability to go from horizontal to vertical is a trick we have to play here. Only here we had a problem last time,” Somanath pointed out.

The challenge is also to ensure that less fuel is consumed, distance calculations are correct and all algorithms work properly, the ISRO chief said. However, this time the ISRO team has made arrangements to ensure that Vikram tries to get the property even if there are some discrepancies in the calculations, Somanath explained.

According to him, the lander will have four payloads: Chandra’s Surface Thermo Physical Experiment (ChaSTE) will perform measurements of the thermal properties of the lunar surface near the polar region. The RAMBHA-LP payload measures the density of near-surface plasma (ions and electrons) and its changes over time; NASA’s Laser Retroreflector Array for precise positioning measurement of the lander on the lunar surface in future orbits; and the Lunar Seismic Activity Instrument.

The rover named “Pragyan” has three payloads: The Laser Induced Breakdown Spectroscope (LIBS) will determine the elemental composition of the lunar soil and rocks around the lunar landing site. The Alpha Particle X-Ray Spectrometer (APXS) payload will derive the chemical composition and infer the mineralogical composition to improve our understanding of the lunar surface. Spectropolarimetry for a Habitable Planet (SHAPE) is an experimental payload to study the spectropolarimetric signature of a habitable Earth in the near-infrared (NIR) wavelength range on Pragyan.