ISRO chairman S Somanath announced on Tuesday that Vikram, the lander of India’s upcoming lunar mission Chandrayaan-3, possesses the capability to achieve a gentle landing on the lunar surface on August 23, even in the scenario where all sensors and two of its engines are non-operational.
During a discussion about Chandrayaan-3: India’s Pride Space Mission, Mr Somanath emphasized that the design of the Vikram lander has been carefully crafted to ensure its capability to manage potential failures.
Mr. Somanath mentioned that even in the event of a complete sensor failure and other system malfunctions, Vikram is designed to execute a landing, contingent upon the proper functioning of its propulsion system.
Having launched on July 14, Chandrayaan-3 successfully achieved lunar orbit entry on August 5. In preparation for Vikram’s lunar landing on August 23, the mission involves three additional de-orbiting manoeuvres. Scheduled for August 9, August 14, and August 16, these manoeuvres will progressively lower the craft’s orbit to 100 km x 100 km around the Moon, as detailed by Mr Somanath.
After the ‘deboost’ process, which decelerates the lander, a separation procedure for the lander propulsion module will be undertaken. Subsequently, the landing on the lunar surface is scheduled for August 23,” he elucidated.
“Furthermore, we have ensured that even if two of Vikram’s engines encounter issues once again, it retains the capability to successfully complete the landing,” affirmed the ISRO chairman.
Thus, the comprehensive design revolves around ensuring Vikram’s capability to withstand numerous potential failures, given the proper functioning of the algorithms,” he emphasized.
The most significant hurdle facing the ISRO team, as per him, is to transform the horizontal orientation of ‘Vikram’ into a vertical one during the lunar landing.
Mr Somanath explained that following its separation from the orbiter, the lander will initially traverse in a horizontal direction. By employing a sequence of manoeuvres, it will be gradually repositioned to adopt a vertical posture, facilitating a secure landing on the lunar surface.
This endeavour holds utmost significance, given that ISRO faced challenges in ensuring a safe lunar landing for its lander during the Chandrayaan-2 mission.”
The key manoeuvre lies in transitioning from a horizontal to a vertical orientation, which is the critical aspect we need to address. It was during this phase that we encountered difficulties previously,” highlighted Mr Somanath.
Additionally, the challenge involves optimizing fuel consumption, ensuring accurate distance calculations, and ensuring the seamless operation of all algorithms, emphasized the ISRO chief.
Nonetheless, the ISRO team has taken precautions this time to guarantee that Vikram endeavours to achieve a proper landing, even in the presence of certain calculation discrepancies,” elucidated Mr Somanath.
He further stated that the lander will integrate four payloads: Chandra’s Surface Thermo Physical Experiment (ChaSTE), which will be responsible for conducting measurements of the thermal characteristics of the lunar surface in the vicinity of the polar region.
The RAMBHA-LP payload is designated to gauge the density of near-surface plasma (comprising ions and electrons) and monitor its temporal variations. NASA’s Laser Retroreflector Array will be incorporated for precise positional measurements of the lander on the lunar surface for future orbiters. Additionally, an Instrument for Lunar Seismic Activity will also be part of the payload suite.
The rover, named ‘Pragyan’, is equipped with three payloads. One of these is the Laser laser-induced breakdown Spectroscope (LIBS), designed to analyze the elemental composition of lunar soil and rocks in the vicinity of the landing site.
The Alpha Particle X-Ray Spectrometer (APXS) payload is tasked with deducing the chemical makeup and extrapolating mineralogical composition, thereby contributing to our deepened comprehension of the lunar surface.
Within Pragyan, there exists an experimental payload called Spectro-polarimetry of Habitable Planet Earth (SHAPE), designed to investigate the spectro-polarimetric characteristics of our habitable planet Earth within the near-infrared (NIR) wavelength spectrum