India’s ambitious third lunar mission Chandrayaan 3 spacecraft on Monday underwent another maneuver that brought it even closer to the lunar surface, ISRO said. The National Space Agency, based here, said the spacecraft had now reached a “near-circular orbit” around the moon. After its launch on July 14, Chandrayaan-3 entered lunar orbit on August 5, followed by two low-orbit maneuvers on August 6 and 9.
ISRO tweet: “Orbit circularization phase begins. A near-circular orbit of 150 km x 177 km was achieved by the precision maneuver performed toda”.
Another operation is planned for August 16, around 8:30 a.m., it said. As the mission progresses, ISRO is performing a series of maneuvers to gradually lower Chandrayaan-3’s orbit and place it above the lunar poles. According to ISRO sources, the spacecraft will perform one more maneuver to reach 100 km orbit on August 16, after which the lander consisting of the lander and the rover will separate from the propulsion module.
The lander is then expected to undergo a “deboost” (slowing down process) and make a soft landing in the south polar region of the moon on August 23.
Last week, ISRO chairman S Somnath said the most critical part of the landing was the process of transferring the speed of the lander from an altitude of 30 km to the final landing and that the ability to transfer the spacecraft from a horizontal to a vertical direction was “a trick we have to play”.
He said: “the speed at the beginning of the landing process is almost 1.68 km per second, but this speed is horizontal to the surface of the moon. Chandrayaan 3 is tilted almost 90 degrees here, it has to become vertical. So this whole process of turning from horizontal to vertical is a very interesting calculation mathematically. We did a lot of simulations. This is where we had a problem last time (Chandrayaan 2).”
Furthermore, it is necessary to ensure that the fuel consumption is lower, the distance calculation is correct and all the algorithms work correctly. “Extensive simulations have gone through, the guidance design has changed and a lot of algorithms have been put in place to ensure that the required variances are handled at all these stages … to try and get the landing right,” he said.
Through five moves in the three weeks since launch on July 14, ISRO has put the Chandrayaan-3 spacecraft into an orbit further and further away from Earth.
Then, on August 1, in a key maneuver a slingshot move the spacecraft was successfully launched from Earth orbit toward the Moon. After this translunar injection, the Chandrayaan 3 spacecraft escaped Earth orbit and began following a path that took it close to the Moon.
Chandrayaan-3 is the follow-up mission to Chandrayaan-2 to demonstrate the end-to-end capability of safely landing and roaming on the lunar surface. It consists of an original propulsion module, a lander module and a rover, with the aim of developing and demonstrating the new technologies needed for interplanetary missions.
The propulsion module will carry the lander and rover configuration up to 100 km into lunar orbit. The propulsion module has a Spectro-Polarimetry of Habitable Planet Earth (SHAPE) payload to study spectral and polarimetric measurements of Earth from lunar orbit.
The mission of Chandrayaan-3 is to demonstrate a safe and soft landing on the lunar surface, demonstrate rover loitering on the moon, and conduct in-situ science experiments.
The lander will have the ability to soft-land at a specified lunar location and will deploy a rover that will perform in-situ chemical analysis of the lunar surface as it moves. The lander and rover have scientific payloads to conduct experiments on the lunar surface.
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