BENGALURU: The fifth and final lunar-bound manoeuvre on the Chandrayaan 3 spacecraft was carried out on Wednesday morning, bringing it closer to the lunar surface at an orbit of 153km x 163km. The manoeuvre was conducted at Bengaluru-based ISRO Telemetry Tracking and Command Network (ISTRAC).
“With this, the lunar-bound manoeuvres are completed. It’s time for preparations as the Propulsion Module and the Lander Module gear up for their separate journeys,” ISRO said in a post on X (formerly Twitter). Separation of the lander module from the propulsion module will be done on August 17, it said.
At altitude of 30 km, module will try soft-landing
On separating from the propulsion module, and over the next few days, the lander will undergo a process of slowing down and arrive in an orbit of 30km x 100km. Once over the Moon’s south pole, at an altitude of 30km, the lander module, carrying the rover, will attempt the soft-landing at a spot that will first scan the surface features before making the touchdown on August 23 evening, scheduled for 5.47 pm.
On completing a successful landing, the lander will release the rover, which will conduct on-site experiments. T he rover carries two payloads: the Alpha Particle X-Ray Spectrometer, which will derive the chemical composition and infer mineralogical composition to further enhance the understanding of the lunar surface; and the Laser Induced Breakdown Spectroscope, which will determine the elemental composition of lunar soil and rocks around the lunar landing site.
Meanwhile, the lander module’s three payloads will be activated. Its RAMBHA-LP (Langmuir Probe) will measure the near surface plasma (ions and electrons) density and its changes with time; the Chandra’s Surface Thermo-physical Experiment (ChaSTE) will carry out measurements of thermal properties of lunar surface near polar region; and the Instrument for Lunar Seismic Activity (ILSA) will measure seismicity around the landing site and delineating the structure of the lunar crust and mantle.
The propulsion module’s payload, the Spectro-polarimetry of HAbitable Planet Earth (SHAPE), an experimental payload, has been studying the spectro-polarimetric signatures of the habitable planet Earth in the near-infrared (NIR) wavelength range (1-1.7 μm) while it entered the Moon orbit phase. The propulsion module’s role will end after the lander separates from it. Chandrayaaan 3’s mission life is 14 days (one lunar day).
Chandrayaan 3, unlike its two predecessors, Chandrayaan 1 and 2, does not have an orbiting mission. Its main aim is to achieve a successful landing at the lunar south pole. The mission was expected to be the first to land near the lunar south pole. However, Roscosmos’ Luna 2 from Russia, which was launched almost a month after Chandrayaan 3, is likely to get there a day or two before.
This mission was launched on July 14 on board the Launch Vehicle Mark-III-M4 (LVM3-M4) rocket from Satish Dhawan Space Centre, Sriharikota. On being inserted into the Earth’s orbit a few minutes after the launch, the propulsion module was sent on its way to the Moon on August 1 in a slingshot manoeuvre after five progressively raised orbits.