The Indian Space agency ISRO announced that the Chandrayaan-3 Lander module is in ‘normal health’ and that it reduced its orbit for the first time. This is the maiden manoeuvre to be performed individually by the lander module. It was on Thursday (August 17) that the integrated spacecraft had separated into two parts — Lander Module (LM) and Propulsion Module (PM). Till Thursday, all manoeuvres of the integrated spacecraft (LM and PM), were being performed by the Propulsion module.
The Lander Module (LM) health is normal.
LM successfully underwent a deboosting operation that reduced its orbit to 113 km x 157 km.
The second deboosting operation is scheduled for August 20, 2023, around 0200 Hrs.
With the Chandrayaan-3 propulsion module included, India now has three of its crafts circling the moon. This includes Chandrayaan-1(defunct), Chandrayaan-2 orbiter and the Chandrayaan-3 propulsion module. India commenced its lunar exploration journey in 2008 with Chandrayaan-1 and then followed it up with Chandrayaan-2 in 2019, and Chandrayaan-3 in July this year.
The 4 vehicles in Chandrayaan-3 mission
Any spacefaring mission is like a relay race – there are many performers and each one completes their task and hands over to the next. On July 14th, the LVM3 rocket was the vehicle that carried the 3.9 tonne spacecraft (comprising propulsion module, lander and rover) into the earth’s orbit. Performing its task in about 16 minutes, India’s largest rocket injected the satellites into the desired orbit.
Then on, the craft’s propulsion module gradually pushed and steered the craft away from the earth, using its onboard engines. Until July 31st, the craft orbited the earth and then fired its engines to gain more velocity, pushing itself to rendezvous with the moon in a few days (Lunar transfer trajectory). On August 5th, the craft reached the vicinity of the moon and fired its engines to slow itself down, reduce its orbit and get captured by Lunar gravity.
From August 5th till August 17th, the craft has been circling the moon. Once in a few days, the craft retro-fired its engines to slow down and reduce its orbit and get closer to the Lunar surface. On Thursday, 17th August, as the craft was in a 153kmx163km orbit, the propulsion module and lander module separated. This means that the propulsion module has completed its core task of getting the craft to an orbit around the moon.
Henceforth, it will be the responsibility of the Vikram lander to test its cameras, sensors and engines, as it prepares for a Lunar landing. The lander craft will commence reducing its orbit on Friday and eventually cut down its velocity from a few kilometres per second to 1 metre per second, which is the ideal speed for lunar soft-landing.
After the successful soft-landing, the lander is meant to open its ramp and allow the ‘Pragyan’ rover to roll out onto the Lunar surface. In close coordination with each other, the lander, rover and propulsion module would then carry out their respective scientific tasks and send data back to Earth. As far as the lander and rover are concerned, ISRO is looking at an operational life of one Lunar day or two weeks on Earth. However, after the lunar night passes and the new dawn breaks, when the sunlight is available, it is possible that the lander and rover come back to life.