Chandrayaan-3 integrated spacecraft separates into two parts, the propulsion module and the lander module

Entering its conclusive stage, the Indian lunar mission Chandrayaan-3 has now transitioned control to the Chandrayaan-3 lunar lander. On Thursday (August 17) around 1 pm IST, the Indian Space Research Organisation (ISRO) proclaimed the division of the Chandrayaan-3 integrated spacecraft into two entities: the propulsion module and the lander module.

While the propulsion module persists in its lunar orbit, the lander module is en route to the lunar surface, primed for its planned gentle touchdown scheduled for August 23.

In a tweet, ISRO conveyed, “LM is successfully separated from the Propulsion Module (PM). LM is set to descend to a slightly lower orbit upon a deboosting planned for tomorrow around 1600 Hrs., IST.”

With the incorporation of the Chandrayaan-3 propulsion module, India now boasts three craft circling the moon: Chandrayaan-1 (inactive), Chandrayaan-2 orbiter, and the Chandrayaan-3 propulsion module. India’s lunar odyssey commenced in 2008 with Chandrayaan-1, followed by Chandrayaan-2 in 2019, and now Chandrayaan-3 in July of this year.

Analogous to a relay race, a space mission involves various participants, each accomplishing their designated tasks before passing the baton to the next. On July 14, the LVM3 rocket facilitated the launch of the 3.9-ton spacecraft (comprising the propulsion module, lander, and rover) into Earth’s orbit. In approximately 16 minutes, India’s largest rocket successfully deployed the satellites into their intended trajectory.

Following this, the craft’s propulsion module gradually guided and propelled it away from Earth employing its onboard engines. Until July 31, the craft circled Earth before activating its engines to enhance velocity, propelling itself toward a rendezvous with the moon (lunar transfer trajectory). By August 5, the craft had neared the moon and employed its engines to decelerate, reduce orbit, and be captured by lunar gravity.

From August 5 to August 17, the craft orbited the moon. Intermittently, the craft conducted retro-firing of its engines to further lower its orbit, closing in on the lunar surface. On Thursday, while in a 153 km x 163 km orbit, the propulsion and lander modules disengaged, signifying the completion of the propulsion module’s pivotal role in establishing lunar orbit.

Hereon, the Vikram lander will undertake tests on its cameras, sensors, and engines, preparing for the gentle lunar landing. The lander will commence orbit reduction on Friday (August 18), progressively decelerating from a few kilometers per second to the optimal one meter per second for a soft lunar landing.

After a successful landing, the lander will open its ramp, allowing the ‘Pragyan’ rover to traverse the lunar surface. Coordinating closely, the lander, rover, and propulsion module will execute their respective scientific objectives and transmit data back to Earth.

Regarding the lander and rover, ISRO anticipates an operational span of one lunar day or approximately two weeks on Earth. Nevertheless, with the advent of the lunar dawn following the lunar night, they may revive as sunlight becomes accessible.