Chandrayaan-3: Critical day for Indian spacecraft today. Here’s what will happen

The Indian Space Research Organisation (ISRO) has planned to further lower the lunar spacecraft to a 100 km x 100 km orbit today. And on 17 August, the separation of the lander module from the propulsion module is set to take place.

Now only about a week is left for this crucial Moon mission to reach its final stage.

After this, the lander is expected to undergo a “deboost” (the process of slowing down) and make a soft landing on the south polar region of the Moon next week.

The final landing of the Chnadrayaan-3, comprising Vikram (landeR) and Pragyan (rover) is projected to take place on Moon’s surface on 23 August.

Chandrayaan-3’s final journey

On Wednesday morning, Chandrayaan-3’s manoeuvre is planned, which is expected to place the spacecraft in a circular orbit of 100 km. On Thursday, Vikram and Pragyan sitting inside the ISRO’s lunar spacecraft will break away from the propulsion module. Vikram will have to be put in the elliptical orbit and ISRo will carry out manoeuvres, helping to achieve this.

According to a report by the Times of India, the manoeuvres will eventually put Vikram in an orbit where the Perilune (closest point to the Moon) is 30 km and Apolune (farthest point from Moon) is 100 km. The final landing of Chandrayaan-3 will be attempted from this orbit.

ISRO scientists will have to overcome the phase where the spacecraft’s horizontal orientation needs to change to a vertical one before it makes the final descent on 23 August.

Last week, ISRO Chairman S Somnath had said the most critical part of the landing is the process of bringing the velocity of the lander from 30 km height to the final landing, and that the ability to transfer the spacecraft from horizontal to vertical direction is the “trick we have to play” here. He said, “The velocity at the start of the landing process is almost 1.68 km per second, but this speed is horizontal to the surface of the moon. The Chandrayaan 3 here is tilted almost 90 degrees, it has to become vertical. So this whole process of turning from horizontal to vertical is a very interesting calculation mathematically. We have done a lot of simulations. It is here where we had the problem last time (Chandrayaan 2).” Further, it has to be ensured that fuel consumption is less, the distance calculation is correct, and all the algorithms are working properly. “Extensive simulations have gone, guidance design has been changed, and a lot of algorithms have been put in place to make sure that in all these phases required dispersions are handled….to attempt to make a proper landing,” he said.

About Chandrayaan-3

It is India’s third lunar mission and second attempt at achieving a soft landing on the Moon’s surface. It is a follow-on to the unsuccessful 2019 lunar mission – Chandrayaan-2. It will demonstrate India’s end-to-end capability in safe landing and roving on the lunar surface. With this mission, India aims to become the fourth country in the world to achieve this feat, joining the ranks of the United States, Russia, and China.

Chandrayaan-3’s development phase commenced in January 2020 with the launch planned sometime in 2021. However, the Covid-19 pandemic brought an unforeseen delay to the mission’s progress.

Updated: 16 Aug 2023, 08:31 AM IST