Chandrayaan-3 Update: Lander module separation scheduled for 1-1:30 pm; spacecraft to be placed 30-100 km closer to Moon

The separation of Chandrayaan-3’s lander module comprising the Vikram lander from the propulsion module has been scheduled on August 17 between 1:00 pm to 1:30 pm. Post its separation, the lander is expected to undergo a process of slowing down, known as deboost, to place it in an orbit where the Peruline or the closest point to the Moon is 30 kms and Apolune or the farthest point from the Moon is 100km.

The Indian Space Research Organisation (ISRO) previously said in a post formerly Twitter that Chandrayaan-3 is placed into an orbit of 153 km x 163 km after August 16 orbit reduction maneuver. 

"Today’s successful firing, needed for a short duration, has put Chandrayaan-3 into an orbit of 153 km x 163 km, as intended. With this, the lunar bound maneuvres are completed. It’s time for preparations as the Propulsion Module and the Lander Module gear up for their separate journeys. Separation of the Lander Module from the Propulsion Module is planned for August 17, 2023," ISRO said in a post on X. 

Following its launch on July 14, the Chandrayaan-3 spacecraft entered into the lunar orbit on August 5. ISRO has conducted a series of maneuvers to reduce Chandrayaan-3’s orbit and position the spacecraft over lunar poles. After this, orbit reduction maneuvers were carried out on August 6,9 and 14.

Moreover, former ISRO chief K Sivan said that he is optimistic about Chandrayaan-3’s landing on the Moon on August 23. Sivan, who was the ISRO boss during Chandrayaan-2 mission, said the lander’s touch down on August 23 “is a great moment we are looking forward to”. He added the Chandrayaan-2 also went through all these phases successfully but an “issue” came up during the landing’s second phase.

Commenting on the Chandrayaan-3 mission, ISRO chief S Somanath said that Chandrayaan-3 has a failure-based design instead of a success-based design. “The ability to handle parameter variation or dispersion was very limited in Chandrayaan-2. So, instead of success-based design, we are doing a failure-based design in Chandrayaan-3. What all can fail, and how to protect it — this is the approach that we have taken,” Somanath told PTI.

He added that the landing process of Chandrayaan-2 spacecraft was marred by challenges as five engines used for the reduction of velocity in a process called retardation produced more thrust than expected. This caused error accumulation, causing the spacecraft to take rapid turns for course correction by itself but not allowed so by the software.

The craft was designed to land in an area 500x500 sq meter area for which the craft increased velocity , even though it was much closer to ground. He added that the Chandrayaan-3 spacecraft has been designed to land safely anywhere instead of a particular place. The area of landing has also been expanded to 4 km x 2.5 km in case conditions turn abnormal, the ISRO boss said.

Somanath also told India Today that ISRO has increased the tank capacity of the spacecraft and a sophisticated gear is being used. He added that this time around, the quantity of propellants has been increased.

(With inputs from Pramod Madhav)

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