The Indian Space Research Organisation (ISRO) is set to make history, when its third Moon mission, Chandrayaan-3’s, Lander Module attempts to land on the lunar surface at approximately 6.04 pm on Wednesday. It all comes down to the final 15 minutes, when the lander carries out a critical technical manoeuvre, transferring its high-speed horizontal position to a vertical one - in order to facilitate a gentle descent on to the surface.
ISRO on Tuesday said everything was going as per plan and the “mission is on schedule”. Ahead of its landing, the lander module established contact with the Chandrayaan-2 lunar orbiter on Monday, opening up another line of communication with Earth. ISRO said the orbiter greeted the lander with the message “welcome, buddy”. ISRO also posted images of the far side of the Moon captured by the lander.
If the mission is successfully completed, India will become the fourth country to master the technology of soft-landing on the lunar surface after the US, China and the erstwhile Soviet Union. India will also become the first country to reach the unexplored larger south pole of the Moon.
ISRO’s Telemetry Tracking and Command Centre (ISTRAC) in Bengaluru will issue a command at 5.47 pm that will signal the spacecraft to begin the descent. From a velocity of about 6,000 km/hour in the orbit, the spacecraft will have to slow down to near zero as it makes a touchdown. It is designed to land safely even at speeds of 10 km/hour.
The descent will be completely autonomous – artificial intelligence and computer logic driven – with the mission control at ISTRAC keeping a close watch. The final approach will be a heady cocktail of anxiety, nervousness and anticipation. It was in these last moments that Chandrayaan-2 developed problems and fell on the Moon’s surface. Four missions, including Luna-25 of Russia two days ago, have met a similar fate in the last four years.
To ensure the success of the Chandrayaan-3 mission, ISRO has made a number of adjustments, including strengthening the legs of the landers, reducing the number of engines, increasing the amount of fuel, and adding additional sensors, among other things. Earlier this month, ISRO Chairman S. Somanath said that even if all sensors fail while attempting to make the soft landing on the lunar surface, the lander would still be able to land provided that the propulsion system works.
He added that this time they have made all the systems more robust and have changed the guidance design and introduced newer algorithms. The rover would be deployed a short time after ISRO successfully makes a soft and safe landing of the lander on the lunar surface. During its mobility, the rover will conduct in-situ chemical study of the lunar surface.