Learning It The Hard Way: What ISRO has planned for Chandrayaan-3's safe landing

Russia was all set to make history with its Luna-25 mission. However, now that Luna-25 has crashed into the moon, India’s Chandrayaan-3 mission’s lander module is now the lone contender in the race to make a soft touch down on south pole of lunar surface. Russia’s space agency has revealed that their their spacecraft took an unexpected turn and spiralled out of control, before it crashed hard onto the moon’s surface, thereby failing its objectives. A few years ago, ISRO was in a similar position with the Chandrayaan-2 mission. Even though we’ve seen successful moon landings more than 20 times before, the process continues to be a massive challenge. In recent history, only China has been able to pull off three solid touchdowns. Most of the successful landings on the moon happened way back in the 1960s and 1970s, back when weren’t aiming for the lunar poles. Now that Luna’s attempt has crashed, we’ve got the Chandrayaan-3 mission’s lander module leading the lunar touchdown race all by itself. And while there is always a chance that things may go wrong, the folks at ISRO have a genius plan to make sure this time the Vikram lander sticks its landing, no matter what curveballs come its way. A few days ago, the chairman of ISRO, S Somanath, revealed the steps that they have taken this time around to ensure the Chandrayaan-3’s Vikram lander doesn’t mess up, even if its sensors and engines go awry. “The entire design of the lander has been made in a manner that makes sure that it would be able to handle failures,” the ISRO chief said. “If everything fails, if all the sensors fail, nothing works, it (Vikram) still will make a soft landing. That’s how it has been designed - provided that the propulsion system works well,” Somanath said. In several of our reports, we have talked about that pivotal moment when Vikram goes from a horizontal position to a vertical one, as it begins its final descent. That transition is a make-or-break for the entire mission. The plan is to begin deboosting rapidly as it makes its way to the surface. At a certain point, the lander will separate from the lander propulsion module, but this has to be done at a critical point - do it too early, and the lander module may get imbalanced and tilt over. Do it too late, and it may not slow down enough for a soft touch down and may slam onto the moon, damaging some of the more delicate components.