Hours after India’s dream of placing a lander spacecraft on moon crashed early on September 7, the Indian Space Research Organisation’s teams associated with the still orbiting Chandrayaan 2 mission were looking for clues in the last minutes of data from the lander Vikram’s descent.
The lander Vikram was to have set itself down on the moon’s surface at 1.55 a.m. on September 7. It had been descending for 12 minutes. Three minutes before that, it lost contact with earth and went blank. It was 2.1 km above the moon’s surface then, ISRO said soon after it detected the setback around 2 a.m.
Prime Minister Narendra Modi, Principal Scientific Adviser K. VijayRaghavan and former ISRO chairmen were at the mission control room of ISTRAC at the critical time.
A success would have made India the fourth country to place a spacecraft on moon after the then USSR, the U.S. and China. Also, India would have been the first country to reach close to the lunar south pole.
ISRO now shifts its focus to making the best use of the orbiter, which is moving and working well, at 100 km above moon. The orbiter carries eight of the 13 Indian payloads — three of which were on the lander and two on the rover Pragyan sitting within the lander.
In an interview to Doordarshan, ISRO chairman K. Sivan said that its life is now 7.5 years instead of the earlier one year as its fuel has been used economically. It carries a camera with the best ever resolution of 0.3 m ever used in a lunar mission to date.
Soon after the debacle an ISRO official said that over the next 14 sun-lit earth days, they would continue to jog Vikram’s earth link to life.
In a series of 27 tweets in the afternoon, Dr. VijayRaghavan said, “Ninety to ninety five per cent of the mission objectives have been accomplished and [Chandrayaan 2] will continue to contribute to lunar science notwithstanding the loss of communication with the lander.”
ISRO echoed the views later: the orbiter is precisely placed in its orbit and “its precise launch and mission management have ensured a long life of almost seven years instead of the planned one year”.
Dr. VijayRaghavan hailed the project review teams who resumed work after the debacle; they made presentations while Mr. Sivan chaired the sessions. “They are already addressing causes and learning from the events,” he said.
The descent trajectory of Chandryaan 2’s Vikram lander is displayed on a screen at the ISRO Telemetry, Tracking and Command facility near Bengaluru on September 7, 2019.
What went wrong?
What went wrong with a perfectly laid plan that had a dream run and a perfect path for 48 days?
According to a senior space scientist who has worked on both Chandrayaan and Mangalyaan missions, an increased horizontal velocity may have cast the lander away from the planned site (shown with red lines on the consoles). ISRO may have lost its link with the lander. “The search for it may be wider now. Only subsequent visits of the orbiter should tell us where it is,” he said.
He feared that instead of losing velocity as it came down, the lander may have gained velocity at some point. It may also have lost its orientation or altitude — which then increased its velocity. An altitude loss or tilt can also cause a loss of link or telemetry. Add to it the already working speed and moon’s gravity - and it could have crashed to death from a height of 2 km.
Although the terrain between two craters was mapped well, obstruction by hills sand high rises cannot be ruled out, according to him.
