Chandrayaan-2: Three months on, ISRO yet to make public Vikram lander failure report details

“Generally ISRO has been open about failure analysis studies of missions. I would prefer that. Each government and each person, however, sees it differently,’’ a former senior ISRO official who was part of the Chandrayaan-2 failure analysis committee said.

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Although an FAC report has been submitted by a panel of experts, its details are yet to be made public nearly three-and-a-half months since the lander crashed.

So far, the only official statement on causes of the crash has come in the form of an answer to a question on Chandrayaan-2 mission in Lok Sabha on November 20 from Minister of State in Prime Minister’s Office Jitendra Singh.

Singh said the moon lander separated from Chandrayaan-2 orbiter on September 2 as planned and was positioned “to achieve soft landing on the moon surface’’ on September 7.

The minister said: “The first phase of descent was performed nominally from an altitude of 30 km to 7.4 km above the moon surface. The velocity was reduced from 1683 m/s to 146 m/s. During the second phase of descent, the reduction in velocity was more than the designed value. Due to this deviation, the initial conditions at the start of the fine braking phase were beyond the designed parameters. As a result, Vikram hard landed within 500m of the designated landing site.”

ISRO chairman K Sivan had said Singh’s statement was based on the FAC report.

But the details made public so far remains sketchy on aspects such as what caused the exaggerated reduction in velocity and how these problems will be addressed if a Chandrayaan-3 mission is undertaken in 2020.

This is unlike the ISRO’s previous record.

For instance, after the failure of an operational fourth flight of the heavy lift GSLV rocket — the GSLV-F02 mission — on July 10, 2006, a 15-member FAC was tasked with providing a report in a month. After the report was submitted to the government, ISRO made the details public on September 6, 2006, on its website. In 2010, when GSLV D3, a developmental flight and the fifth heavy lift GSLV rocket, failed after launch on April 15, an FAC report was submitted with the government on May 24, 2010. Details of the report were made public on July 9.

The same year, when GSLV F06, an operational sixth flight for GSLV rocket, failed on December 25, ISRO went public on December 31, with findings of an analysis of failure done by a preliminary FAC comprising space experts.

The agency has also made public causes of failures in past missions such as its first experimental satellite launch vehicle SLV 3 in July 1979, failures of the first and second developmental flights of Augmented Satellite Launch Vehicle in March 1987 and July 1988, and the first developmental flight of ISRO’s Polar Satellite Launch Vehicle in September 1993.