BANGALORE, India — The Indian Space Research Organisation (ISRO) is blaming the premature demise of its Chandrayaan-1 lunar orbiter on overheating of the spacecraft’s onboard electronics.
ISRO spokesman S. Satish said agency scientists planning the mission underestimated the temperatures Chandrayaan-1 would encounter at its initial 100-kilometer mapping orbit.
As a result, Chandrayaan-1’s thermal protection systems were designed to keep spacecraft electronics running cool amid in-orbit temperatures expected to top out around 75 degrees Celsius. When the thermal environment proved hotter, problems ensued. While everything points to overheating as the most likely grounds for the mission failure, an expert committee will conduct a thorough study to pinpoint the exact cause, Satish said. He declined to say who will head the enquiry, whether the committee will include experts from outside ISRO, or when its report would be available.
ISRO announced Aug. 31 that it was officially terminating its $85 million Chandrayaan-1 lunar mission three days after mission controllers in Bangalore abruptly lost radio contact with the spacecraft.
Launched in October 2008, the 11-instrument orbiter was expected to last at least two years.
Despite the truncated mission, ISRO officials maintain that Chandrayaan-1 largely met its scientific agenda, returning enough data about the Moon to keep scientists busy doing analysis for six months to three years.
ISRO, however, has come under criticism for keeping Chandrayaan-1’s problems largely under wraps while presenting the mission as a grand success until the loss of radio contact.
Heat-related problems began to surface within two weeks of launch, forcing ISRO to temporarily deactivate some of the payloads. ISRO acknowledged that Chandrayaan-1 was overheating due to higher than anticipated orbital temperatures.
Mission managers put in place a thermal management plan that would keep onboard temperatures around 40 degrees Celsius while allowing the spacecraft’s international complement of instruments to do their jobs.
More components began to succumb to heat in April. Although Chandrayaan-1 lost two star trackers in close succession, ISRO did not disclose the loss of the second sensor until mid-July.
When ISRO raised Chandrayaan-1’s orbit from 100 kilometers to 200 kilometers to help beat the heat, the agency publicized the maneuver as a way to study the Moon’s gravitational field variation and map the lunar surface at a wider swath.
ISRO Chairman Madhavan Nair has since admitted to the Press Trust of India news agency that many of the heat-related problems were not anticipated at all, and Chandrayaan-1 was “a learning experience.”
“Valuable lessons will no doubt be learnt from the Chandrayaan-1 experience,” the Hindu newspaper wrote in an editorial criticizing ISRO’s lack of transparency. “What India’s upstanding space agency needs to do better next time is square with the public that has given it its steadfast support.”
