An Indian Polar Satellite Launch Vehicle (PSLV) failed to place a navigation satellite into its planned orbit Aug. 31 when the rocket’s payload fairing failed to deploy.
The PSLV, flying a mission designated PSLV-C39, lifted off on schedule at 9:30 a.m. Eastern from the Satish Dhawan Space Centre on the east coast of India. Initial phases of the launch appeared to go as planned, but observers noted that, as the flight progressed, the vehicle appeared to deviate from its planned trajectory according to telemetry displays shown during the webcast.
Launch controllers later confirmed that vehicle’s upper stage and payload, the Indian Regional Navigation Satellite System (IRNSS) 1H satellite, had reached a lower orbit than planned. The payload was in an orbit of 167 by 6,555 kilometers, while the planned transfer orbit for the mission was 284 by 20,650 kilometers.
A launch controller later confirmed that the rocket’s payload fairing, scheduled to separate 3 minutes and 23 seconds after liftoff during the operation of the rocket’s upper stage, had failed to do so. The additional mass of the payload fairing may account for the apparent underperformance of the PSLV’s upper stages, and would also prevent the satellite’s deployment regardless of orbit.
The Indian space agency ISRO did not immediately comment on the failure. An ISRO webcast of the launch abruptly ended shortly after the announcement of the failed payload fairing separation.
ISRO, in a statement later Aug. 31, confirmed that the payload fairing, which it calls the “heat shield,” failed to separate, dooming the mission. “[A]ll the flight events took place exactly as planned, except heat shield separation,” the agency said. “This resulted in satellite separation occurring within the heat shield. The satellite is inside the heat shield resulting in the unsuccessful mission.”
The failure is the first for the PSLV in 20 years. In September 1997, a PSLV launch placed the IRS-1D remote sensing satellite into a lower-than-planned orbit when the rocket’s fourth stage underperformed. The satellite was able to use its onboard propulsion to raise its orbit. The only total PSLV failure was rocket’s inaugural flight in September 1993, when it suffered an attitude control failure.
The failure would be a significant setback for India’s space program. The PSLV had become the workhorse for the program, launching a series of communications, remote sensing, navigation and science satellites. India had been working to increase the vehicle’s launch rate. The PSLV flew six times in 2016, and this was the third PSLV mission of 2017.
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PSLV had also become a popular choice for small satellite developers, who took advantage of frequent launches to sun-synchronous orbits and excess capacity on those missions to fly as secondary payloads. A PSLV launch in February set a record for the most satellites on a single flight, with 104 payloads; all but three were cubesats provided by international customers.
The sole payload of this launch, IRNSS-1H, was intended to be a replacement for India’s first navigation satellite, IRNSS-1A, whose three onboard atomic clocks had failed. The overall IRNSS system provides position, navigation and timing data for India and the surrounding region.