Isro loses contact with telecom satellite

New Delhi: India's space agency said on Sunday it had lost contact with a telecommunications satellite successfully launched on Thursday, the trouble emerging while engineers were nudging the spacecraft in steps towards its assigned parking slot high above the equator.

The Indian Space Research Organisation said communication from the GSAT-6A satellite "was lost" between the second orbit-raising operation on Saturday and a scheduled third orbit-raising operation on Sunday.

India's Geosynchronous Satellite Launch Vehicle had on Thursday successfully ferried GSAT-6A into a geosynchronous transfer orbit (GTO) - a highly elliptical orbit in which the spacecraft's nearest point to Earth is about 170km and its farthest point, about 36,600km.

In orbit-raising operations, Isro's spacecraft control engineers were to fire an onboard motor - called the liquid apogee motor (LAM) - thrice to move GSAT-6A into its final geostationary orbit over 83 East longitude, about 36,000km above the equator.

The GSAT-6A satellite - described by ISRO as a platform to demonstrate technologies such as a 6m unfurlable antenna and handheld ground terminals and network management techniques to facilitate satellite-linked mobile communications - had a planned mission life of about 10 years.

On Friday morning, Isro engineers activated the LAM for about 36 minutes and moved GSAT-6A into a higher elliptical orbit - 5,054km at its nearest point to Earth, 36,412km at its farthest.

The second orbit-raising operation had been successfully conducted on Saturday with the LAM engine activated for about 53 minutes, Isro said in a statement on Sunday.

"After successful long duration firings, when the satellite was on course to normal operating configuration for the third and final firing, scheduled for April 1, communication from the satellite was lost," the agency said. "Efforts are under way to establish the link with the satellite."

Senior Isro officials monitoring these developments were not available for comment over the telephone and the agency' spokespersons declined to respond to phone calls.

But a former Isro official said spacecraft control engineers would be scrambling through telemetry data sent back by the satellite until cessation of communication to determine the cause of the trouble and figure out ways to reconnect with the satellite.

The official said Isro would be expected to issue a statement on the fate of GSAT-6A within hours to days.

"I would avoid speculation and wait for an official statement. But a golden rule is: never try several new or unproven systems, however attractive, on a single satellite bus," the official said.

Space analysts familiar with satellite operations but not associated with the GSAT-6A mission said that in the absence of communication, the fate of the satellite would hinge on the stability of its current orbit. An unstable orbit would decay over time and the satellite would burn up in the atmosphere during re-entry.

A 2004 analysis by an official of a space insurance underwriter, XL Insurance, cited by SpaceNews, had noted that satellites are much more likely to fail during their first year in orbit than at any time after that.

The SpaceNews report, also published in 2004, had cited XL figures that said that seven per cent of commercial geostationary satellites launched since 2000 had failed in their first 12 months of operations.

The figures varied with manufacturers - a 38 per cent failure rate for one builder to a near zero failure rate for two other builders, the report said.

China, Russia and the US have lost satellites in orbit.