India’s GSLV Fleet Grounded Following Failure

by

The failure of India’s Geosynchronous Satellite Launch Vehicle (GSLV) July 10 could delay next year’s planned launch of an Israeli-built telescope aboard a similar rocket and also might lead the country to temporarily lease Ku-band capacity aboard foreign satellites, officials here said.

The GSLV will be grounded at least a year following the failure, which destroyed the domestically built Insat-4C television broadcasting satellite. The rocket was destroyed on command when it veered off course seconds after lifting off from the Satish Dhawan Space Center at Sriharikota.

The combined value of the rocket and satellite was roughly 2.5 billion Indian rupees ($54 million), with the launcher accounting for 1.5 billion rupees of that total. The mishap came just one day after the failure of India’s Agni 3 intermediate-range ballistic missile in its first test flight.

Shortly after the mishap, officials with the Indian Space Organisation (ISRO) said it would not affect the schedule of the nation’s planned Chandrayaan-1 lunar orbiter, which will include foreign payloads . Chandrayaan-1 is slated to launch atop an ISRO Polar Satellite Launch Vehicle in late 2007.

The Polar Satellite Launch Vehicle has a liquid-fueled second-stage engine similar to the strap-on boosters that have been implicated in the GSLV failure. But ISRO officials believe it was a manufacturing error, rather than a design flaw, that caused one of the GSLV’s four strap-on boosters to lose thrust, said B.N. Suresh, director of ISRO’s Vikram Sarabhai Space Centre in Trivandram.

“Each one of [the overseas partners on Chandrayaan-1] is calling and asking us if the mission is on schedule,” Mylswamy Annadurai, ISRO’s director of the Moon mission, told Space News July 12. “And we have been telling them we are going ahead as planned.”

The next Polar Satellite Launch Vehicle mission, carrying India’s Cartosat 2 mapping satellite, a recoverable experiments capsule and Indonesia’s Lapan Tubsat satellite, is expected to take place in September as scheduled, ISRO said.

However, Israel’s Tauvex space telescope, which is slated to launch atop a GSLV in early 2007 along with India’s GSat-4 satellite, may be delayed depending on the outcome of the failure investigation , according to ISRO spokesman S. Krishnamurthy. That launch will be the first of a new GSLV variant featuring a domestically developed cryogenic upper stage.

The failure investigation will be carried out by a 15-member team led by K. Narayana, former director of the Satish Dhawan Space Centre. The team, which will include experts from ISRO centers, academia and research institutions, is expected to submit its report in about a month, ISRO said in a July 12 press release.

Preliminary indications are that a problem with one of the vehicle’s four liquid-fueled strap-on boosters was the cause of the accident. During a televised interview shortly after the failure, Gopalan Madhavan Nair, chairman of ISRO, said pressure in the suspect motor “dropped to zero,” making the vehicle uncontrollable.

Some ISRO scientists, not involved in the launch, noted that pressure drops have occurred before with the GSLV strap-on motors. In March 2001, for example, ISRO was forced to scrub the GSLV’s maiden flight when monitoring systems detected inadequate thrust on one of the strap-on motors. The booster was replaced and the launch was carried out the following month.

Although the payload on that mission was delivered into a slightly lower-than-expected orbit, that was due to an upper stage issue.

The pressure drop on the July 10 launch, the second operational flight of the GSLV and the fourth overall, occurred about six seconds after liftoff, according to an ISRO official, who did not want to be identified.

Nambi Narayanan, a retired ISRO rocket scientist, told Space News that ISRO used to test each strap-on motor for five seconds and reassemble it for use in actual flight. “The reliability of these motors that have been in use for about 20 years was found to be so high that testing of individual motors was found unnecessary and the practice was stopped.” At 2,180 kilograms, Insat-4C was the heaviest payload ever placed atop the GLSV, which was developed to launch India’s indigenously built Insat series of geostationary-orbiting telecommunications and meteorological satellites. All previous Insat-series satellites have been launched by American or, more recently, European rockets.

The Insat-4 series comprises seven satellites, the first of which, Insat-4A, was launched in December 2005 by a European Ariane 5 rocket. Insat-4B is slated to launch atop an Ariane 5 late this year or early next year. The four remaining satellites are manifested on GSL V rockets, with launches scheduled for 2007-2010.

In response to Space News questions, Nair said the next GSLV mission will take place about a year after the recommendations of the investigative team are implemented and noted that the Insat-4D satellite is not slated to fly until 2007 or 2007. “Hence, we do not foresee any need for booking a foreign launcher at this time,” he said.

Customers that booked capacity on the Insat-4C satellite should not be affected by its loss, said K.R. Sridharamurthy, executive director of Antrix Corp., ISRO’s commercial arm. All of Insat-4C’s 12 Ku-band transponders had been booked, seven of them by Sun TV of Chennai, India. In addition, Sri Lanka’s state-owned broadcaster Rupavahini had booked capacity aboard Insat-4C.

“We will accommodate some of the customers in spare transponders on other Insat satellites,” Sridharamurthy said in a July 12 interview. The in-orbit Insat fleet includes some 20 transponders that are held in reserve for such contingencies, he said.

India has policies that heavily favor ISRO satellites for domestic services. But if necessary, Sridharamurthy said, ISRO could lease transponder capacity aboard foreign satellites as a “stop-gap” measure until Insat-4B is up and operating. “This has always been our approach,” he said, citing past examples where India has leased capacity on satellites operated by foreign companies such as SES Americom and Thaicom.

“When Insat-2D failed in 1998, ISRO bought Arabsat’s satellite in orbit,” Sridharamurthy noted.

ISRO officials admit the launch failure is a blow to ISRO’s ambitions to enter the global launch services market. “People in this business do understand the risk involved,” Sridharamurthy said. “But after this incident, we need to reassure them and build confidence in them.”