The Indian Space Research Organization plans to launch its heavy-lift Geosynchronous Satellite Launch Vehicle (GSLV) by April 2013, a senior space scientist says.

“We are now into the final leg of certain tests which will validate the mission involving [the] indigenous cryogenic engine. Most tests have been completed except for the high altitude test, which validates the mission of our cryogenic engine. We hope to complete this and launch the GSLV mission by April 2013,” says P.S. Veeraraghavan, director of the Vikram Sarabhai Space Center. VSSC is a unit of ISRO, where the design and development activities of satellite launch vehicles and sounding rockets are carried out and made ready for launch operations.

GSLV will be launched with an Indian-built cryogenic third stage, which ISRO has developed to replace the Russian hydrogen-fueled engine used on the GSLV Mk.1 model, the rocket’s early variant.

GSLV-Mark I & II is capable of placing the INSAT-II class of satellites (2,000 kg-2,500 kg) into Geosynchronous Transfer Orbit (GTO).  GSLV is a three-stage vehicle and stands 49 meters tall, with a 414-ton liftoff weight. It has a maximum diameter of 3.4 meters at the payload fairing.

The first stage comprises a S125 solid booster with four liquid (L40) strap-ons. The second stage (GS2) is a liquid engine and the third stage (GS3) is a cryogenic stage. 

 GSLV’s first flight took place on April 18, 2001 with the launch of the 1,540 kg GSAT-1. It was followed by six more launches: GSLV-D2 on May 8, 2003, carrying a GSAT-2 weighing 1,825 kg; GSLV-F01 on Sept. 20, 2004, putting in space the 1,950 kg EDUSAT; GSLV-F02 on July 10, 2006; GSLV-F04 on Sept. 2, 2007, carrying INSAT-4CR with a payload of  2,130 kg; GSLV-D3 on April 15, 2010; and GSLV-F06 on Dec. 25, 2010, ISRO says.

Besides the 2006 launch failure, two previous GSLV liftoffs were unsuccessful.

The GSLV mission’s “D3” in April 2010, using the ISRO-designed and built cryogenic engine for the first time, failed due to the malfunctioning of a fuel booster turbo pump. The launch vehicle was carrying a 2,200 kg GSAT-4 payload.

“We did a thorough analysis of the D3 flight and identified the reasons behind its failure,” Veeraraghavan says. “The analysis called for a redesign of certain components in the cryogenic propulsion system, and the same has now been addressed and is being put through multiple testing.”

The space agency has conducted several ground tests, and other tests are still being done. Once all the testing is successful, the cryogenic stage will be integrated into the GSLV vehicle for the launch, another space agency official says.

The two GSLV failures led ISRO to take a cautious approach in resuming launch operations, he adds.

The VSSC is also working on the next variant of GSLV Mk.3 launch vehicles. The GSLV Mk.3 is designed to launch communications satellites weighing more than 4 metric tons – about 8,800 lb. – once it begins orbital flights in 2014.

“This will make India totally self-reliant in the area of launch vehicles,” Veeraraghavan says

The center is also developing reusable launch vehicles that can deliver a spacecraft into the orbit and return for repeat use. This will bring down the cost of space transport, he adds.

ISRO plans to launch GSLV at least twice before placing the country’s second robotic lunar mission – Chandrayaan 2 – on the launcher for a flight to the Moon in 2014.

GSLV photo: ISRO