ISRO’s GSLV-D5 satellite takes off successfully from Sriharikota

Geosynchronous Satellite Launch Vehicle (GSLV-D5), carrying communication satellite GSAT-14, has been launched successfully from the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh at 4:18 pm today. After Indian Space ResearchOrganisation’s successful launch of its first rocket to Mars, all eyes are now glued on whether the GSLV-D5, powered by its own crucial cryogenic engine, would be successful or not.

The last attempt, in August 2013, was dramatically scrubbed a couple of hours before liftoff, when launch officials detected a leak in the hydrazine fuel system on the rocket’s second stage. So a successful return-to-flight of the GSLV programme this weekend would loft into orbit much more than a communication satellite: the rocket would carry aloft the spirit of India’s space scientists. Standing 161 feet tall and weighing 640 tonne at liftoff, the GSLV-D5 belongs to the GSLV-Mk III series and is the heaviest rocket built in India.

After the last launch attempt failed, Isro engineers worked tirelessly to redesign the launcher’s liquid hydrogen-fuelled second stage. They seem to be leaving nothing to chance this time round, swarming all over the launcher with technical toothcombs to ensure an uninterrupted countdown and liftoff.

“The solid first stage and core base shroud have also been inspected and the affected elements replaced. The vehicle’s four strap-on engines, too, have been replaced,” says S Somnath, GSLV-Mk III’s project director.

The most important objective of the GSLV-D5 mission, however, is to flight-test the rocket’s all-important third stage: the indigenously-built cryogenic upper stage (CUS). The CUS, expected to be the mainstay of future GSLV flights, replaces the Russian cryogenic engine which was used in the rocket’s earlier experimental flights.

There will be a lot of crossed fingers at Sriharikota during the launch, considering the new engine had a disastrous maiden flight in April 2010, shutting down less than a second after ignition, with the rocket plunging into the sea. The GSLV’s significance lies in the fact that the future of the global satellite market lies in the field of communications. The GSAT 14 satellite piggybacking the GSLV-D5 carries six Ku-band and six extended C-band transponders to help in digital audio broadcasting and other communications across the entire subcontinent.

Designed to last for a dozen years in its orbit, the satellite will replace the GSAT-3 (EDUSAT) which has been in orbit for 10 years.

The big boosters in the GSLV series can hoist heavy communication satellites into geosynchronous orbits 36,000 km above the equator. In this position, the satellite keeps pace with Earth’s rotation and, as a result, appears stationary from the ground. This makes it easier to build simpler antennas on the ground, which do not have to track moving satellites in the sky. But powerful GSLV Mark IIIs (like the GSLV-D5) that can carry five-tonne satellites need cryogenic engines.

These engines use fuels like oxygen and hydrogen in liquid form — stored at extremely low temperatures — to produce enormous amounts of thrust per unit mass (engineering parlance for the mass of fuel the engine requires to provide maximum thrust for a specific period such as, say, pounds of fuel per hour per pound of thrust).

Rockets powered by cryogenic motors, therefore, need to carry much less fuel than would otherwise be required. Cryogenic fuels are also extremely clean as they give out only water while burning. A successful GSLV-D5 flight will make India only the sixth nation to possess this cutting edge technology, joining the United States, Russia, France, Japan and China in an elite club.

India’s cryogenic motor development encountered some rough weather in 1993 when exaggerated US jitters — that India might utilise its space capabilities for military purposes — led to Moscow chickeningout of a cryo-engine technology transfer deal with New Delhi.

Of course, the real reason for guarding cryogenic engine technology so zealously probably had more to do with economics than national security. India’s arrival in the global heavy-lift launch market as a low cost launch source would have threatened the business interests of Europe, Russia, and the US. In hindsight, though, it seems to have been a disguised blessing for Indian scientists who were forced to develop the technology on their own. The GSLV will reduce India’s dependence on foreign launchers like the ESA’s Ariane to launch INSAT-class satellites.

Isro sources speak of plans to fly two more GSLVs at six-month-intervals before using the third one for the Chandrayaan-2 Moon mission. The GSLV-Mark III is also earmarked for launching human space flights in future and building orbiting space stations.

Isro has built up an impressive portfolio of comparatively cheap space products and services that are attractive to foreign space agencies that want to outsource space missions.