India's largest rocket lost control and erupted in a fireball Saturday, dealing another blow to the country's space program after back-to-back failures of the Geosynchronous Satellite Launch Vehicle.
The 167-foot-tall launcher blasted off from the Satish Dhawan Space Center at 1034 GMT (5:34 a.m. EST), or just after 4 p.m. local time Saturday. The launch site is on Sriharikota Island on the east coast of India.
Trouble struck the rocket less than a minute after liftoff, when video footage showed the vehicle veering from its flight path, tumbling out of control and being engulfed in a fireball.
"Controllability of the vehicle was lost after about 47 seconds because we found the control command did not reach the actuators (of the strap-on boosters)," said K. Radhakrishnan, chairman of the Indian Space Research Organization.
The GSLV is propelled off the launch pad by a single solid-fueled core motor and four L40 strap-on boosters.
The liquid-fueled L40 boosters are each powered by a single engine producing about 170,000 pounds of thrust. The engines burn hydrazine and their nozzles pivot to steer the rocket during the first two-and-a-half minutes of flight.
Something prevented computer steering commands from reaching the engine gimbal system, Radhakrishnan said in a press conference several hours after the rocket accident.
"What has caused this interruption at 47 seconds has to be studied in detail," Radhakrishnan said. "We hope to get an assessment of exactly what occurred."
Radhakrishnan said the rocket "developed large amplitude errors relating to higher angle of attack" when the steering system failed. The anomaly induced severe structural loads "leading to the breaking up of the vehicle," the ISRO chief said.
Safety officials issued a destruct command a few seconds later as the GSLV was at an altitude of nearly 30,000 feet, according to Radhakrishnan.
Footage showed rocket debris falling into the Bay of Bengal just offshore the launch site. A cloud of twisting exhaust and orange-brown gas hovered over Sriharikota.
The rocket was carrying GSAT 5P, the largest spacecraft ever launched by an Indian booster. GSAT 5P was designed to replace an aging satellite and extend television and telephone services across India.
Indian space officials postponed the mission from Monday to resolve a minor valve leak inside the GSLV's Russian third stage.
Saturday's mishap was the second failed launch this year for the GSLV, which is India's most powerful rocket. The GSLV has now launched seven times, and ISRO declared four of those missions failures.
A GSLV flight April 15 fell short of orbit due to a fuel pump anomaly on an indigenous cryogenic third stage. India is developing and testing a homemade upper stage to replace engines purchased from Russia.
While engineers fix the problem from April, ISRO approved a pair of GSLV flights using India's last two Russian-supplied third stages. After Saturday's launch, one more Russian unit is left in India's inventory.
In the early stages of designing the GSLV booster for communications satellites, India struck a deal with Russia to provide hydrogen-fueled rocket engines and technical know-how.
The agreement was quashed in 1992 after U.S. authorities imposed sanctions on Glavkosmos, the Russian company providing technology to India. The United States feared the transfer of missile technology from the fractured Soviet Union to developing states.
India responded by purchasing seven readymade cryogenic engines from Russia and starting the design of an indigenous upper stage from scratch.
Officials planned another test flight of the Indian third stage in 2011, but that schedule was announced prior to Saturday's launch accident. ISRO calls the second-generation all-Indian rocket the GSLV Mk.2.
The GSLV was supposed to deploy the 5,093-pound GSAT 5P communications payload about 19 minutes after blastoff Saturday, according to the Indian Space Research Organization.
GSAT 5P's weight forced Russian and Indian engineers to modify parts of the rocket to lift the satellite, which is the heaviest spacecraft ever orbited by ISRO.
The Russian third stage was lengthened 3.6 feet to fit an extra 6,000 pounds of propellant inside. The additional cryogenic hydrogen and oxygen was designed to permit the upper stage engine to burn about two minutes longer than on previous flights.
Indian officials said the GSLV needed the additional performance to haul GSAT 5P into the correct orbit.
The launch was also supposed to test a new composite payload fairing. The larger shroud had a diameter of 4 meters, or 13.1 feet, while earlier GSLV missions flew with 3.4-meter aluminum fairings.
After reaching a final perch more than 22,000 miles above the equator, GSAT 5P was expected to start a 12-year mission serving television, telephone and data networks across India.
GSAT 5P was to be stationed in geosynchronous orbit at 55 degrees east longitude, replacing capacity in another satellite nearing the end of its design life.
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