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Fatal Blast at Rocket Plant Will Not Affect ISRO Programs
By K.S. JAYARAMAN
Space News Staff Writer
posted: 11:01 am ET, 15 March 2004
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BANGALORE, India — The fatal explosion Feb. 23 at India’s main rocket-testing and launch center occurred during fabrication of a new-generation solid-propellant motor that is not used on any satellite launchers or ballistic missiles, according to an Indian space official.
Rajeev Lochan, assistant scientific secretary of the Indian Space Research Organisation (ISRO), said the motor was not connected with any ISRO rocket or to India’s Agni intermediate-range ballistic missile.
"We keep designing and testing motors to optimize such parameters as the specific impulse and burning time," Lochan said Feb. 25 in a telephone interview. "This activity goes on all the time as part of technology development."
The accident killed six workers and injured three, shattering ISRO’s strong safety record over 40 years. It flattened Building 117 — one of several that make up the Solid Propellant Booster plant at the Satish Dhawan Space Centre on Sriiharikota Island off India’s east coast just north of Chennai. The center was established in 1971 and the 2,500-hectare propellant plant was built in 1977.
ISRO chairman Gopalan Madhavan Nair, who supervised salvage operations at the plant, told Indian national television that the "sad event" was an accident and that no sabotage was suspected. He announced compensation of 500,000 rupees ($11,000) each to the families of those who were killed.
A seven-member panel headed by R. Aravamudan, former head of the Satish Dhawan Space Center, will investigate and submit a preliminary report in one week and a final report in six weeks, Nair said. ISRO said in a statement that the inquiry would cover "the events that led to the fire, extent of damage and corrective measures required for the future."
Some ISRO officials, who did not want to be named, said the committee’s task will be difficult because much of the physical evidence was damaged in the fire, which melted the crane used during the operation.
Therefore the committee will have to rely heavily on testimony from the survivors, who are in critical condition.
Indian solid-rocket motors typically contain aluminum powder, which serves as fuel; ammonium perchlorate, the oxidizer; and hydroxyl terminated polybutadiene; a binding agent. These components are mixed to form a slurry that is cast around a mandrel centered inside the motor casing and cured in an oven at about 60 degrees Celsius. The teflon coated mandrel is then lifted out by crane, leaving a hollow tube along the length of the motor that allows the combustion gases to escape and produce the desired thrust.
In its press release, ISRO said the nine-person crew in the building’s so-called cast-cure facility had "satisfactorily concluded the removal of the mandrel and was attending to the removal of the bottom plate of the casting assembly" when the motor segment, containing 14.5 metric tons of propellant, ignited.
The tragedy sent shock waves that rippled beyond India’s scientific community. "At a time when the nation’s imagination has been ignited by visions of a trip to the moon the fire has come as a major embarrassment," the national daily newspaper Indian Express exclaimed in an editorial.
Vasant Gowariker, a leading space scientist who was responsible for setting up the Solid Propellant Booster plant, said the facility had "an outstanding safety record" prior to the accident. "We had one accident 12 years ago when one person died but nothing like this," he said in an interview.
Nair said the mishap would not affect any ISRO programs. India’s next launch from Sriharikota, a Geostationary Satellite Launch Vehicle mission to loft the Gsat-3 satellite, is scheduled for July.
The accident site is at least 5 kilometers away from the launch pad at Sriharikota. "We located the motor testing plant in a remote corner of the launch complex to isolate such accidents," Gowariker said. No two buildings at the plant are within 1 kilometer of one another, he added.
ISRO spokesman S. Krishnamurthi assessed damage at 7 million rupees, but noted the Solid Propellant Booster "was provided with two cast-cure facilities to meet any contingencies like this."
But the incident has raised questions about the adequacy of safety measures at the plant. "If the tragedy leads to a safer work culture those men who lost their lives will not have died in vain," the national daily Hindu newspaper wrote in an editorial. Two of those who died in the accident were casual laborers and not regular employees.
An ISRO rocket expert, who did not want to be named, said the agency should discontinue using casual labor in propellant mixing operations, especially given the large quantities of fuel often involved.
The first stage of ISRO’s Polar Satellite Launch Vehicle, for example, carries 129 to 140 metric tons of propellant, and motors currently under development will carry 200 metric tons of propellant.
Gowariker declined to venture a guess as to what might have gone wrong. "There is always the risk of human error. One cannot preclude this possibility," he said. Another ISRO propulsion expert observed that a simple act like forcing a bolt to free the motor assembly from the bottom casting plate could produce enough of a spark to ignite the propellant.
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