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SPACE: GSLV LAUNCH
Mission Aborted
Not for long though, as initial
analysis shows that the glitch may not be serious
By Raj Chengappa in Sriharikota
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WHISTLE-STOP: Even as the rocket's engine are shut down one catches
fire
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Up to the last second
of the 57-hour countdown, everything had gone according to the manual.
At the mission control centre at Sriharikota, two hours from Chennai,
scientists sat hunched behind computer consoles, constantly glancing at
the five giant television screens that monitored the spacecraft on the
concrete launchpad. Three digital clocks ticked away furiously-one indicated
when the countdown had begun, another how close it was to blast-off and
a third showed the time in GMT.
As T-0-or ignition time-approached, a few took
up vantage points on the terrace of the control centre. They knew that
as a sound-and-light show there is nothing to beat the sight of a rocket
as tall as 12-storeys and weighing 400 tonnes thunder its way across an
azure sky. It is an all too brief visual signature of the enormous toil
that goes into rocket building. The 18-minute flight would tell the scientists
whether their efforts spanning 87,600 hours-10 years-was worth it.
It was also to be a supreme moment for the country's
space effort. For the first time India was sending up a rocket that would
hurl a 1.53 tonne satellite 36,000 km into space. Called the Geo-synchronous
Satellite Launch Vehicle (GSLV), it was a quantum leap over spacecraft
that the Indian Space Research Organisation (ISRO) had built before. Earlier
launch vehicles could send a satellite with half the weight to only 1,000
km into space. Now GSLV was to put ISRO truly in league with the big boys.
On the television screen, minutes before launch
time, the rocket snorted fumes like some prehistoric monster. Most of
it came from the pipes feeding super-cooled liquid fuels being pumped
into the upper stage motor. As the final countdown began, the anxiety
was similar to watching Harbhajan Singh hit the winning run in the Chennai
cricket Test. 5.4.3.2.1.0. Everyone looked to the heavens. But three seconds
later the countdown commentator intoned blandly: "Mission aborted."
A loud thump and red fumes billowing from the launch pad told their own
sorry story.
There is little doubt that the premature termination
of GSLV's maiden flight represents a setback to the Indian space programme.
But the failure has a silver lining: the mission had been terminated before
lift-off, leaving most of the rocket, costing Rs 125 crore, intact. The
next day when the scientists could safely approach the craft after 200
tonnes of its highly inflammable liquid propellants had been drained,
their spirits lifted. The damage did not appear to be as serious as they
had initially believed. Late that night a relieved K. Kasturirangan, ISRO
chairman, told India Today: "The problem is not something intractable
and a quick turnaround for another launch is possible."
So what went wrong in the first place? The first-stage
rockets were to blast the launcher to a height of 73 km in space in just
160 seconds at a speed of 2.6 km a second, or seven times the speed of
sound. To generate the enormous thrust required to propel this mass of
steel and aluminium into space, ISRO scientists had employed the largest
booster in their repertoire: a 20-m hunk of a rocket that packed 129 tonnes
of solid fuel. They then strapped on to it four of ISRO's most powerful
liquid fuel engines that together carried 160 tonnes of fuel.
It was the trickiest phase because all the four
strap-on motors had to generate an equal amount of thrust. If one of them
malfunctioned, it would send the rocket spinning uncontrollably into the
Bay of Bengal. So ISRO scientists built a safety mechanism which first
fired the strap-ons and gave them four seconds to see if they performed
optimally before igniting the giant solid booster. If they didn't, the
system would automatically shut off all the four motors, preventing a
catastrophic failure.
That was precisely what happened on the muggy afternoon of March 28. After
the four strap-ons were ignited, the motor designated as S3, facing north-east,
generated 10 per cent less than the expected thrust. The computers automatically
sent a command terminating the launch by shutting off the fuel supply
to the four engines. But scientists were worried when they noticed smoke
billowing from the S4 motor. They even suspected a possible fuel leak
initially. But on closer inspection they discovered that high winds had
deflected the flame from S3 on to it and the insulation paint had caught
fire. The motor was not damaged. Mission Director T.N. Perumal joked,
"This is a classic case of smoke without any real fire."
That the team could laugh at the end of the
24 harrowing hours of investigation demonstrated that things were not
terribly wrong. Initial indications are that there was an uneven flow
of the oxidiser to the thrust chambers that resulted in its aberrant performance.
Yet the entire system of high-speed generators that pump the oxidiser
into the chambers, the valves that control its flow and the fuel itself
would have to be tested to see what really malfunctioned. If it is limited
to these areas, then the team need not dismantle the entire rocket. It
already has a spare strap-on motor and after a thorough check of all the
systems that would restore its shaken confidence, it could go in for a
launch in the next couple of months itself. As Kasturirangan says, "Today's
despair could lead to tomorrow's success." And that tomorrow may
not now be as far away.
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