Success in space

Print edition : April 28, 2001

With the April 18 launch of the Geo-synchronous Satellite Launch Vehicle India moves closer to achieving total self-reliance in building launch vehicles and putting communication satellites into orbit.

INDIA'S space quest truly came of age on April 18 when the gigantic Geo-synchronous Satellite Launch Vehicle (GSLV) roared skyward from the spaceport at Sriharikota, Andhra Pradesh, and 17 minutes later put in orbit the Geo-synchronous Satellite (GSAT) weighing 1,540 kg. That unequivocally demonstrated the Indian Space Research Organisation's (ISRO) capability to put a satellite into a Geo-synchronous Transfer Orbit (GTO) at a height of 36,000 km above the earth. India thus joins a select club of countries that have the capability to put a 2,000 kg satellite into a GTO. The other members are: the United States, Russia, Japan, China and the European Consortium of Arianespace.

The success marks the end of India's dependence on others for launching its communication satellites. Till now the indigenous INSAT satellites, weighing 2,500 kg, were put in orbit either by the U.S. space shuttle or by the Ariane vehicle of Arianespace from Kourou island, French Guiana.

The lift-off of the Geo-synchronous Satellite Launch Vehicle from Sriharikota on April 18.-COURTESY: ISRO

ISRO is now close to achieving total self-reliance in building launch vehicles and satellites. The first-generation INSATs were built in the U.S. and orbited by vehicles of the U.S. or Arianespace. The second-generation INSATs were built by the ISRO Satellite Centre, Bangalore, but launched by Ariane vehicles. Now, not only the GSAT was built by ISRO but the GSLV was India's own. The GSLV used new, highly complex technologies for the first time. They included four liquid strap-on engines and the upper cryogenic engine, which imparted the final velocity to the satellite to go into orbit. The cryogenic stage was imported from Russia.

Dr. K. Kasturirangan, Chairman, ISRO, said the GSLV success was "the most exciting and fruitful mission" of ISRO. "It was an exceptional mission and the first of its kind." He added: "It is the longest 17 minutes in our lives... You saw the velocity and the trajectory it took. It went exactly as we planned. Words cannot describe our feelings."

The success was relished all the more because ISRO recovered "remarkably in just three weeks" to prepare the GSLV again after its earlier flight was aborted one second before lift-off on March 28 owing to a problem in the gas injector in one of the strap-on engines. The engine did not develop enough thrust, and by aborting the flight the vehicle was saved. ISRO teams immediately swung into work.

Dr. K. Kasturirangan, Chairman of the Indian Space Research Organisation, at the post-launch press conference along with G. Madhavan Nair, Director of the Vikram Sarabhai Space Centre, R.V. Perumal, Director of the GSLV Mission, and K. Narayana, Director of the SHAR Centre.-S. MAHINSHA

The vehicle was drained of its liquid and cryogenic propellants. A tear-down analysis of the engine revealed that the blame lay with defective plumbing in the oxidiser flow line. This led to a reduction in the flow of liquid propellants. The anomalous engine was replaced with a stand-by engine.

For the April 18 launch, the 56-hour countdown went off without a hitch. Ten minutes before lift-off, the automatic launch sequence (ALS) computer took control, eliminating any manual intervention. At the appointed time of 3-43 p.m, the GSLV, painted white and gray and emblazoned with the Indian tricolour, took off majestically into the clear blue sky from its launch pad at SHAR, 100 km from Chennai. The strap-on engines fired and performed flawlessly for 4.6 seconds. Then the core first stage was ignited. The vehicle rose, picked up speed and thundered into the sky eastward.

G. Madhavan Nair, Director, Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, which was the lead centre in building the vehicle, said, "Most of the engineering technology performed at the height of their perfection in this GSLV... The vehicle was built in the shortest possible time and with minimum effort. It is a breakthrough in launch vehicle technology and it will strengthen the foundation for the future launch vehicles of the country."

GSAT, the satellite on board, which was placed in a geo-synchronous transfer orbit.-K. GAJENDRAN

R.V. Perumal, GSLV Mission Director, whom Dr. Kasturirangan repeatedly called "the bridegroom of the day", said the 56-hour countdown to the lift-off was "smooth". "The fact that the satellite was put into orbit gives us the information that the performance was normal and that the mission is a success."

Perumal told Frontline that the April 18 launch was that of a developmental flight. "We built a reliable vehicle in which we married complex technologies associated with propulsion, aerodynamics, control, guidance" and added new features such as fins in the strap-ons to ensure stability.

An important difference between the PSLV and the GSLV, he explained, was in the firing of the strap-ons. "In the PSLV, we first ignite the core motor and the vehicle lifts off. Then the two solid strap-on motors are ignited. In the GSLV, we first ignite the four liquid strap-on engines and check them for their satisfactory ignition and performance, and then ignite the core motor after 4.6 seconds. The advantage in using the liquid engines is that we can start and stop them (that is, switch them on and switch them off)."

Dr. K. Sudhakara Rao, Vehicle Director GSLV.-S. MAHINSHA

K. Narayana, Director, SHAR Centre, said: "It is a great day for all of us at ISRO, especially those at SHAR. We have been waiting for this day for many years, and it gives great moral support." Within a couple of hours, Narayana busied himself for the PSLV lift-off scheduled for June/July. "SHAR will witness many more successful missions," he said.

D. Narayana Moorthi, Director, Launch Vehicles' Programme, ISRO Headquarters, Bangalore, who joined ISRO three decades ago, said the GSLV's success was "a dream come true for many of us." "Our ultimate aim was to build a geo-synchronous launch vehicle. This feat has been achieved by starting from scratch, creating expertise, technology, human power and infrastructure, and going through three generations of launch vehicles (SLV-3, ASLV and PSLV). What else can we ask for in our careers than to be part of this historic event?"

THE three-stage GSLV is 49 metres tall and weighs 401 tonnes at lift-off. The first stage, one of the biggest of its kind in the world, consists of the core powered by 129 tonnes of the solid propellant hydroxyl terminated poly butadiene (HTPB). Around this core solid stage are strung four liquid engines. The liquid propellants are unsymmetrical dimethyl hydrazine as fuel and nitrogen tetroxide as oxidiser. Each liquid stage carries 40 tonnes of propellants. The second stage is again a liquid stage. The third, uppermost stage is powered by cryogenic propellants, which are liquid hydrogen and liquid oxygen. They weigh 12.5 tonnes.

Dr. P.S. Nair, Satellite Director-S. MAHINSHA

The five liquid stages used in the GSLV mission form a novel feature. The liquid stages and the uprated core solid stage were all derived from the PSLV, which has become the workhorse of ISRO for orbiting remote-sensing satellites. The PSLV had four successful flights in a row, the last one in 1999. Perumal said: "The PSLV is the real base on which the GSLV rests."

The GSAT is a state-of-the-art communication satellite. It has payloads to demonstrate digital audio broadcasts, Internet services, compressed digital television experiments and developmental communications.

According to N. Vedachalam, Director, Liquid Propulsion Systems Centre (LPSC), Mahendra-giri, Tamil Nadu, "We (LPSC) developed the liquid engines. They developed a thrust of 240 tonnes (each) assisting the central rocket. The second liquid stage also did an excellent job. So we successfully demonstrated the performance of the high-thrust liquid engine in this flight."

N. Vedachalam, Director, Liquid Propulsion Systems Centre-S. MAHINSHA

The Russian cryogenic stage also performed flawlessly. Dr. L.N. Kiselev was happy that "such a small stage could make such a big contribution". The cryogenic stage imparted a velocity of more than 5 km a second out of the total final velocity of 10.2 km a second for the satellite to go into orbit. Cryogenic technology involves the use of liquid hydrogen at -265- Celsius and liquid oxygen at -240-C. Dr. Kasturirangan said: "We are using cryogenic technology for the first time and the cryogenic systems are a class by themselves in terms of complexity and performance."

While the Russians supplied the cryogenic stage, the liquid hydrogen and the liquid oxygen were made in India. ISRO fabricated the electronics, control and guidance systems in the cryogenic and other stages.

There was heart-pounding tension in the Mission Control Centre (MCC) at SHAR as launch hour approached. The MCC is the nerve centre of the mission, connected with all pre-launch and post-launch activities. Dr. Kasturirangan, Madhavan Nair, Perumal, Narayana, Vehicle Director Dr. K. Sudhakara Rao, Satellite Director Dr. P.S. Nair, and Project Director for the cryogenic stage Kiselev sat in front of their computer consoles, looking tense.

D. Narayana Moorthi, Director, Launch Vehicles' Programme-S. MAHINSHA

K.V. Seshu, programmer of the flight, announced: "Twenty minutes to go." Then a beautiful view of the rocket loomed into view on the closed circuit television screen. The rocket towered over the jungle foliage. The radio crackled: "Mission Director, roger; Vehicle Director, roger; Satellite Director, roger." Seshu's voice boomed again: "Mark three minutes and counting... 55 seconds, 20 seconds... ten, nine, eight, seven... zero, NOW, plus one, plus two, plus three..."

Flames leapt up from the liquid engines, and they performed flawlessly for 4.6 seconds. Then the core first stage was ignited, and the GSLV rose slowly at first and then blazed skyward.

The next 17 minutes were the most tortuous for the ISRO personnel. The first stage burnt for 100 seconds while the liquid strap-on engines continued to thrust for 162 seconds taking the vehicle to an altitude of 75 km. The vehicle's velocity at this point was 2.63 km a second. The second stage was ignited before the burn-out of the first-stage strap-ons. The second stage burnt for another 147 seconds, taking the vehicle to an altitude of 126 km and increasing its velocity to 5.18 km a second. By then, the heat shield that protects the satellite during the vehicle's ascent into the dense upper atmosphere peeled away and fell into the Bay of Bengal.

After the second stage separated at 314 seconds from the lift-off, the cryogenic stage was ignited. It burnt for about 700 seconds taking the vehicle to an altitude of 195 km. According to Perumal, the cryo stage injected the satellite into orbit at a velocity of 10.2 km a second. The cryo stage was "tumbled" out so that it did not collide with the spacecraft, he said.

By then, the satellite was 5,000 km away from SHAR, somewhere over Indonesia. Signals from the telemetry stations at SHAR, Port Blair, Brunei and Biak in Indonesia showed that the spacecraft systems were performing normally. Its perigee was 181 km and apogee about 32,000 km. This was a highly elliptical orbit. It would be circularised at 36,000 km altitude by firing the propulsion systems on board the GSAT.

When the 17 minutes ended, it was celebration time at MCC and all over SHAR. Dr. Kasturirangan was teary-eyed. He hugged Perumal, and shook hands with Madhavan Nair, Sudhakara Rao, Vedachalam and Kiselev. Prof U.R. Rao, former ISRO Chairman, beamed with joy.

When the ISRO Chairman conveyed the happy news over phone, to Prime Minister A.B. Vajpayee, said: "Congratulations, congratulations and congratulations." Vajpayee also asked him to convey his congratulations to "each and every colleague of yours in ISRO". Vajpayee, his voice choked with emotion, told the ISRO Chairman, "The nation is proud of you." Union Minister of State for Science and Technology Vasundhara Raje Scindia also congratulated the ISRO staff and recalled that when the flight was aborted on March 28, she had said that "it will be a stepping stone to success".

Sudhakara Rao called it "a very sophisticated vehicle because it should not climb too much or it should climb not down too low." He said ISRO had done 5,000 simulations of the flight. "We flew the vehicle in the computer micro-processor every 20 milliseconds. All this gave us the confidence that the vehicle design was all right."

Dr. P.S. Goel, Director, ISRO Satellite Centre, Bangalore, said that all systems on board the satellite were performing well. Dr. A.K.S. Gopalan, Director of Space Applications Centre, Ahm-edabad, which fabricated the payloads, said the spacecraft would be used for digital audio broadcasting. Dr. P.S. Nair, Satellite Director, said the life of the satellite was three years but it might last up to five years.

According to Dr. Kasturirangan, ISRO's efforts, beginning with the launching of the SLV-3 in 1979 and 1980, the ASLV, then the PSLV and now the GSLV "mark the culmination of a series of efforts in providing a capability for launching INSAT class of two-tonne communication satellites. This is a very significant step towards achieving self-reliance in deploying satellites in GTO."

Dr. B.N. Suresh, Deputy Director, VSSC, said "the entire avionics worked very well". A specialist in avionics, he was in charge of the control and guidance systems of the vehicle. He said there was some underperformance from the upper cryogenic stage but it was of a small value. There was 0.7 per cent error in the overall velocity with which the satellite was injected into orbit. If the satellite was put into orbit at a velocity of 10.2 km a second, it went into orbit 60 to 70 metres a second less than 10.2 km a second.

Dr. Suresh said an additional 10 kg of fuel was loaded on board the GSAT. This came in handy for firing the propulsion motors on board the satellite to raise the apogee from 32,000 km to 36,000 km.

An ISRO scientist said: "We made it to the real GTO of 3,000 km by 36,000 km last night (April 19). We will now do the final manoeuvring. The satellite is doing excellently well."

The operations carried out on it on April 19 involved a well-coordinated and synchronised commanding operation among three ground stations: Lake Cowichan in Canada, Fucino in Italy and the Master Control Facility (MCF) at Hassan in Karnataka.

Date Satellite Launcher November 21, 1963 - Nike-Apache February 21, 1969 - Pencil Rocket (India-made: 10 kg)April 19, 1975 Aryabhata Cosmos (USSR)June 7, 1979 Bhaskara Cosmos (USSR)August 10, 1979 Rohini SLV-3July 18, 1980 Rohini SLV-3May 31, 1981 Rohini SLV-3June 19, 1981 APPLE Ariane (ESA)November 20, 1981 Bhaskara-II CosmosApril 10, 1982 INSAT 1A Delta (U.S.)April 17, 1983 Rohini SLV-3August 30, 1983 INSAT 1B U.S. space shuttleMarch 24, 1987 SROSS A ASLV-D1 March 17, 1988 IRS-1A Vostok (USSR)July 13, 1988 SROSS B ASLV-D2July 22, 1988 INSAT-1C ArianeJune 12, 1990 INSAT-ID DeltaAugust 29, 1991 IRS-1B Vostok May 20, 1992 SROSS C ASLV-D3July 10, 1992 INSAT-2A Ariane July 23, 1993 INSAT-2B ArianeSeptember 20, 1993 IRS-1E PSLV-D1May 4, 1994 SROSS ASLV-D4 October 15, 1994 IRS-P2 PSLV-D2December 7, 1995 INSAT-2C ArianeDecember 28, 1995 IRS-1C Molniya (Russia)March 21, 1996 IRS-P3 PSLV-D3June 4, 1997 INSAT-2D ArianeSeptember 29, 1997 IRS-1D PSLV-C1April 2, 1999 INSAT-2E ArianeMay 26, 1999 IRS-P4, Tubsat Kitsat PSLV-C2March 22, 2000 INSAT-3B Ariane 5April 18, 2001 GSAT GSLV

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