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New Delhi, April 15, 2010
India's first flight test of its indigenously developed Cryogenic Upper Stage (CUS) on GSLV-D3, the third developmental mission of its Geosynchronous Satellite Launch Vehicle, ended up as a failure this afternoon as it first deviated from its path and then splashed into the sea.
The GSLV-D3 was launched from the Satish Dhawan Space Centre at Sriharikota at 4.27 pm today and would have put the 2200 kg GSAT-4, an experimental advanced technology communication satellite that carries communication and navigation payloads, into Geosynchronous Transfer Orbit (GTO.
The cryogenic engine, developed after 18 years of work by scientists and engineers of the Indian Space Research Organisation (ISRO) on this complex technology, is crucial for putting communication satellites heavier than two tonnes into GTO.
As the GSLV-D3 lifted off in perfect fashion at 4.27 pm, the excitement in the mission control centre was palpable and everyone waited in anticipation of the big moment.
And then there was a hush in the hall as the vehicle seemed to have deviated from its path. After several anxious moments, ISRO Chairman K Radhakrishnan announced that the mission had not fully met all the parameters.
"The performance of the vehicle was normal upto the burnout of the second stage and the vehicle got a velocity of 4.9 km/second as planned," he said.
"In the cryo stage, the ignition command was issued as planned by the onboard computer. Indications are that the cryo engine ignited. This is to be confirmed after detailed analysis of the data," he said.
"However, we saw the vehicle was tumbling, indicating the controllability was lost, most probably as the two vernier engines - smaller cryo engines - would not have ignited and developed the necessary control force," he said.
Later, at a press conference, Dr Radhakrishnan said the mission engineers were not very sure whether the main engine had ignited. He said this was something that could be confirmed only after studying the flight data in detail.
"What we saw was that the vehicle was tumbling, lost its control, lost its altitude and finally splashed down into the sea," he said.
According to him, the scientists would need to analyse the data over the next two to three days before coming to a conclusion about what really happened and why and also work out the corrective measures to be incorporated into the next test flight.
Dr Radhakrishnan said a detailed analysis of the flight data would be carried and ISRO would find out the reason for the non-ignition of the vernier engines. He said ISRO would also confirm whether the main cryogenic engine had ignited.
"And then we will put all our efforts to ensure that we have next flight with an indigenous cryogenic engine within a year from now," he said.
"Our team has the capacity, the resilience," he said. The target is to carry out all the corrections and have the next flight within one year. "This is the challenge," he said.
Dr Radhakrishnan spoke briefly about the saga of the cryogenic engine, which India started developing in 1993 after Russia stopped supplying the engines to it.
He said the engineers, scientists, technicians and everyone at ISRO had worked very hard to reach this level, which was the culmination of the efforts of 18 years of work on a very complex technology.
According to him, reaching the flight test stage was in itself a major achievement. "But we have to go a long way and we will do that in the next one year," he said.
He said such failures were part of the development of any complex technology. "We have to face it. We have to work with dedication and focus. We are confident Team ISRO will do it," he said.
Eminent scientist Yash Pal and former ISRO Chairmen such as K Kasturirangan and G Madhavan Nair were amongst those present on the occasion and were seen chatting with Dr Radhakrishnan later.
The successful test of the indigenous CUS would have pushed India into an elite group of space-faring countries such as the United States, Russia, Japan and China, as well as Europe, and further strengthened its position as a major space power.
Envisaged mainly as a technology demonstrator for advanced satellite communications, GSAT-4 would have enabled the testing of many future communication satellite technologies.
GSLV-D3 was the sixth flight of ISRO's GSLV as well as its third developmental flight. The major changes incorporated in GSLV-D3 as compared to its previous flight, GSLV-F04, included the indigenous CUS, advanced telemetry system and advanced mission computers and larger composite payload fairing.
India had sourced cryogenic stages (CS) from Russia for the past five flights of GSLV.
GSLV is designed to inject the 2 tonne class of communication satellites into GTO. Usually, geostationary satellites are first injected into the elliptical GTO by launch vehicles. Later, the satellites are taken to the circular Geostationary Orbit using their own propulsion system. Geostationary Orbit lies at a height of 36,000 km over the equator.
The 50 m tall GSLV, with a lift-off mass of 416 ton, is a three-stage vehicle with solid, liquid and cryogenic stages. The solid core motor of the first stage of GSLV is one of the largest rocket motors in the world and uses 138 tons of Hydroxyl Terminated Poly-Butadiene (HTPB) based propellant (fuel-oxidiser combination).
The second stage (carrying 38.5 tons of propellant) as well as the four strap-on motors of the first stage (each carrying 42 tons of propellant) use liquid propellant Vikas engine burning UH25 and Nitrogen Tetroxide.
The third stage of GSLV carrying 12.5 tons of propellants is a cryogenic stage that uses liquid Hydrogen as fuel and liquid Oxygen as oxidiser.
GSLV employs S-band telemetry and C-band transponders for enabling vehicle performance monitoring, tracking, range safety/flight safety and Preliminary Orbit Determination (POD).
Cryogenic Stage is a rocket stage that is much more efficient and provides more thrust for every kilogramme of propellant it burns compared to solid and earth-storable liquid propellant stages.
Specific impulse (a measure of the efficiency) achievable with cryo fluids (liquid Hydrogen and liquid Oxygen) is of the order of 450 sec compared to 300 sec for earth storable and solid fuels, giving a substantial payload advantage; for an upper stage, with every one second increase in the specific impulse, the payload gain is of the order of 15 kg, an ISRO press release had said earlier.
However, cryogenic stage is technically a very complex system compared to solid or earth-storable liquid propellant stages due to the use of propellants at extremely low temperatures and the associated thermal and structural problems.
Oxygen liquefies at -183 deg C and Hydrogen at -253 deg C. The propellants, at these low temperatures, are to be pumped using turbo pumps running at around 40,000 rpm. It also entails complex ground support systems like propellant storage and filling systems, cryo engine and stage test facilities, transportation and handling of the cryo fluids and related safety aspects, the release said.
ISRO's Cryogenic Upper Stage Project (CUSP) envisaged the design and development of the indigenous Cryogenic Upper Stage to replace the stage procured from Russia and used in GSLV flights.
CUSP was intended to develop a cryogenic stage with regenerative cooled engine, producing a thrust of 69.5 kilo Newton (kN) in vacuum. As part of this effort, cryogenic engines were realised and tested earlier for a cumulative duration of 7760 sec. In the stage level hot test, apart from cryogenic engine, all other stage elements worked in unison as per flight standards.
In December 2008, a major milestone was achieved with the flight acceptance hot test of the indigenous Cryogenic engine. This hot test was an important step in acquiring a coveted status for the country among space faring nations which have successfully mastered this critical and most complex technology. With this, India came a step closer to becoming totally self reliant in all aspects of launch vehicle technology.
The release said indigenous CUS was powered by a regeneratively cooled cryogenic engine, which works on staged combustion cycle. This main engine, and two smaller (cryogenic) steering engines together develop a nominal thrust of 73.55 kN in vacuum. The main engine of CUS achieves a specific impulse of 452 seconds. During the flight, CUS fires for a nominal duration of 720 seconds.
GSAT-4 was the 19th geostationary satellite of India built by ISRO and fourth in the GSAT series. Its three GSAT predecessors were launched by GSLV during 2001, 2003 and 2004 respectively.
The technology experiments to be carried onboard GSAT-4 were an on-board structural dynamics experiment, velocity measurement package and a thermal control coating experiment.
It also carried communication as well as navigation payloads: the Ka - band bent pipe and regenerative transponder and GAGAN payload operating in C, L1 and L5 bands
The intended applications for Ka band included Wide band Multimedia Services, Mobile Information System, SPACE LAN, e-Commerce and High Bandwidth Internet.
GAGAN was a navigational payload operating in C, L1 and L5 bands. It forms segment of GAGAN Satellite Based Augmentation System (SBAS) developed by India.
GAGAN stands for GPS Aided Geo Augmented Navigation. Through SBAS, the positional information from the GPS satellites is improved by a network of ground based receivers and the same is made available to any user through geostationary satellites.
GAGAN is a Wide Area Differential Global Positioning System (WADGPS) employing a geostationary satellite overlay system. It was conceived to provide a position accuracy of better than 7.6 metre needed for the precision landing of civilian aircraft.
Photos: Courtesy ISRO