Space Transporation

The Indian space programme began in the 1960s with the launch of modest Rohini sounding rockets for scientific investigations over the geo-magnetic equator passing over Thumba near Thiruvananthapuram. Since then, India has achieved self-reliance in satellite launch vehicle programme with the operationalisation of Polar Satellite Launch Vehicle (PSLV) and Geosynchronous Satellite Launch Vehicle (GSLV).

Polar Satellite Launch Vehicle (PSLV)
The major achievement during the year was the tenth launch of India’s Polar Satellite Launch Vehicle (PSLV-C7) on January 10, 2007, carrying four satellites – India’s CARTOSAT-2 and Space capsule Recovery Experiment (SRE-1), Indonesian LAPAN-TUBSAT and Argentina’s PEHUENSAT. All the satellites were placed precisely in the specified polar orbit of 635 km at an inclination of 97.9 degree with respect to equator.

PSLV-C7 ready for lift-off

PSLV is the workhorse launch vehicle of ISRO with nine consecutively successful flights so far. Since its first successful launch in 1994, PSLV has launched eight Indian remote sensing satellites, an amateur radio satellite, HAMSAT, Space capsule Recovery Experiment (SRE-1) and six small satellites for foreign customers into 600-800 km high polar SSOs. Besides, it has also launched India’s exclusive meteorological satellite, Kalpana-1, into Geosynchronous Transfer Orbit (GTO). PSLV will also be used to launch India’s first spacecraft mission to moon, Chandrayaan-1, during 2008.

Encapsulation of SRE-1 inside DLA

The 44 m tall PSLV has a lift-off mass of 295 tonne. It is a four-stage launch vehicle with the first and the third stages as well as the six strap-ons surrounding the first stage using HTPB based solid propellant. The first stage is one of the largest solid propellant boosters in the world. Its second and fourth stages use liquid propellants. PSLV’s bulbous payload fairing has a diameter of 3.2 metre. The vehicle has S-band telemetry and C-band transponder systems for monitoring its health and flight status respectively. It also has sophisticated auxiliary systems like stage and payload fairing separation systems.

PSLV-C7 lift-off

PSLV was originally designed to put 1,000 kg class of India’s remote sensing satellites into a 900 km polar SSO. The payload capability of PSLV has been successively enhanced and PSLV-C7 launched the four payloads into a 635 km high polar SSO with an inclination of 97.92 deg with respect to the equator. For the first time, a Dual Launch Adopter (DLA) was used in PSLV to accommodate the payloads. The 680 kg main payload, CARTOSAT-2, was mounted over DLA. The 550 kg Space capsule Recovery Experiment (SRE-1) was mounted inside DLA. The 56 kg LAPAN-TUBSAT was mounted on the equipment bay while the 6 kg nano-satellite, PEHUENSAT-1, was mounted on DLA. Some of the modifications incorporated in PSLV-C7 compared to the previous flight, PSLV-C6, were:
• Use of DLA.
• Reduction of propellant from 2.5 tonne to 2 tonne in the fourth liquid propellant stage, PS4.
• Modifications in PSLV fourth stage control electronics.
• Incorporation of Video Imaging System to capture payloads and DLA separation events.
• Altitude based Day of Launch wind biased steering programme during Open Loop Guidance.
• Deletion of Secondary Injection Thrust Vector Control (SITVC) systems for one of two strap-ons that is ignited in the air.
• Reduction of PSLV first stage SITVC injectant by 500 kg.

PSLV-C8, planned for 2007-08, will launch the 360 kg Italian satellite, AGILE, under a commercial agreement as the primary payload and India’s Advanced Avionics Module (AAM) weighing 180 kg as the secondary payload. PSLV configuration for this flight will be modified to use only the core vehicle (without the six solid propellant strap-on motors) and the liquid propellant loading in the fourth stage will be reduced from the nominal 2 tonne to 1.6 tonne. During the year, mission software design and simulation have been completed. The flight packages of AAM have been realised.

A new improved version of the solid propellant strap-on motor for PSLV, PSOM-XL, had been static tested in December, 2005. PSOM-XL, with a length of 13.5 m, has the capacity to carry 12.4 tonne of propellant compared to 9 tonne in the present motor. PSOM-XL will enable improve the capability of PSLV from the present 1,450 kg to 1600 kg and will be employed in future PSLV flights including launching of Chandrayaan-1 and the microwave remote sensing satellite, RISAT.

Configuration studies for a three stage PSLV is continuing.

Passengers on board PSLV-C7: A-CARTOSAT-2, B-SRE-1, C-LAPAN-TUBSAT, D-PEHEUNSAT-1

PSLV-C7 payloads prior to closure of heatshield

Geosynchronous Satellite Launch Vehicle (GSLV)

The 49 m tall GSLV, with a lift off mass of 414 tonne is a three-stage vehicle with solid, liquid and cryogenic stages. The first stage of GSLV is one of the largest rocket motors in the world and uses Hydroxyl Terminated Poly-butadiene (HTPB) base propellant. The second stage as well as the four strap-on motors use liquid propellant ‘Vikas’ engine burning UH25 and Nitrogen Tetroxide. The third stage of GSLV 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). The Payload Fairing, which is 7.8 m long and 3.4 m in diameter, protects the vehicle electronics and the spacecraft during its the ascent through the atmosphere. It is discarded when the vehicle has reached an altitude of about 115 km. The Redundant Strap Down Inertial Navigation System (RESINS) / Inertial Guidance System (IGS), housed in the equipment bay guides the vehicle from lift-off to spacecraft injection. The digital auto-pilot and closed-loop guidance scheme ensure the required attitude maneuver and guided injection of the spacecraft to the specified orbit.

GSLV employs various separation systems such as Flexible Linear Shaped Charge (FLSC) for the first stage, pyro actuated collet release mechanism for the second stage and Merman band bolt cutter separation mechanism for the third stage. Spacecraft separation is by spring thusters mounted at the separation interface.

GSLV was declared operational after both its developmental test flights conducted in April 2001 and May 2003 were successful. In its first operational flight, GSLV-F01, successfully launched India’s first exclusive satellite for educational services, EDUSAT, in September 2004. The vehicle has been improved successively in the last four flights to increase its payload capability from 1,530 kg in its first test flight to 2,168 kg in the fourth flight.
During the year, the second operational flight, GSLV-F02, with INSAT-4C on board, was launched from the Second Launch Pad (SLP) at Satish Dhawan Space Centre SHAR (SDSC SHAR), Sriharihota on July 10, 2006. GSLV-F02 was intended to place INSAT-4C, into a 170 km x 36,000 km GTO with an orbital inclination of 20.7 degree with respect to equator. However, GSLV-F02 could not complete the mission. About 55 sec into the flight, GSLV-F02 started deviating significantly from its nominal flight path resulting in the vehicle breaking up at 62 sec after lift-off. The debris fell into Bay of Bengal.

GSLV-F02 flight – sequence of events

The Failure Analysis Committee (FAC), constituted for investigating the failure, has reviewed the performance of GSLV-F02 from lift-off to the end of flight. FAC has concluded that the performance of all vehicle subsystems, except one strap-on stage was normal until 56.4 sec. The primary cause for the failure was the sudden loss of thrust in one out of the four liquid propellant strap-on stages (S4) immediately after lift-off at 0.2 sec. With only three strap-on stages working, there was significant reduction in the control capability. However the vehicle attitude could be controlled till about 50 sec. At the same time the vehicle reached the transonic regime of flight and the vehicle attitude errors built up to large values, resulting in aerodynamic loads exceeding the design limits thus leading to break up of the vehicle.
The thrust of the liquid engines used in the strap-on stages is precisely controlled by a set of regulators. Detailed analyses have indicated that in S4 engine the thrust control was not effective. Instead of stabilising at 5.85 MPa (Mega Pascal) chamber pressure, it reached 7.11 MPa at 2.8 sec after ignition. This was much beyond the design limits and the engine failed at 0.2 sec after lift-off, that is 5 sec after its ignition.

Simulations and analyses of flight data and verification through calibration tests have led to the conclusion that the propellant regulator in the failed engine had much higher discharge coefficient in its closed condition. The reason for this could be an inadvertent error in manufacturing, which escaped the subsequent inspection, and acceptance test procedures. This regulator has functioned satisfactorily in all the previous 50 engines manufactured and tested so far.

The larger flow of propellant led to higher operating pressure in the gas generator (4.7 MPa against design specification of 3.6 MPa). Due to this higher operating pressure of the gas generator, the water flow rate into it got reduced. The combined effect of larger flow of propellants and reduced flow of water led to a very high gas temperature of 1823 K against design specification of 900 K and pressure of 4.7 MPa against the design specification of 3.6 MPa. The very high operating pressure and temperature resulted in the structural failure of the gas generator. The consequent abrupt stopping of the turbo pumps that feed propellants at very high pressures to the engines led to loss of thrust of S4 engine. The water calibration tests conducted simulating the malfunction of the propellant regulator hardware could closely reproduce the flight phenomenon thereby confirming the larger flow area.

FAC has concluded that the design of GSLV is robust and recommended implementation of strict control on fabrication, inspection and acceptance procedures. Among others, FAC has recommended fabrication processes to be critically reviewed and updated. It has recommended for independent inspection of all critical dimensions of components and subassemblies by in-house agencies. Further, long duration hot test on one out of every 20 engines fabricated has been recommended to ensure that production process is under control. In addition, FAC has recommended strengthening the process of clearance of launch during Automatic Launch Sequence (ALS) phase. FAC conclusions and recommendations have been accepted and necessary action has been initiated to implement all of them.

Activities related to the follow-on GSLV to launch
INSAT-4CR are progressing well for the planned launch in 2007-08. The work on GSLV-D3 with indigenous cryogenic stage is also progressing well.

Cryogenic Upper Stage Project (CUSP)
The third stage of GSLV which is cryogenic is much more efficient and provides more thrust for every kilogram of propellant it burns compared to solid and earth-storable liquid propellants. 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 10 kg.
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 becomes a liquid at –183 deg C and Hydrogen liquefies at –253 deg C. The propellants, at these low temperatures, are to be pumped using turbo pumps running at 42,000 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.

Cryogenic stage under test

Cryogenic Upper Stage Project (CUSP) envisages design and development of the indigenous cryogenic upper stage to replace the existing stage procured from Russia currently used in GSLV flights. CUSP envisages the development of cryogenic stage with regenerative cooled engine, which produces a thrust of 69.5 kN in vacuum. As part of this effort, the cryogenic engines have been realised and tested earlier for a cumulative duration of 6,000 sec. In the stage level hot test, all stage elements like engine, insulated propellant tanks, booster pumps, fill and drain systems, pressurization systems, gas bottles, igniters, cold gas orientation and stabilisation system, etc, as per flight standards are working in unison.
During the year a major milestone was achieved with the hot test of Cryogenic Upper Stage on October 28, 2006 for a duration of 50 sec. This hot test has demonstrated the design adequacy and performance of the integrated flight system, further tests for this flight unit are planned to validate robustness of the design. After completion of the qualification tests, the indigenous cryogenic stage is planned to be flight tested in GSLV- D3 mission next year.

GSLV-Mk III
GSLV-Mk III is envisaged to launch four tonne satellite into geosynchronous transfer orbit. GSLV-Mk III is a three-stage vehicle with a 110 tonne core liquid propellant stage (L-110) and a strap-on stage with two solid propellant motors, each with 200 tonne propellant (S-200). The upper stage will be cryogenic with a propellant loading of 25 tonne (C-25). GSLV Mk-III will have a lift-off weight of about 629 tonne and will be 42.4 m tall. The payload fairing will have a diameter of 5 metre and a payload volume of 100 cubic metre.

Silica phenolic throat insert for L-110 stage of GSLV-Mk III

Aero-elastic test of GSLV-Mk III model

During the year, wind tunnel tests were completed and vehicle aero-elastic test activities commenced. The vehicle configuration update was completed. All major facilities including propellant plant, vehicle assembly and integration building, mobile launch pedestal and facilities at work centres have reached the final phase of completion. The L110 engine has been qualified with successful completion of 240 seconds hot tests.

Propellant hardware insulation, lining and machining building for GSLV-Mk III at SDSC SHAR

First batch of light alloy structure and motor case segments were realised at work centres. The avionics system designs have been completed and first batch of packages are being realised for qualification. Avionics assemblies layout has been finalised and integration trials for package assembly are being carried out.

The first developmental flight is expected in 2009-10.

Rohini Sounding Rockets
DOS has developed a series of sounding rockets known as Rohini (RH) with diameters ranging from 200 to 560 mm and capable of carrying up to 200 kg payload to 300-400 km altitude for conducting scientific experiments. During the year (till December 2006), 22 RH-200 sounding rockets were launched including 20 for the Middle Atmosphere Dynamics (MIDAS) programme. Two RH-300 Mk-II sounding rockets were launched for mesospheric airglow emission studies.

Two RH-200 SV rockets were launched to test miniaturised payloads and four rockets were provided to University of Tromso, Norway for scientific missions.

During the year, static test of RH-560M motor with increased propellant loading has been conducted. This new motor is to be used in RH-560M+RH-560M sounding rocket for demonstration of scramjet propulsion. The configuration of this new rocket has also been finalised.

Space capsule Recovery Experiment (SRE-1)
Space capsule Recovery Experiment (SRE-1), was launched into a 635 km polar orbit along with CARTOSAT-2 by PSLV-C7 on January 10, 2007. Weighing 550 kg, it was intended to demonstrate the technology of orbiting platform for performing experiments in microgravity conditions and recover the same after completion of the experiments. SRE-1 was also intended to provide important technology inputs in navigation, guidance and control during the
re-entry phase, hypersonic aero-thermodynamics for reusable Thermal Protection System (TPS), recovery through deceleration and floatation besides acquisition of basic technology for reusable launch vehicles.

SRE-1 carried two experiments, an Isothermal Heating Furnace [IHF] and a Biomimetic (Biomineralisation of Inorganic materials) experiment.

SRE-1

SRE-1 comprised aero-thermo structure, spacecraft platform, deceleration and floatation system besides the micro-gravity payloads. It had a sphere-cone-flare configuration with a spherical nose of about 0.5 m radius, base diameter of 2 m and 1.6 m height. The parachute, pyro devices, avionics packages of triggering unit and sequencer, telemetry and tracking system and sensors for measurement of system performance parameters were placed inside capsule.

SRE-1 was successfully manoeuvered to deorbit and reenter the earth atmosphere on January 22, 2007. In preparation for its reentry, SRE-1 was put into an elliptical orbit with a perigee of 485 km and an apogee of 639 km on January 19, 2007. The critical de-boost operations were executed from ISTRAC, Bangalore supported by a network of ground stations at Bangalore, Lucknow, Mauritius, Sriharikota, Biak in Indonesia, Saskatoon in Canada, Svalbard in Norway besides shipborne and airborne terminals.

Indian Coast Guard ship Sarang approaching SRE-1 after its splashdown in Bay of Bengal

The de-boost started with the firing of on-board rocket motors and SRE-1 was reoriented for its re-entry into the dense atmosphere. The capsule made its re-entry at an altitude of 100 km with a velocity of 8 km/sec. By the time SRE-1 descended to an altitude of 5 km, aerodynamic breaking had considerably reduced its velocity to 101 m/sec. Pilot and drogue parachute deployments helped in further reducing its velocity to 47 m/sec. The main parachute was deployed at about 2 km altitude and finally, SRE-1 splashed down in the Bay of Bengal with a velocity of 12 m/sec. Immediately after SRE-1 splashing into sea, the flotation system got triggered and kept the capsule floating. Recovery operations were supported and carried out by the Indian Coast Guard and Indian Navy using ships, aircraft and helicopters.

Recovery of SRE-1

During its stay in orbit for 12 days, the two experiments on board SRE-1 were successfully conducted under micro gravity conditions. One of the experiments was related to study of metal melting and crystallisation under micro gravity conditions. This experiment,
jointly designed by the Indian Institute of Science, Bangalore and Vikram Sarabhai Space Centre, Thiruvananthapuram, was performed in an Isothermal Heating Furnace. The second experiment, designed by National Metallurgical Laboratory, Jamshedpur, was intended to study the synthesis of nano-crystals under micro gravity conditions. This experiment can help in designing better biomaterials having closest proximity with natural biological products. The experimental results will be analysed in due course by the principal scientific investigators of the two experiments.

Technologies for Advanced Space Transportation
During the year activities towards the first flight of a Dual Mode Ramjet Flight Test Demonstrator (DMRJ-FTD) has made substantial progress. The static test of RH-560 sounding rocket solid propellant motor for DMRJ-FTD has been conducted qualifying the pyrogen ignitor. Wind tunnel models have been realised and tested up to Mach-4 and Mach-7. Detailed mission Monte-Carlo analysis has been carried out to obtain required dwell time within the Mach number – dynamic pressure window.

Supersonic Combustion Test using gaseous hydrogen and kerosene as fuels have continued during the year. Air hydrogen combustion modeling has been incorporated in the in-house computational fluid dynamics software “PARAS-3D” as a major step towards simulation of full SCRAMJET engine under flight conditions.

Aerodynamics characterisation, mission design and simulation, structural design, subsystem definitions and Thermal Protection System (TPS) design for reusable launch vehicle technology demonstration have been carried out during the year.

Launch Infrastructure

SDSC SHAR supported two launches — PSLV-C7 on January 10, 2007 and earlier GSLV-F02 on July 10, 2006 — during the year. SDSC also supported the Space Capsule Recovery operations.

Works related to S-200 solid propellant motor plant for GSLV-Mk III is in advanced stage of completion. Vehicle assembly and test facility, range instrumentation and computer system facilities as well as propellant servicing facilities required for GSLV-Mk III have also made substantial progress during the year. Second satellite preparation facility was commissioned at SDSC SHAR during the year.

Precision Coherent Monopulse C-band (PCMC) Radar-1 and PCMC Radar-2 have been commissioned in permanent buildings.