PSLV-C4 Launch Successful – METSAT Placed in Orbit

In its seventh flight conducted from Satish Dhawan Space Centre, SHAR, Sriharikota, India’s Polar Satellite Launch Vehicle, PSLV-C4, successfully launched an exclusive meteorological satellite, METSAT, into Geosynchronous Transfer Orbit. The PSLV carrying METSAT lifted-off at 3.55 pm Indian Standard Time and the satellite was injected into orbit about 20 minutes later. Immediately after its injection, the solar array on board the satellite automatically deployed as per the plan.

PSLV-C4 is the seventh flight of Polar Satellite Launch Vehicle (PSLV) and its first flight to place a satellite – the 1060 kg METSAT – into a Geosynchronous Transfer Orbit (GTO). Initially, PSLV was designed for launching 900 kg Indian Remote Sensing Satellites (IRS) into a 900 km polar Sun Synchronous Orbit. Since its first launch in 1993 from Sriharikota, the four stage PSLV has been successively improved to enhance its capability.

Some of the changes that have been made in PSLV since its previous launch on October 22, 2001 when it successfully launched three satellites, viz., India’s Technology Experimental Satellite (TES), the German BIRD and the Belgian Proba. Major changes made to PSLV include the improvements brought about in the performance of the third stage solid propellant motor by optimising the motor case and propellant loading. Also, the propellant in the fourth stage liquid propellant motor has been increased from 2 tonnes to 2.5 tonnes. Besides, PSLV-C4 employs a carbon composite payload adopter resulting in substantial payload advantage.

Flight Profile

Compared to the earlier PSLV launches, The flight path of PSLV-C4 has been modified to inject the METSAT into a Geosynchronous Transfer Orbit of 250 km perigee (nearest point to Earth) and 36,000 km apogee (farthest point to Earth). This orbit will be elliptical in shape and will be inclined at angle of 18 degrees to the equator.

About 1251 seconds (about 21 minutes) after lift-off, METSAT will separate from the fourth stage of PSLV in Geosynchronous Transfer Orbit.

METSAT’s solar array will be automatically deployed immediately after its separation from the fourth stage of PSLV-C4. The deployment of the array as well as the general health of the satellite will be monitored by a ground station of the ISRO Telemetry, Tracking and Command network (ISTRAC) located on the Indonesian island of Biak. The Master Control Facility (MCF) at Hassan in Karnataka will take control of METSAT for all its post launch operations. Ground stations at Lake Cowichan (Canada), Fucino (Italy) and Beijing (China) will support MCF in monitoring the health of the satellite and its orbit raising operations.

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After its launch into GTO, METSAT’s orbit will be raised to the final Geostationary Orbit by firing the satellite’s Liquid Apogee Motor. The satellite will be commissioned into service after the completion of orbit raising operations and positioning it in its designated orbital slot of 74 East longitude as well as the in-orbit testing of all the onboard systems.

About PSLV

In its present configuration, the 44.4 metre tall, 295 tonne PSLV has four stages using solid and liquid propulsion systems alternately. The first stage is one of the largest solid propellant boosters in the world and carries 138 tonnes of Hydroxyl Terminated Poly Butadiene (HTPB) based propellant. It has a diameter of 2.8 m. Its motor case is made of maraging steel. The booster develops a maximum thrust of about 4,628 kilo Newton (kN).

Six strap-on motors, four of which are ignited on the ground, augment the first stage thrust. Each of these solid propellant strap-on motors carries nine tonne of HTPB based propellant and produces 662 kN thrust.

The second stage employs indigenously built Vikas engine and carries 40 tonne of liquid propellant — Unsymmetrical Di-Methyl Hydrazine (UDMH) as fuel and Nitrogen tetroxide (N2O4) as oxidiser. It generates a maximum thrust of about 725 kN.

The third stage uses 7.6 tonne of HTPB-based solid propellant and produces a maximum thrust of 260 kN. Its motor case is made of polyaramide fibre.

The fourth and the terminal stage of PSLV has a twin engine configuration using liquid propellant. With a propellant loading of 2.5 tonne (Mono-methyl hydrazine as fuel and Mixed Oxides of Nitrogen as oxidiser), each of these engines generates a maximum thrust of 7.4 kN.

The 3.2 m diameter metallic bulbous heat-shield of PSLV, which is made of isogrid construction, protects the spacecraft during the PSLV’s passage through the dense atmosphere.

PSLV flight control system includes: a) First stage: Secondary Injection Thrust Vector Control (SITVC) for pitch and yaw, reaction control thrusters for roll and SITVC in two strap-on motors for roll control augmentation, b) Second stage: Engine gimbal for pitch and yaw and, hot gas reaction control for roll, c) Third stage: flex nozzle for pitch and yaw and PS-4 RCS for roll and d) Fourth stage: Engine gimbal for pitch, yaw & roll and on-off RCS for control during the coast phase.

PSLV’s Inertial Navigation System (INS) is situated in its equipment bay, which is located on top of the vehicle’s fourth stage. INS guides the vehicle from lift-off to spacecraft injection into orbit.

The PSLV is provided with instrumentation to monitor the vehicle performance during the flight. S-band PCM telemetry and C-band transponders cater to this requirement. The tracking system provides real-time information for flight safety and for preliminary orbit determination once the satellite is injected into orbit.

PSLV employs a large number of stage auxiliary systems for stage separation, heat shield separation and jettisoning, etc.

The Vikram Sarabhai Space Centre, Thiruvananthapuram, designed and developed PSLV. The inertial systems for the vehicle were developed by the ISRO Inertial Systems Unit at Thiruvananthapuram. The Liquid Propulsion Systems Centre also at Thiruvananthapuram developed the Liquid propulsion stages for the second and fourth stages of PSLV as well as the reaction control systems. Satish Dhawan Space Centre, SHAR is the launch centre of ISRO for all its launch vehicles. ISTRAC provides Telemetry, Tracking and Command support.

METSAT

METSAT is the first exclusive meteorological satellite built by ISRO. So far, meteorological services had been combined with telecommunication and television services in the INSAT system. METSAT will be a precursor to the future INSAT system that will have separate satellites for meteorology and telecommunication & broadcasting services. This will enable large capacity to be built into INSAT satellites, both in terms of transponders and their radiated power, without the design constraints imposed by meteorological instruments.

For meteorological observation, METSAT carries a Very High Resolution Radiometer (VHRR) capable of imaging the Earth in the visible, thermal infrared and water vapour bands. It also carries a Data Relay Transponder (DRT) for collecting data from unattended meteorological platforms. METSAT will relay the data sent by these platforms to the Meteorological Data Utilisation Centre at New Delhi. Such platforms have been installed all over the country.

METSAT weighs 1060 kg which includes about 560 kg of propellant. The propellant carried by METSAT is mainly required to raise the satellite from the Geosynchronous Transfer Orbit to its final Geostationary orbit.

The satellite has a solar array generating 550 watts of power. The array will be deployed immediately after its injection into Geosynchronous Transfer Orbit (GTO). METSAT’s 18 Ampere-Hour Nickel-Cadmium battery will supply electrical energy when the satellite is in the Earth’s shadow (eclipse).

One of the new elements used in METSAT is the light weight planar array antenna which transmits the data from the Very High Resolution Radiometer (VHRR) and Data Relay Transponder (DRT). The satellite carries two high capacity magnetic torquers to take care of all disturbance torques including the solar radiation pressure effects experienced in the geostationary orbit. METSAT has been designed using a new spacecraft bus employing lightweight structural elements like Carbon Fibre Reinforced Plastic (CFRP).

METSAT was developed by ISRO Satellite Centre, Bangalore. The Meteorological payloads were developed by Space Applications Centre, Ahmedabad. Master Control Facility at Hassan is responsible for all post launch operations on the satellite.

The launch of METSAT will prove the versatility of PSLV to launch both Polar and Geostationary satellites. Together with GSLV, it will enable India to launch communication and meteorology as well as remote sensing satellites of different weight classes. The exclusive meteorological satellite, METSAT, once commissioned, is expected to vastly improve the meteorological services being provided by INSAT systems.

PSLV-C4 Salient Features

PSLV Propulsive Stages at a Glance
 

Indian Launches So Far