PSLV SUCCESSFULLY LAUNCHES THREE SATELLITES
Sriharikota, May 26, 1999

ISRO’s Polar Satellite Launch Vehicle, PSLV-C2, successfully launched today three satellites simultaneously – the Indian Remote Sensing Satellite, IRS-P4 (OCEANSAT), KITSAT-3 of Republic of Korea and DLR-TUBSAT of Germany marking a significant milestone in the Indian space programme. The three satellites were placed in a near circular polar sunsynchronous orbit at an altitude of 727 km. The 110 kg, KITSAT-3 and 45 kg DLR-TUBSAT were launched under a commercial agreement, thus marking India’s entry into competitive launch services market.

PSLV-C2 lifted off from SHAR Centre, Sriharikota today at 11.52 am at the opening of the launch window, IRS-P4 was injected into orbit about 1010 sec after lift-off followed by the injection of KITSAT-3 and DLR-TUBSAT, respectively. In the flight sequence, the 294 tonne, 44.4 m tall PSLV lifted off from the launch pad with the ignition of first stage motor along with four strap on motors. The remaining two strap on motors ignited about 25 seconds later.

    The first set of four strap-on motors separated as planned at 68 sec after lift-off and the second set of two strap-on motors separated at 90 sec. The fist stage of PSLV separated at 112 sec and the second stage ignited immediately thereafter. The heat-shield was jettisioned at 156 sec as planned when the vehicle had reached an altitude of 125 km thus having cleared the dense atmosphere. The second stage separation and the third stage ignition occurred at 281 sec and the third stage separation occurred at 503 sec after lift off. The last stage ignited after a long coasting of the vehicle at 585 sec at an altitude of 613 km and the fourth stage thrust cut-off occurred at 984 sec when the vehicle had reached an altitude of 719 km.

The first satellite to be separated from the fourth stage was IRS-P4 mounted on top at 1010 sec from lift-off. This was followed by a 40 deg yaw manoeuvre of the fourth stage and separation of KITSAT-3 which was mounted on the equipment bay. Subsequently, the fourth stage was further yaw-manoeuvred for another 40 deg. and DLR-TUBSAT, mounted diagonally opposite to KITSAT-3 was injected into orbit. The sequence of separation was planned in such a way as to avoid any collision between the three satellities and the spent fourth stage.

Soon after injection into orbit, the two solar arrays on board IRS-P4 were automatically deployed by an on-board sequencer. This event was monitored by ISRO Telemetry, Tracking and Command Network station at Mauritius. The preliminary data received from IRS-P4 indicates normal performance of the satellite. IRS-P4 is now orbiting the earth with a period of 99.4 minute. The release of hold-down an tilt mechanisms of Ocean Colour Monitor (OCM) and initial testing of Multi-frequency Scanning Microwave Radiometer (MSMR) are planned during the 15^th orbit, tomorrow. After detailed testing of various systems and fine orbital corrections, IRS-P4 is expected to become operational in about ten days.

As per the post launch sequence of events for KITSAT-3, the telemetry system on board is switched on three and a half hours after separation and the first contact with the command ground station on Korea is expected at 7.30 pm IST this evening. Normal operations of KITSAT-3 is expected to commence in about four weeks. The first signals from DLR-TUBSAT are expected to be received at the University ground station in Berlin, Germany, also by 7.30 pm IST this evening.

PSLV-C2 is the fifth flight of the vehicle and second operational flight. It may be recalled that the first developmental test flight of PSLV (PSLV-D1) took place on September 20, 1993. The second developmental test flight (PSLV-D2) was conducted on October 15,1994, when the Indian Remote Sensing Satellite, IRS-P2, was successfully placed in a polar sunsynchronous orbit. The third developmental flight (PSLV-D3) was conducted on March 21, 1996, when IRS-P3 was placed in a polar sunsynchronous orbit. PSLV was declared operational after the PSLV-D3 and the first operational flight, PSLV-C1, was used to place Indian Remote Sensing Satellite (IRS-1D) in a polar sunsynchronous orbit on September 29, 1997. IRS-1D is functioning well since its launch.

PSLV is now used for launching Indian Remote Sensing Satellites . Besides, it is now offered for launching satellites of other agencies either as auxiliary payloads or as main payloads depending upon the payload weight and capacity of the vehicle. Besides the two auxiliary payloads, KITSAT-3 and DLR-TUBSAT, launched by PSLV-C2 today, Antrix has already signed an agreement with VERHAERT Design and Development N.V, Belgium, for launching a small satellite, PROBA, in a one of the follow- on flights of PSLV.

In the present configuration, the 44.4 metre tall, 294 tonne, PSLV, can launch 1200 kg in 820 km polar orbit. It 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 tonne of propellant. It has a diameter of 2.8 m. The motor case is made of maraging steel which is indigenously produced. The booster develops a maximum thrust of about 4,630 kN. The first stage thrust is augmented by six solid propellant strap-on motors, four of which are ignited on the ground. Each of these produces 662 kN thrust.

The second stage employs indigenously manufactured Vikas engine and carries 40.0 tonne of liquid propellant – Unsymmetrical Di-methyl Hydrazine as fuel and Nitrogen tetroxide as oxidiser. It generates a maximum thrust of about 725 kN.

The third stage uses 7.2 tonne of solid propellant and produces a maximum thrust of 340 kN. The fourth and the terminal stage of PSLV has a twin engine configuration using liquid propellant. With a propellant loading of 2 tonne, each of these engines generates a maximum thrust of 7.4 kN.

The metallic bulbous heat-shield of PSLV, 3.2 m in diameter and protects the spacecraft during the atmospheric regime of the flight. PSLV 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 and role and, on-off RCS for control during the coast phase.

The main on-board instrumentation packages used for telemetry, tracking and command are: PCM/S-band telemetry systems, C-band transponders, besides a host of power and signal conditioning packages. PSLV employs a large number of stage auxiliary systems for stage separation, heat-shield separation and jettisoning etc.

With Vikram Sarabhai Space Centre in Thiruvananthapuram acting as the leadcentre, major responsibilities for design and development of PSLV were shared by Liquid Propulsion Systems Centre in Thiruvananthapuram and SHAR Centre in Sriharikota. ISRO Inertial Systems Unit, Thiruvananthapuram, developed the navigation systems for PSLV, ISRO Telemetry, Tracking and Command Network (ISTRAC) provides telemetry and tracking support to PSLV mission through its stations at Sriharikota, Mauritius and Thruvananthapuram.

Well over 150 industries, both in public and private sectors, are involved in the fabrication of a variety of hardware for PSLVs light alloy structures for interstages, motor cases, electronic packages, heat-shield, precision coherent radars etc. Even in the field of chemicals and materials, industries played a vital role. For example, the maraging steel and HTPB resin are produced by the industries.
 

Indian Remote Sensing Satellite, IRS-P4 (OCEANSAT)

Indian Remote Sensing Satellite, IRS-P4 (OCEANSAT), is the first satellite primarily built for ocean applications. The 1050 kg satellite carries onboard, an ocean colour Monitor (OCM) and a Multifrequency Scanning Microwave Radiometer (MSMR). OCM is a solid state camera operating in eight narrow spectral bands. The camera is used to collect data on chlorophyll concentration, detect and monitor phytoplankton blooms and obtain data on atmospheric aerosols and suspended sediments in the water. MSMR, which operates in four microwave frequencies both in vertical and horizontal polarisation is used to collect data on sea surface temperature, wind speed, cloud water content and water vapour content in the atmosphere above the ocean. IRS-P4 will thus vastly augment the IRS satellite system of ISRO which at present comprises four satellites, IRS-1B, IRS-1C, IRS-P3 and IRS-1D and extend remote sensing applications to several newer areas.

IRS-P4 is being monitored and controlled from the Spacecraft Control Centre of ISTRAC with a network of stations at Bangalore, Lucknow, Mauritius, Bearslake in Russia and Biak in Indonesia. In the initial phase, a TTC station at Weilheim in Germany, will also provide TTC support. The data reception and processing will be carried out by the National Remote Sensing Agency (NRSA) at Hyderabad.
 

KITSAT-3

KITSAT-3 is an engineering satellite built by Satellite Technology Research Centre, Korea Advanced Institute of Science and Technology, Republic of Korea. The main objective of the satellite is to develop fundamental technology for high performance microsatellites. Weighing about 110 kg, the satellite carries a Multispectral Earth Imaging System and a Space Environment Scientific Experiment.
 

DLR-TUBSAT

DLR-TUBSAT is a micro satellite jointly developed by Technical University of Berlin and German Space Centre, DLR. Weighing 45 kg, the microsatellite will carry out tests on advanced technologies involving three exis attitude control.
 

Prime Minister witnesses PSLV Launch

The PSLV-C2 launch from Shriharikota today was witnessed by Prime Minister, Mr. Atal Bihari Vajpayee, Minister of HRD and Science & Technology Dr. Murali Manohar Joshi, Minister of Sate for External Affairs Mrs. Vasundhara Raje, Minister of Sate for Urban Development Mr. B Dattatreya, Governor of Andhra Pradesh Mr. C. Rangarajan, Chief Minister of Andhra Pradesh Mr. N. Chandrababu Naidu, Director General R&D of the Ministry of Science & Technology in Republic of Korea, Dr. Yoon Chung, Director-General of Satellite Research Center of the Republic of Korea Prof. Soon Dal Choi and Ambassador of Germany in India, besides senior Government officials and scientists.

The successful launch of PSLV-C2 today, the fourth successive successful flight in the PSLV series, has demonstrated the capability of Indian scientists to build operational launch vehicles to place Indian satellites in orbit from within the country. Today’s flight also points to the ISRO entering into commercial launch services market having proved the capability to launch multiple satellites in a single flight.