India's PSLV-C6 Successfully Launches Two Satellites


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In its ninth flight conducted from Satish Dhawan Space Centre (SDSC) SHAR, Sriharikota, today (May 05, 2005), ISRO's Polar Satellite Launch Vehicle, PSLV-C6, successfully launched the 1560 kg Indian Remote Sensing satellite, CARTOSAT-1, and the 42.5 kg HAMSAT into a 632 x 621 km high polar orbit. This is the highest payload weight that PSLV has launched so far.

President of India, Dr A P J Abdul Kalam, witnessed the launch from the Mission Control Centre. Last evening Dr Abdul Kalam had dedicated to the nation, the newly established Second Launch Pad at SDSC SHAR and for the first time, this state-of-the-art Second Launch Pad (SLP) was used for the launch of PSLV. SLP successfully supported the launch mission in the integrate-transfer-and-launch concept. After its integration in the Vehicle Assembly Building, PSLV-C6 was transported on rails to the Umbilical Tower (UT) located one km away using the Mobile Launch Pedestal. Final operations like fuel filling, gas charging and vehicle check out were carried out in the last few days at the UT.

At the end final count down, PSLV-C6 lifted off from SDSC SHAR, Sriharikota at 10:15 am IST with the ignition of the core first stage and four of the six strap-on motors. The remaining two strap-on motors were ignited at 25 sec after lift-off. The important flight events included the separation of the ground-lit strap-on motors, separation of air-lit strap-on motors and the first stage, ignition of the second stage, separation of the payload fairing after the vehicle had cleared the dense atmosphere, second stage separation, third stage ignition, third stage separation, fourth stage ignition and fourth stage cut-off. After these events, CARTOSAT-1 was successfully separated from the fourth stage 1078 seconds after lift off. 40 seconds later HAMSAT was also separated from the fourth-stage equipment bay.

Both the satellites have been placed in polar Sun Synchronous Orbit (SSO) at an altitude of 632 x 621 km with an inclination of 97.8 deg with respect to the equator. The solar panels of CARTOSAT-1 were deployed soon after its injection into orbit.

PSLV was designed and developed by ISRO to place 1,000 kg class Indian Remote Sensing satellites into polar Sun-synchronous Orbit (SSO). Since its first successful flight in October 1994, the capability of PSLV has been enhanced from 850 kg to the present 1,600 kg into 618 km Sun Synchronous Orbit. PSLV has also demonstrated multiple satellite launch capability.

In its present configuration, the 44.4 metre tall, 294 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 tonne of Hydroxyl Terminated Poly Butadiene (HTPB) based propellant. The booster develops a maximum thrust of about 4,762 kN. Six strap-on motors, each carrying nine tonne of solid propellant produces 645 kN thrust.

The second stage employs indigenously built Vikas engine and carries 41.5 tonne of liquid propellant -- UH25 as fuel and Nitrogen tetroxide (N2O4) as oxidiser. It generates a maximum thrust of about 800 kN. The third stage uses 7.6 tonne of HTPB-based solid propellant and produces a maximum thrust of 246 kN. 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 and Mixed Oxides of Nitrogen), each of these engines generates a maximum thrust of 7.3 kN.

The 3.2 m diameter metallic bulbous payload fairing of PSLV protects the spacecraft during the atmospheric regime of the flight.

With eight consecutively successful launches, PSLV has proved itself as a reliable vehicle for launching Indian remote sensing satellites. PSLV is already slated to be used for India's first unmanned mission to moon, Chandrayaan-1.

Vikram Sarabhai Space Centre (VSSC), Thiruvananthapuram, designed and developed PSLV. ISRO Inertial Systems Unit (IISU) at Thiruvananthapuram developed the inertial systems. The Liquid Propulsion Systems Centre (LPSC), also at Thiruvananthapuram, developed the liquid propulsion stages for the second and fourth stages of PSLV as well as reaction control systems. SDSC SHAR processed the solid motors and carried out launch operations. ISRO Telemetry, Tracking and Command (ISTRAC) provided telemetry, tracking and command support.

CARTOSAT-1: CARTOSAT-1 is the eleventh satellite in the Indian remote sensing satellite series. It is intended for cartographic applications. It carries two panchromatic cameras that take black-and-white stereoscopic pictures in the visible region of the electromagnetic spectrum. The imageries will have a spatial resolution of 2.5 metre and cover a swath of 30 km. The imageries will be useful for generating digital elevation maps for urban and rural development, land and water resources management, disaster assessment, relief planning and management and environmental impact assessment. CARTOSAT-1 also carries a Solid State Recorder with a capacity of 120 Giga Bits to store the images taken by its cameras.

Soon after its injection into orbit, the two solar panels of CARTOSAT-1 were deployed. The satellite health is being continuously monitored from the Spacecraft Control Centre of ISTRAC at Bangalore with the help of its network of stations at Bangalore, Lucknow, Mauritius, Bearslake in Russia and Biak in Indonesia. Further operations on the satellite like, checking out the various subsystems,, switching on the cameras, and, finally, orbit trimming will be carried out in the coming days.

With ISRO Satellite Centre (ISAC), Bangalore, as the lead Centre, CARTOSAT-1 was realised with major contributions from Space Applications Centre (SAC), Ahmedabad, LPSC at Bangalore, and IISU, Thiruvananthapuram. ISTRAC is responsible for initial and in-orbit operation of CARTOSAT-1. The National Remote Sensing Agency (NRSA), Hyderabad receives and processes the data from CARTOSAT-1.

HAMSAT: HAMSAT is a Micro-satellite for providing satellite based Amateur Radio services to the national as well as the international community of Amateur Radio Operators (HAM). It will meet the long felt need of the Amateur Radio Operators in the South Asian region who possess the required equipment and operate in the UHF/VHF band based Satellite Radio Communication. One of the transponders of HAMSAT has been developed indigenously involving Indian Amateurs, with the expertise of ISRO and the experience of AMSAT-INDIA. The second transponder has been developed by a Dutch Amateur Radio Operator and Graduate Engineering student at Higher Technical Institute, Venlo, The Netherlands.

HAMSAT is India's contribution to the international community of Amateur Radio Operators. This effort is also meant to bring ISRO's Satellite services within the reach of the common man and popularise Space Technology among the masses.

With the successful launch of CARTOSAT-1 and HAMSAT today, PSLV has reiterated its reliability and versatility for launching satellites of different weight classes precisely into specified orbits.

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