The PSLV or Polar Satellite Launch Vehicle is an expendable launch system operated by the Indian Space Research Organisation (ISRO). It was developed to
allow India to launch its Indian Remote Sensing (IRS) satellites into sun synchronous orbits, a service that was, until the advent of the PSLV, commercially viable only from Russia. PSLV can also launch small size satellites into geostationary transfer orbit (GTO).
allow India to launch its Indian Remote Sensing (IRS) satellites into sun synchronous orbits, a service that was, until the advent of the PSLV, commercially viable only from Russia. PSLV can also launch small size satellites into geostationary transfer orbit (GTO).
A sun-synchronous orbit (also rarely called a heliosynchronous orbit) is a geocentric orbit which combines altitude and inclination in such a way that an object on that orbit passes over any given point of the Earth's surface at the same local solar time. The surface illumination angle will be nearly the same every time. This consistent lighting is a useful characteristic for satellites that image the earth's surface in visible or infrared wavelengths (e.g. weather, spy and remote sensing satellites). There is, of course, a yearly oscillation of the actual solar time of passage because of the eccentricity of the Earth's orbit.
The 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 metric tonnes of Hydroxyl-terminated polybutadiene (HTPB) binded propellant with a diameter of 2.8 m. The motor case is made of maraging steel. The booster develops a maximum thrust of about 4,430 kN. Six strap-on otors,four of which are ignited on the ground, augment the first stage thrust.
Each of these solid propellant strap-on motors carries nine metric tonne of HTPB propellant and produces 677 kN thrust. Pitch and yaw control of the PSLV during the thrust phase of the solid motor is achieved by injection of an aqueous solution of strontium perchlorate in the nozzle to constitute Secondary Injection
Thrust Vector Control System (SITVC). The injection is stored in two cylindrical aluminum tanks strapped to the solid rocket motor and pressurized with nitrogen. SITVC in two strap-on motors is for roll control augmentation.
Thrust Vector Control System (SITVC). The injection is stored in two cylindrical aluminum tanks strapped to the solid rocket motor and pressurized with nitrogen. SITVC in two strap-on motors is for roll control augmentation.
The second stage employs the Vikas engine and carries 41.5 metric tonne (40 metric tonne till C-5 mission) of liquid propellant — Unsymmetrical Di-Methy.Hydrazine (UDMH) as fuel and Nitrogen tetroxide (N2O4) as oxidizer. It generates a maximum thrust of 800 kN (724 till C-5 mission). Pitch & yaw control is obtained by hydraulically gimbaled engine (±4°) and two hot gas reaction control for roll.
The third stage uses 7 metric tonne of HTPB-based solid propellant and produces a maximum thrust of 324 kN. It has as Kevlar-polyamide fiber case and a submerged nozzle equipped with a flex-bearing-seal gimbaled nozzle (±2°) thrust-vector engine for pitch & yaw control. For roll control it uses the RCS (Reaction Control System) of fourth stage.
The fourth and the terminal stage of PSLV has a twin engine configuration using
liquid propellant. With a propellant loading of 2 metric tonne (Mono-Methy Hydrazine as fuel + Mixed Oxides of Nitrogen as oxidiser), each of these engines
generates a maximum thrust of 7.4 kN. Engine is gimbaled (±3°) for pitch, yaw &
roll control and for control during the coast phase uses on-off RCS. PSLV-C4 used
a new lightweight carbon composite payload adopter to enables greater GTO payload capability.
After some delays, the first launch of the PSLV occurred on 20 September 1993.
Although all main engines performed as expected, an altitude control problem was reported in the second and third stages. After this initial setback, ISRO met
complete success with the third developmental launch in 1996. Further successful
launches followed in 1997, 1999, and 2001.
Although all main engines performed as expected, an altitude control problem was reported in the second and third stages. After this initial setback, ISRO met
complete success with the third developmental launch in 1996. Further successful
launches followed in 1997, 1999, and 2001.
In September 2002, the 1060 kg KALPANA-1 was launched by PSLV-C4 into GTO. On 17 October 2003, the 1360 kg Earth observing ResourceSat1 was launched by PSLV-C5. On May 5, 2005, PSLV-C6 launched two satellites into orbit; CARTOSAT-I a stereoscopic Earth observation satellite with cartographic applications, weighing 1560 kg, and HAMSAT providing satellite based radio service for amateur radio operators, weighing 42।5 kg into a high polar orbit (632 x 621 km).
PSLV will continue be the work horse of the ISRO for its launches, especially for
LEO satellites and the Chandrayaan Projects. It has undergone several improvements with each subsequent version, especially those involving thrust,
efficiency and weight.
On January 10, 2007, the PSLV-C7 carried four satellites - the 680 kg Indian
remote sensing satellite CARTOSAT-2, the 550 kg Space Capsule Recovery Equipment (SRE-1), Indonesia's LAPAN-TUBSAT (60kg) and Argentina's 6kg nanosatellite called NANO PEHUENSAT-1 into orbit.
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