On the July 15th of this year, Indian Space Research Organization (ISRO) has launched the Polar Satellite Launch Vehicle (PSLV 17) carrying GSAT-12, a geostationary satellite into the space. The launch has taken place at the Satish Dhawan Space Centre located at sriharikota, Andhra Pradesh.

The launching was happened at 4.40 pm. Thirty minutes later, it injected the satellite into an orbit with a closest point to earth of 284 km and an farthest point of 21,000 km. According to the ISRO, the satellite has launched 8 km away from the planned orbit.
Isro Telemetry Tracking and Command Network (ISTRAC)’s ground station at Biak, Indonesia acquired the signals from GSAT-12 immediately after the injection of the satellite. The solar panels of the satellite were deployed automatically. Initial checks on the satellite have indicated normal health of the satellite.

The Indian National Satellite (Insat) system, established in 1983, is one of the largest domestic communication satellite systems in the Asia Pacific region. The GSAT-12 joins this system providing 175 transponders in the S, C, Ext C and Ku band.

The Satellite  is believed to cost Rs. 80 crore (about $18 million). The PSLV, along with the fuel, costs Rs. 110 crore (about $24 million).

The PSLV rocket is being used this time against the more powerful GSLV, because of the moderate weight of the payload and the nearness of the orbit. The main difference between PSLV and GSLV is the firing off of the main motor and those strapped on. For the PSLV, the core motor fires, followed by the strap-on thrusters, which ignite after lift-off. For the GSLV, the secondary thrusters fire first and about four and a half seconds later, the core rocket fires for lift-off. The GSLV has a cryogenic engine and can carry heavier payloads to higher orbits, since the engine can deliver more thrust. GSLV was the vehicle used for delivering the INSAT satellites into orbit.

Polar Satellite Launch Vehicle was the first operational launch vehicle of the ISRO. It is 44.4 meters in height and weighs about 295 tonnes at lift-off. It has 4 stages using solid and liquid propulsion systems alternately. The first stage is one of the largest solid propellant boosters in the world and carries 139 tonnes of propellant. A cluster of six strap-ons attached to the first stage motor, four of which are ignited on the ground and two are air-lit. It has a very high reliability. PSLV is commonly known as the workhorse of the ISRO.

It has the capacity of launching the 1600 kg of satellites to 620 km sun-synchronous polar orbit and 1050 kg satellite in geo-synchronous transfer orbit (GTO).

PSLV has launched 12 times continuous till now.

PSLV-C17 launched GSAT – 12 on July 15, 2011 (Successful)
PSLV-C16 launched RESOURCESAT – 2YOUTHSAT and X-SAT on April 20, 2011 (Successful)
PSLV-C15 launched CARTOSAT-2BALSAT-2ANLS 6.1 & 6.2 and STUDSAT on July 12, 2010 (Successful)
PSLV-C14 launched Oceansat – 2 and Six Nanosatellites on September 23, 2009 (Successful)
PSLV-C12 launched RISAT-2 and ANUSAT on April 20, 2009 (Successfully)
PSLV-C11 launched CHANDRAYAAN-I, on October 22, 2008 (Successful)
PSLV-C9 launched CARTOSAT-2AIMS-1 and Eight nano-satellites on April 28, 2008 (Successful)
PSLV-C10 launched TECSAR on January 23, 2008 (Successful)
PSLV-C8 launched AGILE on April 23, 2007 (Successful)
PSLV-C7 launched CARTOSAT-2SRE-1, LAPAN-TUBSAT and PEHUENSAT-1 on January 10, 2007 (Successful)
PSLV-C6 launched CARTOSAT-1 and HAMSAT on May 5, 2005 (Successful)
PSLV-C5 launched RESOURCESAT-1(IRS-P6) on October 17, 2003 (Successful)
PSLV-C4 launched KALPANA-1(METSAT) on September 12, 2002 (Successful)
PSLV-C3 launched TES on October 22, 2001 (Successful)
PSLV-C2 launched OCEANSAT(IRS-P4), KITSAT-3 and DLR-TUBSAT on May 26, 1999 (Successful)
PSLV-C1 launched IRS-1D on September 29, 1997 (Successful)
PSLV-D3 launched IRS-P3 on March 21, 1996 (Successful)
PSLV-D2 launched IRS-P2 on October 15, 1994 (Successful)
PSLV-D1 launched IRS-1E on September 20, 1993 (Unsuccessful)  

The GSAT-12 is the latest geosynchronous communication satellite. Its mission is to meet the country’s demand on the communication. It was configured to carry the 12 extended C-band transponders. The 12 extended C-band transponders increases the capacity in the INSAT system for various communication services like Tele-education, Telemedicine and for Village Resource Centres (VRC).

The technical specifications of the GSAT-12 are as follows:

Mission Communication
Weight 1410 kg (Mass at Lift – off)
559 kg (Dry Mass)
Power Solar array providing 1430 Watts and one 64 Ah Li-Ion batteries
Physical Dimensions 1.485 x 1.480 x 1.446 m cuboid
Propulsion 440 Newton Liquid Apogee Motors (LAM) with Mono Methyl Hydrazine (MMH) as fuel and Mixed oxides of Nitrogen (MON-3) as oxidizer for orbit raising.
Attitude Orbit Control 3-axis body stabilised in orbit using Earth Sensors, Sun Sensors, Momentum and Reaction Wheels, Magnetic Torquers and eight 10 Newton and eight 22 Newton bipropellant thrusters
Antennae One 0.7 m diameter body mounted parabolic receive antenna and one 1.2 m diameter polarisation sensitive deployable antenna
Orbit Geosynchronous (83° longitude)
Mission life About 8 Years

ISRO has recorded a continuous success story with the Polar Satellite Launch vehicle only. The another space vehicle which we have presently is the Geosynchronous Satellite Launch Vehicle, has recorded only 57% of success only. It has the capacity of launching the 2000-2500 kg of weight into GTO, carrying a payload of 2-2.5 tonnes. It has launched 7 times in which only 4 times successful, from the time 2001, when it was first launched.

The other space vehicle, GSLV MARK III is on progress which is scheduled to take its first launch in 2012.  It has the capacity of launching the4500-5000 kg. The vehicle envisages multi-mission launch capability for GTO, LEO, Polar and intermediate circular orbits.


Posted by

Sai Prashanth ( MGIT ECE 4th year)

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