How PSLV was tailored to launch a satellite into a Geosynchronous transfer orbit?
PSLV was tailored to launch METSAT aka Kalpana-1, India's first exclusive Meteorological satellite, METSAT, into a Geo-synchronous Transfer Orbit (GTO).That was the first time a PSLV was used to launch a satellite into GTO. It was the seventh flight of PSLV [C-4].
PSLV is meant for launching satellites into the Low-Earth orbit and Polar orbits. It has proved itself as a reliable workhorse for putting resource satellites into the polar sunsynchronous orbit. In an innovative venture, ISRO engineers successfully modified a PSLV for launching a weather satellite into the geostationary orbit. The METSAT mission in which the weather satellite, later named Kalpana-1, was launched, has revealed how the efficiency of a rocket can be optimised and tailor-made for a different mission.The challenge was clear. A PSLV’s orbital injection velocity is 7.5 km a second. A GSLV needs a velocity of 10 km a second to take a satellite to a height of about 36,000 km at. one end of the - oval-shaped orbit around the Earth.The velocity of a PSLV has therefore to be increased by nearly 40 per cent. It should not, however, exceed it; if it Speeds up to over 11.2 km/ s, the satellite would escape the Earth’s gravity.The target was made realistic. While a GSLV typically places 2 tonnes in a geosynchronous transfer orbit (GTO), the weight of the payload (METSAT) was set at 1,055 kg. But the increased height of the orbit demanded additional velocity.The engineers turned to basic physics in the first instance.They increased the nozzle area ratio of-the rocket by reducing the throat, and by having a lighter nozzle on the motor. The efficiency of the rocket increased. The mass of the third stage was reduced by nearly 70 kg and more powerful solid propellants were deployed.The fuel capacity of the liquid : fourth stage was increased from 2 T to 2.5 T, and its burn time was also increased by 25 per cent. In-addition, some of the inert mass was reduced and the result was a spectacular launch of METSAT into a GTO of 180 km x 36,000 km.
This mission proved the flexibility of PSLV.
PSLV is meant for launching satellites into the Low-Earth orbit and Polar orbits. It has proved itself as a reliable workhorse for putting resource satellites into the polar sunsynchronous orbit. In an innovative venture, ISRO engineers successfully modified a PSLV for launching a weather satellite into the geostationary orbit. The METSAT mission in which the weather satellite, later named Kalpana-1, was launched, has revealed how the efficiency of a rocket can be optimised and tailor-made for a different mission.The challenge was clear. A PSLV’s orbital injection velocity is 7.5 km a second. A GSLV needs a velocity of 10 km a second to take a satellite to a height of about 36,000 km at. one end of the - oval-shaped orbit around the Earth.The velocity of a PSLV has therefore to be increased by nearly 40 per cent. It should not, however, exceed it; if it Speeds up to over 11.2 km/ s, the satellite would escape the Earth’s gravity.The target was made realistic. While a GSLV typically places 2 tonnes in a geosynchronous transfer orbit (GTO), the weight of the payload (METSAT) was set at 1,055 kg. But the increased height of the orbit demanded additional velocity.The engineers turned to basic physics in the first instance.They increased the nozzle area ratio of-the rocket by reducing the throat, and by having a lighter nozzle on the motor. The efficiency of the rocket increased. The mass of the third stage was reduced by nearly 70 kg and more powerful solid propellants were deployed.The fuel capacity of the liquid : fourth stage was increased from 2 T to 2.5 T, and its burn time was also increased by 25 per cent. In-addition, some of the inert mass was reduced and the result was a spectacular launch of METSAT into a GTO of 180 km x 36,000 km.