Why in News:
The Indian Space Research Organisation (ISRO) is planning the inaugural flight of its indigenously developed Small Satellite Launch Vehicle (SSLV) by year end.
The SSLV is being designed by Indian scientists to carry smaller commercial satellites into the low-earth orbit less than 2,000 km above the earth’s surface.
Three stage solid propelled engine.
Uses of SSLV:
- Time Saving: can be assembled in just 3-5 days as compared to 30-40 days for a normal-size rocket
- Cost Saving: made in just one-tenth the cost of a PSLV, which is worth around 150 crore
- SSLV weighs just 110 tonnes, which is 1/10th the mass of a PSLV rocket
- It can carry a payload of up to 500kg to the low earth and 300kg to the sun synchronous orbit, making it ideal for launching small satellites
- The SSLV is the much-needed solution to fill the gap in the portfolio of small launch vehicles SLV is perfectly suited for launching multiple microsatellites and supports multiple microsatellites at a time and supports multiple orbital drop-offs
Polar Satellite Launch Vehicle:
Polar Satellite Launch Vehicle (PSLV) is the third generation launch vehicle of India. It is the first Indian launch vehicle to be equipped with liquid stages.
- It can take up to 1,750 kg of payload to Sun-Synchronous Polar Orbits of 600 km altitude.
- PSLV has also been used to launch various satellites into Geosynchronous and Geostationary orbits, like satellites from the IRNSS constellation.
- Four stage launch vehicle:
- The PS4 is the uppermost stage of PSLV, comprising of two Earth storable liquid engines.
- The third stage of PSLV is a solid rocket motor that provides the upper stages high thrust after the atmospheric phase of the launch.
- PS2: PSLV uses an Earth storable liquid rocket engine for its second stage, known as the Vikas engine, developed by Liquid Propulsion Systems Centre.
- PS1: PSLV uses the S139 solid rocket motor that is augmented by 6 solid strap-on boosters.
- PSLV has been used to launch satellites like RISAT, HySIS, IRNSS, CARTOSAT, ASTROSAT, Chandrayaan-1 etc
Geosynchronous Satellite Launch vehicle:
Geosynchronous Satellite Launch Vehicle Mark II (GSLV Mk II) is the largest launch vehicle developed by India, which is currently in operation. This fourth generation launch vehicle is a three stage vehicle with four liquid strap-ons. The indigenously developed cryogenic Upper Stage (CUS), which is flight proven, forms the third stage of GSLV Mk II.
- GSLV’s primary payloads are INSAT class of communication satellites that operate from Geostationary orbits and hence are placed in Geosynchronous Transfer Orbits by GSLV.
- Due to their geo-synchronous nature, the satellites in these orbits appear to remain permanently fixed in the same position in the sky, as viewed from a particular location on Earth, thus avoiding the need of a tracking ground antenna and hence are useful for the communication applications.
- GSLV’s capability of placing up to 5 tonnes in Low Earth Orbits broadens the scope of payloads from heavy satellites to multiple smaller satellites.
- Three stage launch vehicle:
- 3rd stage: Developed under the Cryogenic Upper Stage Project (CUSP), the CE-7.5 is India’s first cryogenic engine, developed by the Liquid Propulsion Systems Centre
- 2nd stage: One Vikas engine is used in the second stage of GSLV. The stage was derived from the PS2 of PSLV where the Vikas engine has proved its reliability.
- 1st stage: The first stage of GSLV was also derived from the PSLV’s PS1. The 138 tonne solid rocket motor is augmented by 4 liquid strap-ons.
- GSLV has been used to launch satellites like GSAT, INSAT, Chandrayaan-2 etc
The tight launch schedule of PSLV and the unavailability of the launch vehicle has often deterred the agency from accepting several foreign satellites. Most of the private customer satellites, usually nano-satellites, were launched as additional payloads during a main PSLV mission. The SSLV, which can carry 500 kg to the low earth orbit, can be assembled within days by a smaller team and at a drastically reduced price as compared to PSLV. A separate launch vehicle was required to meet this growing demand from private agencies, including giants like Google and Amazon who want to put their satellites into orbit without waiting much.