Image Source Oct 31, 2020 21:13 IST · 3 min read
Augmented Satellite Launch Vehicle (ASLV)
The Augmented Satellite Launch Vehicle or Advanced Satellite Launch Vehicle, also known as ASLV, was a Small-lift launch vehicle five-stage solid-fuel rocket developed by the Indian Space Research Organisation (ISRO) to place 150 kg satellites into LEO (Low earth orbit).The ASLV made four launches, of which one was successful, two failed to achieve orbit, and a third achieved a lower than planned orbit which decayed quickly. The type made its maiden flight on 24 March 1987, and its final flight on 4 May 1994.
Polar Satellite Launch Vehicle (PSLV)
The Polar Satellite Launch Vehicle (PSLV) is a third generationan expendable medium-lift launch vehicle designed and 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.PSLV first successful launch in October 1994 can also launch small size satellites into Geostationary Transfer Orbit (GTO).
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.
India's first lunar probe Chandrayaan-1 (2008), India's first interplanetary mission, Mars Orbiter Mission (Mangalyaan (2013)) and India's first space observatory, Astrosat are some notable payloads launched by PSLV.
On 15 February 2017, PSLV-C37 successfully deploying 104 satellites in sun-synchronous orbit making it the highest number of satellites sent to space on a single launch, the record was previously held by Russia.
The PSLV is capable of placing multiple payloads into orbit, this allowed the feat of launching 10 satellites into different orbits in 2008.
Geosynchronous Satellite Launch Vehicle (GSLV)
The first development flight of the GSLV (Mk I configuration) was launched on 18 April 2001 was a failure as the payload failed to reach the intended orbit parameters. The launcher was declared operational after the second development flight successfully launched the GSAT-2 satellite.GSLV MK-II
GSLV MK-II is meant to lift satellites in the weight category 2.5 tons to 5 tons. This is a three-stage launch vehicle with first stage using solid rocket motor, second stage using liquid fuel, and the third stage, called Cryogenic Upper Stage (CUS), using cryogenic engine.GSLV MkIII
GSLV MkIII, chosen to launch Chandrayaan-2 spacecraft, is a three-stage heavy lift launch vehicle developed by ISRO.The 640-tonne rocket, equal to the weight of 200 fully-grown Asian elephants, is the country's heaviest but shortest rocket with a height of 43 metre.
GSLV Mk III is designed to carry 4 ton class of satellites into Geosynchronous Transfer Orbit (GTO) or about 10 tons to Low Earth Orbit (LEO), which is about twice the capability of the GSLV Mk II.
The first developmental flight of GSLV Mk III, the GSLV-Mk III-D1 successfully placed GSAT-19 satellite to a Geosynchronous Transfer Orbit (GTO) on June 05, 2017 from SDSC SHAR, Sriharikota.
This is India's first fully functional rocket to be tested with a cryogenic engine that uses liquid propellants - liquid oxygen and liquid hydrogen.
Geosynchronous and Geostationary orbits
High Earth Orbit is when a satellite reaches exactly 42,164 kilometres from the centre of the Earth (about 36,000 kilometres from Earth's surface). At this altitude, the satellite enters a sort of "sweet spot" in which its orbit matches Earth's rotation. This special, high Earth orbit is called geosynchronous.A special case of geosynchronous orbit is the geostationary orbit, which is a circular geosynchronous orbit in Earth's equatorial plane. A satellite in a geostationary orbit remains in the same position in the sky to observers on the surface.
The Lagrange points
Other orbital "sweet spots", just beyond high Earth orbit, are the Lagrange points. At the Lagrange points, the pull of gravity from the Earth cancels out the pull of gravity from the Sun.Anything placed at these points will feel equally pulled toward the Earth and the Sun and will revolve with the Earth around the Sun.