ISRO Launch Vehicles: PSLV, GSLV, LVM3 and SSLV Notes

The correct answer is C, LVM3. Chandrayaan-3 weighed close to 3,900 kg at lift-off, far beyond the reach of any lighter Indian rocket, so it flew on LVM3, the vehicle earlier named GSLV Mk III. The same vehicle had launched Chandrayaan-2 in July 2019.

Option A, PSLV-XL, carried Chandrayaan-1 in 2008 and the Mars Orbiter Mission in 2013, both far lighter spacecraft, and is the distractor most candidates fall for. Option B, GSLV Mk II, lifts about 2,250 kg to a transfer orbit, which is not enough for a lunar lander of this mass. Option D, SSLV, is built for satellites of a few hundred kilograms and could not carry a fraction of the payload. Remember the split: the two Chandrayaan missions with landers went on LVM3, while the orbiter-only Chandrayaan-1 and the Mars mission went on PSLV.

The correct answer is B, SLV-3 carrying Rohini RS-1. On 18 July 1980 the four-stage, all-solid SLV-3 placed the small Rohini RS-1 satellite in a low earth orbit from Sriharikota, and India became the sixth nation able to launch its own satellite. A. P. J. Abdul Kalam was the project director of the vehicle.

Option A names the Augmented Satellite Launch Vehicle, which came later and carried the SROSS series; its first two flights failed. Option C is wrong on both counts, because the PSLV first flew in 1993 and IRS-1A of 1988 was launched by a Soviet rocket. Option D pairs the right vehicle with the wrong satellite: Aryabhata, India's first satellite, was launched in 1975 by a Soviet launcher from Kapustin Yar, five years before India had a vehicle of its own. Keep 1975 for the first satellite and 1980 for the first Indian launch.

The correct answer is C, four. The PSLV is unusual in alternating propellants between its stages: the first and third stages burn solid propellant and the second and fourth burn liquid propellant. The liquid fourth stage can be restarted and throttled, which is what lets the vehicle drop satellites into more than one orbit on the same flight.

Option B, three, is the number of stages in GSLV Mk II and in LVM3, and is the answer candidates give when they mix the vehicles up. Option A, two, matches no Indian orbital vehicle. Option D, five, is closer to the Augmented Satellite Launch Vehicle, which is counted as a five-stage rocket because of its strap-on boosters. Note that the six strap-on motors on the larger PSLV versions are not counted as a separate stage, since they burn alongside the first stage.

The correct answer is C, the third stage. The GSLV has three stages: a solid core first stage with four liquid strap-on motors, a liquid second stage using a Vikas engine, and a cryogenic upper stage that burns liquid hydrogen with liquid oxygen. A cryogenic stage is placed on top because its very high efficiency matters most once the vehicle is above the thick air and needs the last, largest gain in speed.

Option A is wrong because a cryogenic engine cannot give the heavy thrust needed at lift-off, which is why solid motors do that work. Option B is the liquid Vikas stage, which uses propellants that are liquids at ordinary temperatures and is therefore not cryogenic. Option D does not exist on this vehicle, as the GSLV has only three stages; a fourth stage belongs to the PSLV, and that fourth stage is liquid, not cryogenic.

The correct answer is B, the PSLV. Chandrayaan-1 went up on PSLV-C11 in October 2008 and the Mars Orbiter Mission on PSLV-C25 in November 2013, both in the extended PSLV-XL configuration with six long strap-on motors. Both spacecraft were light enough for the PSLV to place them in a high ellipse from which their own engines raised them towards the moon and Mars.

Option A, GSLV Mk III, now called LVM3, was not yet operational in 2008 and was used later for Chandrayaan-2 and Chandrayaan-3. Option C, SLV-3, could lift only about 40 kg and was retired in the early 1980s. Option D, GSLV Mk II, is meant for communication satellites bound for geostationary orbit and was not used for either interplanetary mission. This pairing of vehicle with mission is the single most asked point in the chapter.

The correct answer is B, the Satish Dhawan Space Centre SHAR at Sriharikota in Andhra Pradesh. It is India's only orbital launch site, on the east coast, so vehicles can fly out eastwards over the Bay of Bengal and take the free gain from the earth's rotation while the spent stages fall harmlessly into the sea. It was earlier called the SHAR Centre and was renamed after Satish Dhawan.

Option A, the Vikram Sarabhai Space Centre, designs and develops launch vehicles but does not launch them, and the nearby Thumba station is used only for small sounding rockets. Option C, the U R Rao Satellite Centre, builds and tests satellites. Option D, the Space Applications Centre, develops the payloads and instruments the satellites carry and works on applications of the data. Learn the four centres as a set of jobs: rocket, launch, satellite, payload.

The correct answer is C, 104. PSLV-C37 carried the Cartosat-2 series satellite as its main passenger along with two Indian nano-satellites and 101 small foreign satellites, releasing all of them one after another from its restartable liquid fourth stage. The flight is a standing example of the PSLV's ability to serve as a shared ride for many small payloads.

Option A, 36, is the size of a batch of communication satellites carried on a later commercial LVM3 flight, which is why the number feels familiar. Option B, 68, and option D, 140, match no Indian launch. The point examiners test is the combination of vehicle, date and number, so fix the three together: PSLV-C37, 15 February 2017, 104 satellites, with the Cartosat-2 series satellite as the primary payload.

The correct answer is A, the Vikram Sarabhai Space Centre at Thiruvananthapuram, ISRO's lead centre for launch vehicle design and development, including solid propulsion, aerodynamics and vehicle structures. Its companion, the Liquid Propulsion Systems Centre, develops the liquid and cryogenic engines that those vehicles fly with.

Option B, the National Remote Sensing Centre at Hyderabad, receives, processes and distributes satellite imagery. Option C, the Master Control Facility at Hassan in Karnataka, does not build anything: it controls geostationary satellites once they are in orbit. Option D, the Physical Research Laboratory at Ahmedabad, founded by Vikram Sarabhai in 1947, carries out space science research and is the cradle of the Indian space programme rather than a rocket factory. Match each centre to one verb: develop, receive, control, research.

The correct answer is C, GSLV-D5 in January 2014. That flight carried the GSAT-14 communication satellite and was the first success of the indigenous cryogenic upper stage, which put India among the small group of countries able to build such an engine. Cryogenic technology is hard because liquid hydrogen must be held near minus 253 degrees Celsius and pumped into a running engine.

Option A, GSLV-D1 of April 2001, was the vehicle's first flight and used a Russian-supplied cryogenic stage, not an Indian one. Option B, GSLV-D3 of 2010, was the first attempt to fly the Indian stage and it failed, so the flight is remembered as the attempt rather than the success. Option D, the first orbital flight of LVM3 in June 2017, used the larger C25 cryogenic stage and came three years after the technology had already been proved on GSLV-D5.

The correct answer is A, the SSLV, or Small Satellite Launch Vehicle. It has three solid stages and a small liquid velocity trimming module, carries up to about 500 kg to a 500 km low earth orbit, and is designed to be assembled and launched by a small team within days so that a customer with one satellite need not wait for a shared ride.

Option B, PSLV-CA, is the core-alone version of the PSLV flown without strap-on motors; it is a lighter configuration of a large rocket, not a small vehicle in its own right. Option C, ASLV, was an experimental vehicle of the 1980s and 1990s with a capacity of about 150 kg and is no longer in service, so it cannot be the answer to a question about a current vehicle. Option D, LVM3, is at the opposite end of the family as India's heaviest operational rocket.