Relevance: GS-2: Achievements of Indians in science & technology; indigenization of technology and developing new technology; Awareness in the fields of Space.

Key Phrases: Indian Space Research Organisation, Launch Vehicles, Polar Satellite Launch Vehicle, Geosynchronous Satellite Launch Vehicle, Satellites or payloads, Sounding Rockets, Satellite Launch Vehicle, ASLV, Small Satellite Launch Vehicle, RLV-TD.

Why in News?

• On February 14, the Indian Space Research Organisation (ISRO) launched its first space mission of the year. An earth observation satellite named EOS-04 along with two other smaller satellites were launched into space using a PSLV rocket.

Key Points:

• Launchers or Launch Vehicles or Rockets are used to carry spacecraft to space.
  • The rockets have powerful propulsion systems that generate the huge amount of energy required to lift heavy objects like satellites into space, overcoming the gravitational pull of the earth.
  • Satellites, or payloads, sit inside the rocket, and are ejected once they reach near their intended orbit in space.
• Most satellites have small propulsion systems and carry small amounts of fuel, because they encounter very little drag, or force, in outer space.
• Rockets have several detachable energy-providing parts.
  • They burn different kinds of fuels to power the rocket. Once their fuel is exhausted, they detach from the rocket and fall off, often burning off in the atmosphere due to air-friction, and getting destroyed.
  • Only a small part of the original rocket goes till the intended destination of the satellite.
  • Once the satellite is finally ejected, this last part of the rocket either becomes part of space debris, or once again burns off after falling into the atmosphere.
• Satellites carry one or more instruments that do the scientific work for which they are sent into space.
  • Their operational life sometimes extends up to decades.
  • But rockets, or launch vehicles, become useless after the launch. Their only job is to take the satellites to their intended orbits.

Launch vehicles used by ISRO

India has two operational launchers: Polar Satellite Launch Vehicle (PSLV) and Geosynchronous Satellite Launch Vehicle (GSLV).

• Sounding rockets are one or two stage solid propellant rockets used for probing the upper atmospheric regions and for space research.
  • They also serve as easily affordable platforms to test or prove prototypes of new components or subsystems intended for use in launch vehicles and satellites.
  • ISRO started launching indigenously made sounding rockets from 1965 and experience gained was of immense value in the mastering of solid propellant technology.
  • In 1975, all sounding rocket activities were consolidated under the Rohini Sounding Rocket (RSR) Programme.
  • RH-75, was the first truly Indian sounding rocket, followed by RH-100 and RH-125 rockets.
• The first launch vehicle developed by ISRO was simply called SLV, or satellite launch vehicle.
  • Satellite Launch Vehicle-3 (SLV-3) was India's first experimental satellite launch vehicle, which was an all solid, four stage vehicle weighing 17 tonnes with a height of 22m and capable of placing 40 kg class payloads in Low Earth Orbit (LEO).
• It was followed by the Augmented Satellite Launch Vehicle or ASLV.
  • These two could carry small satellites, weighing up to 150 kg, to the lower earth orbits.
  • ASLV operated till the early 1990s before PSLV came on the scene.

  

• PSLV’s (Polar Satellite Launch Vehicle) first launch was in 1994, and it has been ISRO’s main rocket ever since. Today’s PSLV, however, is vastly improved and several times more powerful than the ones used in the 1990s.
  • Presently, it has three Variants: PSLV - CA (Core Alone), PSLV-G, PSLV - XL.
  • PSLV is the most reliable rocket used by ISRO till date, with 52 of its 54 flights being successful.
  • The vehicle successfully launched two spacecraft – Chandrayaan-1 in 2008 and Mars Orbiter Spacecraft in 2013 – that later traveled to Moon and Mars respectively
• GSLV (Geosynchronous Satellite Launch Vehicle) is much more powerful rocket, meant to carry heavier satellites much deeper into space.
  • 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.
  • Till date, GSLV rockets have carried out 18 missions, of which four ended in failure.
  • GSLV carried the Chandrayaan-2 mission, and is slated to take the Gaganyaan manned space mission as well.
• The next variant of GSLV is GSLV Mk III, with indigenous high thrust cryogenic engine and stage, having the capability of launching 4 tonne class of communication satellites, to the geosynchronous transfer orbit, close to 36,000 km from earth’s surface.
  • It can take 10,000-kg satellites to the lower earth orbits. Mk-III versions have made ISRO entirely self-sufficient for launching its satellites.
  • Before this, it used to depend on the European Arianne launch vehicle to take its heavier satellites into space.
• ISRO has also developed a launch vehicle specifically for small and micro-satellites, called Small Satellite Launch Vehicle, or SSLV, and is targeted at rising global demand for the launch of such satellites.
  • SSLV is meant to offer cost-effective launch services for satellites up to 500 kg.
  • The inaugural SSLV launch is slated for March, 2022. It is supposed to carry an indigenous earth observation satellite EOS-03 into space.
  • The development and manufacture of the SSLV are expected to create greater synergy between the space sector and private industries – a key aim of the space ministry.
  • One of the mandates of the newly-created ISRO commercial arm, New Space India Limited (NSIL) is to mass-produce and manufacture the SSLV and the more powerful PSLV in partnership with the private sector in India through technology transfers.
• Reusable rockets: The future rockets are meant to be reusable. Only a small part of the rocket would be destroyed during the mission. The bulk of it would re-enter the earth’s atmosphere and land very much like an airplane, and can be used in future missions.
  • Reusable rockets would cut down on costs and energy, and also reduce space debris, which is becoming a serious problem because of the large number of launches.
  • Fully-reusable rockets are still to be developed, but partially-reusable launch vehicles are already in use.
• ISRO has also developed a reusable rocket, called RLV-TD (Reusable Launch Vehicle Technology Demonstrator) which has had a successful test flight in 2016.
  • The configuration of RLV-TD is similar to that of an aircraft and combines the complexity of both launch vehicles and aircraft.

Conclusion:

• The year’s first successful launch laid the groundwork for 2022 where ISRO will look to regain launch momentum if missions that had been lost due to Covid-19 and successive lockdowns. Several missions that had been delayed will be aimed to return on track throughout the year.
• Department of Space has planned 19 missions to be launched in 2022. During the year, ISRO will lift off 08 launch vehicle missions, 07 spacecraft missions, and 04 technology demonstrator missions.

Source: Indian Express, ISRO

Mains Question:

Q. Explaining in brief the various types of launch vehicles used by ISRO, bring out the difference between PSLV and GSLV systems.