May 10, 2022


Q What is the context  ?

A In 2021, a high-level panel was established to examine the failed Geosynchronous Satellite GSLV-F10/Earth Observation Satellites (EOS)-03 mission and recommended measures for making the Cryogenic Upper Stage (CUS) more robust.

Q What is a Geosynchronous Satellite Launch Vehicle (GSLV)?

Q What is Cryogenic Upper Stage?

Q What are Earth Observation Satellites?

Launch vehicles used by ISRO
Satellite Launch Vehicle (SLV):
  • The first rocket developed by ISRO was simply called SLV, or Satellite Launch Vehicle.
  • It was followed by the Augmented Satellite Launch Vehicle or ASLV.
Augmented Satellite Launch Vehicle (ASLV):
  • SLV and ASLV both could carry small satellites, weighing up to 150 kg, to lower earth orbits.
  • ASLV operated till the early 1990s before PSLV came on the scene.
Polar Satellite Launch Vehicle (PSLV):
  • PSLV’s 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.
    • It is the first Indian launch vehicle to be equipped with liquid stages.
  • PSLV is the most reliable rocket used by ISRO till date, with 52 of its 54 flights being successful.
    • It successfully launched two spacecraft – Chandrayaan-1 in 2008 and Mars Orbiter Spacecraft in 2013 – that later traveled to Moon and Mars respectively.
    • ISRO currently uses two launch vehicles – PSLV and GSLV (Geosynchronous Satellite Launch Vehicle), but there are lots of different variants of these.
Small Satellite Launch Vehicle (SSLV):
  • SSLV is targeted at rising global demand for the launch of small and micro-satellites.
  • SSLV is meant to offer cost-effective launch services for satellites up to 500 kg.
  • It is supposed to carry an indigenous earth observation satellite EOS-03 into space.
Geosynchronous Satellite Launch Vehicle (GSLV):
  • GSLV is a much more powerful rocket, meant to carry heavier satellites much deeper into space. Till date, GSLV rockets have carried out 18 missions, of which four ended in failure.
  • It can take 10,000-kg satellites to lower earth orbits.
  • The indigenously developed Cryogenic Upper Stage (CUS), forms the third stage of GSLV Mk II.
  • 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.
    • GSLV-Mk III is a fourth generation, three stage launch vehicle with four liquid strap-ons. The indigenously developed CUS, which is flight proven, forms the third stage of GSLV Mk III.
    • The rocket has three-stages with two solid motor strap-ons (S200), a liquid propellant core stage (L110) and a cryogenic stage (C-25).
Reusable Rockets/ Future 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.