ISRO successfully tests hybrid propulsion system, to aid future technologies

ISRO successfully tests hybrid propulsion system, to aid future technologies

#GS-03 Science and Technology

For Prelims

About Hybrid Propulsion System:

Fuel Used:

  • HTPB-based (hydroxyl-terminated polybutadiene) aluminised solid fuel and liquid oxygen (LOX) as oxidiser.

Advantages of the new system:

  • Conventional HTPB-based solid propellant motors used in rockets use ammonium perchlorate as oxidiser.
  • While both HTPB and LOX are environment friendly, the cryogenic LOX is safer to handle.
  • Unlike conventional solid motors, the hybrid technology imparts restarting and throttling capabilities on the motor.
  • The use of liquids facilitates throttling and control over the flow rate of LOX.


Conventional Rocket Fuels:

  • The Indian Space Research Organisation (ISRO) conventionally uses the fuel UDMH (Unsymmetrical Di-Methyl Hydrazine), which is highly toxic and corrosive, along with the nitrogen Tetroxide as the oxidiser. This combination is called a “dirty combination.”
  • Due to the pollution and toxicity of these materials, most of the countries across the world are shifting to cleaner fuels such as liquid methane or kerosene.


About rocket propulsion:

  • Rockets work under Newton’s third law of motion which states that “To every action there is always opposed an equal reaction; or the mutual actions of two bodies upon each other are always equal and directed to contrary parts.”
  • When the fuel explodes out of the rocket engine, the outward going fuel exerts a force which is equal in magnitude but opposite in direction to the force of the exploding fuel. This is what propels the rocket.
  • However, since rockets are designed to work in outer space, where there is a lack of oxygen, it must carry its on oxidizer in order to allow the fuel to burn.

About Vikram Sarabhai Space Centre (VSSC):

  • VSSC was founded at Thumba, a coastal village at Thiruvananthapuram, the capital city of Kerala, in 1962.
  • The Centre is named after Dr Vikram A Sarabhai, who is celebrated as the father of Indian Space Programme.
  • VSSC is the lead centre of ISRO responsible for the design and development of launch vehicle technology.
The  major  programmes  at  VSSC  include:
  • Polar  Satellite  Launch  Vehicle  (PSLV),
  • Geosynchronous Satellite Launch Vehicle (GSLV) and
  • Rohini Sounding Rockets

as well as the development of

  • Geosynchronous Satellite Launch Vehicle (GSLV) Mk Ill,
  • Reusable Launch Vehicles,
  • advanced technology vehicles,
  • air-breathing propulsion and
  • critical technologies towards human spaceflight.