13. GSLV D5, GSAT 14, Cryogenic Technology and ISRO

Another landmark of ISRO is the successful deployment of the Geosynchronous Satellite Launch Vehicle (GSLV-D5) from the Satish Dhawan Space Center in Sriharikota, Andhra Pradesh. Launching GSLV is a huge accomplishment, because it used the cryogenic engine of the indigenous people. Let us see specific keywords related to space technology and ISRO, such as GSLV D5, GSAT-14 and others.

GSLV D5 : The rocket

For beginners: There are two separate bodies known as Rocket and Satellite. Rocket or launch vehicle is the vehicle used to launch satellites. In another sense h, there is a rocket engine in the launch vehicle, and this rocket engine is fired to launch satellites into the orbits, for example, PSLV, GSLV etc. are examples of launching vehicles. Satellite’s examples include GSAT, INSAT, IRS, etc.

GSLV D5: GSLV D5 is a rocket (launch vehicle) that is used to launch the satellite GSAT 14. However, the rocket engine that was used in this launch vehicle was a cryogenic one. This uses cryogenic propellants at low temperature.

What is special about the GSLV D5 launch? India has already been successful in launching so many satellites using launch vehicles in the PSLV and GSLV series. Henceforth, for the very first time, India successfully launched a satellite using its own indigenously developed cryogenic engine. In the GSLV’s prior missions, India was using Russian Technology for cryogenic engines. But now, India has mastered cryogenic technology and have emerged as a major space power.

GSLV is a 3-stage, solid, liquid and cryogenic) launch vehicle. This is expected to inject  2 ton class of communication satellites to Geosynchronous Transfer Orbit (GTO). The first and second stages of GSLV-D5 are similar to those of the earlier GSLV missions. The third stage is the Cryogenic Indigenous Stage.

Propellants used in the three stages of GSLV

  • 1 Stage (Strap- Ones) : UH25 & N2O4.
  • 1 Stage (Core Stage) :  HTPB.
  • 2 Stage : UH25 & N2O4.
  • 3 Stage : LH2 & LOX.

HTPB : Hydroxyl Terminated Poly Butadiene, LH2: Liquid Hydrogen, LOX : Liquid Oxygen.
N2O4 : Nitrogen Tetroxide, UH25 : Unsymmetrical Dimethyl Hydrazine + 25% Hydrazine Hydrate.

Cryogenic propellants used in this mission: liquid oxygen at -183 degrees Celsius and liquid hydrogen at -253 degrees’ Celsius.

About the cryogenic engine

CE-7.5 is India’s indigenous cryogenic engine This cryogenic rocket engine is used to power the GSLV upper stage. The engine was build as a part of the Cryogenic Upper Stage Project (CUSP). Although it will replace the KVD-1 (RD-56) that is currently powering the GSLV’s upper stage.

Advantages: Effective, cryogenic rocket stage gives more thrust than solid and earth-storable fluid propellant rocket stages for each kilogram of the propellant that it burns. Compared to Earth’s storable liquid propellants, a particular impulse (efficiency measure) obtained with cryogenic propellants (liquid hydrogen and liquid oxygen) is much higher which gives it a considerable payload benefit.

However, the cryogenic stage is a very complicated system as compared to solid or earth-storable liquid propellant stages because it uses propellants at exclusively low temperatures and the associated structural and thermal problems.

GSLV Variants:

The key variants are GSLV Mk I and GSLV Mk II. However, GSLV Mk.II variant uses an Indian cryogenic engine, the CE-7.5, and is capable of launching 2500 kg into a geostationary transfer orbit. or GTO Previous GSLV vehicles (GSLV Mk.I) have used Russian cryogenic engines. GSLV Mk.I had three sub-variants like GSLV Mk.I (a), GSLV Mk.I (b) and GSLV Mk.I (c).

GSAT 14 : The Satellite

GSAT-14 is a 1,982-kg  communication satellite. GSAT-14 is expected to replace the GSAT-3 satellite, that was launched in 2004. Geosynchronous Satellite Launch Vehicle Mk.II (GSLV D5) lanuched GSAT-14, that incorporated an Indian-developed cryogenic engine on the third stage.

Once reaching Geosynchronous Transfer Orbit (GTO), GSAT-14 will use its own propulsion system to reach its geostationary orbital home and will be stationed at 74º East longitude.

GSAT-14 will support the nation in delivering various satellite communications services, including tele-education and telemedicine. The satellite holds six C-band transponders and six Extended C-band transponders to protect the entire Indian territory. GSAT-14 also carries two Ka-band beacons to research how the weather affects satellite Ka-band communications. Two solar arrays are used to drive the satellite and generate 2 600 watts of power.


  • India had 25 consecutive successes in the last two decades of its Polar Satellite Launch Vehicles (PSLVs).
  • GSLV could not deemed as successful. GSLV has attempted eight launches till today, since its first launch in 2001 through its most recent launch in 2014. The three launches have been successful, four for failed, and one was a partial failure, placing the satellite into an unplanned, but recoverable, orbit.
  • While PSLV can carry satellites up to 2 tonnes to a lowearth orbit, GSLV was needed for the launch of heavier satellites, especially of the telecommunication variety that need to be put in a 36,000km geosynchronous orbit.

Perigee and Apogee

Movement of a satellite in Earth's orbit

Perigee is the point nearest to earth while Apogee is the farthest point from earth. After a flight of 17 minutes 5 seconds, GSAT-14 satellite was precisely injected into a Geosynchronous Transfer Orbit with a Perigee (nearest point to Earth) of 175 km and an Apogee (farthest point to Earth) of 35,945 km with an orbital inclination of 19.3 degrees with respect to the equator.

Practice question:

  1. Mark a difference between GSLV and PSLV. Discuss cryogenic technology with respect to India’s latest launch.
  2. Write a short note on Perigee and Apogee .
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