Geostationary Transfer Orbit (GTO)

Geostationary Transfer Orbit (GTO) Latest News

ISRO’s Breakthrough in Semi-Cryogenic Engine Development for LVM3

Why in the News?

• ISRO has achieved a breakthrough in developing a semi-cryogenic engine (liquid oxygen/kerosene engine) with a high thrust of 2,000 kN (kilonewtons).
• The first successful hot test of the Engine Power Head Test Article (PHTA) was conducted at the ISRO Propulsion Complex, Mahendragiri, Tamil Nadu.
• This engine will be used in the semi-cryogenic booster stage of the Launch Vehicle Mark-3 (LVM3), enhancing India’s space launch capabilities.

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About Geosynchronous Transfer Orbit (GTO)

What is a Transfer Orbit?

• A Transfer Orbit is used to move a satellite from one circular orbit to another in a fuel-efficient manner.
• The Hohmann Transfer Orbit is a commonly used maneuver for such transfers.

Geostationary Transfer Orbit (GTO)

• GTO is a highly elliptical orbit with:
  • Perigee (closest point to Earth): 180-200 km above Earth’s surface.
  • Apogee (farthest point from Earth): ~35,900 km (near geostationary orbit).
• Why is GTO Used?
  • Satellites are first placed in GTO before they use their own propulsion system to move to a final geostationary orbit (GEO).
  • This reduces the energy required from the launch vehicle, making it more fuel-efficient.

What is a Semi-Cryogenic Engine?

A semi-cryogenic engine is a type of liquid rocket engine that uses:

• Liquid Oxygen (LOX) as an oxidiser (cryogenic component).
• Refined kerosene (RP-1) as fuel (stored at ambient temperature).

Significance of ISRO’s Semi-Cryogenic Engine Development

• Engine power head test success: The hot test of the Power Head Test Article (PHTA) was conducted for 2.5 seconds to validate the ignition and boost strap mode operation.
  • All engine parameters performed as expected.
• Developed by: Liquid Propulsion Systems Centre (LPSC) under ISRO.
• Upcoming plans: Further series of tests on PHTA before realizing the fully integrated engine.
• Replacement for Current LVM3 Core Stage:
  • The SC120 stage (powered by SE2000 engine) will replace the existing L110 stage in LVM3.
  • Payload capacity in Geosynchronous Transfer Orbit (GTO) to increase from 4 tonnes to 5 tonnes.

Cryogenic vs Semi-Cryogenic Engines

Geostationary Transfer Orbit (GTO) FAQs

Q1: What is a Geosynchronous Transfer Orbit (GTO)?
Ans: GTO is an elliptical orbit used to transfer satellites from low Earth orbit (LEO) to a geostationary orbit (GEO) using a propulsion system.

Q2: What is the difference between GTO and GEO?
Ans: GTO is a temporary elliptical orbit, whereas GEO is a circular orbit where satellites remain fixed relative to Earth’s surface.

Q3: Why do rockets first place satellites in GTO instead of directly in GEO?
Ans: Direct placement in GEO requires more fuel; GTO allows satellites to use onboard propulsion to reach GEO efficiently.

Q4: What is the typical altitude range of GTO?
Ans: The perigee (closest point to Earth) is around 180-250 km, while the apogee (farthest point) is nearly 35,786 km.

Source: TH