Context: ISRO has successfully demonstrated the bootstrap mode start on the CE20 cryogenic engine, which powers the upper stage of the Launch Vehicle Mark-3 (LVM3).
This marks a major technological milestone, proving that the engine can restart autonomously in space without external start-up systems, enabling multi-orbit missions with no payload penalties.
What is Bootstrap Mode?
Bootstrap mode is a method where a rocket engine initiates its own start-up sequence using its internal fuel flow and system pressure, without relying on external gas bottles, pyrotechnic starters, or auxiliary devices.
This leads to lighter, simpler, and restartable cryogenic engines—crucial for missions requiring multiple injections such as GTO → GEO, constellation deployments, and deep-space manoeuvres.
Significance of the Test
- Enables in-orbit restarts, a capability essential for advanced mission profiles.
- Improves LVM3’s competitiveness for multi-burn commercial missions.
- Reduces dependency on heavy external start-up systems, improving payload capacity.
- Boosts India’s emerging heavy-lift and human-spaceflight architecture.
About the CE20 Cryogenic Engine
- Class: India’s first fully indigenous 200 kN-class cryogenic engine (~20–22 tonnes thrust).
- Stage: Powers the C25 upper stage of LVM3.
- Propellants:
- Liquid Oxygen (LOX)
- Liquid Hydrogen (LH₂)
- Operates on a gas-generator cycle optimised for high-altitude performance.
- Operational Record:
- In service since 2014–15 developmental flights.
- Used in Chandrayaan-2, Chandrayaan-3, and all LVM3 commercial launches including OneWeb missions.
- Role: Enables high specific impulse required for GTO, Earth escape, and lunar transfers.
What is a Cryogenic Engine?
A cryogenic engine burns liquid hydrogen and liquid oxygen stored at temperatures below –250°C.
These engines deliver high efficiency and thrust-to-weight ratio, making them essential for heavy payloads and deep-space missions. They are, however, complex due to extreme temperatures and precision requirements.
About the LVM3 Rocket
- Class: India’s heaviest operational launcher.
- Capability:
- 4–4.5 tonnes to GTO
- 8 tonnes+ to LEO
- Stages:
- S200 solid boosters
- L110 liquid core stage
- C25 cryogenic upper stage (CE20 engine)
- Achievements:
- Chandrayaan-2 and 3
- OneWeb commercial missions
- Selected as the launch vehicle for Gaganyaan after human-rating modifications.
- Reliability: Strong success record since 2017, establishing India in the global heavy-lift sector.
Human-Rated LVM3 for Gaganyaan
A specialised version of LVM3 with:
- Strengthened structures
- Redundant systems
- Upgraded CE20 engine
- Enhanced safety margins
This variant meets crew-safety standards required for India’s first human spaceflight mission.