Context: The recent safe return of NASA astronauts Sunita Williams and Barry Wilmore from the International Space Station (ISS) has brought attention to the critical importance of robust safety protocols in human spaceflight. The mission lasted nine months and highlighted NASA's behind-the-scenes efforts to ensure astronaut safety—physically and mentally.
Relevance of the Topic: Prelims: Key facts related to Gaganyaan Human Spaceflight safety.
As India advances towards its maiden human space mission, Gaganyaan, the Indian Space Research Organisation (ISRO) is meticulously putting similar protocols in place, drawing from both historical precedents and modern aerospace research.
Safety Protocols in Gaganyaan (Human Spaceflight Mission)
1. Crew Escape System:
- Human-rated LVM3 (launch Vehicle Mark-3) is equipped with a Crew Escape System that acts like an emergency door — allowing the astronauts to rapidly detach and escape safely from the rocket, if anything goes wrong after the rocket has taken off.
- It uses a tower-like structure on the top of the rocket containing solid fuel engines designed to ignite quickly and produce a tremendous amount of thrust in a short period of time, propelling the space capsule upwards and away from the rocket.
- The Crew Escape System adjusts its response depending on how high the rocket is. It uses LEM for low altitudes and HEM for high altitudes, ensuring the astronauts can escape safely at any stage during launch.
- Low-altitude Escape Motor (LEM): Used in the initial seconds after takeoff. Produces enough thrust to quickly pull the crew module away from the rocket when it is still near the ground.
- High-altitude Escape Motor (HEM): Activates when the rocket is much higher in the sky. Provides enough pulling force to separate the crew module from the rocket safely, even at high speed and altitude.
2. Pad Abort System: Emergency Escape Right After Ignition:
- Pad Abort refers to a life-threatening emergency that happens just moments after the rocket engines ignite, while the rocket is still on or very close to the launchpad.
- In this scenario, both motors LEM and HEM of ISRO's Crew Escape System are activated. Together, they provide maximum thrust to quickly pull the entire crew module and escape system away from the rocket as fast as possible. After escaping, the crew module will splash down safely in the sea at a pre-decided location.
3. Safety in Orbit:
- ISRO’s Gaganyaan crew capsule consists of a pair of interconnected modules:
- Crew module: serves as the living quarters for the crew and passengers)
- Service module: carries the fuel, engines, control systems, etc.
- By the time the spacecraft reaches near its target orbit, the Crew Escape System is no longer needed and is discarded in space.
- If an emergency arises before reaching full orbit, the service module’s propulsion system can change the flight path and bring the crew module down safely on a sub-orbital trajectory (meaning it will come back to Earth without completing an orbit).
- If something goes wrong after the spacecraft is already in orbit, then both the service module’s engines, and the crew module’s small thrusters will work together to slow down the spacecraft and guide it back into Earth’s atmosphere for a safe return.
4. Returning to the Earth:
- Once reentry has begun, atmospheric friction will heat the capsule’s outer heat shield to up to 1800º C. The crew in the crew module will be protected by the shield. Once the capsule has descended to a particular altitude, the crew will slow its descent using retrograde thrusters and deploy parachutes.
5. Final Descent Using Parachutes:
- Gaganyaan crew capsule will decelerate throughout re-entry using a multi-stage parachute system (10-parachute system) to reduce speed in phases:
- Apex cover separation parachutes deploy at 15.3 km altitude from the ground and at 276 m/s speed.
- After that, drogue parachutes are deployed to stabilise and decelerate the capsule to 70 m/s up to a height of 3 km.
- Then the three primary canopies will be deployed, reducing the drop speed to 10-12 m/s.
- Splashdown: Just before or after splashdown in the sea, the parachutes are disconnected using a pyrotechnic mechanism.
Also Read: Gaganyaan Mission