How will Gaganyaan astronauts return safely to earth?, Pg10

Key Highlights:

• The Gaganyaan crew module will orbit Earth at approximately 7,800 m/s and use aerobraking to reduce speed during re-entry.
• A multi-stage parachute system will deploy when the module is within 12 km of the ground for a soft landing.
• Landing on land requires a touchdown speed of 1-2 m/s, while sea landings can tolerate 7-9 m/s due to water's energy absorption.
• The Indian Navy will lead the Gaganyaan recovery operation in the Bay of Bengal, using flotation bags and specialized gear.

Detailed Insights:

• Aerobraking is the primary method for shedding kinetic energy during re-entry, with parachutes and braking motors used for a soft landing.
• Sea landings are preferred when large, empty land territories are unavailable, despite requiring specialized recovery ships and crew safety measures.
• Using parachutes alone to reduce velocity to less than 2 m/s is impractical due to the exponential increase in parachute size and deployment challenges.
• The landing zone is elliptical due to the concentration of kinetic energy along the flight track and minimal lateral deviation capabilities.
• Recovery teams use predictive tracking, electronic signaling, and visual aids like GPS coordinates, homing signals, fluorescent dye, and strobe lights to locate the module.
• After splashdown, flotation bags will inflate, and naval divers will secure the module before it is winched onto a ship for crew extraction.

Scientific/Technical Concepts Involved:

• Aerobraking: Using atmospheric drag to decelerate a spacecraft during re-entry.
• Kinetic Energy: The energy an object possesses due to its motion.
• Multi-Stage Parachute System: A sequence of parachutes deployed to gradually reduce speed.

Gaganyaan: Parachute