Space Re-entry:
Space re-entry has gained attention with advancing human spaceflight missions, especially India’s Gaganyaan programme, which focuses on safely returning astronauts to Earth.
- Space re-entry refers to the process by which a spacecraft or crew capsule returns from orbit and safely passes through Earth’s atmosphere to land on the surface.
- The re-entry corridor is a narrow, precisely defined atmospheric window through which a spacecraft must enter Earth’s atmosphere to ensure safe return.
- Too shallow (Overshoot): The spacecraft may skip off the atmosphere and return to space.
- Too steep (Undershoot): Extreme heat and deceleration forces can destroy the vehicle or endanger the crew.
- Hence, maintaining the correct entry angle is critical for survival.
- The spacecraft turns opposite to its direction of travel and fires engines to reduce orbital velocity, allowing gravity to pull it into the atmosphere.
- Atmospheric drag converts kinetic energy into heat, slowing the capsule rapidly.
- Heat shields protect the capsule using ablation or insulation to withstand temperatures generated during re-entry.
- Semi-ballistic design and attitude control help maintain the vehicle within the re-entry corridor and guide it toward the landing zone.
- Ionised plasma forms around the capsule, temporarily blocking radio communication.
- At lower altitudes, multi-stage parachutes reduce speed for safe splashdown or landing.
