How Gaganyaan's crew module will slow down using ten parachutes

The brief in 7 cards

1. Context1 / 7
   • Gaganyaan is India's human spaceflight programme. It aims to send Indian astronauts to low Earth orbit and bring them back safely.
   • The astronauts will return in the crew module, a capsule designed to land in the sea.
   • A returning capsule travels far too fast for a safe landing. It must lose almost all its speed before touchdown.
   • The Hindu's Text & Context explainer describes how the capsule's parachute system does this.
   • The first uncrewed test flight, called G1, is planned before any astronaut flies. Minister Jitendra Singh has said the first human flight is scheduled for 2027.
2. Key highlights2 / 7

   Air does most of the work: Atmospheric drag removes most of the capsule's speed on re-entry. Parachutes provide the final, controlled slowdown.

   Ten parachutes, four types: Two apex cover separation, two drogue, three pilot and three main parachutes open in a set sequence.

   Built-in backup: Only two of the three main parachutes are needed for a safe landing. The third is a spare.

   Gentle landing: In the first integrated air-drop test, the main parachutes slowed the module to about 8 metres per second before splashdown.

   Heavier test: In April 2026, ISRO dropped a 5.7-tonne dummy module from about 3 km. This matched the weight planned for the uncrewed G1 mission.

   Joint effort: ISRO designs the system with DRDO. The Air Force carries out the drops, and the Navy and Coast Guard handle sea recovery.

3. Key concepts3 / 7
   1. Atmospheric re-entry and drag

   • Re-entry is the return of a spacecraft from space into Earth's atmosphere.
   • Drag is the force air exerts against a moving object. Hold your hand out of a moving car's window and you feel it push back.
   • The capsule has a broad, rounded base called a blunt body. This shape creates strong drag and slows the capsule sharply.
   • Friction with the air also heats the capsule intensely. A heat shield on its base protects the crew.

   News connection: Drag and the heat shield handle the fiery first stage of return. Parachutes take over only once the capsule has slowed enough.

   2. Staged deployment and opening shock

   • When a parachute opens, it jerks the capsule suddenly. This jolt is called opening shock.
   • The faster the capsule is moving, the harsher the jolt. The force depends on dynamic pressure, which rises with the square of speed.
   • So doubling the speed makes the jolt about four times stronger.
   • Analogy: stopping a speeding car by slamming the brakes throws everyone forward. Braking in stages gives a smooth stop.
   • Reefing helps too. The main parachutes first open only partly, held by a line, then open fully. It is like opening a door slowly against a strong wind.

   News connection: Gaganyaan uses small drogues at high speed and large mains only at lower speed, so no single step causes a dangerous jolt.

   3. Redundancy and fault tolerance

   • Redundancy means carrying more parts than strictly needed, so one failure does not cause disaster.
   • Fault tolerance is the system's ability to keep working safely after a part fails.
   • Analogy: a car carries a spare tyre. A puncture does not end the journey.
   • ISRO has tested scenarios with one drogue and one main parachute failing.

   News connection: Two of Gaganyaan's three main parachutes are enough, so one failure still allows a safe landing.

   4. Terminal velocity

   • A falling object speeds up until air drag pushing up equals gravity pulling down. After that, its speed stays steady. This steady speed is terminal velocity.
   • A bigger parachute creates more drag, so it lowers the terminal velocity.
   • That is why the main parachutes are large, about 25 metres across. They bring the capsule's steady falling speed down to a safe level.

   News connection: The main parachutes reduce the module's descent to roughly 8 m/s, a speed the capsule and crew can safely absorb at splashdown.

4. Way forward4 / 7

   Keep testing failure cases: Continue tests that deliberately fail parachutes, so the backup design is proven under real stress.

   Test the full flight path: Use sub-orbital test platforms to check the system at higher altitudes, closer to real mission conditions.

   Build supply chains at home: Develop Indian sources for special fabrics such as Kevlar and Nomex, to reduce dependence on imports.

5. Note5 / 7

   The ten-parachute sequence, step by step

   Step 1 — Apex cover separation (2 parachutes): Small parachutes, about 2.5 m across, pull away the protective cover on top of the capsule. This exposes the parachute bay.

   Step 2 — Drogue (2 parachutes): Cone-shaped ribbon parachutes, 5.8 m across, open at high speed. They stop the capsule from tumbling and slow it down.

   Step 3 — Pilot (3 parachutes): The drogues are released. Three small pilot parachutes then pull the three main parachutes out.

   Step 4 — Main (3 parachutes): The large main parachutes open in stages and bring the capsule to a slow, steady descent.

   Step 5 — Release after landing: Quick-release devices cut the parachutes free after touchdown. This stops wind from dragging or tipping the capsule in the water.

   Why the pilots are needed: the capsule's blunt shape leaves a zone of turbulent air behind it. The small pilots help pull the large mains cleanly through this rough air.

6. Note6 / 7

   How ISRO tests it: a ladder of trials

   Rocket sled tests: At DRDO's Terminal Ballistics Research Laboratory in Chandigarh, parachutes are fired along a rail track at high speed. This tests them under crash-like forces on the ground.

   Extreme conditions: Drogues have been tested at steep angles and high air pressure. A February 2026 test pushed a drogue beyond the highest loads expected in flight.

   Main parachute drops: In integrated main airdrop tests (IMAT), parachute assemblies are dropped from aircraft. One test checked what happens when the main parachutes open unevenly.

   Full system drop 1 (IADT-01): On 24 August 2025, a 4.8-tonne dummy module was dropped from about 3 km by a Chinook helicopter. The test simulated an abort on the launch pad.

   Full system drop 2 (IADT-02): On 10 April 2026, a 5.7-tonne dummy module was dropped near Sriharikota. All ten parachutes worked in sequence, and the Navy recovered the module.

   The logic: Test each part, then push it past its limits, then test failures, then test the whole system, then practise recovery.

7. Note7 / 7

   Materials and partners

   Nylon: Used for the canopy. It stretches slightly, which helps absorb the shock of opening.

   Kevlar: Used for the suspension lines. It is very strong for its weight.

   Nomex: Used where parts face heat. It resists burning.

   VSSC and ADRDE: ISRO's Vikram Sarabhai Space Centre and DRDO's Aerial Delivery Research and Development Establishment designed the parachutes together.

   Air Force and Navy: The Air Force flies the drop tests. The Navy recovers the capsule from the sea, as it will on real missions.

   Next step: The notes describe a proposed ISRO sub-orbital platform to test the recovery system at about 10–17 km altitude. [VERIFY: Confirm the platform's name and status.]

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