How will Gaganyaan’s Crew Module deploy its Parachutes?

Context:

Gaganyaan’s success depends on bringing astronauts safely back to Earth. Its parachute-based deceleration system stabilises and slows the returning crew module before splashdown. It comprises 10 parachutes of four types, deployed in a carefully controlled sequence

What is the Gaganyaan Mission?

• Gaganyaan is India’s human spaceflight programme led by the Indian Space Research Organisation (ISRO). It aims to demonstrate India’s capability to send humans to Low Earth Orbit (LEO) and return them safely to Earth.
• The mission is designed to carry three astronauts (Vyomanauts) to an approximately 400-km orbit for a short-duration mission.
• Orbital module: Consists of a Crew Module, which houses astronauts and returns to Earth, and a Service Module, which provides power, propulsion and other support in orbit.
• The astronauts will undertake microgravity experiments and technology demonstrations.
• The Human-rated LVM3 will serve as the launch vehicle.
• The Human Space Flight Centre (HSFC) coordinates the programme.
• The return journey will culminate in a low-velocity splashdown in the sea.

ISRO’s current programme roadmap envisages uncrewed missions before the first crewed orbital mission targeted for 2027. 

Why are parachutes needed during re-entry?

• When the Crew Module returns from orbit, it possesses very high kinetic energy. During atmospheric re-entry, aerodynamic drag generated by the atmosphere removes a major part of its velocity. However, atmospheric drag alone is insufficient to bring the spacecraft down gently.
• The parachute-based deceleration system therefore performs the final stages of velocity reduction and stabilisation before splashdown.
• The key challenge is that a parachute cannot simply be opened at very high speed. Sudden deployment would generate enormous opening shock and aerodynamic loads, potentially damaging the parachute or imposing dangerous deceleration on the crew.

Hence, Gaganyaan uses a multi-stage, redundant parachute system.

How will Gaganyaan’s parachutes deploy?

The operational Gaganyaan system contains 10 parachutes of four types. 

• Stage 1: Apex Cover Separation (ACS) parachutes: Two small ACS parachutes are deployed first. Their primary function is not to slow the Crew Module for landing. Instead, they help remove the protective apex cover from the parachute compartment.
• Stage 2: Drogue parachutes: After the apex cover is separated, two drogue parachutes are deployed. Their functions are to stabilise the Crew Module, reduce its velocity during the early stage of parachute-assisted descent and prepare the vehicle for deployment of the main parachutes. 
• Stage 3: Pilot parachutes: Once the drogue phase is complete, three pilot parachutes are deployed. These are smaller parachutes whose principal function is to extract the three main parachutes from their packed configuration.
• Stage 4: Main parachutes: The three pilot parachutes independently extract three large main parachutes. The main parachutes provide the major deceleration required for the final descent and bring the Crew Module to a safe splashdown velocity.

ISRO’s 2025 Integrated Air Drop Test demonstrated the complete sequence using a simulated Crew Module, with the three main parachutes reducing terminal velocity to approximately 8 m/s. 

Why is the deployment done in multiple stages?

• Avoiding excessive opening shock: A spacecraft descending through the atmosphere is subjected to significant dynamic pressure. If a large main parachute were opened suddenly while the Crew Module was still travelling too fast, the resulting aerodynamic force could:
  • Tear or damage the canopy.
  • Overload suspension lines and structural components.
  • Produce excessive deceleration for the astronauts.
  • Destabilise the Crew Module.

The solution is progressive deceleration. Each stage operates after the vehicle reaches an appropriate flight condition.

How are the parachutes tested?

Because parachute failure during an actual crewed mission could be catastrophic, Gaganyaan’s parachutes undergo testing under simulated flight conditions.

• Rail Track Rocket Sled (RTRS) tests: At the Terminal Ballistics Research Laboratory (TBRL), Chandigarh, rocket-powered sleds accelerate test articles along a rail track to reproduce high-speed deployment conditions. These tests have been used for components including the drogue, pilot and apex-cover-separation parachutes. 
• Integrated Air Drop Tests (IADT): A simulated Crew Module is released from an aircraft or helicopter, and the complete parachute sequence is tested.
  • IADT-01 (2025): A simulated ~4.8-tonne Crew Module was released from about 3 km using an IAF Chinook.
  • IADT-02 (2026): A ~5.7-tonne simulated Crew Module was released from about 3 km, and the complete 10-parachute sequence was successfully demonstrated.
• Integrated Main Parachute Air Drop Tests: These tests specifically qualify the large main parachutes under high-load and failure scenarios. In 2026, ISRO conducted IMAT-05, using an IAF IL-76 to drop a simulated main-parachute configuration from 2.5 km. It was the fifth test in the IMAT series. 

What happens after splashdown?

• The parachutes cannot simply remain attached indefinitely after landing. After splashdown, wind or water currents acting on the inflated canopy could drag the Crew Module or destabilise/capsize it.
• Therefore, the main parachutes are released using parachute-release mechanisms, including pyrotechnic systems. This is particularly important because Gaganyaan’s recovery operation involves the Indian Navy and other recovery assets.

What materials are used?

• Aerospace parachutes require a combination of:
  • High tensile strength.
  • Low mass.
  • Thermal resistance.
  • Flexibility and elasticity.
  • Resistance to repeated folding and packing.
  • Ability to withstand high dynamic loads.

Common advanced materials include:

• Nylon: Used extensively in parachute canopy fabrics because of its strength, elasticity and relatively low mass. Its elasticity helps absorb part of the shock during inflation.
• Kevlar: Its high tensile strength and heat resistance make it useful in load-bearing components such as suspension lines, risers and reinforcement elements.
• Nomex: A heat-resistant aramid material used in applications where components may experience elevated temperatures.

Aerospace parachutes are not simply larger versions of conventional parachutes. They are highly engineered systems integrating materials science, aerodynamics, pyrotechnics, structural engineering and control of dynamic loads.

Practice Prelims MCQ: 

Q. With reference to the Gaganyaan Crew Module, consider the following statements:

1. Its parachute-based deceleration system comprises four types of parachutes.
2. Drogue parachutes primarily help stabilise and decelerate the Crew Module before deployment of the main parachutes.
3. Three main parachutes are deployed independently through pilot parachutes.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Answer: (d)