IADT-1: A Key Step in Gaganyaan’s Journey

Why in the News?

1. In August 2025, the Indian Space Research Organisation (ISRO) successfully conducted its first Integrated Air Drop Test (IADT-1).
2. This marks a key step in the preparations for India’s maiden human spaceflight mission, Gaganyaan.
3. In the test, a nearly five-tonne dummy crew capsule was released from a helicopter to evaluate whether its parachute system could effectively slow down the capsule for a safe splashdown.

What is IADT-1?

1. The Integrated Air Drop Test (IADT-1) is an experiment designed to replicate the final phase of a spacecraft’s return to Earth.
2. In this test, ISRO released a dummy crew module from a helicopter at a height of about 3 km to examine the parachute-based deceleration system.
3. The objective was to check if the parachutes opened in the correct sequence and slowed the module down to around 8 m/s before splashdown.
4. Although this test cannot recreate actual re-entry conditions, since helicopters cannot lift spacecraft high enough, it effectively simulates the last stage of landing.
5. In a real mission, the crew module will first slow down due to atmospheric drag and its heat shields, followed by the deployment of drogue parachutes, and finally three large 25-metre main parachutes to ensure safe descent.
6. IADT-1 focused on validating this sequence to guarantee the safety of astronauts during splashdown.
7. This trial builds upon earlier missions such as the Test Vehicle Abort Mission (TV-D1) conducted in October 2023, which tested the crew escape system in a sub-orbital flight.
8. Together, these experiments form critical steps in preparing for India’s first human spaceflight under the Gaganyaan mission.

How was the test carried out?

1. For IADT-1, an Indian Air Force Chinook helicopter lifted a 8-tonne dummy crew module to a designated altitude.
2. At that height, the capsule was released, after which automated systems initiated the sequential deployment of parachutes.
3. The test confirmed that the touchdown conditions matched expectations, proving that the parachute system design worked effectively in real-world conditions.
4. The exercise required extensive modelling, instrumentation, and coordination among multiple agencies.
5. Apart from the Air Force, the DRDO provided materials and safety systems, while the Indian Navy and Coast Guard prepared for post-splashdown recovery
6. According to Vikram Sarabhai Space Centre Director A. Rajarajan, his centre was responsible for nearly 90% of IADT-1 activities.
7. ISRO highlighted that in any crewed mission, the phases of ascent, descent, and recovery are the riskiest.
8. Astronaut survival after orbital stay depends heavily on whether the parachutes deploy correctly during re-entry and landing.
9. A failure in parachute deployment would be catastrophic, which makes such ground-based testing indispensable before attempting human spaceflight.

How did the parachute system work?

1. The crew module carried four different types of parachutes, each performing a specific role in slowing the capsule.
2. The sequence began with the deployment of two 2.5-metre Apex Cover Separation Parachutes, which removed the apex cover protecting the parachute compartment from re-entry heat.
3. Next, two 5.8-metre drogue parachutes were deployed to stabilise the crew module and bring down its velocity significantly.
4. After the drogue parachutes completed this initial deceleration stage, they detached, allowing the release of three 3.4-metre pilot parachutes.
5. Each pilot parachute then independently deployed one of the three large 25-metre main parachutes, which further slowed the capsule to a safe speed for splashdown.

Where does IADT lie on the roadmap?

1. The Gaganyaan mission’s ultimate goal is to send Indian astronauts to low-Earth orbit on a human-rated LVM3 rocket.
2. Human spaceflight demands human-rating of every system, which means building redundancies, life-support, and autonomous fault-detection mechanisms.
3. To achieve this, ISRO is conducting a series of tests covering different mission phases: launch, abort, descent, landing, and recovery.
4. The Crew Escape System (CES) tests demonstrate whether astronauts can be pulled away from the rocket during a launch failure.
   2023. TV-D1 was carried out in October 2023.
   2024. TV-D2 will attempt a more complex abort scenario.
5. After IADT-1, the next milestone is the uncrewed Gaganyaan-1 (G1) mission, which will carry Vyommitra, a humanoid robot designed to replicate astronaut functions.
6. Alongside these, further drop tests, subsystem trials, and more IADTs will continue to refine systems before astronauts are cleared to fly.
7. By the time the first human mission (H1) takes place, ISRO would have completed several thousand tests.
8. Some critical systems under development include:
   1. Environmental Control and Life Support System (ECLSS): For oxygen supply, waste management, fire safety, and thermal regulation.
   2. Integrated Vehicle Health Management System (IVHMS): To autonomously detect faults and trigger aborts.
   3. Upgraded LVM3 rocket: Modified to meet the reliability standards required for carrying humans.
9. India has also had to indigenise many advanced technologies, such as escape motors, specialised composites, and safety materials, since they were not available from abroad.

India’s Long-Term Goals in Human Spaceflight

1. Gaganyaan is only the beginning, it serves as the foundation of India’s broader human spaceflight programme.
2. The Indian government has set two major milestones:
   2035. Establishing the Bharatiya Antariksh Station (BAS) by 2035.
   2036. Achieving an Indian crewed lunar landing by 2040.
3. To realise these objectives, ISRO will need to develop capabilities for repeated flights, longer orbital stays, and deep-space technologies.
4. While timelines may shift (for instance, IADT-1 was initially planned for April 2024 but took place in August 2025), each milestone strengthens India’s technological base for more ambitious missions.
5. The upcoming TV-D2 mission will further demonstrate the Crew Escape System by simulating an abort scenario, after which the crew module will descend with thrusters and parachutes for recovery.
6. Alongside Gaganyaan, ISRO is advancing supporting technologies such as in-orbit docking, demonstrated through the SpaDeX mission in May 2025. This capability will be crucial for BAS, Chandrayaan-4, and future crewed missions.
7. The first human mission (H1) is currently scheduled for 2027, though it is expected to face delays.

Challenges and Way Forward

Conclusion

The IADT-1 success is a safety validation milestone for Gaganyaan and a stepping stone to India’s broader human spaceflight roadmap. While challenges remain in technology, timelines, and mission complexity, each test strengthens ISRO’s capabilities. With consistent effort, indigenisation, and sustained support, India is well on its path to joining the select group of nations with independent human spaceflight capacity, paving the way for a space station and a future crewed lunar mission.