BENGALURU: After several delays, the
Indian Space Research Organisation (
Isro), early Sunday completed the first integrated air-drop test (IADT-01), a critical exercise to validate the parachute system that will bring back astronauts safely under the
Gaganyaan mission, from its spaceport in
Sriharikota.
The IADT-01, VSSC director A Rajarajan told TOI soon after the test, involved dropping a simulated crew module with a mass of around 5 tonnes from an Indian Air Force (IAF) Chinook helicopter from an altitude of 3.1km.
In line with Isro’s plan, the drop took place over the Bay of Bengal and lasted about an hour from take-off to recovery, though the final parachute deployment sequence was completed in just 2-3 minutes. “The test met all the objectives that we had,” Rajarajan said.
The IADT-01 was designed to evaluate the full suite of parachutes that will slow down and stabilise the crew module during re-entry and splashdown of the actual human spaceflight mission.
Isro) said it had successfully demonstrated the end-to-end performance of the critical parachute-based deceleration system that will be used in the Gaganyaan mission.
The test, carried out in one of the typical mission scenarios, was part of the overall qualification programme for the system. “This was an end-to-end validation of the parachute-based deceleration system for the Crew Module, tested in a real-world environment,” Isro said.
In Gaganyaan flights, this parachute system is deployed during the terminal phase of descent, slowing down the Crew Module before splashdown. Its role is to reduce touchdown velocity to safe limits for crew recovery at sea. For the trial, the layout of the parachute system was identical to that planned for the mission itself. It comprised four types of parachutes: Apex Cover Separation (ACS), Drogue, Pilot, and Main parachutes. There were two each of ACS and Drogue parachutes and three each of Pilot and Main.
“The sequence began with the firing of the ACS mortars that deployed two ACS parachutes, ensuring safe separation of the apex cover,” Isro explained. This was followed by the deployment of two drogue parachutes, each 5.8 m in diameter, which provided the first stage of deceleration.
Once this phase was complete, the drogues were released using pyro-based mechanisms, clearing the way for three pilot parachutes to be deployed. These, in turn, extracted the three large main parachutes of 25 m diameter each, which slowed the module to a terminal velocity of about 8 m/s. The entire series of events was executed in precise sequence, allowing the simulated Crew Module to achieve a safe splashdown. After touchdown, the parachutes were detached automatically.
Isro said the test simulated a possible abort scenario at the launch pad, allowing onboard avionics to command and control the deceleration process. The avionics suite also measured and telemetered performance data to the ground, while simultaneously storing it onboard in a Solid State Data Recorder. Following splashdown, the module was successfully recovered and ferried by INS Anvesha to Chennai port.
To prepare for this test, extensive modelling was carried out to account for the dynamics of carrying the module underslung beneath the helicopter. “We conducted multiple sorties with a dummy module and the Chinook to validate the mission profile and refine standard operating procedures,” Isro said. Only after clearance by the Test Authorisation Board was the actual trial flown.
The agency said that the achievement was the result of close coordination among multiple stakeholders. In addition to Isro centres, the Defence Research and Development Organisation, the Indian Air Force, Indian Navy, and Indian Coast Guard contributed to the operation. Further tests of the parachute system under different deployment conditions are planned in the days ahead, the agency confirmed.
Isro has planned multiple IADT sorties to fine-tune the parachute deployment sequence further. The agency is also preparing for upcoming tests such as the second Test Vehicle Demonstration (TV-D2) mission and the first uncrewed Gaganyaan mission (G1), which will pave the way for India’s maiden human spaceflight.
While both TV-D2 and G1 are targeted for later this year, there have been no official statements by Isro with exact dates. Isro chairman V Narayanan has said on multiple occasions in the past few months that they will be achieved by the end of this year. However, sources indicated that G1 could even slip to early next year, but refrained from committing to a date.
As reported by TOI earlier, after the initial pre-mission trials for IADT-01 in May 2024, Isro had put the actual exercise on hold because a need to revisit “some aspects” of the helicopter selected to carry out the test, arose.
“...During the pre-mission trials for the first IADT in Sriharikota, it was noticed that the helicopter may have ‘some issues’ that needed to be addressed. That is progressing now,” a source had told TOI. Those issues have since been resolved and sources said that once the complete analysis of the IADT-01 test data is complete, plans for future tests will be drawn up.
Isro’s initial plans were to conduct seven IADTs, with the final number depending on the test results.