Exclusive | Gaganyaan: ISRO's crew module to undergo in-flight abort tests on mini-rocket 'TV'

The Indian Space Research Organization (ISRO) is performing a host of tests in the run up to the ambitious 'Gaganyaan' astronaut mission. In a latest development, the Indian space agency has taken possession of an indigenously designed and developed Simulated Crew Module (SCM). The SCM is a near-total replica of the structure that will house Indian astronauts during the Gaganyaan mission. In the coming months, ISRO will be flight testing this SCM, on-board a new mini-rocket known as Test Vehicle (TV). WION spoke to DrSUnnikrishnan Nair, Director of ISRO's Vikram Sarabhai Space Centre (VSSC), the lead facility for the development of rockets. Both TV and SCM were also developed by the teams at VSSC, in Kerala's Thiruvananthapuram.

On Friday, ISRO said that DrS. Unnikrishnan Nair, Director, VSSC, received the Simulated Crew Module from V.N. Sai Prakash, MD, Manjira Machine Builders in a ceremony held in Hyderabad. Dr S. Somanath, Chairman, ISRO and Dr R. Umamaheswaran, Director HSFC, graced the occasion through virtual presence.

In a rocket launch where astronauts are being ferried to space, crew safety is of paramount priority. To ensure this, ISRO is working on demonstrating the capability to abort (eject) and rescue the crew module alone, during different stages of the rocket's flight and under varying conditions. Similar to how a pilot can rapidly (in micro-seconds) eject from a fighter aircraft, the entire crew module (structure) will be able to eject itself from the rocket, by using small, high-thrust, solid-propelled escape motors (mini-rockets).

"The actual crew module and the full-fledged GSLV Mk3 rocket are very expensive, so they cannot be used for conducting multiple abort tests. In order to perform low-cost and highly-efficient testing, we have developed the Simulated Crew Module and a mini liquid-fuelled rocket known as Test Vehicle (based on a single L40 Booster of the GSLV Mk2 rocket)," DrNair explained. Our goal is to perform abort tests and check all systems at different stages- at the launchpad, when the rocket is flying and transitioning from subsonic to supersonic, when the rocket is undergoing maximum dynamic pressure, he added.

The mass, aerodynamic characteristics, center of gravity, moment of inertia and several technical and engineering parameters of the SCM are exactly the same as the original crew module. Similarly, it also has provisions for parachutes and pyro systems, just like the original. This will help test how the abort system and its multiple associated systems would work under varying, challenging flight conditions. In 2018, ISRO had tested the abort mechanism at the launchpad from a stationary setup. But the real test would be to conduct an abort when the crew module is being flown atop the rocket.

"The abort mechanism we are using includes multiple mini-rockets or escape motors. During the tests, we will identify how many of these rockets need to be fired at different altitudes to ensure a safe ejection. For example, aborting at the launchpad would mean firing all mini-rockets. Whereas, when the rocket is flying at an altitude of 20 km, only a few mini-rockets would have to be fired for a safe abort. There are different combinations (high-altitude and low-altitude escape motors) for different contingency scenarios. Such testing will also help understand whether the forces exerted by our abort system are suitable and tolerable for human limits," Dr Nair elaborated.

ISRO plans to perform at least four missions with the Test Vehicle, before proceeding to the two Unmanned Missions involving the human-rated GSLV Mk3 rocket. The maiden mission involving astronauts is expected to be carried out after the two Unmanned missions. At present, the Test Vehicle is ready at our spaceport, the Satish Dhawan Space Centre in Sriharikota, said Dr. Nair. The Test Vehicle is a low-cost platform that ISRO hopes to utilise for demonstrating a wide-range of technologies- vertical landing, recovery and re-use of rocket stages, hypersonic scramjet, etc.