From Liftoff To Recovery: Decoding TV-D1's Role In Gaganyaan Mission

The Indian Space Research Organisation (ISRO) achieved a significant milestone with the launch of the first uncrewed flight mission of the Gaganyaan programme on Saturday at 10:00 am IST. This mission, known as the Test Vehicle Development Flight (TV-D1) or Test Vehicle Abort Flight, lifted off from the Launch Pad at the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh. The TV-D1 mission is a critical step in the Gaganyaan programme, designed to demonstrate the performance of the Crew Escape System and marks the beginning of Gaganyaan's uncrewed flight testing phase.

One of the most significant aspects of the TV-D1 mission is the in-flight abort demonstration of the Crew Escape System. This demonstration involves the jettisoning of the Crew Escape System while the Crew Module is in flight. This test is essential for assessing specific flight parameters and ensuring the effective separation of the Crew Escape System from the Crew Module, a crucial safety measure for astronauts in case of an emergency.

Abort at Mach Number 1.2

The decision to abort the TV-D1 mission at Mach number 1.2 is driven by the fact that this stage presents the greatest challenges in terms of vibrations and other critical parameters. Any anomalies that may arise are most likely to occur during this phase. Mach number 1.2 corresponds to a speed of about 360 meters per second. Once the Crew Module reaches this speed, the abort command will be initiated. The primary role of the Crew Escape System is to safely remove the Crew Module from the launch vehicle, ensuring that both the Crew Module and the Crew Escape System travel in a different direction from the launch vehicle.

Subsystem Evaluation and Deceleration Testing

Within the TV-D1 mission, various subsystems of the test vehicle will be rigorously evaluated. Additionally, the deceleration systems of the Crew Module will undergo testing at higher altitudes, addressing another critical aspect of astronaut safety.

Unpressurized Crew Module

The TV-D1 mission utilises an unpressurized Crew Module, in contrast to the pressurised version that will be used in the crewed missions of the Gaganyaan programme. Notably, both versions share the same mass and size, along with identical deceleration and recovery systems, including complete sets of parachutes. The crewed flight tests of Gaganyaan will simulate Earth-like atmospheric pressure conditions. The choice of an unpressurized Crew Module for the first developmental flight test primarily aligns with the mission's primary goal of testing the Crew Escape System, which functions consistently with both pressurized and unpressurized modules. Future missions may explore the use of a pressurized Crew Module.

Dual Redundant Avionic Systems

A crucial aspect of ensuring mission safety is the presence of dual redundant avionic systems. This means that two sets of systems inside the Crew Module handle functions such as navigation, sequencing, telemetry, instrumentation, and power.

Test Vehicle and Crew Module Flight

The TV-D1 mission employs a single-stage liquid-propelled test vehicle featuring a VIKAS engine. This vehicle carries both the Crew Module and the Crew Escape System to an altitude of 11.7 kilometers in approximately 60 seconds. At this point, the abort command is issued, triggering the Crew Escape System to extract the Crew Module from the launch vehicle. The Crew Module is then taken to an altitude of 16.7 kilometers before the Crew Escape System is jettisoned. Afterward, the Crew Module descends under gravity's influence.

Recovery Process

The recovery process involves the removal of the apex parachute, followed by the deployment of drogue parachutes from the Crew Module to decrease its velocity. The main parachute comes into play when the Crew Module reaches an altitude of 2.5 kilometers above sea level. Eventually, the Crew Module safely splashes down into the Bay of Bengal, where it will be recovered by the Indian Navy. The splashdown location is approximately 10 kilometers from the coast of Sriharikota.

The TV-D1 mission serves as a crucial step in India's pursuit of human spaceflight, aligning with the Gaganyaan programme's goals of ensuring astronaut safety and the successful execution of future crewed missions. As ISRO continues to make advancements, India is well on its way to achieving its historic Gaganyaan objectives.

The Gaganyaan mission team

The Gaganyaan mission team is made up of over 10,000 scientists and engineers from ISRO and other organisations. The team is working on all aspects of the mission, from the development of the spacecraft to the training of the astronauts.