Gaganyaan mission: All about TV-D1 test flight and its objectives

Flight Test Vehicle Abort Mission-1 (TV-D1) (Image courtesy: @ISRO/X)

ISRO is now geared for the Gaganyaan mission after the historic success of the Chandrayaan-3's landing on the south pole of the moon, and the launch of Aditya-L1 to explore the mysteries of the Sun. An essential component of the Gaganyaan mission is the TV-D1 test platform, designed for the validation of the Crew Escape System's (CES) efficiency.

ISRO emphasizes that this crucial test will evaluate the system's capability to protect astronauts during critical mission challenges, including launch failures and emergency scenarios.

Test flight TV-D1 set for liftoff

The Gaganyaan program involves four emergency escape test launches. The first test flight, TV-D1, is scheduled to take off at 8 am on October 21 from the Satish Dhawan Space Center in Sriharikota. Following TV-D1, there will be subsequent test flights, including TV-D2, and an uncrewed mission featuring robotic payloads, referred to as LVM3-G1. Missions D3 and D4 are also in the pipeline. Subsequently, another uncrewed mission involving robotic payloads, LVM3 G2, is planned. According to the ISRO, these tests are essential to evaluate critical technologies vital for the success of Gaganyaan and to validate the mission's human safety precautions before proceeding to the first crewed mission in 2024.

Objectives of the TV-D1 test

The primary aim of this test flight is to conduct an "In-flight Abort Demonstration of the Crew Escape System" at Mach 1.2, representing supersonic conditions.

This vital test simulates an emergency situation early in the mission, necessitating the swift separation and safe retrieval of the Crew Module (CM). It involves the deployment of recovery systems like parachutes and deceleration mechanisms to ensure a controlled descent and secure landing for both the module and the astronauts on board (in future). ISRO emphasizes the importance of this test in evaluating the system's capacity to protect astronauts in situations like launch failures or critical mission challenges, where Mach 1.2 speed is a critical phase, especially during the initial stages of launch and ascent.

(A speed that is 1.2 times the speed of sound in the surrounding medium is indicated by a Mach number of 1.2, referring to supersonic conditions.)

How the test begins

The test begins with the activation of the newly developed Test Vehicle, the TV-D1 single-stage liquid rocket developed for this abort mission. At a speed of Mach 1.2, the Crew Escape System (CES) is activated to replicate an in-flight abort.

The CES and the Crew Module (CM) separate from the Test Vehicle at an altitude of approximately 17 km. Following this, the autonomous abort sequence begins, including CES separation and parachute deployment. The mission concludes with the safe landing of the CM in the sea, approximately 10 km from Sriharikota's coast, with the assistance of the Indian Navy's dedicated vessel and diving team. The success of this test flight paves the way for subsequent qualification tests and unmanned missions, ultimately leading to India's first Gaganyaan mission with astronauts.

Gaganyaan test flight TV-D1: Speed, altitude, and separation

TV mission reaches Mach 1.2 speed, flies at an altitude of 11.7 kilometers, maintains a flight path angle of 60 degrees, and experiences dynamic pressure of 22.6 kilopascals.

Separation of the Crew Module (CM) from the Crew Escape System (CES) occurs at Mach 0.5, at an altitude of 17 kilometers, with dynamic pressure levels ranging from 2-3 kilopascals.

Deployment of the drogue parachute takes place at an altitude of 16.7 kilometers, and the main parachute is deployed at an altitude of 2.5 kilometers.

What is Crew Module (CM)

During the Gaganyaan mission, the Crew Module (CM) serves as the pressurized environment for astronauts. However, for the Test Vehicle Abort mission-1 (TV-D1), an unpressurized version of the CM is used. This unpressurized CM matches the size and mass of the actual Gaganyaan CM. It contains all the necessary systems for deceleration and recovery, including a complete set of parachutes, recovery aids actuation systems, and pyrotechnic devices.