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On Saturday, less than two months after the Chandrayaan-3 Moon landing, ISRO will carry out the first of a series of tests of systems and procedures with the aim to ultimately launch an Indian astronaut into space, perhaps in 2025.
The Flight Test Vehicle Abort Mission-1 (TV-D1) will demonstrate the performance of the Crew Escape System of the Gaganyaan project. The flight will be the first of two abort missions to test the safety mechanisms that will allow the Gaganyaan crew to leave the spacecraft in an emergency.
The test exercise will see the rocket rise to an altitude of almost 17 km before an abort signal is triggered, leading to the separation of the crew module, which will descend using a parachute for a splashdown in the Bay of Bengal.
The test mission will last a total 532 seconds from liftoff at 8 am to the crew module splashdown about 10 km from the Sriharikota coast. The rocket, ISRO’s new, low-cost Test Vehicle, will reach a peak relative velocity of 363 metres/ second (about 1307 km/ hr) during the flight. The crew module will be empty for the test.
Saturday’s TV-D1 flight will demonstrate, first, the new Test Vehicle — this is the reason why the test has been named Test Vehicle-Demonstration 1 (TV-D1).
Second, it will demonstrate a basic version of the crew module — the capsule in which the astronauts will be seated during the Gaganyaan human space flight. The test will check the functioning of systems for separating the crew module from the rocket in case of a mid-flight emergency (abort mission) and the escape of astronauts.
ISRO’s technical definition of the TV-D1 mission is, “In-flight Abort Demonstration of Crew Escape System (CES)”. The flight will “simulate the abort condition during the ascent trajectory corresponding to a Mach number of 1.2 encountered in the Gaganyaan mission”, including crew module separation and its safe recovery.
While the full-fledged test flight of the crew module into space and back will be carried out on the human rated LVM3 rocket (an upgraded version of the heavy lift GSLV Mk III rocket) in 2024, for the TV-D1 mission, ISRO will use a low-cost basic rocket it has built specifically to test systems.
This Test Vehicle will use existing liquid propulsion technology, but has innovations such as the throttleable and restartable L110 Vikas engine (which forms the core second stage of the LVM3 rocket), which is capable of controlling propellant use.
The only previous test flight of the crew module — called the Crew module Atmospheric Re-Entry Experiment or CARE — on December 18, 2014, used a GSLV Mk III rocket. But since each GSLV Mk III launch costs Rs 300-400 crore, ISRO has developed the cheaper Test Vehicle. The Gaganyaan human space flight programme has a budget of around Rs 9,000 crore.
“We will have many tests flights of the human capsule using a developmental launch vehicle called the Test Vehicle…,” ISRO chairman Dr S Somanath had said in 2018, when he was director of the Vikram Sarabhai Space Centre, which has developed the new rocket. “It (the Crew Escape System of the Gaganyaan mission) is the key, and we need to test it a number of times without incurring large costs.”
ISRO will use the Test Vehicle for several concepts that are under development, including the Scramjet engine technology for re-usable space launch vehicles.
On October 11, 2018, a failure of the Russian Soyuz FG rocket led to a premature end of Expedition 57 to the International Space Station (ISS). As soon as the failure was detected at an altitude of 50 km, the crew module was separated from the rocket in an emergency operation, and the two astronauts aboard the mission, Alexey Ovchinin of Roscosmos and Nick Hague of NASA, landed on Earth 402 km from the launch site at Baikonur cosmodrome in Kazakhstan. The failure of the Soyuz MS 10 mission was the first mid-flight failure of a Soyuz rocket since 1975, and the first failure of the Soyuz FG rocket in 55 launches.
ISRO has put safety of the crew at the centre of the Gaganyaan project, and has persuaded the union government that the 2022 deadline set by the Prime Minister on August 15, 2018 should be relaxed in order to ensure a safe and successful mission.
The crew module must be safe for astronauts under conditions of very high heat and pressure, and must have a reliable escape mechanism in the event of an emergency. ISRO is developing environmental control and life support systems for the crew module, as well as an integrated vehicle health management system which can sense anomalies that could put the life of an astronaut at risk, and trigger actions to abort the mission.
Some of these systems will be tested in the TV-D1 flight. The 2014 CARE test had assessed technologies including “the performance of parachute-based deceleration system, and a “Pad Abort Test-PAT” was conducted in July 2018.
After a flight of about a minute, at an altitude of 11.7 km, the Crew Escape System will separate from the Test Vehicle; and after about 90 seconds, the crew module will separate from the escape system. It will deploy parachutes, and descend slowly to the surface over about seven minutes. A diving team and ship of the Indian Navy will recover the crew module from the Bay of Bengal.
“This Test Vehicle mission with this CM (crew module) is a significant milestone for the overall Gaganyaan programme as a near-complete system is integrated for a flight test. The success of this test flight will set the stage for the remaining qualification tests and unmanned missions, leading to the first Gaganyaan mission with Indian astronauts,” ISRO said.
Dr Somanath has said that the timeframe for the Gaganyaan mission is now 2024 and even beyond, if failures are experienced in the development stages. “…We do not want to rush… The primary objective of human space flight is a sure-shot, safe mission. We have redefined it in such a way that we will achieve success in the very first attempt,” he said earlier this year.
“The current schedule is that there will be an unmanned mission in the beginning of next year. This year we will have the abort missions. The manned mission is being talked about for the end of 2024 or early 2025. It depends on various other scenarios,” the chairman said.
ISRO has completed the human rating of the LVM 3 rocket which will be used for the Gaganyaan mission. On May 13, 2022, it completed the static test of a human-rated solid rocket booster (HS200) that will be used in the first stage of the rocket. The testing of the human-rated versions of the liquid propellant L110-G engine for the second stage of propulsion and the third stage C25-G engines with cryogenic propellant has also been completed.
Four astronauts from the Indian Air Force have undergone training in Russia. They will undergo further training ahead of the final mission.
