Ax-4 Crew Begins Historic Journey Home from Space Station
After a landmark 18-day stay aboard the International Space Station (ISS), Indian Air Force Group Captain Shubhanshu Shukla and his three international crewmates are set to begin their carefully orchestrated return to Earth on Monday. The Axiom-4 (Ax-4) mission, a historic first for India's human spaceflight program, will conclude with a 21-hour journey culminating in a splashdown in the Pacific Ocean.
The crew, which also includes Commander Peggy Whitson of the USA, Poland's Sławosz Uznański, and Tibor Kapu of Hungary, successfully conducted over 60 scientific experiments during their time in orbit. Among these were seven key studies for the Indian Space Research Organisation (ISRO), focusing on critical areas like the cultivation of microalgae, the effects of microgravity on muscle health, and plant growth in space. These experiments are vital for informing India's future ambitions, including the planned Gaganyaan mission.
The crew's return aboard the SpaceX Crew Dragon spacecraft, named "Grace," is a multi-stage process requiring precise execution from both the astronauts and ground control teams.
The Return Sequence
1. Departure Preparations:
The process begins approximately three hours before departure. The crew will carefully stow valuable scientific samples, including ISRO's experiments, within the pressurized cabin of the Crew Dragon. They will then don their custom-fitted SpaceX pressure suits as a primary safety measure for the journey home. On the ground, mission control centers at SpaceX and NASA will conduct final verifications of the spacecraft’s essential systems.
2. Undocking and Separation:
At approximately 4:30 p.m. IST on Monday, the Crew Dragon will undock from the ISS's Harmony module. A series of carefully timed thruster burns will gently push the spacecraft away from the station, initiating its independent flight. A subsequent burn about ten minutes later will increase the separation rate, ensuring a safe distance is maintained.
3. The Journey Through Orbit:
For the next 21 hours, the spacecraft will orbit the Earth. During this phase, the crew, with Shukla serving as pilot, will monitor all systems via touchscreen controls, ensuring everything from life support to navigation is functioning correctly. This period also allows ground teams to finalize the re-entry trajectory for a precise landing.
4. The Fiery Re-entry:
The most dynamic phase of the return begins about 21 hours after undocking. The spacecraft will jettison its external "trunk," which houses the solar panels, and switch to internal battery power. A 12-minute deorbit burn will then slow the capsule, angling it for its descent into Earth's atmosphere at a staggering speed of 27,000 km/h.
The capsule's heat shield will endure temperatures up to 1,900°C, protecting the crew inside. During this intense 15-minute period, the astronauts will experience G-forces up to four times their body weight and a temporary communications blackout caused by the plasma sheath forming around the spacecraft.
5. Splashdown and Recovery:
At an altitude of 5.5 kilometers, two drogue parachutes will deploy to dramatically slow the capsule. These will be followed by four large main parachutes, which will gently lower the spacecraft to a final splashdown in the Pacific Ocean, scheduled for around 3:00 p.m. IST on Tuesday. A SpaceX recovery ship will be on standby to retrieve the capsule and its crew within minutes, where they will undergo immediate medical checks before beginning their rehabilitation.
This successful return will not only be a personal triumph for the crew but also a significant milestone for international cooperation and a proud moment for India's advancing space program.
