Undocking to splashdown: How Shubhanshu Shukla will return from space
What's the story
Indian astronaut Shubhanshu Shukla and his three Axiom-4 mission crewmates will return to Earth from the International Space Station (ISS) today. The Dragon spacecraft carrying them will undock from the ISS at 4:30pm IST and follow a pre-planned trajectory for re-entry into Earth's atmosphere. The splashdown is expected off California's coast tomorrow at around 3:00pm IST, marking a journey of some 22.5 hours after undocking.
Return procedure
Dragon spacecraft to perform several checks before undocking
The return to the spacecraft, which is docked to the ISS's space-facing Harmony module, is a multi-step process. It includes several checks and the careful execution of standard procedures. The crew, led by US astronaut Peggy Whitson, will first inspect the Dragon spacecraft in detail before undocking. They will then perform tasks like cargo loading, crew prep, hatch closure and pressurization of the spacecraft.
Pre-undocking tasks
Crew will check critical systems before heading back
The crew will check critical systems like life support, propulsion, as well as communication to ensure everything is functioning properly before heading back to Earth. They will also check for air leaks between the Dragon and ISS docking port to ensure a proper seal before hatch closure. Inside the spacecraft, all items including experiments and personal belongings will be secured so they don't float around in microgravity.
System setup
Hatch closure and sealing
Once the hatch is closed and sealed, which maintains cabin pressure during the departure and flight, everything inside the spacecraft will be secured again. This hatch is generally closed a few hours ahead of undocking. The crew will then configure Dragon's systems for undocking including navigation and propulsion. The actual undocking is automated by the spacecraft's onboard system, but the astronauts will monitor closely and shall be ready to intervene if necessary.
Mission control
What happens during the return journey?
A final "go" or "no-go" decision will be made in consultation with mission control. The return journey is tipped to take about 22 hours, culminating in a splashdown in the Pacific Ocean. Once ready, power and data cables called umbilicals will disconnect and 12 latches will open putting the capsule into a soft-capture state. Then using 12 Draco thrusters, Dragon will perform "Burn Zero," a brief burn that helps it gently depart from ISS without sticking at docking port.
Statement
Here's what Shukla had to say
Soon after, Dragon will perform "Departure Burn One," which shall increase its speed and distance from the ISS. This trip will culminate in a splashdown on Earth. During a farewell address from the ISS, Shukla expressed gratitude for the incredible journey and thanked all those involved in the mission. He also spoke about India's future in space exploration, saying "Our journey ahead into space exploration may be long and arduous but it has begun."