Explainer: The complex procedures Shubhanshu Shukla, his crew need to begin their journey home-OxBig News Network

The US National Aeronautics and Space Administration (NASA) has announced that the four-member crew of the Axiom-4 mission, including Indian astronaut Group Captain Shubhanshu Shukla, will depart the International Space Station (ISS) on July 14.

By then, Shukla and his space mates would have spent 19 days aboard the ISS, orbiting 415 km above Earth. Their Dragon C-213 spacecraft, piloted by Shukla, had docked with the ISS on June 26 after a 28-hour journey from NASA’s Kennedy Space Centre in Florida.

“We are working with the station program, watching the Axiom-4 progress carefully. The current undocking target is July 14,” Steve Stitch, Manager, NASA Commercial Crew Program, said at a press conference.

“Pending favourable weather conditions, the Axiom Mission 4 (Ax-4) crew is set to undock from the International Space Station no earlier than Monday, July 14, at 7:05 am ET (about 4.30 India time). Commander Peggy Whitson, Pilot Shubhanshu “Shux” Shukla, and Mission Specialists Sławosz “Suave” Uznański-Wiśniewski and Tibor Kapu are making the most of their final days on orbit, pushing forward a wide range of experiments that could shape the future of space exploration and improve life on Earth,” a post by Axiom Space, a private company collaborating for the mission with NASA and SpaceX, said when it was Friday morning in India.

Re-entering the Dragon, attached with ISS’s space facing Harmony module, is not a simple task, but involves a complex series of established protocols, multiple steps and methodical sequences, all of which have to be executed carefully.

To begin with, the crew, led by US astronaut Peggy, will perform thorough checks on the Dragon spacecraft, manufactured by SpaceX. This includes validating the integrity of critical onboard systems such as life support, propulsion and communications to ensure the spacecraft is ready for undocking and re-entry into the Earth’s atmosphere.

They will also check for any air leaks between the Dragon and the ISS’s docking port to confirm a secure seal to ensure safety before closing the hatch. This step is the same as the ingress process.

They will secure all equipment, experiments, and personal items inside the Crew Dragon to prevent objects from floating during microgravity maneuvers. The Ax-4 crew, having conducted over 60 scientific experiments, will ensure all research materials are properly stowed for return to Earth.

After the hatch is closed and a proper seal is ensured, which is critical to maintain the spacecraft’s internal environment during departure and flight, the crew will secure all equipment, scientific cargo and personal items inside the spacecraft to prevent objects from floating during microgravity manoeuvres. The hatch is generally closed several hours before undocking.

The crew will don their specially designed spacesuits, which are worn during dynamic phases like undocking and re-entry to protect against potential depressurisation or any other emergency.

The final steps before undocking will involve configuring the Dragon’s flight systems including powering up the navigation and propulsion systems. The undocking process is autonomous, controlled by the Dragon’s onboard systems, but the crew will monitor the process and be ready to intervene if manual override is required.

All through, the Ax-4 crew will remain in constant communication with mission control on ground as well as the seven-member crew of Expedition-73 manning the ISS, for coordination, checks and validating procedures.

A final “go” or “no-go” decision, in consonance with mission control will be taken. The return journey is expected to take about 17 hours and the Dragon will splash down into the Pacific.

The crew has undergone extensive training at NASA’s Johnson Space Centre to ensure that they are proficient in managing the undocking sequence, operating the spacecraft’s systems and responding to contingencies and also prepared to handle the physical stress of re-entry and manage the transition from microgravity to Earth’s gravity.

The last day onboard the ISS will involve working with the Expedition-73 crew to complete final handover formalities and wrapping up experiment data or equipment. The crew are involved in conducting over 60 experiments related to space science. A farewell ceremony is also expected.