Sunita Williams after the SpaceX capsule docked át the ISS on Sunday.
Astronauts Sunita Williams and Butch Wilmore began a 17-hour return journey to Earth on Tuesday aboard a SpaceX capsule, departing the International Space Station where they had spent over nine months instead of the initially planned eight days.
The Dragon capsule, carrying Williams, Wilmore, another Nasa astronaut Nick Hague and Russian cosmonaut Alexandr Gorbunov, undocked from the ISS at 1.05am US Eastern Time (10.35am IST) and is scheduled for a splashdown off the Florida coast at 5.57pm (3.27am on Wednesday IST).
Dragon’s departure from the ISS and re-entry is designed to be fully autonomous, requiring no action from the crew onboard, a Nasa official said, while the US space agency live-streamed the undocking that occurred around 420km above the western Pacific Ocean.
After the separation, the capsule activated its onboard thrusters to increase its distance from the ISS — “departure burns” that would be followed by a series of “phasing burns” that will lower its orbit and align its trajectory with the splashdown site.
During their return journey, the astronauts — the quartet called Nasa’s SpaceX Crew-9 — will be able to sleep and have a meal before preparing for the capsule’s parachute-assisted splashdown. A SpaceX recovery vehicle will pick up the astronauts after the splashdown.
Williams and Wilmore had flown to the ISS in June last year as test pilots for the maiden crewed flight of Boeing’s Starliner spacecraft. But as Starliner approached the ISS, Nasa and Boeing engineers noted helium leaks and thruster issues on the spacecraft. After probing the issues, Nasa decided to prioritise safety and brought a pilotless Starliner back to Earth, extending Williams’s and Wilmore’s originally planned eight-day trip to over nine months.
During their 286 days on the ISS during this mission, Williams and Wilmore have orbited the Earth 4,576 times and travelled over 194 million km, a Nasa official said. That distance is equivalent to nearly four times the Earth-Mars distance when the two planets are at their closest.
The Crew-9 astronauts have helped conduct around 150 experiments in space, spending over 900 hours on scientific research on the ISS — an orbiting lab preparing to celebrate in November this year 25 years of continuous human presence.
Tasks for the astronauts also involved spacewalks for routine ISS maintenance as well as for science projects. One project had involved collecting swabs from the outer surface of the station to determine whether microbes can survive the harsh space environment.
Williams now holds the record for the longest cumulative spacewalking time by a woman, logging 62 hours and 6 minutes across the nine spacewalks through her three missions in space.
After the splashdown, each astronaut will undergo medical evaluation and health tests that will help specialists design a “reconditioning” programme to restore their physical performance to their preflight baseline levels, a Nasa official said. The specialists will tailor each astronaut’s rehabilitation plan based on the results of the evaluation and health tests.
Astronauts who have spent multiple months in microgravity typically face physical challenges such as bone density loss, balance issues and other physiological changes, including difficulties in adjusting to Earth’s gravity.
A Dragon capsule had on Sunday ferried Crew-10 — Nasa astronauts Anne McClain, Nichole Ayers, Japanese astronaut Takuya Onishi and Russian cosmonaut Kirill Peskov — to the ISS to replace Crew-9.
Besides the Crew-10 quartet, Crew-9 has left behind on the ISS three others — Nasa astronaut Don Pettit and Russian cosmonauts Alexey Ovchinin and Ivan Vagner. The three are scheduled to return aboard a Soyuz spacecraft in April this year.
Williams’s and Wilmore’s stay on the ISS is not the single-longest flight in space history. That distinction belongs to the late Russian cosmonaut Valeri Poliyakov who spent 437 days aboard Russia’s Mir space station in 1994-95, followed by Nasa astronaut Frank Rubio who spent 371 days aboard the ISS during 2022-23. Among Nasa astronauts, Mark Vande Hei and Christina Koch have also spent more than 300 days in space while Peggy Whitson has spent 289 days on the ISS.