"Even though it's weightless, the sash is heavy" — Onishi and Yui's simultaneous stay in space

"There's no gravity, but I'm inheriting a heavy sash," said Kimiya Yui, who arrived at the International Space Station (ISS) and joined Takuya Onishi, who was selected as an astronaut candidate in the same year as Yui was and had been staying there since March. This marked the fourth time in history that multiple Japanese astronauts have simultaneously stayed in space. Yui expressed his enthusiasm for his second long-duration mission, saying, "I want to create new history and deliver many topics that make people think the future is bright." After Onishi completed his duties as ISS commander and the handover to Yui, he safely returned to Earth in the early hours of the 10th of August, Japan time, and underwent rehabilitation and medical examinations. Science Portal followed the developments from Yui's departure from Earth to Onishi's return.

Two astronauts selected as candidates in the same year high-five while floating

At 12:43 AM on the 2nd, the American company SpaceX's "Crew Dragon" spacecraft No. 11, carrying Yui and three American and Russian astronauts, was launched from the Kennedy Space Center in Florida aboard the company's large Falcon 9 rocket. After separating from the rocket about 10 minutes later, the launch was successful. The spacecraft continued its automated flight and docked with the ISS at approximately 430 kilometers altitude at 3:27 PM the same day.

After confirming the airtightness of the connection and other factors, the hatch was opened, and Yui emerged into the ISS with a broad smile at around 5 PM as the second person to enter. He embraced and high-fived Onishi, who was waiting for him, rejoicing in their reunion. This was the fourth time Japanese astronauts have simultaneously stayed in space: in 2010 with Soichi Noguchi and Naoko Yamazaki, in 2021 with Akihiko Hoshide and Noguchi, and also with businessmen Yusaku Maezawa and Yozo Hirano, who stayed at the ISS as tourists.

With the arrival of four crew members, the ISS temporarily became a large household with 11 people. At the welcome ceremony, Yui said, "I want to make this long-duration stay the best one together with everyone."

During the approximately six-month stay period, the Japan Aerospace Exploration Agency (JAXA) plans to carry out the following experiments using the Japanese Experiment Module "Kibo": ▽Testing carbon dioxide removal technology for future crewed exploration ▽Investigating errors in precision instruments under zero gravity conditions ▽Verifying the operation of information terminals, cameras, and drone-type filming robots used by astronauts ▽Studying the effects of zero gravity on plant cell division ▽Investigating how solid materials burn in zero gravity in preparation for fires ▽Recreating the formation process of chondrules, microscopic particles, in furnaces to understand planetary formation ▽Studying the properties of materials with melting points above 2000℃ by floating them in furnaces. Additionally, they plan robot competitions for young people domestically and internationally, public experiment applications, deployment of microsatellites from universities, and photography by exposing cameras outside the station. Yui is expected to handle the majority of these tasks.

Yui was born in Nagano Prefecture in 1970. He graduated from the National Defense Academy of Japan with a specialization in science and engineering in 1992 and joined the Japan Air Self-Defense Force. After serving at the Air Staff Office of the Ministry of Defense, he was selected as an astronaut candidate by JAXA in 2009. In 2015, he stayed on board the ISS for about five months, where he captured the cargo spacecraft "Kounotori" No. 5 with a robotic arm, installed experimental equipment, and conducted numerous experiments. He served as Chief of the JAXA Astronaut Group from November 2016 to March 2023.

"The place upon which I staked my entire youth"

Commemorating their simultaneous stay, Onishi and Yui held a press conference via link with reporters gathered at JAXA's Tokyo facility on the 4th.

Onishi said, "I'm really happy to be able to stay with Yui, even for a short time. Being given the major responsibility of commander is the result of the trust built by senior members of JAXA and the significant contributions from the operation of 'Kibo' and 'Kounotori.' I worked with the thought of adding even a little to Japan's trust, and I believe I was somehow able to fulfill this major role."

Upon receiving a special sash from Onishi, Yui responded, "This (sash) contains the history of Japan's space development and the thoughts of those involved and those supporting us, so even though it's weightless, it's really heavy. I want to deliver many topics that make everyone in Japan feel that the future is bright when they see ISS activities."

The United States plans to end ISS operations in 2030. When asked by a reporter whether they felt "the ISS is still too good to waste" or "the end of its lifespan is approaching," Onishi said, " I don't have the impression that maintenance has increased much compared with my previous stay (his 2016 long-duration mission), and personally, I think it can still be used. However, whether that's the optimal solution is another question. There's the challenge of handing over low orbit utilization to the private sector and revitalizing the space industry. I believe the ISS's social role is approaching its end." Yui added, "Low orbit activities are important and cannot be interrupted. The handover of roles from the ISS to the next commercial station must go smoothly, like a relay race."

When asked "What does the ISS mean to you personally?" Onishi quoted a passage from American poet Samuel Ullman's work: "Youth is not a time of life; it is a state of mind." He revealed, "The ISS is the place upon which I staked my entire youth as an astronaut, and it's a very special existence." Yui said, "It's truly the hope in my heart. This is probably my last stay, but I want everyone to feel that hope too."

Between handover duties, the two conducted a "photo contest" on X (formerly Twitter). They posted side-by-side photos they took of Japanese airspace from inside the ISS and asked the public, "Which one do you like better?" There were 11,200 votes, and Onishi won by a 15% margin.

Incidentally, there is an astronaut other than the two who was selected as a candidate in the same year, Norishige Kanai. A former Maritime Self-Defense Force submarine medical officer, he stayed at the ISS from December 2017 to June 2018, handling various experiments, extravehicular activities, and the capture of American cargo spacecraft.

Is Earth a "harsh environment"? Social media posts immediately after return

On the 6th of this month, just before Onishi's return, an ISS commander handover ceremony was held inside the station. Onishi said, "This is humanity's outpost, a place to advance science and technology and conduct exploration. Handing over command is very gratifying," and passed the key, the symbol of command, to his successor, Russia's Sergei Ryzhikov. Ryzhikov, referring to the history of the 1975 docking between the Soviet Soyuz spacecraft and the American Apollo spacecraft during the Cold War, when astronauts exchanged visits, said with emphasis, "Unfortunately, on our beautiful planet, people cannot always understand each other, but in space, we can cooperate effectively."

Onishi had served as commander since April 19. He was the third Japanese commander after Koichi Wakata in 2014 and Hoshide in 2021. As the ISS site commander, he fulfilled the heavy responsibility of overseeing astronauts and monitoring the station's conditions and activities. After bidding farewell, he boarded the Crew Dragon 10 spacecraft, which is the same aircraft as the one operated in the outbound travel, with three American and Russian crew members. On the morning of the 9th at 7:15 AM, they separated from the ISS. The craft gradually descended and entered the atmosphere. Opening parachutes, it splashed down at 12:33 AM on the 10th off San Diego, California.

Upon returning, he resumed posting on X. "When I lie in bed, I feel like my body is sinking into the bed," and "I can walk this much about 10 hours after returning (with video), but I'm desperately trying to maintain my body's balance. Everyone living in such harsh conditions is really amazing," he wrote humorously about his physical changes and experiences with medical examinations.

Onishi was born in Tokyo in 1975. He graduated from the Department of Aeronautics and Astronautics at the University of Tokyo's School of Engineering in 1998 and joined All Nippon Airways. After serving as a co-pilot, he was selected as an astronaut candidate by JAXA in 2009. He was certified as an astronaut in 2011. From July to October 2016, he stayed on board the ISS for four months, capturing the American commercial cargo spacecraft "Cygnus" No. 6 with a robotic arm, supporting extravehicular activities, working on enhancing Kibo's equipment, and conducting numerous experiments. In 2020, he was certified as a JAXA Flight Director for Kibo operations control, supporting astronaut activities from the ground. This was his second flight.

"Successful failure" leader Lovell dies

At the timing of the report of these events, news of a major figure's death also came in. According to NASA and other sources, Jim Lovell, who served as commander of "Apollo 13," which achieved a return to Earth despite an explosion during flight in 1970, died on the 7th in Lake Forest, Illinois. He was 97 years old. The cause of death has not been announced.

Born in Ohio in 1928, he became a Navy pilot and was selected as a NASA astronaut in 1962. He succeeded in a 14-day flight with "Gemini 7" in 1965, anticipating crewed lunar flights, and achieved the first rendezvous with another crewed spacecraft (flight involving matching speeds and approaching). He flew on "Gemini 12" in 1966. In 1968, he achieved the first lunar orbital flight with "Apollo 8."

Apollo 13 aimed for the lunar surface following missions 11 and 12 in 1969, but two days after launch, an oxygen tank in the service module exploded. Abandoning the lunar landing, Lovell and the other two astronauts temporarily took refuge in the lunar lander. They minimized drinking water and power consumption and endured the cold temperatures inside the spacecraft through various innovations. More than three days after the explosion, they returned safely to Earth.

Because the astronauts' lives were saved despite facing a critical crisis, this accident has been passed down as a "successful failure." It was also depicted in the movie "Apollo 13" (1995, USA), which Onishi watched as a student, and which made him strongly aware of the astronaut profession.

Although Lovell made a strong impression on Apollo 13, there was also a striking episode where waste scattered from bags in the zero-gravity cabin of Gemini 7, causing him trouble. Moreover, at that time, he lost one toothbrush inside the spacecraft and had to share the remaining one with fellow crew member Frank Borman. When reflecting on the efforts and hardships of space development pioneers, one cannot help but feel respect.