Sławosz Uznański-Wiśniewski

Sławosz Uznański-Wiśniewski (; ; born 12 April 1984) is a Polish astronaut and engineer working at the European Space Agency (ESA), formerly employed at CERN. In June 2025, he became the second Polish national to go to space, marking the country's return to crewed spaceflight after nearly 47 years and its first mission aboard the International Space Station. He was the 701st person in space and the 635th person to reach orbital flight.

Early life and education Sławosz was born in Łódź, at that time the Polish People's Republic (PRL), on 12 April 1984 to art historian parents Piotr Uznański and Maja Marquardt-Uznańska. The day of his birth fell on the 23rd anniversary of the first human orbital spaceflight. Every birthday, Uznański's mother would wish him "all the best wishes on Cosmonaut Day". Growing up in the 1980s, after Mirosław Hermaszewski's spaceflight in 1978, Uznański's childhood dream was to go to space. In his teenage years, he was on the Polish national sailing team.

Uznański was raised in Łódź, attending the Adam Asnyk 8th General Education High School. He was a member of the 24th Łódź Scouting Group "Ilczi" of the Polish Scouting and Guiding Association. In 2008, he graduated with honours with master's degree from the Łódź University of Technology and from the University of Nantes; in the same year, he also received a engineer diploma from the Polytech Nantes. In 2011, he received a doctor's degree with distinction from the University of the Mediterranean Aix-Marseille II for his thesis on radiation-tolerant designs for space applications.

Career and ESA

During his doctorate, Uznański worked at the STMicroelectronics manufacturing facility in Crolles, France. In 2019, he was a technical expert and reviewer for the Horizon 2020 programme; investigating European autonomy and technological competitiveness in the space industry for the European Research Executive Agency (REA). In an interview, Uznański revealed that Mirosław Hermaszewski (Poland's first cosmonaut) supported him throughout the process and was the first person to call him with congratulations on the morning after he was selected. His intensive preparation programme with ESA, NASA, SpaceX, and JAXA took him to training centres in several countries.

Axiom and Ignis

Uznański joined the ESA to undergo his training for Axiom Mission 4 (Ax-4) on 1 September 2023. It was expected to launch no earlier than April 2025. On board the Crew Dragon that would take the mission to the ISS, Uznański would bring the same Polish flag that flew to space in 1978 attached to Hermaszewski's spacesuit as well as the Polish national dish of pierogi (prepared in lyophilised form by Polish chef ). Uznański's POLSA mission is named Ignis. Andrzej Pągowski, who designed a poster for Hermaszewski's 1978 spaceflight, created a new poster for the Ignis mission that was also taken by Uznański-Wiśniewski to be presented aboard the ISS. The astronaut also took to space with him a piece of Baltic amber from Sobieszewo Island and his scouting krajka. The Axiom 4 flight was delayed several times between May and June 2025 for a number of reasons, including unfavourable weather, excessively strong winds in the upper parts of the atmosphere within the flight corridor of the rocket, problems with the Dragon capsule, and a fuel leak detected only a several dozen hours before one of the planned start dates on 10 June. The flight dates were originally planned for 29 May, 8 June, 10 June, 12 June, 18 June, and 22 June 2025. The astronauts spent one and a half months in quarantine before lift-off. and ultimately successfully launched from LC-39A at 6:31 am UTC (2:31 am EDT) on that day.

Travelling with the speed of at an altitude of 200 kilometres, Uznański-Wiśniewski delivered the following address to the Polish nation: Blockquote "Dear Poles,

Following a 28-hour rendezvous, Ax-4 docked with the ISS at 10:31 am UTC (6:31 am EDT) on 26 June, 2025. Hatches were opened at 12:14 am UTC (8:14 am EDT), allowing Uznański-Wiśniewski and his crew mates to be formally welcomed onto the station. With their arrival, the ISS crew of Expedition 73 grew to 11 astronauts from 6 different countries. During the welcoming ceremony, Uznański-Wiśniewski received a badge that signified he was the 635th person to reach orbital flight. When handed the microphone, he stressed the importance of the experimental side of the mission.

On board the ISS, Uznański-Wiśniewski and his peers were set to take part in 60 experiments evaluated by researchers from 31 countries. The next day, the crewed capsule splashed down in the Pacific Ocean off San Diego on 9:32 am UTC (5:32 am EDT), ending their mission after more than 20 days in space on Tuesday, 15 July, 2025. Uznański-Wiśniewski underwent rehabilitation at the European Astronaut Centre near Cologne in Germany.

Personal life

Uznański-Wiśniewski speaks Polish, English, and French. In his spare time, he enjoys exploring the world through high-altitude mountaineering expeditions, trips to remote areas of the planet, and sailing escapades.

In January 2025, Sławosz Uznański married Aleksandra Wiśniewska, a politician, political scientist, humanitarian, and social activist. The couple took on the double-barrelled surname of Uznańscy-Wiśniewscy. Their wedding bands, made of meteorite and a bullet from Aleksandra's humanitarian missions, were taken by Sławosz to space.

Cultural significance Anticipating the second Polish crewed spaceflight, the Silesian–Dąbrowa Bridge in Warsaw was illuminated with blue light. Similar events took place in other parts of Poland, such as Gdynia, where the Emigration Museum was also illuminated in blue. In June 2025, Łódź artists and Grzegorz Fajngold, playing as the band Maszynowa, created the song Kosmos dla wszystkich ("Cosmos for everyone") to commemorate Uznański-Wiśniewski's flight. The track was recorded on the day of Axiom 4 mission's lift-off. The fact that Uznański-Wiśniewski took to space pierogi made by a Kielce-based company was honoured in August 2025 through the Misja pierogi: z Kielc do kosmosu ("Mission pierogi: from Kielce to the cosmos") mural on the wall of the Poczta Polska (Polish mail service) building in Kielce. The mural, painted by a team led by Małgorzata Warsiewicz, was positively received by the locals.

Honours and awards Jubilee medal for the 600th anniversary of Łódź, given in 2023 to distinguished persons from the city ESA Astronaut Wings in 2023 Universal Astronaut Insignia for orbital flight 635 – awarded in 2025 by the Association of Space Explorers Honorary Citizenship of Łódź