Nasa has unveiled its new class of astronaut candidates, who could fly to the space station and on future missions to the Moon.
They have gone through an interview process with several rounds, team exercises, a thorough medical check and aptitude tests.
The six men and four women were selected from a pool of about 12,000 applicants.
The candidates will now undergo two years of training before graduating.
"We've always had a frontier to expand and the frontier now is upwards, out into the cosmos," said Nasa's administrator Bill Nelson.
The group will participate in what's known as the basic Astronaut Candidate training programme, which is designated to develop the knowledge and skills they will require once they are selected for a flight.
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The candidates are required to complete military water survival exercises, fly Nasa's T-38 training jets, and become scuba-qualified to prepare them for the spacewalk training - which takes place in a huge pool at Johnson Space Center in Houston.
Final selection as an astronaut is not guaranteed: they are required to complete the training to a satisfactory level.
Those who do graduate become eligible for flights to the space station and to the Moon - providing Nasa's Artemis programme is not delayed. They are unlikely to be assigned to flights straight away, however, as they continue to develop their skills for a while after becoming fully-fledged astronauts.
The new astronaut candidates are:
Nicole Ayers, 32, a major in the US Air Force from Colorado
Marcos Berríos, 37, also a US Air Force major. He grew up in Guaynabo, Puerto Rico
Christine Birch, 35, a former track cyclist with the US team who has a doctorate in biological engineering
Deniz Burnham, 36, a lieutenant in the US Navy reserve and a drilling engineer from Wasilla, Alaska
Luke Delaney, 42, a research pilot at Nasa and a retired major in the US Marine Corps
Andre Douglas, 35, a staff member at Johns Hopkins University who has served in the US Coast Guard
Jack Hathaway, 39, a commander in the US Navy, who hails from Connecticut
Anil Menon, 45, a flight surgeon for Elon Musk's company SpaceX who helped launch the first private flight to the International Space Station
Christopher Williams, 38, a medical physicist who grew up in Potomac, Maryland
Jessica Wittner, a lieutenant commander in the US Navy from California
"Each of you has amazing backgrounds," Pam Melroy, a former Nasa astronaut and the agency's deputy administrator, told the candidates. "You bring diversity in so many forms to our astronaut corps and you stepped up to one of the highest and most exciting forms of public service."
Former US track cyclist Christine Birch offered advice for other budding astronauts. "If you do the little things well, they add up to something big," she explained - perhaps including being able to go into space.
The first astronauts belonging to Nasa's previous class - Kayla Barron and Raja Chari, who graduated in January 2020 - made their first flights into orbit last month. But for other successful candidates, the path to a flight assignment can take several years longer.
Back in the 1990s and 2000s, Nasa had only one way of getting into space - the shuttle. These candidates join the agency at a challenging and complex time, but also an exciting one.
Nasa astronaut Reid Wiseman said: "We are in the golden age of human spaceflight."
Nasa remains a partner in the International Space Station (ISS), so candidates need to understand the ISS systems and demonstrate a working knowledge of Russian.
Some will be assigned to fly on either of the two spacecraft Nasa uses to fly to the ISS - SpaceX's Crew Dragon and Boeing's Starliner. Others will be selected for missions to the Moon under Nasa's Artemis programme.
These astronauts will need a deep understanding of Nasa's Orion spacecraft and the lander the agency plans to use to get to the lunar surface. This is likely to be based on Elon Musk's Starship vehicle currently under development at a SpaceX facility in southern Texas.
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