NASA announced Monday its 10 latest trainee astronauts, who include a firefighter turned Harvard professor, a former member of the national cycle team, and a pilot who led the first-ever all-woman F-22 formation in combat.

The 2021 class was whittled down from a field of more than 12,000 applicants and will now report for duty in January at the Johnson Space Center in Texas, where they will undergo two years of training.

"We're going back to the Moon, and we're continuing on to Mars -- and so today we welcome 10 new explorers," NASA administrator Bill Nelson said at an event to welcome the recruits.

"Alone, each candidate has 'the right stuff,' but together they represent the creed of our country: E pluribus unum – out of many, one," he added.

The 10 candidates, who range in age from 32 to 45, will learn how to operate and maintain the International Space Station, train for spacewalks, develop robotics skills, safely operate a T-38 training jet, and learn Russian to communicate with their counterparts.

After they graduate, they could be assigned to missions aboard the ISS or deeper into space, including NASA's planned return to the Moon later this decade under the Artemis mission, which will include the first woman and person of color to set foot on lunar soil.

The field was open to US citizens who hold a master's degree in a STEM (science, technology, engineering and mathematics) field -- the first time such a requirement was added -- and passed an online test. The master's degree requirement could also be met by a medical degree or completion of a test pilot program.

- Childhood dreams -

"I first became interested in becoming an astronaut at a very, very early age," said Jessica Wittner, 38, a lieutenant commander in the US Navy who is a test pilot and aerospace engineer.

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Christina Birch (C) is introduced at NASA's astronaut candidate announcement event on December 6, 2021 at Ellington Field in Houston, Texas / © AFP

"I was that little girl in school who would play with rockets in the park by the house and loved science class."

Others include fighter pilot Nichole Ayers who has more than 200 combat hours and is one of a few women currently flying the F-22 jet. In 2019 Ayers led the first all-woman formation of the aircraft in combat.

Christopher Williams, 38, is an assistant professor of medical physics at Harvard University.

"I was splitting my time between helping to research better ways we can target radiation therapy for cancer, and then actually working as part of a multidisciplinary team to treat patients," said Williams, who holds a doctorate in astrophysics from MIT and has served as a volunteer emergency medical technician and firefighter.

Anil Menon, 45, is a lieutenant colonel in the US Air Force who was previously SpaceX's first flight surgeon before an earlier stint at NASA.

A physician born to parents from India and Ukraine, he was a first responder during the 2010 earthquake in Haiti, 2015 earthquake in Nepal, and the 2011 Reno Air Show accident.

Christina Birch, 35, holds degrees in mathematics and biochemistry and molecular biophysics, as well as a doctorate in biological engineering from MIT.

She left a career in academia to race as a track cyclist on the US team, qualifying for the Olympics and winning World Cup medals in the team pursuit and Madison race.

NASA's last class graduated in 2017. Two of its members, Raja Chari and Kayla Barron, are currently serving aboard the ISS.