More than fifty years after the end of the Apollo program, NASA plans to return to the Moon by 2024 as a "proving ground" to test the next generation of spacecraft ahead of an eventual crewed mission to Mars.

The new program has been named Artemis after Apollo's twin-sister in Greek mythology, and the space agency has said that the mission will see the first woman to stride the lunar surface.

So, who will she be? No one knows for sure, but it's a likely bet the candidate will be selected from among NASA's current roster of 12 female astronauts.

They're aged between 40 and 53, and are former military pilots, medical doctors and scientists who were picked from among thousands of applicants since the late 1990s.

Predicting who will join Neil Armstrong in the annals of history isn't an exact science, but several former astronauts and experts interviewed by AFP say the proximity of the deadline mean it probably won't be a new recruit.

Scientists and soldiers

The four women of the 21st class of astronauts, recruited in 2013, represent a good mix of youth and experience. Currently between the ages of 40 and 41, they will all have made their first space forays between now and 2020.

Anne McClain, an ex-army helicopter pilot, will be in the International Space Station (ISS) until the end of June.

Well spoken, with a self-assured gaze and a light smile, she embodies the ineffable "right stuff" of NASA's early recruits.

Also currently in the ISS is Christina Koch, an engineer and passionate mountain climber. She will soon beat the record for the longest time a woman has been in space, at 11 months.

But their two female colleagues from the same class, Jessica Meir, a marine biologist who specializes in penguins and geese, and former F/A 18 fighter pilot Nicole Mann, who flew in Iraq and Afghanistan, are also highly qualified.

They are both in the middle of their training to go to the ISS.

Opaque process

There's no upper age limit for space. The iconic John Glenn made his last flight at the age of 77 as a US senator.

There's nothing therefore excluding the highly experienced Sunita Williams, who is preparing for her third space mission and will be 58 in 2024.

Especially since NASA has long "appreciated the leadership skills that came along with test pilots," according to Kent Romninger, the former chief of the astronaut office from 2002 to 2006.

  NASA women astronauts (top row) Stephanie D. Wilson, Jessica U. Meir, Christina H. Koch, Kathleen Rubins, (middle row) Sunita L. Williams, K. Megan McArthur, Shannon Walker, Tracy Caldwell Dyson, (bottom row) Jeanette J. Epps, Anne C. McClain, Nicole Aunapu Mann and Serena M. Aunon-Chancellor.

NASA plans to return to the moon by 2024 as a "proving ground" to test the next generation of spacecraft.

"Suni," as she's known, has piloted about thirty different aircraft in her military career.

Two other women, Serena Aunon-Chancellor and Kate Rubins, have also flown to space recently.

The other five haven't flown since 2010 but remain on active duty.

There are five women in the 2017 batch but they have yet to complete their initial training.

They're not ruled out yet, but the calendar isn't on their side -- especially since NASA tends to stick to a cycle of astronauts once their order is set, says Michael Lopez-Alegria, a former astronaut who spent 20 years with the agency.

When it comes down to the final call, though, the process "is fairly opaque," he conceded.

The mission forsees a four-member crew, two of whom will walk the Moon. Why not have two women?

Agence France-Presse