By the end of the year, Hayley Arceneaux will be the youngest American in space and one of the first tourists to enter orbit unaccompanied by professional astronauts.

It is a feat made all the more remarkable by her battle to overcome a childhood cancer that robbed the 29-year-old of her dream of becoming an astronaut herself.

Due to the bone cancer she overcame, Arceneaux has steel rods in her left leg -- which until recently were enough to shatter her hopes of going into space.

Enter Jared Isaacman, a young American billionaire with a passion for space exploration who chartered a SpaceX Falcon 9 rocket at his own expense and decided to take three people with him, including Arceneaux.

Arceneaux said she hopes to be an inspiration with "this precedent that it's going to set and what it's going to show these other kids going through cancer treatment."

The first person chosen for this unprecedented mission, named Inspiration4 and set to take off at the end of 2021, was in fact Arceneaux.

The young woman was treated as a child at St Jude's Children's Research Hospital in Memphis, Tennessee, which specializes in childhood diseases, including cancer.

Isaacman hopes to raise $200 million for the hospital on his space mission.

"I got a phone call pretty much out of the blue in early January, and it was from St Jude... They basically said, 'Do you want to go to space?'" Arceneaux told AFP.

"Immediately I said, 'Yes, yes, absolutely!'" said Arceneaux, who now works for the same hospital that cared for her, as a medical assistant.

As a child, she visited the NASA space center in Houston, Texas. "Of course, I wanted to be an astronaut," she said. "But then a few months later I was diagnosed with cancer, and it really changed my whole world."

"Until now, astronauts have had to really be physically perfect, which is not a category that I fall into because of surgeries I've had on my leg. And that's one thing I'm so excited about with this mission, it is opening space travel up to anyone," Arceneaux said.

'Dream big'

"Being the youngest American to go to space is such an honor but honestly, what I'm more excited about is being the first pediatric cancer survivor to go to space," she said.

"I would just love to inspire my patients to dream big and to not limit themselves. And I really hope to show them while I'm in space that absolutely anything is possible."

One of the two remaining seats on the mission will be drawn from those who enter a raffle and are encouraged to donate to St Jude's.

The other will be picked by a panel of judges from entrepreneurs who use an e-commerce tool from Isaacman's company, Shift4 Payments.

They are to be announced later this month and will begin their training with Isaacman and Arceneaux. "First, we're going to do the centrifuge training, getting our body ready for the G forces that we're going to feel," she explained.

In the meantime, Arceneaux has had "so many questions, from what am I going to wear in space, what am I going to eat in space, can I put on makeup in space?"

"Silly little questions, but also how is this working, how is the rocket going up, how are we going to orbit the Earth?" she added.

SpaceX has said that during the multi-day mission, the astronauts will orbit Earth every 90 minutes.

The mission will go up in SpaceX's Dragon capsule, the same model that successfully carried four astronauts into orbit and to the International Space Station in mid-November 2020.

After the mission, the spacecraft will reenter the atmosphere for a water landing off the Florida coast.