February 23, Kathmandu
The first bone cancer survivor to become an astronaut. The first person with a prosthetic body part to visit space. And the youngest American ever to orbit Earth.
In January, the physician assistant was picked to join the crew of the world's first all-civilian space mission.
Ms Arceneaux was ecstatic but, at first, she had to keep her lips sealed.
"I've held onto the biggest secret of my life for a month and a half. So now I get to share it with the world," she told the BBC.
Her selection for the historic mission was announced on Monday by the St Jude Children's Research Hospital in Memphis, Tennessee, where Ms Arceneaux was once a cancer patient as a child and now works.
Later this year, she will launch from Florida on a Falcon 9 rocket made by SpaceX, the company founded by business mogul Elon Musk.
"I think this mission is going to inspire people in so many ways," Ms Arceneaux said. "It shows them that anything is possible."
There will be no professional astronauts on board the spacecraft.
Rather, Ms Arceneaux will be joined by two contest winners and flight commander Jared Isaacman, a 38-year-old billionaire who is paying for the entire mission.
At the age of 10, Ms Arceneaux was a bone cancer patient at St Jude.
As part of her treatment at the hospital, Ms Arceneaux had chemotherapy and surgery to replace some of her leg bones with artificial ones.
The emergence of private space missions in recent years has enabled more of us to reach for the stars.
"Until this mission, I could have never been an astronaut," Ms Arceneaux said. "This mission is opening space travel to people who are not physically perfect."
After checking with her family to "make sure they were not adamantly opposed", and her brother and sister-in-law who - as aerospace engineers - "really reassured me how safe space travel is", she agreed to join the crew.
Mr Isaacman is planning to select and reveal the remaining two crew members by March.
One will be the winner of a sweepstake competition, whose proceeds will be donated to St Jude.
The other will go to the winner of a contest which asks entrepreneurs to design an online store using software made by Shift4, Mr Isaacman's payment technology company.
"I'm really not nervous. I've met the lead engineers for every aspect of this mission. I really trust them."
Compared to what she went through as a child, space travel should be no problem.
"Getting to represent cancer patients and survivors is an incredible honor. It really wasn't that long ago that I was in their shoes," she said.
"When you're going through cancer treatment, you're so focused on the day-to-day. It can be really difficult to look toward the future. I hope that this mission will allow them to imagine their future."