She recently underwent a grueling six-hour underwater simulation at NASA’s Neutral Buoyancy Laboratory in Houston, Texas, to test her readiness for a real spacewalk.

It takes nearly an hour to get Coogan suited up, and once submerged in the 12-metre-deep pool – which holds a full-scale replica of the International Space Station (ISS) – she faces one of the most physically and mentally demanding aspects of astronaut training. Inside the suit, every movement is deliberate and energy must be conserved. “You do a lot of mental preparation. Every single movement counts,” she says.

This simulation, which mimics the microgravity of space, is part of her attentive training at the Johnson Space Centre. Coogan was selected over 22,000 applications when ESA opened recruitment for new astronauts. Now, with the goal of reaching the ISS by 2030, she is following in the footsteps of the UK Pioneers Helen Sharman and Tim Peake.

Throughout the day, Coogan methodically navigates the submerged ISS, clinging to handrails, executing repair tasks, and communicating with mission control. She even responds to an unexpected emergency drill, towing an unconscious fellow astronaut back to safety. “Rosemary has the endurance of a champion,” says NASA instructor Jenna Hanson. “She crushed it.”

Her training isn’t limited to spacewalks. Coogan has also mastered spacecraft interiors and even space toilets, explaining how every aspect of astronaut life is part of preparing for the real deal.

As NASA eyes the moon once again with its Artemis program, Coogan dreams big. “Any way I could be a part of that, I would be absolutely delighted,” she says.

After a long day underwater, Coogan emerges tired but beaming. “It was challenging, but really enjoyable,” she says.