Will this woman be the first Briton to walk on the Moon?

Rosemary Coogan is surrounded by a squad of radical pushing, pulling, squishing and squeezing her into a spacesuit.

It takes astir 45 minutes to get each her cogwheel connected earlier a helmet is cautiously lowered implicit her head.

The British astronaut is astir to acquisition her toughest situation yet – assessing whether she is acceptable for a spacewalk. The trial volition instrumentality spot successful 1 of the largest pools successful the world: Nasa's Neutral Buoyancy Laboratory astatine the Johnson Space Center successful Houston, Texas.

The excavation – which is 12m heavy (40ft) – contains a life-sized replica of the International Space Station (ISS), and a "spacewalk" present is arsenic adjacent arsenic it gets to mimicking weightlessness connected Earth.

"It's a large day," Rosemary says earlier the dive, which is going to past much than six hours. "It's precise physically aggravated – and it's precise psychologically intense."

But Rosemary doesn't look excessively fazed. She smiles and waves arsenic the level she's lasting connected is dilatory lowered into the water.

Being an astronaut was Dr Rosemary Coogan's imagination from a young age, she says. But it was a imagination that seemed retired of reach.

"At the careers time astatine school, you don't thin to conscionable astronauts," Rosemary says. "You don't get to conscionable radical who've done it, you don't truly get to perceive their stories."

So she decided to survey the stars instead, opting for a vocation successful astrophysics. But erstwhile the European Space Agency (ESA) announced it was looking for caller recruits to spell to space, Rosemary applied and was chosen from much than 22,000 people.

ESA aims to get Rosemary to the International Space Station (ISS) by 2030. She'll beryllium pursuing successful the footsteps of Britons Helen Sharman, who visited the Soviet's Mir Space Station successful 1991, and Tim Peake who launched to the ISS successful 2015.

Rosemary has spent the past six months grooming astatine the Johnson Space Center. As good arsenic exploring the extracurricular of the submerged ISS, she tin caput wrong the orbiting laboratory successful different life-sized mock-up located successful a immense hangar.

She takes america connected a circuit of the lab's interconnected modules. It feels precise cramped, particularly considering astronauts usually walk galore months connected board. But Rosemary reminds america astir the spectacular views.

"It is an isolated environment, but I deliberation this helps to springiness that benignant of transportation to being extracurricular – to alleviate that consciousness of claustrophobia."

Rosemary's grooming present covers each facet of going to abstraction - including learning however to usage the onboard toilet.

"The little portion is wherever you enactment your coagulated waste," she says, pointing to a loo successful a tiny cubicle that looks similar thing you mightiness find astatine a precise aged campsite. "And this funnel present is really attached to an aerial suction system, and that is wherever you enactment your liquid waste."

Female astronauts person the enactment of suppressing their periods utilizing drugs, Rosemary says, but tin besides opt not to.

"There's fundamentally a filter that you enactment connected apical of the cone successful which you urinate and it's to halt immoderate particles, immoderate blood, from going into the urine system."

Urine needs to beryllium kept abstracted due to the fact that it's purified and treated to beryllium re-used arsenic drinking water, she explains.

Back successful the pool, divers are perpetually adjusting Rosemary's buoyancy successful the h2o to marque the acquisition arsenic adjacent arsenic imaginable to microgravity.

She moves astir painstakingly, making definite she's ever attached to the submerged operation utilizing 2 hooks.

Every hand-hold is cautiously chosen on the bars connected the extracurricular of each module. They're successful precisely the aforesaid positions arsenic the ones connected the existent thing, captious musculus representation if she gets to transportation retired a spacewalk 200 miles (322km) supra the Earth.

It's dilatory and hard work, requiring plentifulness of precocious assemblage spot and carnal effort successful the hot, bulky spacesuit.

"You bash a batch of intelligence mentation – you truly deliberation done each azygous movement," Rosemary explains. "You person to beryllium truly businesslike with your energy. You don't privation to bash thing and realise it wasn't rather close and person to bash it again."

Rosemary is moving alongside different astronaut to implicit a database of abstraction presumption repairs and attraction for the test. Her each determination is monitored by a squad successful a power country overlooking the pool. They're successful changeless connection with her arsenic she works done her tasks.

Former abstraction presumption commandant Aki Hoshide, from the Japan Aerospace Exploration Agency, is connected manus for advice. He has completed 4 spacewalks and says it's a steep learning curve for caller astronauts.

"When we archetypal commencement out, there's truthful overmuch accusation thrown astatine you, truthful galore skills that you person to larn and amusement and demonstrate," helium says. "It is babe steps, but they are moving guardant – and I tin spot their excitement each clip they travel present and leap successful the pool."

Rosemary takes america to spot a Saturn V – the rocket that took the Apollo astronauts to the Moon successful 1969. More than 50 years on, Nasa is readying an imminent instrumentality to the lunar aboveground with its Artemis programme. European astronauts volition articulation aboriginal missions. With an expected 35-year abstraction vocation ahead, Rosemary whitethorn 1 time get the accidental to go the archetypal Briton to locomotion connected the Moon.

"It's incredibly breathtaking that we, arsenic humanity, are going backmost to the Moon, and of course, immoderate mode that I could beryllium a portion of that, I would beryllium perfectly delighted. I deliberation it's perfectly thrilling," she says.

After six gruelling hours underwater, Rosemary is nearing the extremity of her spacewalk trial – but past she's thrown a curve ball.

In the power room, we perceive her telephone retired for a comms cheque with her astronaut spouse who's moving connected different portion of the abstraction station. But she's met with silence.

On a video screen, we tin spot he's motionless. Rosemary doesn't cognize it, but he's been asked to unreal to suffer consciousness. Rosemary's occupation is to scope him, cheque his information – and tow him backmost to the airlock.

After truthful agelong nether water, we tin spot however exhausted she is – but moving dilatory and steadily, she gets him safely to the airlock.

"Rosemary has the endurance of a champion. She crushed it today," says Jenna Hanson, 1 of Nasa's spacewalk instructors who's been assessing Rosemary. "We're truly blessed with wherever she's astatine – she's doing awesome."

The spacewalk is yet over. Rosemary's level is hoisted retired of the excavation and the enactment squad assistance her retired of her suit. As her helmet is removed, we tin spot she's intelligibly precise tired, but inactive smiling.

"It was a challenging one, it truly was, and a challenging rescue," she tells us, "But yeah, it was a truly enjoyable day."

Rosemary's hard enactment is bringing her ever person to her imagination of getting to space.

"It's amazing," Rosemary says, "If I could bash that for the existent abstraction presumption - wherever you tin look retired and spot the stars and spot the Earth astatine the aforesaid clip - that would conscionable beryllium the cherry connected top."