Once mistaken for a cleaner, British space scientist Dr Maggie Aderin-Pocock estimates she’s spoken to around half a million kids over the past 20 years, to encourage them to “reach for the stars”.

The scientist and broadcaster – best known for presenting BBC One’s The Sky At Night – knows all too well the barriers that face girls and women when it comes to careers in STEM.

“Looking back, people often ask me, you are a black dyslexic woman from a divorced home – how did you get into STEM?” says the 55-year-old, who grew up in a council flat in North London.

“It goes way back. I think I heard about the moon landings and that really got my attention when I was a child, but I think one of the big players in my life was The Clangers,” she adds – recalling the BBC children’s programme which aired from 1969 to 1974 and depicted a family of mouse-like creatures who lived on a small moon-like planet. Later, she started watching Star Trek too.

“It was the idea that space can be very uniting. From space, you don’t see different borders, you don’t see different countries, you just see people, you just see the planet – and that really appealed to me.”

Aderin-Pocock has now joined the judging panel for the National Trust’s Time + Space Award, which will see four 16–25-year-olds win a package of time, space and support worth £5,000, to explore the answer to a big question set by the panel.

Women now make up 24% of the STEM workforce in the UK, according to STEM Women, meaning there is still a long way to go for gender equality in the industry. Aderin-Pocock, who was awarded an MBE in 2009 for services to science and science education, believes there are both internal and external barriers playing a key part in this.

“With internal barriers, that’s one where it’s sort of a battle to smash stereotypes wherever possible. I go out and meet girls, and they say, ‘I don’t expect to have a career in science because I can’t see myself in that role’ – that’s where I think we need role models,” she explains. “I like to go back in time and highlight fantastic female role models of the past, and show that women have been doing science for many years and making a real difference to science.

“When I was growing up, I thought astronomy was just done by white guys, because I heard about the work done by the Greeks and the Romans and I didn’t really hear about any other cultures doing astronomy – but of course, that is totally a misconception. Every culture across the world has looked up at the night sky and wondered.”

External barriers can be harder to address, Aderin-Pocock says, as that’s about changing other people’s perceptions of what a scientist looks like.

“I remember distinctly going to visit one of my contractors. I turned up looking quite young, having freshly finished my PhD, carrying my briefcase, and the guy at the desk just looked up, handed me some keys and said, ‘Start cleaning the offices at the back and work your way forward’. So, when he saw a young black woman, he just assumed I was a cleaner, and there’s nothing wrong with being a cleaner, but the problem is the assumption,” she says.

“I think I said, as calmly as I could, ‘Well actually, I’m here to see someone who’s working for me at the moment and I’ve come to assess his work’. Just to take it down a notch and try to assert some authority at the same time.

“There are still some challenges where sometimes people make assumptions, but they’re not quite so overt so they’re harder to tackle, and I think those are the ones that we’re facing more now.”

While progress is being made, Aderin-Pocock hopes to see more changes to the way female scientists are taught and celebrated in schools.

“I’ve been to some schools and they’ve got the great and the good of science on the walls – Isaac Newton, Stephen Hawking, all these great people. One school even had Professor Beaker from The Muppets, but didn’t have one woman up there,” she recalls. “I think people are realising that if we’re not celebrating our women, we don’t get the next generation coming through.

“Women have done fantastic work in science, and I think the more we can sing and celebrate that, the better, because it lets the next generation know that – yes, this is for you too.

“One of my favourite role models is a woman called Enheduanna, she lived about 7,000 years ago and her title was chief priestess for the moon goddess. She used to write poetry and look at the night sky. Her poetry survives today and hers was the first female name to be written in the history books. She’s an amazing woman, who we can celebrate today, so women in science and astronomy goes way, way back in time.”

Mattel made a Barbie doll of Aderin-Pocock to celebrate International Women’s Day last year, but her personal career highlight has been inspiring a child at one of her school visits.

“Quite a few years ago, I went out to a school that was for kids who were deaf and had other challenges. I was doing my talk, where I take kids on a tour of the universe, talking about the fact that our galaxy, the Milky Way, contains 300 billion stars, and in the distant, distant future – billions of years’ time – we will collide with another galaxy called Andromeda.

“I went away and about a week later, I got an email saying there was a child in the audience who had selective mutism, so all the time they’d been at school they had never actually asked a question. But after my talk, they came up and asked what happens when galaxies collide. Space had touched someone and it just felt like a really magical moment.”

Dame Dr Maggie Aderin-Pocock is a judge for the National Trust’s Time + Space Award alongside David Olusoga, Tayshan Hayden-Smith and Megan McCubbin. Four 16–25-year-olds will get a £5,000 package of time, space and support to explore the answer to a big question set by the panel.