Her life has been packed with more adventure than most of us could ever imagine, but there is a very special reason why Dr Kathy Sullivan is particularly excited about coming to Scotland. ‘What I had always wanted to do from a very young age,’ Sullivan says over Zoom, ‘was to have the kind of adventurous and inquisitive life that I saw Jacques Cousteau having on television, or the early astronauts having on TV and in magazines.’

This wasn’t the norm for a nine or ten-year-old girl growing up in late 1950s America, but as Sullivan says, ‘my parents didn't give a fig what the common dream was for little boys or girls. If we were interested in something, they would help us pursue that interest and see where it led.’ Where it led Sullivan was initially a degree in foreign languages. However, her university required her to take some science classes in her first year. And that’s where Scotland came in. 

The marine biology course she ended up on (‘quite against my will’) had as one of its core texts an account of the 1926 expedition of the Royal Research Ship Discovery to the Antarctic. ‘That lit up my world,’ says Sullivan. ‘That was exactly the kind of thing I was looking for.’ The Cousteau adventures she had dreamed of suddenly seemed within reach. Twelve weeks into her degree, she switched majors to oceanography and never looked back. The Discovery ship is now berthed in Dundee and, as part of Sullivan’s trip to Edinburgh Science Festival, she has been invited to dine onboard, bringing her full circle to where it all started. 

But before that she will be regaling audiences and inspiring young minds at two Science Festival events: Walk Like An Astronaut for ages 7+ and Above And Below: An Astronaut's View Of Our Planet aimed at those 12 and above. And there is a lot to discuss. Sullivan has led the kind of life that Hollywood makes movies about, starting with the application she sent off to NASA after her PhD (‘the odds are only zero if you don't apply,’ she says), followed by being accepted, going on to complete three space missions, breaking barriers for women in STEM (she was the first American woman to complete a spacewalk, and the first woman to travel to the deepest point of the Mariana Trench in a submersible in 2020), and in later years serving the US government on the President's Council Of Advisors on Science and Technology.  

Space and the deep ocean may seem like polar opposites, but what connects them in Sullivan’s mind is the link between inhospitable environments and the human body. ‘It’s the science and engineering of being able to get there or operate there. We human beings are suited to a relatively narrow range of conditions, pressure and temperature. We generate some waste. We need some replenished air. You’ve got to deal with those realities, whether you’re going into space or down in the deep sea.’

These basic human needs, says Sullivan, are also inextricably tied up with the sense of wonder she feels when in hostile places. ‘Every time I’ve had this opportunity, I just marvel at it. To float up by the window of a spaceship, or sit in a seat in a submersible. Right now, I’m looking through my window onto the deck behind my house. I know I could open that window and walk out onto my deck, right? But in the submersible or spacecraft, it feels like the same experience, except I know if I open the window, I die.’

The dangers of her job were brought home to Sullivan when the first space shuttle she had flown on, Challenger, later exploded in 1986, minutes after it had lifted off, killing all of the crew onboard. Despite this, she went on to undertake two further space missions after the tragedy. And though now in her 70s, her appetite for orbit has never dampened. 

‘You might recall that in 1998 NASA sent John Glenn back into space on a space shuttle, partly because he's John Glenn and deserved a little more time in orbit, and partly to get some medical data on the reaction of an older human to space flight. Well, my take is that, ok, you’ve got some data on how one old fogey responds to space flight. I think you now need to get some data on how one old broad responds. And I think I’m first in line…’

Kathy Sullivan appears at Gordon Aikman Lecture Theatre, Edinburgh, Saturday 5 April; Edinburgh Science Festival, Saturday 5–Sunday 20 April.