Ihave written so often about Wigtown in the past week, people will start thinking that its book festival is the most exciting thing I've gone to in ages.

And it is! However, I don't intend to reprise the glories of the place, or the festival. Those can be taken for granted (though a decent evening meal later than 7pm in the centre of town cannot – but that's another story).

In fact, I would not be mentioning Wigtown again had I not attended the most interesting festival event I've been to in years. I say this not because my partner was taking part in it. Without any disrespect to him, that's not what made it memorable. Rather, it was his fellow speakers who offered a rare example of the impact fiction can have on those whose lives appear to be a million miles away from the seemingly nebulous, airy-fairy world of literature.

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The session was a tribute to Ray Bradbury, who died in June aged 91. The panel included Marek Kukula, public astronomer at the Greenwich Royal Observatory, and an unexpected late guest, Lee Graham, who has been with Nasa for 30 years and is based at the Johnson Space Center in Houston, where he has worked on the space station, shuttle and lunar landing programmes. He took his seat on stage dressed in a Victorian frockcoat with a top hat at his feet, and while no-one batted an eyelid, he felt obliged to explain, no doubt in case the audience thought scientists have a tendency to nuttiness. He had just come, he said, from being photographed for a calendar, dressed as his favourite historical character, HG Wells.

It was only a short step from Wells to Bradbury, and it was Kukula who first paid his respects to this remarkable writer, with a series of photographs recently taken by the Curiosity explorer on Mars. As images of the exquisitely barren planet appeared, he pointed out that although Bradbury published his book The Martian Chronicles in 1950, and had no pretensions to knowing anything about outer space, his descriptions of Mars have proved eerily accurate, barring bone-white cities and canals.

Such is the awe in which Bradbury's work is regarded by the astronomical, astro-physicist fraternity that, within days of the explorer arriving, it was unanimously agreed that the spot where it touched down on the red dust should be called Bradbury Landing. I don't think Graham was entirely joking when he said they had plans in future to build a memorial to him there, for visitors to see.

The conversation that followed was a salutary corrective to those who pigeonhole Bradbury as a writer of science fiction. Famously dismissive of technology – he didn't drive and loathed e-books – Bradbury's art was not to try to envision the way science would evolve, but to picture the future and the moral and emotional issues people very like ourselves would face under testing, alien circumstances. Both Graham and Kukula were voracious readers as boys, a time when science fiction whetted their imagination. It was a sobering moment when Kukula told us that novels by the likes of Bradbury made him and his fellow scientists far more aware of the ethical questions around space exploration, and thus more careful and humble in the way they approach their job today.

Inevitably there was some discussion about the line between sci-fi and so-called proper literature, but the conclusion was obvious: the only true distinction in fiction lies between books that are well written and those that are not. Obviously one sympathises with writers who hate the label, since sci-fi is notorious for the quantity of dross produced in its name. But quite apart from mainstream novelists such as Atwood and Lessing and Ishiguro who work in this arena, there are swathes of fine writers that people like me, who gave up on fantasy years ago, ought to be reading and should feel guilty that we're not. After this inspirational session, I look forward to discovering a galaxy of writers who've hitherto been hidden behind shelves of literary earthlings.