White Mars is about a group of men and women who are marooned on Mars at the end of the 21st century. Living in enormous self-perpetuating domes, they produce their own food and oxygen, and extract water from the planet’s core. On this austere Martian world, members of the colony set out to create a Utopian society. The book examines whether such a society could be created and whether humans can achieve a better world and a happier future.

It was a chance encounter that brought the authors together. Aldiss, who has written over 20 novels, had decided to sell his house near Oxford. Penrose, who is based at Oxford University, was also planning to move and was shown Aldiss’ property by his estate agent. He eventually bought Aldiss’ home, and the two writers became friends as negotiations proceeded.

One night, Aldiss had a vivid dream about a group of people living on Mars. “I woke up, immediately wrote down what I had dreamt and then approached Roger and told him my story,” he explains. “Roger thought it was a great idea, and was very keen to get involved in writing a book. My dream that night forms the crux of the book.”

Luckily for Aldiss, Penrose is something of a science-fiction fan, citing Isaac Asimov, Arthur C Clarke and John Wyndham as particular favourites. “I had felt for some time that I might like to have a go at science fiction and then – rather fortuitously – this collaboration with Brian came along,” explains Penrose. “The idea of a book about a Utopian society might sound boring and starry-eyed, but I don’t think it’s turned out like that.”

So how did the two authors collaborate in practice? “It’s hard to say exactly what happened because it all took so long,” recalls Aldiss. “Like a marriage, it was a mystery even to the parties involved.” However, Aldiss reveals that the bulk of chapter 11, which he says contains most of the hard science, is by Penrose. “But Roger has always been a really bold thinker and he made big contributions elsewhere.”

Penrose is more modest. “Basically, Brian did all the writing and I would add bits of dialogue to help explain some of the science, although I also produced some ideas that significantly altered the plot,” he says. “It was certainly different from what I normally do and gave me the opportunity to explore the implication of some crazy scientific ideas.”

One problem for Penrose was that some of the science-fictional ideas came rather close to his own. “I wanted to differentiate between the two and make sure that our currently accepted scientific knowledge is used correctly in the book.” One way that he does this is through a character called Thorgeson, who explores the “conventional” ideas of physicists at the time. “The irony is that Thorgeson expresses ideas on consciousness that are not dissimilar from my own. While my ideas are currently regarded as unconventional, in the story they are presented as outdated.”

So does Penrose have any plans for further science-fiction books? “Yes, I think I’d like to do some more, but whether on my own or with Brian I’m not sure. It’s just a question of finding the time.”