The Calculating Stars, by Mary Robinette Kowal

This smart, thrilling, brilliant new novel is about the women who are part of the astronaut programme in an alternate 1950s. History diverges from ours on 2 November 1948 when Thomas E Dewey beats Harry S Truman in the US presidential election. By 3 March 1952, the US has put its third satellite into orbit. That morning, a meteorite crashes into Earth with devastating effect.  Washington DC is obliterated.

So, despite the devastation the space programme is well ahead. In our universe, the space race began years after this, on 30 August 1955, when lead engineer Sergei Korolev got the Soviet Academy of Sciences to agree a programme to beat the Americans into orbit. The result was Sputnik (4 October 1957), followed by the first person - Gagarin - sent into space, on 12 April 1961. A month later, President Kennedy announced plans to land people on the Moon by the end of the decade.

Part of the joy of The Calculating Stars is how much of "our" history is woven into the alternate timeline: our heroine, Dr Elma York meets Wernher von Braun, while among her fellow trainee astronauts listed on page 426 are "Collins, Aldrin and Armstrong".  Her husband reads science-fiction by Ray Bradbury, his visions of settlements on Mars apparently coloured by the events in this timeline.

Also great is the technical detail. We encouter this world through Elma's perspective as a former WASP, a qualified pilot and extremely competent mathematician. She works as a human computer, outperforming the nascent IBM machines - at one extremely tense moment in the story, her speed and accuracy with complex numbers are vital. Robinette Kowal's acknowledgements include real astronauts and other experts: she admits she doesn't understand the maths herself. As a nerd for the early days of space travel, there was lots I recognised - and lots that came as new.

"There is something about having your legs over your head that makes you need to pee. This makes it into none of the press releases, but every single astronaut talks about it." (p. 493)

But the book is also excellent on the social detail: the drama of this post-meteorite world is overshadowed by inherent sexism and racism, our Jewish heroine not immune to her own prejudice.  Elma also suffers from anxiety and there's lots on the shame and secrecy surrounding mental illness. Characters are well drawn, and Elma must learn to work alongside people she doesn't necessarily like, managing rivalries and her own privilege, for all she is discriminated against. Each chapter opens with a quote from a newspaper filling in more of the background detail of this world, and full of telling turns of phrase. It all makes for a rich and real version of history, a compelling world in which this adventure takes place.

It is an adventure, full of twists and turns. Robinette Kowal nicely manages the personal stakes with the technical and global. I zipped through the almost 500 pages and am keen for the next instalment.