For most of us, the topic of life on other planets brings to mind thoughts of alien civilisations. Yet the majority of living things that exist on Earth are microbes, and it’s reasonable to suppose that if life is present anywhere else in the universe, it will largely take the same simple form. If astrobiologist Nathalie Cabrol is right, there could be an awful lot of space bugs out there.

Cabrol’s new book is a highly informative survey of the current state of astro­biology, rich in factual detail, if somewhat dry in tone. Born in France and now living in the USA, she was inspired by Carl Sagan, the charismatic American scientist who did much to stimulate serious research on extraterrestrial life. Now director of the Carl Sagan Center for the Study of Life in the Universe, Cabrol met Sagan in 1986, when she was a young researcher. A photograph of the great man hangs next to her desk and his words of wisdom pepper her book.

Two other great influences were her husband, Edmond Grin, a planetary scientist, and the astronomer Frank Drake, famous for devising the Drake Equation, a formula for quantifying the likelihood of finding intelligent extraterrestrial life. Grin and Drake both died in 2022, and Cabrol pays touching tribute to them at the