Suppose an alien craft was detected in the solar system, something like Oumuamua, little understood with a strange trajectory. Would the United Nations investigate it or just blow it up as a threat? That’s where we begin the story in this book – the options are narrowed down because only one spacecraft is close enough to be able to intercept the object (named as Rama), and the United Planets agree to gather as much information as possible. As you would expect, there are disagreements with the approach and Mercury in particular thinks destruction is the way to go.
The story concentrates on the strange geography of the craft – 50km long on its axis, 20km across and rotating every 4 minutes. Yet it has an ocean around the centre of the axis, cities spread out across the plains and few clues as to the nature of the constructors of the craft. It’s a great book, full of ideas that must have been mind-blowing when written in 1973.