It's a neccessary anchor, because if Robinson has a weakness, it's the immemorial weakness of the hard SF writer, which is to assume that the reader is as excited by extreme technological speculation as he is.

Like his characters, the author is still tied to his humanity. But curiously the great set-pieces of the novel are its descriptions of classical music and the urban landscapes of a polluted yet lively Earth. Sunlight is exported to the dark outer reaches of the system by the Vulcanoids, who live inside the orbit of Mercury on an 'almost perfectly circular necklace of burnt but stable' natural satellites so close to the sun that their tidally locked day-sides are at 1,000 kelvin. Space travel is accomplished in hollowed-out asteroids. There's plently of scope for them in 2312. This is a shame, because the structure of 2312 is much more interesting than its plot: an assemblage of documentary data – reminiscent of Dos Passos's USA trilogy or John Brunner's Stand on Zanzibar – that builds into a meditation not so much on what we might become as on what we already are.

Its ending is so contrived that you wonder if Robinson isn't undermining his vision in preparation for some as-yet-unwritten sequel. The tale of terrorism and interplanetary romance is so uncomfortable with itself that it's written in more awkward language than the rest of the book. In the end Swan and Warham, too, have motives of their own. What's happening? Who's responsible? There are so many factions: the Chinese, running the terraforming of Venus from their strongholds of capital on the ruined Earth, have motives of their own Mars broods silently, but has motives of its own even the quantum computers that do the system's mathematical heavy-lifting have motives of their own.

Brought together by the death of Alex, one of the system's upper management team, they witness a terror attack on Mercury's rolling capital city and crisscross the system in search of answers. They grow to love and treasure their differences. Warham is mature and steady, Swan a little flighty and self-centred. He's large, froglike and a Titan, she's thin and from Mercury neither of them is really a he or a she, of course. Into this utopian mix of sandbox and civic responsibility are brought Warham and Swan. What redeems them, to some extent, is Robinson's insistence on the work ethic. They look forward to the regrowth of limbs. They say such things as 'reality made a mistake, and now you're fixing it!' Biologically modified, computer-augmented, successfully 'multi-sexed' and on their way to sub-speciation, they can live for 200 years. Despite that, his characters have a fully space-operatic sense of entitlement. At human speeds, the author warns us, the stars are too far away: they 'exist beyond human time, beyond human reach'. They would leave the system altogether, but physics forbids.

2312 by Kim Stanley Robinson