Poole continued walking towards the window, and the view expanded until at last he could see what lay below him. It was familiar enough: the whole continent of Europe, and much of northern Africa, just as he had seen them many times from space. So he was in orbit after all – probably an equatorial one, at a height of at least a thousand kilometres.

Indra was looking at him with a quizzical smile.

'Go closer to the window,' she said, very softly. 'So that you can look straight down. I hope you have a good head for heights.'

What a silly thing to say to an astronaut! Poole told himself as he moved forward. If I ever suffered from vertigo, I wouldn't be in this business...

The thought had barely passed through his mind when he cried 'My God!' and involuntarily stepped back from the window, Then, bracing himself, he dared to look again.

He was looking down on the distant Mediterranean from the face of a cylindrical tower, whose gently curving wall indicated a diameter of several kilometres. But that was nothing compared with its length, for it tapered away down, down, down – until it disappeared into the mist somewhere over Africa. He assumed that it continued all the way to the surface.

'How high are we?' he whispered.

'Two thousand kay. But now look upwards.'

This time, it was not such a shock: he had expected what he would see. The tower dwindled away until it became a glittering thread against the blackness of space, and he did not doubt that it continued all the way to the geostationary orbit, thirty-six thousand kilometres above the Equator. Such fantasies had been well known in Poole's day: he had never dreamed he would see the reality – and be living in it.