Everyone knew what had happened next; perhaps wisely, there had been no attempt to reproduce it visually. Instead, the image of Europa faded, to be replaced by a portrait as familiar to every Chinese as Yuri Gagarin's was to every Russian.

The first photograph showed Rupert Chang on his graduation day in 1989 – the earnest young scholar, indistinguishable from a million others, utter1y unaware of his appointment with history two decades in the future.

Briefly, to a background of subdued music, the commentator summed up the highlights of Dr Chang's career, until his appointment as Science Officer aboard Tsien. Cross-sections in time, the photographs grew older, until the last one, taken immediately before the mission.

Sir Lawrence was glad of the planetarium's darkness; both his friends and his enemies would have been surprised to see the moisture gathering in his eyes as he listened to the message that Dr Chang had aimed towards the approaching Leonov, never knowing if it would be received.

'... know you are aboard Leonov... may not have much time... aiming my suit antenna where I think...'

The signal vanished for agonizing seconds, then came back much clearer, though not appreciably louder.

'... relay this information to Earth. Tsien destroyed three hours ago. I'm only survivor. Using my suit radio – no idea if it has enough range, but it's the only chance. Please listen carefully. THERE IS LIFE ON EUROPA. I repeat: THERE IS LIFE ON EUROPA...

The signal faded again.

'... soon after local midnight. We were pumping steadily and the tanks were almost half full. Dr Lee and I went out to check the pipe insulation. Tsien stands – stood – about thirty metres from the edge of the Grand Canal. Pipes go directly from it and down through the ice. Very thin – not safe to walk on. The warm upwelling...'

Again a long silence.