All this had been known since the Voyager flyby missions of the 1970s, the Galileo surveys of the 1980s, and the Kepler landings of the 1990s. But, in a few hours, the Chinese had learned more about Europa than all the previous missions combined. That knowledge they were keeping to themselves; one might regret it, but few would deny that they had earned the right to do so.

What was being denied, with greater and greater asperity, was their right to annex the satellite. For the first time in history, a nation had laid claim to another world, and all the news media of Earth were arguing over the legal position. Though the Chinese pointed out, at tedious length, that they had never signed the '02 UN Space Treaty and so were not bound by its provisions, that did nothing to quell the angry protests.

Suddenly, Europa was the biggest news in the Solar System. And the man-on-the-spot (at least to the nearest few million kilometres) was in great demand.

'This is Heywood Floyd, aboard Cosmonaut Alexei Leonov, on course for Jupiter. But as you can well imagine, all our thoughts are now focused upon Europa.

'At this very moment I'm looking at it through the most powerful of the ship's telescopes; under this magnification, it's ten times larger than the Moon as you see it with the naked eye. And it's a really weird sight.

'The surface is a uniform pink, with a few small brown patches. It's covered with an intricate network of narrow lines, curling and weaving in all directions. In fact, it looks very much like a photo from a medical textbook, showing a pattern of veins and arteries.

'A few of these features are hundreds – or even thousands – of kilometres long, and look rather like the illusory canals that Percival Lowell and other early-twentieth-century astronomers imagined they'd seen on Mars.

'But Europa's canals aren't an illusion, though of course they're not artificial. What's more, they do contain water -or at least ice. For the satellite is almost entirely covered by ocean, averaging fifty kilometres deep.

'Because it's so far from the sun, Europa's surface temperature is extremely low – about a hundred and fifty degrees below freezing. So one might expect its single ocean to be a solid block of ice.

'Surprisingly, that isn't the case because there's a lot of heat generated inside Europa by tidal forces – the same forces that drive the great volcanoes on neighbouring Io.

'So the ice is continually melting, breaking up, and freezing, forming cracks and lanes like those in the floating ice sheets in our own polar regions. It's that intricate tracery of cracks I'm seeing now; most of them are dark and very ancient – perhaps millions of years old. But a few are almost pure white; they're the new ones that have just opened up, and have a crust only a few centimetres thick.

'Tsien has landed right beside one of these white streaks -the fifteen-hundred-kilometre-long feature that's been christened the Grand Canal. Presumably the Chinese intend to pump its water into their propellant tanks, so that they can explore the Jovian satellite system and then return to Earth. That may not be easy, but they'll certainly have studied the landing site with great care, and must know what they're doing.

'It's obvious, now, why they've taken such a risk – and why they should claim Europa. As a refuelling point, it could be the key to the entire outer Solar System. Though there's also water on Ganymede, it's all frozen, and also less accessible because of that satellite's more powerful gravity.

'And there's another point that's just occurred to me. Even if the Chinese do get stranded on Europa, they might be able to survive until a rescue mission is arranged. They have plenty of power, there may be useful minerals in the area – and we know that the Chinese are the experts on synthetic-food production. It wouldn't be a very luxurious life; but I have some friends who would accept it happily for that staggering view of Jupiter sprawled across the sky – the view we expect to see ourselves, in just a few days.

'This is Heywood Floyd, saying goodbye for my colleagues and myself, aboard Alexei Leonov.'

'And this is the bridge. Very nice presentation, Heywood. You should have been a newsman.'

'I've had plenty of practice. Half my time was spent on PR work.'

'PR?'

'Public relations – usually telling politicians why they should give me more money. Something you don't have to bother about.'

'How I wish that was true. Anyway, come up to the bridge. There's some new information we'd like to discuss with you.'

Floyd removed his button microphone, locked the telescope into position and extricated himself from the tiny viewing blister. As he left, he almost collided with Nikolai Temovsky, obviously on a similar mission.

'I'm about to steal your best quotes for Radio Moscow, Woody. Hope you don't mind.'

'You're welcome, tovarishch. Anyway, how could I stop you?'

Up on the bridge, Captain Orlova was looking thoughtfully at a dense mass of words and figures on the main display. Floyd had painfully started to transliterate them when she interrupted him.

'Don't worry about the details. These are estimates of the time it will take for Tsien to refill its tanks and get ready for lift-off.'

'My people are doing the same calculations – but there are far too many variables.'

'We think we've removed one of them. Did you know that the very best water pumps you can buy belong to fire brigades? And would you be surprised to learn that the Beijing Central Station had four of its latest models suddenly requisitioned a few months ago, despite the protests of the mayor?'

'I'm not surprised – merely lost in admiration. Go on, please.'

'That may be a coincidence, but those pumps would be just the right size. Making educated guesses about pipe deployment, drilling through the ice and so on – well, we think they could lift off again in five days.'

'Five days!'

'If they're lucky, and everything works perfectly. And if they don't wait to fill their propellant tanks but merely take on just enough for a safe rendezvous with Discovery before we do. Even if they beat us by a single hour, that would be enough. They could claim salvage rights, at the very least.'

'Not according to the State Department's lawyers. At the appropriate moment, we'll declare that Discovery is not a derelict, but has merely been parked until we can retrieve it. Any attempt to take over the ship would be an act of piracy.'

'I'm sure the Chinese will be most impressed.'

'If they're not, what can we do about it?'

'We outnumber them – and two to one, when we revive Chandra and Curnow.'

'Are you serious? Where are the cutlasses for the boarding party?'

'Cutlasses?'

'Swords – weapons.'

'Oh. We could use the laser telespectrometer. That can vaporize milligram asteroid samples at ranges of a thousand kilometres.'

'I'm not sure that I like this conversation. My government certainly would not condone violence, except of course in self-defence.'

'You naive Americans! We're more realistic; we have to be. All your grandparents died of old age, Heywood. Three of mine were killed in the Great Patriotic War.'

When they were alone together, Tanya always called him Woody, never Heywood. She must be serious. Or was she merely testing his reactions?

'Anyway, Discovery is merely a few billion dollars' worth of hardware. The ship's not important – only the information it carries.'

'Exactly. Information that could be copied, and then erased.'

'You do get some cheerful ideas, Tanya. Sometimes I think that all Russians are a little paranoiac.'

'Thanks to Napoleon and Hitler, we've earned every right to be. But don't tell me that you haven't already worked out that – what do you call it, scenario? – for yourself.'