Most of the passengers, accustomed to climbing spacewards with no visible means of support, reacted with considerable shock. Floyd waited for the inevitable explanation; one of his minor pleasures was catching Willis in some scientific error, but this very seldom happened. And even when it did, Willis always had some very plausible excuse.

'Carbon,' he said. 'Incandescent carbon – exactly as in a candle flame – but slightly hotter.'

'Slightly,' murmured Floyd.

'We're no longer burning – if you'll excuse the word -, (Floyd shrugged his shoulders) 'pure water. Although it's been carefully filtered, there's a lot of colloidal carbon in it. As well as compounds that could only be removed by distillation.'

'It's very impressive, but I'm a little worried,' said Greenburg. 'All that radiation – won't it affect the engines – and heat the ship badly?'

It was a very good question, and it had caused some anxiety. Floyd waited for Willis to handle it; but that shrewd operator bounced the ball right back to him.

'I'd prefer Dr Floyd to deal with that – after all, it was his idea.'

'Jolson's, please. Good point, though. But it's no real problem; when we're under full thrust, all those fireworks will be a thousand kilometres behind us. We won't have to worry about them.'

The ship was now hovering some two kilometres above the nucleus; had it not been for the glare of the exhaust, the whole sunlit face of the tiny world would have been spread out beneath. At this altitude – or distance – the column of Old Faithful had broadened slightly. It looked, Floyd suddenly recalled, like one of the giant fountains ornamenting Lake Geneva. He had not seen them for fifty years, and wondered if they still played there.

Captain Smith was testing the controls, slowly rotating the ship, then pitching and yawing it along the Y and Z axes. Everything seemed to be functioning perfectly.

'Mission time zero is ten minutes from now,' he announced. '0.1 gee for fifty hours; then 0.2 until turnaround – one hundred and fifty hours from now.' He paused to let that sink in; no other ship had ever attempted to maintain so high a continuous acceleration, for so long. If Universe was not able to brake properly, she would also enter the history books as the first manned interstellar voyager.

The ship was now turning towards the horizontal – if that word could be used in this almost gravityless environment – and was pointing directly to the white column of mist and ice crystals still steadily spurting from the comet. Universe started to move towards it -

'What's he doing?' said Mihailovich anxiously.

Obviously anticipating such questions, the Captain spoke again. He seemed to have completely recovered his good humour, and there was a hint of amusement in his voice.

'Just one little chore before we leave, Don't worry – I know exactly what I'm doing. And Number Two agrees with me – don't you?'

'Yessir – though I thought you were joking at first.'

'What is going on up on the bridge?' asked Willis, for once at a loss.

Now the ship was starting a slow roll, while still moving at no more than a good walking speed towards the geyser. From this distance – now less than a hundred metres – it reminded Floyd still more closely of those far-off Geneva fountains.

Surely he's not taking us into it – But he was. Universe vibrated gently as it nuzzled its way into the rising column of foam. It was still rolling very slowly, as if it was drilling its way into the giant geyser. The video monitors and observation windows showed only a milky blankness.

The whole operation could not have lasted more than ten seconds; then they were out on the other side. There was a brief burst of spontaneous clapping from the officers on the bridge; but the passengers – even including Floyd – still felt somewhat put-upon.

'Now we're ready to go,' said the Captain, in tones of great satisfaction. 'We have a nice, clean ship again.'

During the next half-hour, more than ten thousand amateur observers on Earth and Moon reported that the comet had doubled its brightness. The Comet Watch Network broke down completely under the overload, and the professional astronomers were furious.

But the public loved it, and a few days later Universe put on an even better show, a few hours before dawn.

The ship, gaining speed by more than ten thousand kilometres an hour, every hour, was now far inside the orbit of Venus. It would get even closer to the sun before it made its perihelion passage – far more swiftly than any natural celestial body – and headed out towards Lucifer.

As it passed between Earth and Sun, the thousand kilometre tail of incandescent carbon was easily visible as a fourth magnitude star, showing appreciable movement against the constellations of the morning sky in the course of a single hour. At the very beginning of its rescue mission, Universe would be seen by more human beings, at the same moment, than any artefact in the history of the world.

The unexpected news that their sister ship Universe was on the way – and might arrive far sooner than anyone had dared to dream – had an effect upon the morale of Galaxy's crew that could only be called euphoric. The mere fact that they were drifting helplessly on a strange ocean, surrounded by unknown monsters, suddenly seemed of minor importance.

As did the monsters themselves, though they made interesting appearances from time to time. The giant 'sharks' were sighted occasionally, but never came near the ship, even when garbage was dumped overboard. This was quite surprising; it strongly suggested that the great beasts – unlike their terrestrial counterparts – had a good system of communication. Perhaps they were more closely allied to dolphins than to sharks.

There were many schools of smaller fish, which no-one would have given a second glance in a market on Earth. After several attempts, one of the officers – a keen angler – managed to catch one with an unbaited hook. He never brought it in through the airlock – the Captain would not have permitted it, anyway – but measured and photographed it carefully before returning it to the sea.

The proud sportsman had to pay a price for his trophy, however. The partial-pressure spacesuit he had worn during the exercise had the characteristic 'rotten eggs' stink of hydrogen sulphide when he brought it back into the ship, and he became the butt of innumerable jokes. It was yet another reminder of an alien, and implacably hostile, biochemistry.

Despite the pleas of the scientists, no further angling was allowed. They could watch and record, but not collect, And anyway, it was pointed out, they were planetary geologists, not naturalists. No-one had thought of bringing formalin – which probably would not work here in any event.

Once, the ship drifted for several hours through floating mats or sheets of some bright green material. It formed ovals, about ten metres across, and all of approximately the same size, Galaxy ploughed through them without resistance, and they swiftly reformed behind her. It was guessed that they were colonial organisms of some kind.

And one morning, the officer of the watch was startled when a periscope rose out of the water and he found himself staring into a mild, blue eye which, he said when he had recovered, looked like a sick cow's. It regarded him sadly for a few moments, without much apparent interest, then slowly returned to the ocean,

Nothing seemed to move very fast here, and the reason was obvious. This was still a low-energy world – there was none of the free oxygen that allowed the animals of Earth to live by a series of continuous explosions, from the moment they started to breathe at birth. Only the 'shark' of that first encounter had shown any sign of violent activity – in its last, dying spasm.