'Nothing in this Universe is safe, Heywood. All I can say is that there are no physiological objections. After all, your environment will be virtually the same aboard Universe as it is here. She may not have quite the standard of – ah – superlative medical expertise we can provide at Pasteur, but Dr Mahindran is a good man. If there's any problem he can't cope with, he can put you into hibernation again, and ship you back to us, COD.'

It was the verdict that Floyd had hoped for, yet somehow his pleasure was alloyed with sadness. He would be away for weeks from his home of almost half a century, and the new friends of his later years. And although Universe was a luxury liner compared with the primitive Leonov (now hovering high above Farside as one of the main exhibits at the Lagrange Museum) there was still some element of risk in any extended space voyage. Especially like the pioneering one on which he was now preparing to embark.

Yet that, perhaps, was exactly what he was seeking – even at a hundred and three (or, according to the complex geriatric accounting of the late Professor Katerina Rudenko, a hale and hearty sixty-five.) During the last decade, he had become aware of an increasing restlessness and a vague dissatisfaction with a life that was too comfortable and well-ordered.

Despite all the exciting projects now in progress around the Solar System – the Mars Renewal, the establishment of the Mercury Base, the Greening of Ganymede – there had been no goal on which he could really focus his interests and his still considerable energies. Two centuries ago, one of the first poets of the Scientific Era had summed up his feelings perfectly, speaking through the lips of Odysseus/Ulysses:

'Three suns', indeed! It was more than forty: