Up on the Hub, Commander Norton stirred a little uneasily. But Mercer, of all men, knew exactly what he was doing. He would already have made enough tests to satisfy himself.

Mercer equalized pressure, unlatched the securing clip of his helmet, and opened it a crack. He took a cautious breath; then a deeper one.

The air of Rama was dead and musty, as if from a tomb so ancient that the last trace of physical corruption had disappeared ages ago. Even Mercer’s ultra-sensitive nose, trained through years of testing life-support systems to and beyond the point of disaster, could detect no recognizable odours. There was a faint metallic tang, and he suddenly recalled that the first men on the Moon had reported a hint of burnt gunpowder when they repressurized the lunar module. Mercer imagined that the moon-dust-contaminated cabin on Eagle must have smelled rather like Rama.

He sealed the helmet again, and emptied his lungs of the alien air. He had extracted no sustenance from it; even a mountaineer acclimatized to the summit of Everest would die quickly here. But a few kilometres further down, it would be a different matter.

What else was there to do here? He could think of nothing, except the enjoyment of the gentle, unaccustomed gravity. But there was no point in growing used to that, since they would be returning immediately to the weightlessness of the Hub.

“We’re coming back, Skipper,” he reported. “There’s no reason to go further until we’re ready to go all the way.”

“I agree. We’ll be timing you, but take it easy.”

As he bounded up the steps, three or four at a stride, Mercer agreed that Calvert had been perfectly correct; these stairs were built to be walked up, not down. As long as one did not look back, and ignored the vertiginous steepness of the ascending curve, the climb was a delightful experience. After about two hundred steps, however, he began to feel some twinges in his calf muscles, and decided to slow down. The others had done the same; when he ventured a quick glance over his shoulder, they were considerably further down the slope.

The climb was wholly uneventful—merely an apparently endless succession of steps. When they stood once more on the highest platform, immediately beneath the ladder, they were barely winded, and it had taken them only ten minutes. They paused for another ten, then started on the last vertical kilometre.

Jump—catch hold of a rung—jump—catch—jump—catch… it was easy, but so boringly repetitious that there was danger of becoming careless. Halfway up the ladder they rested for five minutes: by this time their arms as well as their legs had begun to ache. Once again, Mercer was glad that they could see so little of the vertical face to which they were clinging; it was not too difficult to pretend that the ladder only extended just a few metres beyond their circle of light, and would soon come to an end.

Jump—catch a rung—jump—then, quite suddenly, the ladder really ended. They were back at the weightless world of the axis, among their anxious friends. The whole trip had taken under an hour, and they felt a sense of modest achievement.

But it was much too soon to feel pleased with themselves. For all their efforts, they had traversed less than an eighth of that cyclopean stairway.

Some women, Commander Norton had decided long ago, should not be allowed aboard ship; weightlessness did things to their breasts that were too damn distracting. It was bad enough when they were motionless; but when they started to move, and sympathetic vibrations set in, it was more than any warm-blooded male should be asked to take. He was quite sure that at least one serious space accident had been caused by acute crew distraction, after the transit of a well-upholstered lady officer through the control cabin.

He had once mentioned this theory to Surgeon-Commander Laura Ernst, without revealing who had inspired his particular train of thought. There was no need; they knew each other much too well. On Earth, years ago, in a moment of mutual loneliness and depression, they had once made love. Probably they would never repeat the experience (but could one ever be quite sure of that?) because so much had changed for both of them. Yet whenever the well-built Surgeon oscillated into the Commander’s cabin, he felt a fleeting echo, of an old passion, she knew that he felt it, and everyone was happy.

“Bill,” she began, “I’ve checked our mountaineers, and here’s my verdict. Karl and Joe are in good shape—all indications normal for the work they’ve done. But Will shows signs of exhaustion and body-loss—I won’t bother about the details. I don’t believe he’s been getting all the exercise he should, and he’s not the only one. There’s been some cheating in the centrifuge; if there’s any more, heads will roll. Please pass the word.”

“Yes, Ma’am. But there’s some excuse. The men have been working very hard.”

“With their brains and fingers, certainly. But not with their bodies—not real work in kilogram-metres. And that’s what we’ll be dealing with, if we’re going to explore Rama.”

“Well, can we?”

“Yes, if we proceed with caution. Karl and I have worked out a very conservative profile—based on the assumption that we can dispense with breathing gear below Level Two. Of course, that’s an incredible stroke of luck, and changes the whole logistics picture. I still can’t get used to the idea of a world with oxygen… So we only need to supply food and water and thermosuits, and we’re in business. Going down will be easy; it looks as if we can slide most of the way, on that very convenient banister.”

“I’ve got Chips working on a sled with parachute braking. Even if we can’t risk it for crew, we can use it for stores and equipment.”

“Fine; that should do the trip in ten minutes; otherwise it will take about an hour.”

“Climbing up is harder to estimate; I’d like to allow six hours, including two one-hour periods. Later, as we get experience—and develop some muscles—we may be able to cut this back considerably.”

“What about psychological factors?”

“Hard to assess, in such a novel environment. Darkness may be the biggest problem.”

“I’ll establish searchlights on the Hub. Besides its own lamps, any party down there will always have a beam playing on it.”

“Good—that should be a great help.”

“One other point: should we play safe and send a party only halfway down the stair—and back—or should we go the whole way on the first attempt?”

“If we had plenty of time, I’d be cautious. But time is short, and I can see no danger in going all the way—and looking around when we get there.”

“Thanks, Laura—that’s all I want to know. I’ll get the Exec working on the details. And I’ll order all hands to the centrifuge—twenty minutes a day at half a gee. Will that satisfy you?”

“No. It’s point six gee down there in Rama, and I want a safety margin. Make it three quarters—”

“Ouch!”

“—for ten minutes—”

“I’ll settle for that—”

“—twice a day.”

“Laura, you’re a cruel, hard woman. But so be it. I’ll break the news just before dinner. That should spoil a few appetites.” It was the first time that Commander Norton had ever seen Karl Mercer slightly ill at ease. He had spent the fifteen minutes discussing the logistics problem in his usual competent manner, but something was obviously worrying him. His captain, who had a shrewd idea of what it was, waited patiently until he brought it out.

“Skipper,” Karl said at length, “are you sure you should lead this party? If anything goes wrong, I’m considerably more expendable. And I’ve been further inside Rama than anyone else—even if only by fifty metres.”

“Granted. But it’s time the commander led his troops, and we’ve decided that there’s no greater risk on this trip than on the last. At the first sign of trouble, I’ll be back up that stairway fast enough to qualify for the Lunar Olympics.”