Rendezvous With Rama - Arthur C. Clarke Page 0,13

of the voyage, even if you’re on a one-way trip. So it may make more sense to take your time—ten thousand, a hundred thousand years.

“Bernal and others thought this could be done with mobile worldlets a few kilometers across, carrying thousands of passengers on journeys that would last for generations. Naturally, the system would have to be rigidly closed, recycling all food, air, and other expendables. But, of course, that’s just how the Earth operates—on a slightly larger scale.

“Some writers suggested that these space arks should be built in the form of concentric spheres; others proposed hollow, spinning cylinders so that centrifugal force could provide artificial gravity—exactly what we’ve found in Rama—”

Davidson could not tolerate this sloppy talk. “No such thing as centrifugal force. It’s an engineer’s phantom. There’s only inertia.”

“You’re quite right, of course,” admitted Perera, “though it might be hard to convince a man who’d just been slung off a carrousel. But mathematical rigor seems unnecessary—”

“Hear, hear,” interjected Bose, with some exasperation. “We all know what you mean, or think we do. Please don’t destroy our illusions.”

“Well, I was merely pointing out that there’s nothing conceptually novel about Rama, though its size is startling. Men have imagined such things for two hundred years.

“Now I’d like to address myself to another question. Exactly how long has Rama been traveling through space?

“We now have a very precise determination of its orbit and its velocity. Assuming that it’s made no navigational changes, we can trace its position back for millions of years. We expected that it would be coming from the direction of a nearby star. But that isn’t the case at all.

“It’s more than two hundred thousand years since Rama passed near any star, and that particular one turns out to be an irregular variable—about the most unsuitable sun you could imagine for an inhabited solar system. It has a brightness range of over fifty to one; any planets would be alternately baked and frozen every few years.”

“A suggestion,” put in Dr. Price. “Perhaps that explains everything. Maybe this was once a normal sun and became unstable. That’s why the Ramans had to find a new one.”

Perera admired the old archeologist, so he let her down lightly. But what would she say, he wondered, if he started pointing out the instantly obvious in her own specialty?

“We did consider that,” he said gently. “But if our present theories of stellar evolution are correct, this star could never have been stable, could never have had lifebearing planets. So Rama has been cruising through space for at least two hundred thousand years, and perhaps for more than a million.

“Now it’s cold and dark and apparently dead, and I think I know why. The Ramans may have had no choice—perhaps they were indeed fleeing from some disaster—but they miscalculated.

“No closed ecology can be one-hundred-per-cent efficient; there is always waste, loss—some degradation of the environment and build-up of pollutants. It may take billions of years to poison and wear out a planet, but it will happen in the end. The oceans will dry up; the atmosphere will leak away.

“By our standards, Rama is enormous—yet it is still a very tiny planet. My calculations, based on the leakage through its hull, and some reasonable guesses about the rate of biological turnover, indicate that its ecology could survive for only about a thousand years. At the most, I’ll grant ten thousand.

“That would be long enough, at the speed Rama is traveling, for a transit between the closely packed suns in the heart of the galaxy. But not out here, in the scattered population of the spiral arms. Rama is a ship that exhausted its provisions before it reached its goal. It’s a derelict, drifting among the stars.

“There’s just one serious objection to this theory, and I’ll raise it before anybody else does. Rama’s orbit is aimed so accurately at the solar system that coincidence seems ruled out. In fact, I’d say it’s now heading much too close to the Sun for comfort. Endeavour will have to break away long before perihelion, to avoid overheating.

“I don’t pretend to understand this. Perhaps there is some form of automatic terminal guidance still operating, steering Rama to the nearest suitable star ages after its builders died.

“And they are dead; I’ll stake my reputation on that. All the samples we’ve taken from the interior are absolutely sterile. We’ve not found a single microorganism. As for the talk you may have heard about suspended animation, you can ignore it. There are fundamental reasons