Rendezvous with Rama

44. Space Drive

A hundred kilometres was an adequate safety margin, Norton had decided. Rama was now a huge black rectangle, exactly broadside-on, eclipsing the sun. He had used this opportunity to fly Endeavour completely into shadow, so that the load could be taken off the ship’s cooling systems and some overdue maintenance could be carried out. Rama’s protective cone of darkness might disappear at any moment, and he intended to make as much use of it as he could. Rama was still turning; it had now swung through almost fifteen degrees, and it was impossible to believe that some major orbit change was not imminent. On the United Planets, excitement had now reached a pitch of hysteria, but only a faint echo of this came to Endeavour. Physically and emotionally, her crew was exhausted; apart from a skeleton watch, everyone had slept for twelve hours after take-off from the North Polar Base. On doctor’s orders, Norton himself had used electro-sedation; even so, he had dreamed that he was climbing an infinite stairway.

The second day back on ship, everything had almost returned to normal; the exploration of Rama already seemed part of another life. Norton started to deal with the accumulated office work and to make plans for the future; but he refused the requests for interviews that had somehow managed to insinuate themselves into the Survey and even SPACEGUARD radio circuits. There were no messages from Mercury, and the UP General Assembly had adjourned its session, though it was ready to meet again at an hour’s notice.

Norton was having his first good night’s sleep, thirty hours after leaving Rama, when he was rudely shaken back to consciousness. He cursed groggily, opened a bleary eye at Karl Mercer—and then, like any good commander, was instantly wide awake.

“It’s stopped turning?”

“Yes. Steady as a rock.”

“Let’s go to the bridge.”

The whole ship was awake; even the simps knew that something was afoot, and made anxious, meeping noises until Sergeant McAndrews reassured them with swift hand-signals. Yet as Norton slipped into his chair and fastened the restraints round his waist, he wondered if this might be yet another false alarm.

Rama was now foreshortened into a stubby cylinder, and the searing rim of the sun had peeked over one edge. Norton jockeyed Endeavour gently back into the umbra of the artificial eclipse, and saw the pearly splendour of the corona reappear across a background of the brighter stars. There was one huge prominence, at least half a million kilometres high, that had climbed so far from the sun that its upper branches looked like a tree of crimson fire.

So now we have to wait, Norton told himself. The important thing is not to get bored, to be ready to react at a moment’s notice, to keep all the instruments aligned and recording, no matter how long it takes.

That was strange. The star field was shifting, almost as if he had actuated the Roll thrusters. But he had touched no controls, and if there had been any real movement, he would have sensed it at once.

“Skipper!” said Calvert urgently from the Nay position, “we’re rolling—look at the stars! But I’m getting no instrument readings!”

“Rate gyros operating?”

“Perfectly normal—I can see the zero jitter. But we’re rolling several degrees a second!”

“That’s impossible!”

“Of course it is—but look for yourself…”

When all else failed, a man had to rely on eyeball instrumentation. Norton could not doubt that the star field was indeed slowly rotating—there went Sirius, across the rim of the port. Either the universe, in a reversion of pre-Copernican cosmology, had suddenly decided to revolve around Endeavour; or the stars were standing still, and the ship was turning.

The second explanation seemed rather more likely, yet it involved apparently insoluble paradoxes. If the ship was really turning at this rate, he would have felt it—literally by the seat of his pants, as the old saying went. And the gyros could not all have failed, simultaneously and independently.

Only one answer remained. Every atom of Endeavour must be in the grip of some force—and only a powerful gravitational field could produce this effect. At least, no other known field…

Suddenly, the stars vanished. The blazing disc of the sun had emerged from behind the shield of Rama, and its glare had driven them from the sky.

“Can you get a radar reading? What’s the doppler?”

Norton was fully prepared to find that this too was inoperative, but he was wrong.

Rama was under way at last, accelerating at the modest rate of 0.015 gravities. Dr. Perera, Norton told himself, would be pleased; he had predicted a maximum of 0.02. And Endeavour was somehow caught in its wake like a piece of flotsam, whirling round and round behind a speeding ship…

Hour after hour, that acceleration held constant; Rama was falling away from Endeavour at steadily increasing speed. As its distance grew, the anomalous behaviour of the ship slowly ceased; the normal laws of inertia started to operate again. They could only guess at the energies in whose backlash they had been briefly caught, and Norton was thankful that he had stationed Endeavour at a safe distance before Rama had switched on its drive.

As to the nature of that drive, one thing was now certain, even though all else was mystery. There were no jets of gas, no beams of ions or plasma thrusting Rama into its new orbit. No one put it better than Sergeant-Professor Myron when he said, in shocked disbelief: “There goes Newton’s Third Law.”

It was Newton’s Third law, however, upon which Endeavour had to depend the next day, when she used her very last reserves of propellant to bend her own orbit outwards from the sun. The change was slight, but it would increase her perihelion distance by ten million kilometres. That was the difference between running the ship’s cooling system at ninety-five per cent capacity—and a certain fiery death.

When they had completed their own manoeuvre, Rama was two hundred thousand kilometres away, and difficult to see against the glare of the sun. But they could still obtain accurate radar measurements of its orbit; and the more they observed, the more puzzled they became.

They checked the figures over and over again, until there was no escaping from the unbelievable conclusion. It looked as if all the fears of the Hermians, the heroics of Rodrigo, and the rhetoric of the General Assembly, had been utterly in vain.

What a cosmic irony, said Norton as he looked at his final figures, if after a million years of safe guidance Rama’s computers had made one trifling error—perhaps changing the sign of an equation from plus to minus.

Everyone had been so certain that Rama would lose speed, so that it could be captured by the sun’s gravity and thus become a new planet of the solar system. It was doing just the opposite.

It was gaining speed—and in the worst possible direction.

Rama was falling ever more swiftly into the sun.