Rendezvous With Rama - Arthur C. Clarke [41]
'I think there is some merit in your argument, Mr. Ambassador,' he said slowly. 'Have you any proposals?'
'Yes, sir. Before we know what action to take, we must have the facts. We know the geography of Rama—if one can use that term—but we have no idea of its capabilities. And the key to the whole problem is this: does Rama have a propulsion system? Can it change orbit? I'd be very interested in Dr. Perera's views.'
'I've given the subject a good deal of thought,' answered the exobiologist. 'Of course, Rama must have been given its original impetus by some launching device, but that could have been an external booster. If it does have onboard propulsion, we've found no trace of it. Certainly there are no rocket exhausts, or anything similar, anywhere on the outer shell.'
'They could be hidden.'
'True, but there would seem little point in it. And where are the propellant tanks, the energy sources? The main hull is solid—we've checked that with seismic surveys. The cavities in the northern cap are all accounted for by the airlock systems.'
'That leaves the southern end of Rama, which Commander Norton has been unable to reach, owing to that ten-kilometre-wide band of water. There are all sorts of curious mechanisms and structures up on the South Pole—you've seen the photographs. What they are is anybody's guess.'
'But I'm reasonably sure of this. If Rama does have a propulsion system, it's something completely outside our present knowledge. In fact, it would have to be the fabulous "Space Drive" people have been talking about for two hundred years.'
'You wouldn't rule that out?'
'Certainly not. If we can prove that Rama has a Space Drive—even if we learn nothing about its mode of operation—that would be a major discovery. At least we'd know that such a thing is possible.'
'What is a Space Drive?' asked the Ambassador for Earth, rather plaintively.
'Any kind of propulsion system, Sir Robert, that doesn't work on the rocket principle. Anti-gravity—if it is possible—would do very nicely. At present, we don't know where to look for such a drive, and most scientists doubt if it exists.'
'It doesn't,' Professor Davidson interjected. 'Newton settled that. You can't have action without reaction. Space Drives are nonsense. Take it from me.'
'You may be right,' Perera replied with unusual blandness. 'But if Rama doesn't have a Space Drive, it has no drive at all. There's simply no room for a conventional propulsion system, with its enormous fuel tanks.'
'It's hard to imagine a whole world being pushed around,' said Dennis Solomons. 'What would happen to the objects inside it? Everything would have to be bolted down. Most inconvenient.'
'Well, the acceleration would probably be very low. The biggest problem would be the water in the Cylindrical Sea. How would you stop that from . . .'
Perera's voice suddenly faded away, and his eyes glazed over. He seemed to be in the throes of an incipient epileptic fit, or even a heart attack. His colleagues looked at him in alarm; then he made a sudden recovery, banged his fist on the table and shouted: 'Of course! That explains everything! The southern cliff—now it makes sense!'
'Not to me,' grumbled the Lunar Ambassador, speaking for all the diplomats present.
'Look at this longitudinal cross-section of Rama,' Perera continued excitedly, unfolding his map. 'Have you got your copies? The Cylindrical Sea is enclosed between two cliffs, which completely circle the interior of Rama. The one on the north is only fifty metres high. The southern one, on the other hand, is almost half a kilometre high. Why the big difference? No one's been able to think of a sensible reason.'
'But suppose Rama is able to propel itself—accelerating so that the northern end is forward. The water in the Sea would tend to move back; the level at the south would rise—perhaps hundreds