Pete hesitated. 'As a matter of fact, I feel as if I were wading in quicksand up to my neck. Every move is an effort.'
'Gee, that's too bad! Just what is the surface gravity on Ganymede? About one-third V isn't it?'
'Thirty-two per cent. Or from my point of view, everything here weighs three times as much as it ought to. Including me.'
Matt nodded. 'As if two other guys were riding on you, one on your shoulders, and one on your back.'
'That's about it. The worst of it is, my feet hurt all the time. I'll get over it-'
'Sure you will!
'-since. I'm of Earth ancestry and potentially just as strong as my grandfather was. Back home, I'd been working out in the centrifuge the last couple of earth-years. I'm a lot stronger than I used to be. There's Oscar.' Matt greeted Oscar, then hurried to his room to phone his father in private.
A copter transport hopped Matt and some fifty other candidates to the site of the variable acceleration test-in cadet slang, the 'Bumps.' It was west of the base, in the mountains, in order to have a sheer cliff for free fall. They landed on a loading platform at the edge of this cliff and joined a throng of other candidates. It was a crisp Colorado morning. They were near the timberline; gaunt evergreens, twisted by the winds, surrounded the clearing.
From a building just beyond the platform two steel skeletons ran vertically down the face of the two-thousand- foot cliff. They looked like open frames for elevators, which one of them was. The other was a guide for the testing car during the drop down the cliff.
Matt crowded up to the rail and leaned over. The lower ends of the skeleton frameworks disappeared, a dizzy distance below, in the roof of a building notched into the sloping floor of the canyon. He was telling himself that he hoped the engineer who had designed the thing knew what he was doing when he felt a dig in the ribs. It was Tex. 'Some roller coaster, eh, Matt?'
'Hi, Tex. That's an understatement if I ever heard one.'
The candidate on Matt's left spoke up. 'Do you mean to say we ride down that thing?'
'No less,' Tex answered. 'Then they gather the pieces up in a basket and haul 'em up the other one.'
'How fast does it go?'
'You'll see in a mom- Hey! Thar she blows!'
A silvery, windowless car appeared inside one guide frame, at its top. It poised for a split second, then dropped. It dropped and dropped and dropped, gathering speed, until it disappeared with what seemed incredible velocity- actually about two hundred and fifty miles per hour-into the building below. Matt braced himself for the crash. None came, and he caught his breath.
Seconds later the car reappeared at the foot of the other framework. It seemed to crawl; actually it was accelerating rapidly during the first half of the climb. It passed from view into the building at the top of the cliff.
'Squad nine!' a loudspeaker bawled behind them.
Tex let out a sigh 'Here I go, Matt,' he said. 'Tell mother my last words were of her. You can have my stamp collection.' He shook hands and walked away.
The candidate who had spoken before gulped; Matt saw that he was quite pale. Suddenly he took off in the same direction but did not line up with the squad; instead he went up to the cadet mustering the squad and spoke to him, briefly and urgently. The cadet shrugged and motioned him away from the group.
Matt found himself feeling sympathetic rather than contemptuous.
His own test group was mustered next. He and his fellows were conducted into the upper building, where a cadet explained the test: 'This test examines your tolerance for high acceleration, for free fall or weightlessness, and for violent changes in acceleration. You start with centrifugal force of three gravities, then all weight is removed from you as the car goes over the cliff. At the bottom the car enters a spiraling track which reduces its speed at deceleration of three gravities. When the car comes to rest, it enters the ascending tower; you make the climb at two gravities, dropping to one gravity, and momentarily to no weight, as the car reaches the top. Then the cycle is repeated, at higher accelerations, until each of you has reacted. Any questions?'
Matt asked, 'How long is the free fall, sir?'
'About eleven seconds. We would increase it, but to double it would take four times as high a cliff. However, you will find this one high enough.' He smiled grimly.
A timid voice asked, 'Sir, what do you mean by 'react'?'
'Any of several things-hemorrhage, loss of consciousness.'
'It's dangerous?'
The cadet shrugged. 'What isn't? There has never been any mechanical failures. Your pulse, respiration, blood pressure, and other data are telemetered to the control room. We'll try not to let you die under test.'
Presently he led them out of the room, down a passage and through a door into the test car. It had pendulum seats, not unlike any high-speed vehicle, but semi-reclining and heavily padded. They strapped down and medical technicians wired them for telemetering their responses. The cadet inspected, stepped out and returned with an officer, who repeated the inspection. The cadet then distributed 'sick kits'-cloth bags of double thickness to be tied and taped to the mouth, so that a person might retch without inundating his companions. This done, he asked, 'Are you all ready?' Getting no response, he went out and closed the door.
Matt wished that he had stopped him before it was too late.
For a long moment nothing happened. Then the car seemed to incline; actually, the seats inclined as the car started to move and picked up speed.
The seats swung back to the at-rest position but Matt felt himself getting steadily heavier and knew thereby that
they were being centrifuged. He pressed against the pads, arms leaden, legs too heavy to move.
The feeling of extra weight left him, he felt his normal weight again, when suddenly that, too, was taken from him. He surged against the safety belts.
His stomach seemed to drop out of him. He gulped and swallowed; his breakfast stayed down. Somebody yelled, 'We're falling!' It seemed to Matt the most unnecessary statement he had ever heard.
He set his jaw and braced himself for the bump. It did not come-and still his stomach seemed trying to squirm its way out of his body. Eleven seconds? Why, he had been falling more than eleven seconds already. What had gone wrong?
And still they fell, endlessly.
And fell.
Then he was forced back against the pads. The pressure increased smoothly until he was as heavy as he had been just before the drop. His abused stomach tried to retch but the pressure was too much for it.
The pressure eased off to normal weight. A short while later the car seemed to bounce and momentarily he was weightless, while his insides grabbed frantically for anchorage. The feeling of no weight lasted only an instant; he sagged into the cushions.
The door was flung open; the cadet strode in, followed by two medical technicians. Someone yelled, 'Let me out of here! Let me out of here!' The cadet paid no attention but went to the seat in front of Matt. He unstrapped the occupant and the two medical assistants carried him out. His head lolled loosely as they did so. The cadet then went to the candidate who was kicking up the fuss, unstrapped him, and stepped back. The boy got up, staggered, and shuffled out.
'Anyone need a fresh sick kit?' There were muffled responses. Working swiftly, the cadet helped those who needed it. Matt felt weakly triumphant that his own kit was still clean.
'Stand by for five gravities,' commanded the cadet. He made them answer to their names, one by one. While he was doing so another boy started clawing at his straps. Still calling the roll, the cadet helped him free and let him leave. He followed the lad out the door and shut it.
Matt felt himself tensing unbearably. He was relieved when the pressure took hold-but only momentarily, for he found that five gravities were much worse than three. His chest seemed paralyzed, he fought for air.
The giant pressure lifted-they were over the edge again, falling. His mistreated stomach revenged itself at once; he was sorry that he had eaten any breakfast at all.
They were still falling. The lights went out-and someone screamed. Falling and still retching, Matt was sure that the blackness meant some sort of accident; this time they would crash-but it did not seem to matter.
He was well into the black whirlpool of force that marked the deceleration at the bottom before he realized that
