Artificial Gravity

"Soup's on," announced Lopez. "This is your messroom. Lunch in a few minutes."

Behind Lopez, secured firmly to the far wall, were mess tables and benches. The table tops faced Matt -- under him, over him, or across from him -- what you will. It seemed an impractical arrangement. "I'm not very hungry," one youngster said faintly.

"You ought to be," Lopez answered reasonably. "It's been five hours or more since you had breakfast. We're on the same time schedule here as Hayworth Hall, zone plus eight, Terra. Why aren't you hungry?"

"Uh, I don't know, sir. I'm just not."

Lopez grinned and suddenly looked as young as his charges. "I was just pulling your leg, kiddo. The chief engineer will have some spin on us in no time, as soon as we break loose from the Bolivar. Then you can sit down on your soft, round fanny and console your tender stomach in peace. You'll have an appetite. In the meantime, take it easy."

Two more squads filtered in. While they waited Matt said to Lopez, "How fast will the ship spin, sir?"

"We'll build up to one gravity at the outer skin. Takes about two hours to do it, but we'll eat as soon as we're heavy enough for you groundhogs to swallow your soup without choking."

"But how fast is that, sir?"

"Can you do simple arithmetic?"

"Why, yes, sir."

"Then do it. The Randolph is two hundred feet through and we spin on her main axis. The square of the rim speed divided by her radius -- what's the rpm?"

Matt got a faraway look on his face. Lopez said, "Come, now, Mr. Dodson -- pretend you're heading for the surface and about to crash. What's the answer?"

"Uh-I'm afraid I can't do it in my head, sir."

Lopez looked around. "All right -- who's got the answer?" No one spoke up. Lopez shook his head mournfully. "And you laddies expect to learn to astrogate! Better by far you should have gone to cow colleges. Never mind -- it works out to about five and four-tenths revolutions per minute. That gives one full gravity for the benefit of the women and children. Then it's cut down day by day, until a month from now we're in free fall again. That gives you time to get used to it -- or else."

Someone said, "Gee, it must take a lot of power."

Lopez answered, "Are you kidding? It's done by electric-braking the main axis flywheels. The shaft has field coils wound on it; you cut it in as a generator and let the reaction between the wheel and the ship put a spin on the ship. You store the juice. Then when you want to take the spin off, you use the juice to drive it as a motor and you are back where you started, free for nothing, except for minor losses. Savvy?"

"Er, I guess so, sir."

"Look it up in the ship's library, sketch the hook-up, and show it to me after supper."

However, the data on artificial gravity is a bit out of date. The original research into it had subjects sick at 3 RPM and incapacitated at 6 RPM+. However, more recent research suggests that, by using incremental increases in rotation and making a few limb movements, adaptation can occur with almost no feelings of nausea. The old research (done on about 30 subjects) simply went from zero to full rotation. Moreover, the adaptation can be simultaneous with non- rotational adaptation. So, moving in and out of the rotating habitat for maintenance or whatever is no problem. It's thought that rotation rates of up 7.5 to 10 RPM are possible. This makes Discovery's 5.5m radius centrifuge a real possibility. In fact, with 10 RPM, you could crank it up to a handsome 0.61 G, or 0.34G if you want to play it safe at 7.5RPM.

After lunch, from 1300 to 1600 Bowman would make a slow and careful tour of the ship - or such part of it as was accessible. Discovery measured almost four hundred feet from end to end, but the little universe occupied by her crew lay entirely inside the forty-foot sphere of the pressure hull.

Here were all the life-support systems, and the Control Deck which was the operational heart of the ship. Below this was a small "space-garage" fitted with three airlocks, through which powered capsules, just large enough to hold a man, could sail out into the void if the need arose for extravehicular activity.

The equatorial region of the pressure sphere - the slice, as it were, from Capricorn to Cancer - enclosed a slowly rotating drum, thirty-five feet in diameter. As it made one revolution every ten seconds, this carrousel or centrifuge produced an artificial gravity equal to that of the Moon. This was enough to prevent the physical atrophy which would result from the complete absence of weight, and it also allowed the routine functions of living to be carried out under normal - or nearly normal - conditions.

The carrousel therefore contained the kitchen, dining, washing, and toilet facilities. Only here was it safe to prepare and handle hot drinks - quite dangerous in weightless conditions, where one can be badly scalded by floating globules of boiling water. The problem of shaving was also solved; there would be no weightless bristles drifting around to endanger electrical equipment and produce a health hazard.

Around the rim of the carrousel were five tiny cubicles, fitted out by each astronaut according to taste and containing his personal belongings. Only Bowman's and Poole's were now in use, while the future occupants of the other three cabins reposed in their electronic sarcophagi next door.

The spin of the carrousel could be stopped if necessary; when this happened, its angular momentum had to be stored in a flywheel, and switched back again when rotation was restarted. But normally it was left running at constant speed, for it was easy enough to enter the big, slowly turning drum by going hand-over-hand along a pole through the zero-gee region at its center. Transferring to the moving section was as easy and automatic, after a little experience, as stepping onto a moving escalator.

I have a very basic problem with spin sections in spaceships.

1) The more things are meant to move, the more they wear out. Making a gimbaled joint that doesn't become the maintenance nightmare of the F-14 swing-wing is a tricky proposition -- particularly in space where there's vacuum welding, thermal differences from ambient solar radiation, and worse.

2) How the heck do you get the plumbing to work? I guarantee you that rotating your typical bathroom through 90 degrees will make every water conveyance run wrong. Not to mention the times in transition when it'll be at zero gee.

Or do you put in twice as many bathrooms?

The reason why ships in Ten Worlds don't have spin sections come from the maintenance issues, the fact that the trips themselves are months, not years in duration and that most of the waypoints have spin gravity on can cities.

On a related note, when your spin section arms are extended out, where do your radiators go?

And prior to (the) Mercury (program) we hadn't any real experience at all. We flew transport planes in parabolic courses that might give as much as 30 seconds of almost-zero-g, and that was all we knew. I will not soon forget some of our early low-g experiments. Some genius wanted to know how a cat oriented: visual cues, or a gravity sensor? The obvious way to find out was to take a cat up in an airplane, fly the plane in a parabolic orbit, and observe the cat during the short period of zero-g.

It made sense. Maybe. It didn't make enough that anyone would authorize a large airplane for the experiment, so a camera was mounted in a small fighter (perhaps a T-bird; I forget), and the cat was carried along in the pilot's lap. A movie was made of the whole run.

The film, I fear, doesn't tell us how a cat orients. It shows the pilot frantically trying to tear the cat off his arm, and the cat just as violently resisting. Eventually the cat was broken free and let go in mid-air, where it seemed magically (teleportation? or not really zero gravity in the plane? no one knows) to move, rapidly, straight back to the pilot, claws outstretched. This time there was no tearing it loose at all. The only thing I learned from the film is that cats (or this one anyway) don't like zero gravity, and think human beings are the obvious point of stability to cling to...

What is so funny about a man being dropsick? Those dolts with cast-iron stomachs always laugh - I'll bet they would laugh if Grandma broke both legs.

I was spacesick, of course, as soon as the rocket ship quit blasting and went into free fall. I came out of it fairly quickly as my stomach was practically empty - I'd eaten nothing since breakfast- and was simply wanly miserable the remaining eternity of that awful trip. It took us an hour and forty-three minutes to make rendezvous, which is roughly equal to a thousand years in purgatory to a ground hog like myself.

I'll say this for Dak, though: he did not laugh. Dak was a professional and he treated my normal reaction with the impersonal good manners of a infight nurse - not like those flat-headed, loud-voiced jackasses you'll find on the passenger list of a Moon shuttle. If I had my way, those healthy self-panickers would be spaced in mid-orbit and allowed to laugh themselves to death in vacuum.

Despite the turmoil in my mind and the thousand questions I wanted to ask we had almost made rendezvous with a torchship, which was in parking orbit around Earth, before I could stir up interest in anything. I suspect that if one were to inform a victim of spacesickness that he was to be shot at sunrise his own answer would be, "Yes? Would you hand me that sack, please?"

...

"Dak?" I said as he signed off.

"Later," he answered. "I'm about to match orbits. The contact may be a little rough, as I am not going to waste time worrying about chuck holes. So pipe down and hang on."

And it was rough. By the time we were in the torchship I was glad to be comfortably back in free fall again; surge nausea is even worse than everyday dropsickness.