The speeds of the asteroids, flying boulders, rocks, sand, and space drift that infest the area between Mars and Jupiter vary from about fifteen miles per second near Mars to about eight miles per second near Jupiter. The orbits of this flying junkyard are erratically inclined to the plane of the ecliptic an average of about nine degrees and some of the orbits are quite eccentric as well.
All this means that a ship on a circular orbit, headed 'east,' or with the traffic, may expect the possibility of side-swiping collisions at relative speeds averaging two miles per second, with crashes remotely possible at double that speed.
Two miles per second is only about twice the muzzle velocity of a good sporting rifle. With respect to small stuff, sand and gravel, the Aes Triplex was built to take it. Before the ship reached the danger zone, an all-hands chore in space suits took place; armor-plate segments, as thick as the skin of the ship, were bolted over the ship's quartz ports, leaving only the eyes of the astrogational instruments and the radar antennae exposed.
To guard against larger stuff Captain Yancey set up a meteor-watch much tighter than is usual in most parts of space. Eight radars scanned all space through a global 360°. The only condition necessary for collision is that the other object hold a steady bearing-no fancy calculation is involved. The only action necessary then to avoid collision is to change your own speed, any direction, any amount. This is perhaps the only case where theory of piloting is simple.
Commander Miller put the cadets and the sublieutenants on a continuous heel-and-toe watch, scanning the meteor-guard 'scopes. Even if the human being failed to note a steady bearing the radars would 'see' it, for they were so rigged that, if a 'blip' burned in at one spot on die screen, thereby showing a steady bearing, an alarm would sound- and the watch officer would cut in the jet, fast!
However, even the asteroid belt is very empty space indeed; the chances were strongly against collision with anything larger than a grain of sand. The only difference in the Aes Triplex, aside from the increased work for the junior officers, was a ship's order directing all hands to strap down when sleeping, instead of floating loosely and comfortably about, so that the sleeper would not break his neck in case of sudden acceleration.
P.R.S. Aes Triplex was equipped with two jeeps, nestled in hangar pockets-quite ordinary short-range, chemically-powered rockets except that they were equipped with search radar as powerful as the ship's. When they reached their search area a pilot and co-pilot were assigned to each jeep - and a second crew also, as each rocket was to remain away from the ship a week at a time, then swap crews and go out again.
Lieutenants Brunn, Thurlow, and Novak, and Sublieutenant Peters were designated pilots. A cadet was assigned to each senior lieutenant and Sublieutenant Gomez was teamed with Sublieutenant Peters. Matt drew Lieutenant Thurlow.
Dr. Pickering took over the mess. That left Sublieutenant Cleary as 'George,' the man who does everything-an impossibility, since meteor-guard and search watches would have to be kept up. Consequently the two jeep crews riot actually in space had to help out even during their week of rest.
Each Monday the ship placed the jeep rockets on station so that the three vessels would sweep the largest possible volume of space, with their search fields barely overlapping. The placement was made by the mother ship, so that the jeep would be left with full tanks in the unhappy event that she was not picked up-and thereby have enough fuel to shape an orbit toward the inner planets, if need be.
XII P.R.S. PATHFINDER
MATT TOOK ALONG a supply of study spools on his first week of search intending to play them on the jeep's tiny, earphones-type viewer. He did not get much chance; four
hours out of eight he had to keep his eyes glued to the search scopes. During the four hours off watch he had to sleep, eat, attend to chores, and study, if possible.
Besides that, Lieutenant Thurlow liked to talk.
The bomb officer was expecting Earth-side duty in postgraduate study at the end of the cruise. 'And then I'll have to make up my mind, Matt. Do I stay in and make physics a part-time specialty, or resign and go in for research?'
'It depends on what you want to do.'
'Trite but true. I think I want to be a scientist, full time-but after a few years the Patrol becomes a father and a mother to you. I don't know. That pile of rock is creeping up on us-I can see it through the port now.'
'It is, eh?' Matt moved forward until he, too, could see the undersized boulder that Thurlow had been watching by radar. It was of irregular shape, a pattern of sunlight and sharp, dark shadow.
'Mister Thurlow,' said Matt, 'look-about the middle. Doesn't that look like striation to you?'
'Could be. Some specimens have been picked up that were definitely sedimentary rock. That was the first proof that the asteroids used to be a planet, you know.'
'I thought that Goodman's integrations were the first proof?'
'Nope, you're switched around. Goodman wasn't 'able to run his checks until the big ballistic computer at Terra Station was built.'
'I knew that-I just had it backwards, I guess.' The theory that the asteroids had once been a planet, between Mars and Jupiter, was denied for many years because their orbits showed no interrelation, i.e., if a planet had blown to bits the orbits should intersect at the point of the explosion. Professor Goodman, using the giant, strain-free computer, had shown that the lack of relationship was caused by the perturbations through the ages of the other planets acting on the asteroids.
He had assigned a date to the disaster, nearly half a billion years ago, and had calculated as well that most of the ruined planet had escaped from the System entirely. The debris around them represented about one per cent of the lost planet.
Lieutenant Thurlow measured the angular width of the fragment, noted its distance by radar, and recorded the result as gross size. The rock, large as it was, was too small to merit investigation of its orbit; it was simply included in the space-drift survey. Smaller objects were merely listed while collisions with minute particles were counted by an electronic circuit hooked to the hull of the jeep.
'The thing that bothers me,' went on Thurlow, 'about getting out is this- Matt, have you noticed the difference between people in the Patrol and people not in the Patrol?'
'Haven't I, though!'
'What is the difference?'
'The difference? Uh, why, we're spacemen and they're not. I guess it's a matter of how big your world is.'
'Partly. But don't get carried away by mere size. A hundred million miles of empty space isn't significant-if it's empty. No, Matt, the split goes deeper. We've given the human race a hundred years of peace, and now there is no one left who remembers war. They've come to accept peace and comfort as the normal way of life. But it isn't. The human animal has millions of years of danger and starving and death behind him; the past century is just a flicker of an eyelash in his history. But only the Patrol seems aware of it.'
'Would you abolish the Patrol?'
'Oh, my, no, Matt! But I wish there were some way to make people realize by how thin a barrier the jungle has been shut out. And another thing, too-' Thurlow grinned sheepishly. '-I wish they had some understanding of what we are. The taxpayer's hired man, that's what they think of us.'
Matt nodded. 'They think we're some sort of traffic cop. There is a man back home who sells used copters- asked me why Patrolmen should be pensioned when they retire. He said that he hadn't been able to sit back and take it easy at thirty-five and he didn't see why he should have to support somebody else who did.' Matt looked puzzled. 'At the same time he sort of glamorized the Patrol-wants his son to be a cadet. I don't understand it.'
'That's it. To them we are a kind of expensive, useless prize pet-their property. They don't understand that we ;ire not for hire. The sort of guardian you can hire is worth about as much as the sort of wife you can buy.'
The following week Matt found time to look up what the ship's library afforded on the subject of the exploded planet. There was not much-dry statistics on sizes of asteroids, fragments, and particles, distributional and orbital data, Goodman's calculations summarized. Nothing at all about what he wanted to know-how it happened!-nothing but some fine-spun theories.
He took it up with Thurlow the next time they were out on Patrol. The lieutenant shrugged. 'What do you expect, Matt?'
'I don't know, but more than I found.'
