Up Against It - M. J. Locke [146]
Also nearby were four big tanks, marked as methane, oxygen, nitrogen, and peroxide. They were unusually large. Whoever owned this stroid was obviously a hoarder. Directly behind the ship were what looked like makeshift rocketbike launch ramps. Close to the ridge at the mine entrance squatted two massive machines: a tunneler, spare cables and reels, grinders, a big hopper, and a bagging station. Over all this towered a Brobdingnagian mechanical earthmover for cutting, compressing, and shooting mined ore into space. Racks of smaller equipment parts, several slag piles, and a mountainous midden also stood nearby.
Xuan bounded around, pausing to poke at the ground with a rod. Quite compact, and in some areas there was no dust—only solid nickel-iron ore. Very high quality. He looked up. The sun—near zenith now—moved swiftly across the dark sky, making shadows crawl across the ground. This rock had a rotational period of only a few minutes. It would be good, then, to arrange things so that the sun was rising behind him and into the others’ faces when he opened the back of the machine. It would make it more difficult for them to see what he was doing inside the gravitometer.
Xuan ordered the others to bring his equipment. “Leave the rest there for the moment,” he said, pointing at the bags and boxes lined up at the cargo bay door. “We won’t need any of that unless the gravitometer gives us a low reading.”
He looked for a good place to set up: a place where the ground was firm, stable, and flat. The ore was close to the surface here. Dust and clots of dirt collected in dips and valleys. As a quick test, he dropped a wrench and surreptitiously counted as it drifted downward: sixty seconds to touch down in the dust? Eighty? Quite a bit less than on 25 Phocaea, at any rate. Old claim; big, high-end equipment; well-stocked supplies; high-quality ore: all his instincts were telling him that this rock had been extensively mined—a prime sugar-rock candidate. He only hoped these men were not experienced enough rock hoppers to detect these clues.
He found a spot as close as he could make it to a pile of slag—this would make it harder for them to move behind him while he set up the gravitometer. He prepped the site, sweeping away dirt with a hand brush—tossing small stones and nuggets of metal out of the way—and measured the grade in several spots with a laser level, pausing to wipe away dust that had settled on his faceplate. Meanwhile, the others milled around. The sun set and rose twice while he was prepping the site. He had to time this right.
“We’ll do it here,” he said finally, and pulled a paint can and some lights out of his kit. He marked four points on the stroid surface with phosphorescent paint. “Bring that big box and that table—yes, that one. Put them right here, where I’ve marked with paint. Careful! Don’t jostle the box. You might throw off the calibration.”
Two of the hired hands shuffled and wobbled over, steering the box. Space neophytes, Xuan thought. Jesse the pilot brought the table. Xuan had them move the table around while he adjusted leg lengths and took measurements. Then he fired the bolts that fixed the table to the stroid’s surface. He instructed them to put the box on the table and bolt it on. The flood lights he positioned such that they would cast a shadow on him when he stood behind the gravitometer. Sunup came again while he did this, and sundown.
Gravitometers had been around for centuries. In concept, they were simple. A pendulum’s period—how quickly it swung from peak to peak of its arc—depended on two and only two things: how long the pendulum cord was, and how strong the gravity was. It didn’t matter how hard you swung it or how high the peaks were, the period was always the same. The quicker the swing, the stronger the gravity. The slower the swing, the weaker.
Xuan’s gravitometer was designed to measure the very faint gravities of asteroids, a meter-and-a-quarter tall metal box with a light inside and a window through which you could see the pendulum. The box was bolted