Writers of the Future, Volume 28 by L. Ron Hubbard

Jack’s kludge work. He’d originally wanted to build a manifold of tubes to feed water into each hole evenly, but I had stopped him when I realized he’d have to cannibalize most of Nellie’s internal plumbing to realize the contraption.
    We instead covered the pattern with a shallow tent made from extra sheet plastic, precariously sealed to the surrounding surface with our entire stock of suit repair putty. A hole in the center was cinched up tight around a tube attached to Nellie’s tanks. Jack assured me that if we pumped water in fast enough, it would fill the holes and freeze before evaporating. I wasn’t convinced, but we had nothing to lose, except of course most of our water.
    “What if we do open the lock ? Or activate something ? What if we break it ? ”
    Jack looked up at me, his exasperation obvious even through the dusty visor. “Make up your mind, Malcolm. We’re never going to get another shot at this. It’s us—right now—or we forget about it. They are going to be pissed enough to ship us back home and instead of us figuring this out, some Martian Mickey Mouse will build an enchanted castle around it.”
    He was right. I had made my decision and sealed my allegiance. “Let’s try it.”
    We stood on a pile of excavated dirt at the cube’s edge and pumped the water in under pressure. Wispy vapor curls immediately revealed the gaps in our crude seal. The tent filled and tightened rapidly, to the point we feared it would burst the seal.
    “Stop!” I yelled.
    Jack killed the flow and the plastic almost immediately started to deflate.
    “Crap,” he said. “We’d better look quick.”
    Before we could pull the cover off and check our handiwork, a series of reports—loud enough in the weak Martian air to hear through our helmets—made us both step backward. Fissures appeared in the basalt, radiating outward from under the plastic cover in an oddly uniform pattern.
    “You were right,” Jack muttered. “We broke it.”
    “Maybe not. The lines are all straight and equally spaced, like pie wedges. They don’t look like natural fractures.”
    Before I could say another word, he jumped down onto the surface, tested it with a couple of bounces, then dropped to his knees, shining his helmet light into the cracks. He motioned for me to come down.
    “The basalt is only about a foot thick,” he said. “And it looks like more diamond under it. Holy crap. Do you think this stuff just covers a big block of diamond ? ”
    “Well, it would sure be durable,” I said and joined him. I removed the cover to look at the pattern. It had nearly disappeared, but I could tell by the fragment arrangement that the cracks had each started at a hole, then run across the top and disappeared down the sides into the dirt.
    “Looks like our ice expanded and started the breaks,” I said.
    “No way. One or two cracks maybe, to relieve pressure, but not—” He paused and ran a hand along the edge of several sections, then started pulling on them.
    “Unless of course,” he grunted, “it was designed to break this way.”
    The wedge moved nearly an inch. He stood up and looked at me. “I bet if the whole block had been uncovered, this shell would have fallen away. I think it was meant to fall away.”
    W e used Nellie to dig all morning, but by mid-afternoon had to send her out in search of ice to replenish our air and water supply. So we dug by hand, using our climbing axes. Once we’d totally cleared the second side, Jack slipped his axe blade behind one of the loose basalt sections and started gently rocking it. With an audible pop, the strip collapsed into large chunks that tumbled down on him like stacked blocks pushed over by a petulant child. I heard him grunt and curse over the comm link as he disappeared in a pile of stone and dust.
    “Jack!” I ran to him and started moving yard-wide pieces of stone I wouldn’t have been able to lift on Earth.
    “Crap,” he muttered as I pulled the last piece