Brave New Worlds

search of them. "Soon they'll mine some passages and try to drive us into them," Jakob said. "It's about time we left. "
    "Left?" Oliver repeated.
    "Left the system. Struck out on our own. "
    "Dig our own tunnel," Naomi said happily.
    "Yes. "
    "To where?" Hester croaked.
    Then they were rocked by an explosion that almost broke their eardrums, and the air rushed away. The rock around them trembled, creaked, groaned, cracked, and down the tunnel the ceiling collapsed, shoving dust toward them in a roaring whoosh! "A Boesman!" Solly cried.
    Jakob laughed out loud. They were all scrambling into their vacuum suits as fast as they could. "Time to leave!" he cried, maneuvering their A robot against the side of the chamber. He put one of their Boesmans against the wall and set the timer. "Okay," he said over the suit's intercom. " Now we got to mine like we never mined before. To the surface!"

    The first task was to get far enough away from the Boesman that they wouldn't be killed when it went off. They were now drilling a narrow tunnel and moving the loosened rock behind them to fill up the hole as they passed through it; this loose fill would fly like bullets down a rifle barrel when the Boesman went off. So they made three abrupt turns at acute angles to stop the fill's movement, and then drilled away from the area as fast as they could. Naomi and Jakob were confident that the explosion of the Boesman would shatter the surrounding rock to such an extent that it would never be possible for anyone to locate the starting point for their tunnel.
    "Hopefully they'll think we did ourselves in," Naomi said, "either on purpose or by accident. " Oliver enjoyed hearing her light laugh, her clear voice that was so pure and musical compared to Hester's croaking. He had never known Naomi well before, but now he admired her grace and power, her pulsing energy; she worked harder than Jakob, even. Harder than any of them.
    A few shifts into their new life Naomi checked the detonator timer she kept on a cord around her neck. "It should be going off soon. Someone go try and keep the cows and chickens calmed down. " But Solly had just reached the cows' pen when the Boesman went off. They were all sledgehammered by the blast, which was louder than a mere explosion, something more basic and fundamental: the violent smash of a whole world shutting the door on them. Deafened, bruised, they staggered up and checked each other for serious injuries, then pacified the cows, whose terrified moos they felt in their hands rather than actually heard. The structural integrity of their tunnel seemed okay; they were in an old flow of the mantle's convection current, now cooled to stasis, and it was plastic enough to take such a blast without shattering. Perfect miners' rock, protecting them like a mother. They lifted up the cows and set them upright on the bottom of the ore car that had been made into the barn. Freeman hurried back down the tunnel to see how the rear of it looked. When he came back their hearing was returning, and through the ringing that would persist for several shifts he shouted," It's walled off good! Fused!"
    So they were in a little tunnel of their own. They fell together in a clump, hugging each other and shouting. "Free at last!" Jakob roared, booming out a laugh louder than anything Oliver had ever heard from him. Then they settled down to the task of turning on an air cylinder and recycler, and regulating their gas exchange.

    They soon settled into a routine that moved their tunnel forward as quickly and quietly as possible. One of them operated the robot, digging as narrow a shaft as they could possibly work in. This person used only laser drills unless confronted with extremely hard rock, when it was judged worth the risk to set off small explosions, timed by seismometer to follow closely other detonations back in the mines; Jakob and Naomi hoped that the complex interior of the moon would prevent any listeners from noticing that their explosion was anything more than an echo of the mining blast.
    Three of them dealt with the rock freed by the robot's drilling, moving it from the front of the tunnel to its rear, and at intervals pulling up the cars' tracks and bringing them forward. The placement of the loose rock was a serious matter, because if it displaced much more volume than it had at the front of the tunnel, they would eventually fill in all the open space they had; this was the classic problem of the "creeping worm"