Asteroid 1207 came spinning into the auxiliary ship's viewplate like a glittering black mirage. The eight-mile chunk of rock was the last link in a chain of nine asteroid navigational-markers still needing blinker equipment installation. Minutes later, the Minnow lay neatly berthed in the deepest hollow of the asteroid, the shining wires of its drill grapples anchoring it firmly to the jagged rock. The airlock opened and two men in spacesuits stepped out. They climbed to the top of the nearest h