 How often does the Lunar colony get supplies delivered from earth?
Once in two weeks Earth-time a rocketship came around the horizon from Lunar City with stores for the colony deep underground. He handed over the product of the mine, to be forwarded to Earth. Come nightfall Pop lowered the supplies down the long cable into the Big Crack to the colony far down inside, and freshened up the landing field marks with magnesium marking-powder if a rocket-blast had blurred them. There is nothing like it on Earth, of course. When it was first found, scientists descended into it to examine the exposed rock-strata and learn the history of the Moon before its craters were made. There were air-tight bulkheads for safety, and a hydroponic garden to keep the air fresh, and all sorts of things to make life possible for men under if not on the Moon. In the Moon's slight gravity, a man is really adjusted to existence when he has a well-developed case of agoraphobia. He'd shipped out, whimpering, to the Moon to get far away from Pop, and Pop was just about a mile overhead and there was no way to get around him. It doesn't take too long for the low gravity to tear a man's nerves to shreds. When he was stronger, the doctors told him who he was, and as gently as possible what had happened to his wife and children. All of which happened back on Earth and a long time ago. There was a warning-bell in the shack, and when a rocketship from Lunar City got above the horizon and could send a tight beam, the gong clanged loudly, and Pop got into a vacuum-suit and went out the air lock. He usually reached the moondozer about the time the ship began to brake for landing, and he watched it come in. The pilot killed all forward motion just above the field and came steadily and smoothly down to land between the silvery triangles that marked the landing place. Instantly the rockets cut off, drums of fuel and air and food came out of the cargo-hatch and Pop swept forward with the dozer. With freight costing what it did, fuel and air and food came frozen solid, in containers barely thicker than foil. And a cover of insulating moondust with vacuum between the grains kept even air frozen solid, though in sunlight. When Sattell fled to another continent, Pop followed because he had some distinct memories of his wife—and the way he'd felt about her—and some fugitive mental images of his children.
 Every two weeks
 Every twelve days  Every three months  Once a month  Every two weeks