And the Sea of Tranquillity—a dark, wrinkled plain that looked as if it had gone through the agonies of torture ages past. The marks of almost-vanished volcanoes on it, pale circular rings like pocks of burst bubbles, rambling ridges, and ugly cracks, and here and there domes rising gray out of the surface, like the tops of giant bubbles working their way out of the dry and flaky crust.

Robin watched in dread fascination. He heard the whistling and shrieking of the rocket like a demon in torment. He himself was burning and itching as he was being baked, although he felt no fever. The rocket was warm but getting no warmer. The topmost peak of Theophilus was rushing up into his sky like a fast-growing stone geyser.

He watched it shoot up, saw it grow, saw the ground become clearer and clearer, each ghastly detail spreading out, assuming three-dimension reality. Now the peak was on a level with his eyes, now it was beyond him, and he was in the last few seconds of his fall.

The rocket seemed to be slowing slightly. The atmosphere was possibly getting a trifle thicker at the surface, enough to prolong the agony a minute or two or three longer. Above him the parachute strained and twisted. But still the rocket was falling too fast. It rushed down, straining to complete its act of affinity with a new gravity, as if tired of its brief period of interplanetary freedom, and anxious to pledge allegiance to a new gravitational master.

Below, the moonscape was coming up fast. Robin could see well enough to begin to speculate where exactly he would hit. There was a small circle that must have been a crater scar. There were several dark lines that might be a network of cracks. And there was a dome.

He remembered those domes. They had been quite a recent discovery too. Not easily seen until latter-day instruments showed the surface of the Moon dotted with these odd bumps. Their nature was still a mystery.

It looked as if Robin would find out the hard way what their construction was. For now he was clearly heading directly for the center of the one below him. A bubble-top pushing out from the plain, hard and shiny like lava, glistening in the sun against the gray and dusty surface of the plain around it.

Theophilus's wall was already on the horizon, high and towering. And now Robin realized how terribly fast the rocket was still falling. The mountain was a measuring stick and it was fearful.

There was a moment of dreadful suspense as the rocket raced to a bull's eye on the upthrust center of the dome. The rounded surface rushed up.

Robin flattened himself against the padding, clutched his head in his hands, and stiffened himself. The rocket hummed against the thin air, it vibrated against the parachute, there was a terrible split second of shock when the bullet-shaped structure of the rocket's cargo nose made its contact with its Lunar target, and then a clap of sound in Robin's ear like a blockbuster going off.