Finally the Chinese People’s Republic sent three craft with volunteer crews, toward the Belt. One ship went off course and landed in the Pacific Ocean near San Francisco. After its personnel explained the unique methods by which they had been persuaded to volunteer, they were allowed to stay. The scientists got good technical jobs, the captain started a restaurant, and the political commissar went on the lecture circuit.

But the other two ships continued as per instructions.

Their transmission stopped at about the same distance as the robot radios had, and they were never seen again either.

After that, the big nations decided there was no need for haste in such expensive undertakings. But Norway had just outfitted her own spaceship, and all true Norwegians are crazy. The Hellik Olav went out.

Winge stirred. “I believe I can tell you what happened to the Chinese,” he said.

“Sure,” said Bull. “They stayed on orbit till it was too late. Then the radiation got them.”

“No. They saw themselves in our own situation, panicked, and started back.”

“So?”

“The meteorites got them.”

“Excuse me,” said Langnes, obviously meaning it the other way around. “You know better than that, Professor Winge. The hazard isn’t that great. Even at the highest possible density of material, the probability of impact with anything of considerable mass is so low—”

“I am not talking about that, captain,” said the astronomer. “Let me repeat the facts ab initio, to keep everything systematic, even if you know most of them already.

“Modern opinion holds that the asteroids, and probably most meteorites throughout the Solar System, really are the remnants of a disintegrated world. I am inclined to suspect that a sudden phase change in its core caused the initial explosion—this can happen at a certain planetary mass and then Jupiter’s attraction gradually broke up the larger pieces. Prior to close-range study, it was never believed the asteroidean planet could have been large enough for this to happen. But today we know it must have been roughly as big as Earth. The total mass was not detectable at a distance, prior to space flight, because so much of it consists of small dark particles. These, I believe, were formed when the larger chunks broke up into lesser ones which abraded and shattered each other in collisions, before gravitational forces spread them too widely apart.”

“What has this to do with the mess we’re in?” asked Bull.

Winge looked startled. “Why…that is—” He blushed. “Nothing, I suppose.” To cover his embarrassment, he began talking rapidly, repeating the obvious at even greater length:

“We accelerated from Earth, and a long way beyond, thus throwing ourselves into an eccentric path with a semi-major axis of two Astronomical Units. But this is still an ellipse, and as we entered the danger zone, our velocity gained more and more of a component parallel to the planetary orbits. At our aphelion, which will be in the very heart of the Asteroid Belt, we will be moving substantially with the average meteorite. Relative velocity will be very small, or zero. Hence collisions will be rare, and mild when they do occur. Then we’ll be pulled back sunward. By the time we start accelerating under power toward Earth, we will again be traveling at a large angle to the natural orbits. But by that time, also, we will be back out of the danger zone.