"That's vegetation," Burl broke in. "It must be! Everybody agrees it acts like it. And there are the white polar caps, too."
"You can tell which season is which by the size of the polar ice caps. When one is big, the other is almost gone. Then there's the problem of the canals...."
"Do you believe in them?" asked Burl. "The books disagree. Some think they're real—even say they look as if they had been built by intelligent beings as irrigation channels to take the melting waters of the poles down to the fertile lands. But other astronomers claim they can't see them—or that they're illusions, series of cracks, or lines of dark dust blown by winds."
"Personally, I've come to believe in them," Russ argued. "They've been photographed—something is there. They're very faint, spidery lines, but they certainly are straight and regular. We'll find out soon enough."
Find out they did. Russ was up and about and the normal life of the ship resumed. During their passage of Earth's orbit, they had managed to raise the United States on the ship's radio. For three days they were able to converse with their home base. They exchanged news and data, transmitted back all they had learned and eagerly asked for news.
The men of the crew had the chance to send messages home, and Burl even talked briefly with his father. There had been an important discovery made on Earth.
The lines of force had finally been traced. The distortions visible on Mars, as well as the one from Mercury before its cutoff, had been worked out directionally. There was no doubt that a line of force had been channeled outward to a point in space that now proved to be that of a planet. The planet was Pluto.
"Pluto!" That was the shocked word uttered by everyone within hearing distance when the radio voice said it.
"Pluto! Why, that's the end of the line! The most distant planet," said Oberfield, shocked. "We'll have to go there—all the way!"
That fact sobered everyone. It meant the trip must last many times longer than anyone had expected. But they were a band of men who had achieved great things—they had managed so far to work together in harmony, and they felt that since they had conquered two planets—what were a few more?