For each asteroid which had been identified, and its orbit plotted, there was a pinpoint of light on the screen. For all its beauty, the Map had a very useful purpose ... the registry and identification of asteroid claims among the miners of Mars. Each asteroid registered as a claim showed up as a red pinpoint; unclaimed asteroids were white. But even with the advances of modern astronomy only a small percentage of the existing asteroids were on the map, for the vast majority had never been plotted.
Tom moved up to the Map and activated the magnifier. Carefully he focussed down on the section of the Asteroid Belt they had visited so recently. Dozens of pinpoints sprang to view, both red and white, and beneath each red light the claim-number neatly registered. Tom peered at the section, searching until he found the number of Roger Hunter's last claim.
It was quite by itself, not a part of an asteroid cluster. He stepped up the magnification, peered at it closely. There were a dozen other pinpoints, all unclaimed, within a ten-thousand-mile radius....
But near it, nothing....
No hiding place.
And then, suddenly, he knew the answer. He stared at the Map, his heart pounding in his throat. He cut the magnification, scanning a wide area. Then he widened the lens still further, and checked the coordinates at the bottom of the viewer.
He knew that he was right. He had to be right. But this was no wild dream, this was something that could be proved beyond any question of error.
Across the room he picked up the phone to Map Control. It buzzed interminably; then a sleepy voice answered.
"The Map," Tom managed to say. "It's recorded on time-lapse film, isn't it?"
"'Course it is," the sleepy voice said. "Observatory has to have the record. One frame every hour...."