“I will,” I said, smiling my most reassuring smile. “Don't you worry about that. He can't have gone far.”

Actually, of course, Joshua Wilkins could perhaps have gone quite far — so my first order of business was to eliminate that possibility.

No spaceships had left Mars in the last ten days, so he couldn't be off-planet. There was a giant airlock in the south through which large spaceships could be brought inside for dry-dock work, but it hadn't been cracked open in weeks. And, although a transfer could exist freely on the Martian surface, there were only four personnel air locks leading out of the dome, and they all had security guards. I visited each of those air locks and checked, just to be sure, but the only people who had gone out in the last three days were the usual crowds of hapless fossil hunters, and every one of them had returned when the dust storm began.

I remember when this town had started up: “The Great Fossil Rush,” they called it. Weingarten and O'Reilly, two early private explorers who had come here at their own expense, had found the first fossils on Mars, and had made a fortune selling them back on Earth. More valuable than any precious metal; rarer than anything else in the solar system — actual evidence of extraterrestrial life! Good fist-sized specimens went for millions in online auctions; excellent football-sized ones for billions. There was no greater status symbol than to own the petrified remains of a Martian pentaped or rhizomorph.

Of course, Weingarten and O'Reilly wouldn't say precisely where they'd found their specimens, but it had been easy enough to prove that their spaceship had landed here, in the Isidis Planitia basin. Other treasure hunters started coming, and New Klondike — the one and only town on Mars — was born.

Native life was never widely dispersed on Mars; the single ecosystem that had ever existed here seemed to have been confined to an area not much bigger than Rhode Island. Some of the prospectors — excuse me, fossil hunters — who came shortly after W O's first expedition found a few nice specimens, although most had been badly blasted by blowing sand.