He frowned. "I don't want to sound like an alarmist, but I've pointed out before how suited the asteroids are to them. If once they learned how to duplicate themselves, there'd be no end to them. They have everything here they need to get a fundamental grasp of our science—even to a rocket ship. They could spread through the asteroid belt like a plague."
Sofi bit her lip. Her eyes were opened wide and brilliant. Her cheeks were flushed. She didn't interrupt.
Hen said, "Look what it would mean. An alien, intelligent, almost indestructible race of monsters saddling the planetary system!"
He drove his right fist into his left palm. "A control! That's what we have to discover! A control!"
Hen had no idea what he ate that night at supper. He said suddenly over coffee and cigarettes, "Ceres is approaching an inferior conjunction. If those robots haven't appeared by morning, I'm going to radio the station there for help. Then I'm going to scour every inch of this diminutive world."
"That shouldn't be too difficult for you," Sofi remarked maliciously. "Of course, there's only about two thousand-five hundred square kilometers to cover."
Hen looked disgruntled.
"Maybe they've jumped off," suggested Sofi with a giggle.
He made a remark under his breath.