"Hold it," came Doc's voice. "It's disappeared again. Whup! Now there's one over here on my right, at about a hundred meters. Spherical shape, black, about five and a half or six meters in diameter ... now it seems to be settling into the surface; assuming a hemispherical form.... Whup! Disappeared again! Reel me in, Jon. We've got to get some high-speed shots of this." It never occurred to either of them that there was no point in making these recordings. Explocenter hand-picked its men, and insatiable curiosity was the first requisite. Quick judgment and moral stamina came next. And first, last, and always--'get it down on records'. The Geiger clicked softly on the bulk-head and the needle of the accumulator was working toward the red area, but neither paused to consider these things now. They had made their try, exhausted their resources. * * * * * But in the back of their minds was the knowledge that within a few months a statistician at Explocenter would mark Explounit X-3 "missing", and at the end of the year two more names would be added to the column at Explocenter; that shaft of gray venustron that stood beside the main entrance, whereon was the long, long scroll of names. Simple monument to the men of Explocenter who never came back. "We can't take the big tele-lens outside," mused Doc, "so we'll have to record off the visi-plate. I'll go outside again, and spot for you, and you can line the 'plate on my bearings." "Huh-uh. My turn," retorted Jon. "Why should you have all the fun? I'm going out this time, and you can shoot pictures to your little heart's content. Besides, I'm going to tuck my little personal camera into my helmet under my chin and get some shots on the spot." "All right," snorted Doc. "But don't come crying to papa if you stub your toe. And look both ways before you cross the street. Here--let me blow your nose before you go out in the cold." "Aw go to Helios, you retort-smasher. If I run into a ground squirrel, I'll skin him and bring you some hair." Jon eased down the ladder and shuffled across the smooth surface until he was well clear of the ship. "Nothing yet," he reported, and swept the horizon with his glance. "I could have told you," said Doc nastily. "Your ugly face scared them away." "Yeah," snorted Jon. "Every stenotyper at Explo has your beautiful mug pasted in the top drawer of her desk." "Sure!" agreed Doc smugly. "Well," said Jon impatiently, and under his breath. "Come on, you black boogers--I ain't got all day." Then he gulped. For a huge black sphere materialized about fifty meters to his left and rolled swiftly toward him. Jon beat a hasty retreat. He backed toward the ship, and jogged the camera under his chin to start it operating. The sphere paused a second, then rolled slowly after him. "Steady," came Doc's voice in the phones. "I got a dis-ray on it."