Chet was watching the changing terrain. He saw the place of solid-spouted rock end; saw it flatten out to an undulating surface that had rolled and heaved itself into many-colored shapes. Even in the earthlight the kaleidoscopic colors were vivid in their changing reds and blues and yellow sheens. Then this surface sloped sharply away, though here it was rough with broken rock where half-hardened lava, coughed from that throat, had fallen back and adhered to the molten sides. This rock in the inner crater was gray, pale and ghostly in the earthlight. It went down and still down where Chet's eyes could not follow--down to an utter blackness. Chet was staring speculatively at that waiting dark when the first flash came. Blindingly keen! A flash of white light!--another and another! It blazed dazzlingly into their cabin in vivid dashes and dots--the same signal as before was being repeated! * * * * * A hundred yards away was a little shelf of rock. Chet jerked at O'Malley's shoulder with his metal-cased hand and pointed. "Set her down!" he ordered "Let me out there! We can't put the ship down where those lights are; the throat is too narrow; there may be air-currents that would smash us on a sharp rock. I'll go down! You wait! I'll be back." He was opening the inner door of the entrance port. Another closure in the outer shell made an air-lock. He took time for one grip at the hand of Spud O'Malley, one grin of excited, adventurous joy that wrinkled about his eyes behind the window of his helmet--then he picked up a detonite pistol, examined again its charge of tiny shells, jammed it firmly into the holster at his waist and swung the big door shut behind him. And Pilot O'Malley watched him go with a premonition that he dared not speak. He heard the closing of the outer door; saw the tall, slender figure in a metal suit like a knight of old as Chet waved once, settled the oxygen tank across his shoulders and picked his way carefully over a waste of shattered stone that led down and down into the dark. Then the Irishman looked once at the suit he had expected to wear, stared back where the figure of Chet had vanished, then dropped his head upon his hands while his homely face was twisted convulsively. * * * * * It had come so soon! The great adventure was upon them before he had realized. The reconnaissance--the flashes--and then Chet had gone! And now he was alone in a silent ship that rested quietly in this soundless world. The silence was heavy upon him; it seemed pressing in with actual weight to bear him down. It was shattered at the last by the faintest of whispered echoes from without. Spud was on his feet in an instant, his eyes straining at one lookout after another, each giving him a view of only the desolation he knew and hated.