 What is Rolf's new plan when he spots the rocket?
Sisko Rolf's stocky body was a blur of motion as he cut the rocket jets, doused the twin searchlights, and switched over to the audio beams that served so well on the surface when blind flying was in order. "Trapped us neatly," Rolf said through clenched teeth. Rolf swung the lax controls over hard as the bursts of fire revealed a looming barrier of stone dead ahead, and then he felt the tough skin of the flyer crumple inward. Somehow Rolf found the strength to wrap his fingers around the control levers and snap on a quick burst from the landing rockets. Their mad speed checked momentarily, but the nose of the vertically plunging ship dissolved into an inferno of flame. The ship struck; split open like a rotten squash, and Rolf felt himself being flung far outward through thick blackness. There was light in the narrow pit in which he found himself, light and heat from the yet-glowing debris of the rocket flyer. There could be no ascent from this natural prison-pit, and even if there were he could never hope to reach the surface forty miles and more overhead. Without water and food certain death grinned in his face, for beyond the sand-buried entrance to these lost equatorial caves there were no pressure domes for hundreds of miles. The young patrolman unzippered his jacket pocket and felt for the emergency concentrate bars that were standard equipment. He uncapped the torch and the miniature sun glowed redly from its lensed prison to reveal the rocky corridor stretching out ahead. How many hours later it was when the first faint glow of white light reached his eyes Rolf did not know—it had seemed an eternity of endless plodding along that smooth-floored descending tunnel. "They may have found the sunken seas of Mars," thought Rolf as he moved alertly forward, "water that would give the mining domes new life." He found himself shooting downward into a vast void that glowed softly with a mysterious all-pervading radiance. As the spinner dropped him slowly down into the vast emptiness of the great shining gulf, Rolf could see that a broad band of stone divided the green fertile plains and forests from the desolate desert wastes of the other half. Toward this barrier the spinner bore him, and Rolf was content to let it move in that direction—from the heights of the wall he could scout out the country beyond. The spinner had slowed its speed; it seemed to Rolf that he must be falling free in space for a time, but the feeble gravity of the tiny world tugged at him more strongly as he neared the wall.
 He'll be able to distribute water to Mar's colonies, and get out with Tanner and the girl.
 Now that he knows the location of the water, he'll be able to return to grab it for himself.  He'll have a way out of the caverns at last, be able to escape.  He can escape the fighting and leave Tanner and the girl behind.  He'll be able to distribute water to Mar's colonies, and get out with Tanner and the girl.