 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 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. He uncapped the torch and the miniature sun glowed redly from its lensed prison to reveal the rocky corridor stretching out ahead. "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." 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. So slowly was the spinner dropping that the blackened desolation of the other hemisphere came sliding up beneath his boots. Deftly Rolf nested the spinners again in their pack before he set out toward the heaped-up mass of stone blocks that was the wall. Ten steps he took before an excited voice called out shrilly from the rocks ahead. This mysterious world that floated above the cavern floor might be their headquarters. Rolf realized with a wrench of sudden fear that they actually hung head downward like flies walking across a ceiling. "One," repeated Rolf slowly. A hundred paces away Rolf made the dark shapes of armed warriors as they filed downward from the Barrier into the blackened desolation of the desert half of Lomihi.
 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.