“Possibly. How could you check on that possibility?”
“See whether the rock where they’re growing is any higher or lower than where they aren’t.”
“All right. Let’s see.” And that was why the group was all together when the shell of sandstone gave way under the tank. The human teacher observed less of the event than his pupils. The yielding ledge freed his vehicle for a fall of some fifty feet under three times his normal gravity, and one second was not long enough for him to appreciate the situation. His safety clamps, padded and reinforced though they were, had not been designed for any such shock, though it was just as well they were there. Neither was the shell of the tank, and even the students least familiar with the alien machinery could tell that something was wrong with it. The evidence was not visual; a stink of oxygen permeated the neighborhood and for a moment sent the Mesklinites scurrying as far as they could. Even a creature which doesn?t actually breathe because it is small enough for high-pressure hydrogen to reach all its tissues by direct diffusion may have evolved a sense of smell. The space into which they had dropped was windy, and the oxygen quickly became imperceptible. Estnerdole crept back to the side of the motionless tank; like his fellows, he was of course uninjured. The fall had meant no more to them physically than a similar one on Phobos would have to a human being, though any fall can be expected to provide an emotional jolt to a Mesklinite. “Teacher! Dr. LaVerne! Can you answer us?” There was no response, and after a moment the sailor began to examine the machine in detail, looking for visible damage. The process was hampered by the fact that it was three quarters buried in white powder — the ammonia snow which had been blowing from the north for weeks as winter for Mesklin’s habitable hemisphere drew on. The snow formed a slope of about thirty degrees, extending into a hollow which reached east and west as far as Estnerdole could see. The cavern’s north face was walled by a nearly vertical cliff of clear, glassy material. The roof, now pierced by the hole through which the party had fallen, was rock. Sunlight slanting through the hole was reflected by the ammonia which formed the south side and illuminated the immediate area for the moment, though the light changed constantly as the beam scanned along the slope. The exposed portion of the tank showed no visible cracks; the oxygen must have leaked from some place below. Light was shining from the exposed windows, and Estnerdole made his way to the nearest of these by means of the climbing grips which studded the shell. Destigmet was close behind. Neither was really familiar with the vehicle’s interior, so neither could be sure whether the apparent chaos of objects within was normal or not. The form of the teacher was visible, motionless in the control seat. His armor, which they had seen often enough to know well, appeared intact; but the transparent front of the headpiece seemed to have colored liquid over part of its inner surface. The human being’s head could not be discerned in detail. Neither sailor was familiar with the appearance of human blood, but both had good imaginations — even though they lacked real circulatory systems of their own. “We’ll have to get in somehow and get him out of there,” Destigmet said. “He’ll have to get back to the College somehow, and we certainly can’t carry the tank.”
“But if we break in or open the door, our air will get in too, and he can’t stand that. Shouldn’t we, or some of us, go back ourselves and bring human help?”
“Our air is already inside — at least, his came out, and ours has much higher pressure. Either his armor saved him, or it’s too late already. Certainly if any of us can get out, one should go for help; but the rest must get to him and at least do our best to see that — well, to see whether we can do anything. Come on, everyone — dig out the door and try to get it open while we can still see. One of you climb the hill.” The snow was loose and powdery, defeating any attempt to dig a narrow hole. The door of the tank was on the downhill side, which helped some. The bulk of the vehicle kept the entire mass of white dust from sliding down. Legs working at near-invisible speed hurled the stuff away from the metal in clouds, and as the minutes passed, the lower part of the vehicle grew more and more visible. The five minutes or so of daylight left when they started was not nearly enough to let them shift all those cubic yards of material, but enough light came from the windows to let the Mesklinites work through the night; and within two days the door was uncovered. There would have been no difficulty in opening it, but even Destigmet was a little uneasy about doing so in spite of his earlier logic. “Let’s check the window once more,” he said. “Maybe—” He left the sentence unfinished and began the climb to the nearest window. He had scarcely started, however, when the hull of the tank shifted slightly, tilting toward the cluster of watching Mesklinites. Destigmet had never jumped in his life — the concept was alien to a being reared in nearly three hundred Earth gravities — but his reflexes did something. Suddenly he found himself over twenty yards away from the tank, close to the glassy cliff which formed the other wall of their prison. His fellows had also scattered, but not quite so abruptly. They were delayed mostly by bad traction, the fluffy material under their claws doing most of the initial moving. Destigmet had been on the tank. The latter did not complete its threatened fall, for the moment. It was resting entirely on the loose, white dust which had saved it from flattening like an egg under an elephant’s foot, and most of this had been removed from the downhill side; but it did not yet fall. The Mesklinites approached again with caution. Even they, in a place where everything’s weight seemed negligible to them, had no wish to be underneath that mass if it really did topple. “I thought your weight must have shifted it, but something else must be moving inside,” remarked Estnerdole. “Maybe the teacher is in better shape than we thought.”