From the outlet of the crevice in the rock, they flung themselves into the atmosphere above the gray desert. Their great advantage at this stage was that, at the Martian dawn fringe, there were many updrafts, for the air, chilled fearfully at night, was already warming. At once they were sucked upward, as if by a vertical wind. Still, the first phase of their climb took many hours. They kept watching for upward-moving motes to guide them. Short, rocketlike bursts of heavy neutrons from their Midas Touch cylinders provided the reaction or kick to get them into the swiftest vertical currents.
Mars dropped far below, a dun plain marked here and there by the straight, artificial valleys or "canals." The relative vastness of a world to beings of pinpoint dimensions was nullified by the distance of altitude, until it looked no more extensive than it would have to the eyes that used to be theirs. Mars developed a visible curvature and a rim of haze, fired to redness by the rising sun. The sky above darkened from hard, deep blue toward the blackness of space, and the stars sharpened. The sun blazed whitely, and the frosty wings of its corona began to show. The thinning atmosphere seemed to develop a definite surface far beneath the three voyagers.
They had spoken little in their ascent; but now the free movement of sound was smothered by the increasing vacuum, and there were only gestures and lip movements to convey meanings.
But there was not much that really needed to be said. The plan remained simple: get into trains of upward-jetting molecules, marked by small blurs or warpings of light. Absorb some of that upward surge into yourselves. How often had this same thing happened, without conscious design? Molecules move fast in a high vacuum. Molecular velocity was heat, wasn't it? But here it could not burn. For heat is chained to matter, and here there was just not enough matter to be hot.
Ed thought that they must be getting close to the Martian velocity of escape now. Only three-point-two miles per second. They might have attained it more simply by making greater use of their Midas Touch cylinders. There was scarcely any reactive thrust more efficient than that of neutrons hurled at almost the speed of light. But there was a pride in accomplishing it in a more difficult way. Besides, the energy supply for the weapons must be conserved.
But now Prell signaled with his hand, and they began to use the cylinders in earnest, shifting their course little by little from the vertical and in the direction of the sun. For it was time to curve inward—earthward. Swiftly now, there was no molecular distortion around them at all. Sense of motion faded out. Their high velocity was demonstrated only by the rapid shrinking of Mars behind them; unless, from sunward there came a minute, resisting thrust. Light pressure? But it would take a longer time in space than they meant to be to slow them down at all.
"We've done this much!" Ed said with his lips, but without a voice.
Barbara nodded and tried to smile, and he reached out and pressed her hand. Prell looked awed and bemused.
Ed tried then to read part of their fortunes in the reactions of his strange, minute body to the rigors of space. It was an atomic mechanism more than it was a chemical one. Therefore, it needed no breath. And the strong, radiant energy of the sun warmed it a little, so he did not feel cold. Hard ultraviolet light seemed not to harm it. There was only a sensation as of the shrinking of its hide—perhaps an adaptive reaction of its demoniac vitality—to protect the trace of moisture within it against the dryness of space. The fluid within vitaplasm could be alcohol or liquid air—it was that adaptable. Prell had said this recently. Such fluids did not freeze easily. But they evaporated. So water remained the best body fluid in dry space. For in the full light of the sun, and with a nuclear metabolism, freezing was not a great danger.