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. * * * * * Several days out from Mars the three contacted a small meteor swarm--maybe a fragment of a comet moving sunward and earthward. They moved with the swarm and landed on a chunk of whitish rock perhaps eight inches through at its largest diameter. But to them it was an airless world into which they could burrow, blocking the entrance to their shelter with chalky dust--a fortunate thing, for in the open the sun's glare and aridity of space were drying out even their android tissues and blurring their minds. The meteor proved not quite lifeless, for on it clear crystalline needles crumbled and rose again. Call it silicon biology, proving that one could never know where something might thrive. In a fall into any atmosphere, such growth would surely be burned away without a trace. Ed and Barbara and Prell learned to understand silent speech by watching lip movements. The need for hurry still beat in their minds, but drowsiness crept over them--perhaps another androidal adaptability was functioning here, related to the hibernation of animals in winter. It lessened loss of vitality when conditions were not too favorable. But you could resist its compulsions if you applied your will.