The Space Beasts by Clifford D. Simak - There is no life in space–can't be, because there's no air. But that undeniable fact loses point when your own existence is threatened by that life which can't exist.

It wasn't possible... but there it was! A thing that hung in space on shimmering wings of supernal light.

Wings that had about them that same elusive suggestion of life and motion as one sees in the slow crawl of a mighty river. Wings that were veined with red markings and flashed greenly in the rays of the distant Sun.

The body of the thing seemed to writhe with light and for a fleeting moment Captain Johnny Lodge caught sight of the incredible head . . . a head that was like nothing he had ever seen before. A head that had about it the look of unadulterated evil and primal cruelty.

He heard Karen Franklin, standing beside him, draw in her breath and hold it in her wonder.

"It's a Space Beast," said George Foster, assistant pilot. "It can't be anything else."

That was true. It couldn't be anything else. But it violated all rules of life and science. It was something that shouldn't have happened, a thing that was ruled out by the yardstick of science. Yet, there it was, straight ahead of them, pacing the Karen, one of the solar system's finest rocket-ships, with seeming ease.

"It just seemed to come out of nowhere," said George. "I think it must have passed the ship. Flew over us and then dipped down. I can't imagine what those wings are for, because it travels on a rocket principle. See, there it blasts again."

A wisp of whitish gas floated in space behind the winged beast and swiftly dissipated. The beast shot rapidly ahead, green wings glinting in the weak sunlight.