They Also Serve by Donald E. Westlake, Science Fiction, Adventure, Space Opera (Paperback)

"They built a spaceship, is the long and the short of it," Darquelnoy, the alien who'd been on the earth's moon for ages. observing.

Ebor, an old friend of his, stopped in astonishment. "No "

"Don't tell me no " cried Darquelnoy. "I "saw" it " He was obviously at his wit's end.

"It's unbelievable," said Ebor.

"I know," said Darquelnoy. He led the way into his quarters, motioned Ebor to a perch, and rang for his orderly. "It was just a little remote-controlled apparatus, of course," he said. "The fledgling attempt, you know. But it circled this Moon here, busily taking pictures, and went right back to the planet again, giving us all a terrible fright. There hadn't been the slightest indication they were planning anything "that" spectacular."

"None?" asked Ebor. "Not a hint?"