Randall Garrett

“ When no one else is looking—poof!—Earth is destroyed like that!" Again Beveridge giggled.
Gregson looked at him sourly. "You better leave those crazy magazines alone, Beveridge."
But Lasseux interjected, "We should devote careful attention to what he has said. There may be a grain of truth in it. After all, who moored the spaceship?"
A moment's silence. Then the Russian said, "Assuming one of us is an alien—not that I believe Beveridge's fanciful story—how would we know? Until Earth is destroyed, that is?"
"That's just it," said Lal gloomily. "We wouldn't know. Not until it was too late." ”

“ Empty spaceships do not complicatedly moor themselves outside a space satellite's airlock. Empty spaceships...."
"That's enough, Lasseux," growled the Russian. "Whether it makes sense or no, that spaceship's empty."
"Let's find the hatch," suggested Lal. "Perhaps there's someone injured inside, out of the line of sight."
The five Earthmen covered the surface of the ship, looking for an exterior hatch control. Beveridge found it first—a narrow lever extruding a few inches from the skin of the alien vessel. ”

“ The five men chosen to be the first crew were almost ideal for the job—sensitive, intelligent men, skilled in the techniques of spaceflight, loyal to the countries of their birth. There wouldn't be any chance of collusion among them, of a conspiracy against one country or against Earth itself, as some feared. ”

“ Gregson said.
"We should call the others," said Lal. "All five should be on hand."
"You're right." Gregson touched his belt-stud, giving the signal that called all five crewmen to hand. They appeared quickly—Lasseux, Beveridge, Golovunoff. Silently, Gregson pointed through the view-plate at the newcomer.
After a long look Beveridge shook his head. "That didn't come from Earth," the Englishman said. "Not unless they've developed an entirely new drive principle. And look at the design...."
"That's an alien spaceship, all right," Lasseux said. ”