Derelict by Alan E. Nourse, Science Fiction, Adventure

He stared out at the great ship, feeling a chill of wonder and fear crawl up his spine. "So this is the mysterious puzzle of Saturn," he muttered. "This is what we've been waiting for." There was a curious eager light in Captain Loomis' eyes as he looked up. "Oh, no. Not this." "What?" "Not this. The ships we've seen before were tiny, flat." His little eyes turned toward the ship, and back to Sabo's heavy face. "This is something else, something quite different." A smile curved his lips, and he rubbed his hands together. "We go out for trout and come back with a whale. This ship's from space, deep space. Not from Saturn. This one's from the stars."