Gremlins, Go Home by Ben Bova,Gordon R. Dickson

"Several hundred years ago a band of explorers were marooned on Planet Earth. Alas, the Little People are not strong on gadgetry, and they have had to while away the centuries of their youth, living for the day when they could get off this god-forsaken mudball, this most benighted, desolate--and boring!--planetary slum in the Known Universe. At last, the time has come. All they need now is a human--a young one will do--to help them hijack a Shuttle to take them to where their rescue awaits. And that shouldn't be too hard, for what All-American boy could resist giving a hand to a friendly leprechaun?"--Back cover.