A Plunge Into Space

"A group of scientific adventurers builds a space ship for the purpose of exploring Mars. The motor device is a shield that protects against earth's gravity while being attracted to Mars. On the return trip they discover a stowaway - a Martian girl. The life-support systems of the ship cannot accomodate an extra passenger, and each crew member has some essential skill for bringing the ship safely to earth. The girl becomes the key to life - or death - for the space voyagers."--Publisher description.