On October 16, 1997, the United States is gearing up to colonize space. The Jupiter 2, a futuristic saucer-shaped spacecraft, stands on its launchpad undergoing final preparations. Its mission is to take a single family on a five-and-a-half year journey to an Earth-like planet orbiting the star Alpha Centauri. The Robinson family consists of Professor John Robinson (Guy Williams), his wife Maureen (June Lockhart), and their three children: Judy (Marta Kristen); Penny (Angela Cartwright); and Will (Bill Mumy). The family is accompanied by U.S. Space Corps Major Donald West (Mark Goddard). The Robinsons and Major West are to be cryogenically frozen for the voyage, and they are set to be unfrozen when the spacecraft approaches its destination. Dr. Zachary Smith (Jonathan Harris), Alpha Control's doctor, is revealed to be a saboteur working on behalf of an unnamed nation, with which he communicated under the code name Aeolis-14-Umbra. After disposing of a guard who catches him aboard the spacecraft, Smith reprograms the Jupiter 2's B-9 environmental control robot (Bob May, voiced by Dick Tufeld) to destroy critical systems on the spaceship eight hours after launch. Smith becomes trapped aboard at launch, however, and his extra weight throws the Jupiter 2 off course, causing it to encounter asteroids. This, plus the robot's rampage, causes the ship to prematurely engage its hyperdrive, and the expedition becomes hopelessly lost in the infinite depths of outer space. Smith's selfish actions and laziness frequently endanger the expedition, but his role assumes less sinister overtones in later parts of the series.