Jupiter 2 was a spaceship designed and constructed by the United Global Space Force and was meant to take the Robinson Family to the planet Alpha Prime orbiting in the solar system of Alpha Centauri (though this is not stated in the movie). It was here that the Robinson Family would help with completion of the Hypergate; which thereby, would allow the one back on earth to connect the two so as to allow the human species to journey to another planet capable of sustaining life.
The Jupiter 2 consisted of a shell, that resembled the saucer shaped star ship, from the series, while situated within a similar launch pad gantry system. The Jupiter 2 would lift off by conventional propulsion means into orbit and once above the Earth, would break apart revealing the actual Jupiter 2 star ship.
However, the mission was jeopardized when a lone rogue spy for the Global Sedition Force could sabotage the whole operation and thereby prevent the Robinson Family from reaching their destination. The mission was a failure and the crew and the spaceship Jupiter 2 were now lost in empty space. The Jupiter 2 was being drawn toward the sun, and Major West felt using the ship experimental drive, would propel the ship away from danger. Unfortunately, this was an uncharted jump and the Jupiter 2 leaped into uncharted deep space. The Craft was capable of landing and taking off from planets. It carried a Space Pod and Chariot which were mentioned as destroyed. Also onboard were several long range pods, seen in "The Passengers", a spinoff novel.
This Jupiter 2 is very different from the original ship. In most cases, the original interpretation is considered canon by fans.