Updated: July 17, 2023

The Jupiter-2, ( alternatively the Gemini 12, the Jupiter II or simply the Jupiter ) is the "flying saucer" spaceship of the Robinson Family "The culmination of nearly 40 years of intensive research" at the time of launch, it was considered the "most sophisticated piece of hardware yet devised by the mind of man". ( The Reluctant Stowaway ) However, the "Super-Spaceship" had in fact been based on the warp drive and other technology of a crashed Aeolian vessel, and built by the Irwal Corporation under the tutelage of the craft's sole survivor, P'ezu. ( Voyage to the Bottom of the Soul ) The successor of the sabotaged and destroyed Jupiter-1 spacecraft, The Jupiter-2 was almost doomed to a similar fate when it launched on October 16th, 1997, but incredibly the craft survived to become lost in space, carrying it's crew through years of adventures, and finally bringing them home in 2015. ( The Epilogue )

The Jupiter-2 resembles a "flying saucer" on the exterior, and in fact started the flying saucer phenomenon after travelling back in time to 1947 ( Visit to a Hostile Planet ) It has a dome on top and a large viewport. The actual size of the spacecraft is unclear. The hull of the ship is made of titanium, although parts of it, including the hatch, are made of cosmium steel. In the first few episodes, it glows in most flight scenes, but this was dropped later on. It was launched on October 16, 1997, towards a planet of the star Alpha Centauri for the purpose of colonizing it. Its crew consisted of the Robinson family, Major Don West, and an enviormental control The Robot. The Jupiter-2 mission cost about 30 billion dollars. There was presumably a Jupiter-1 which probably got sabotaged by the same orginization, Aeolus 14 Umbra, who attempted to destroy the Jupiter-2. The Jupiter-1 was seen in the Lost in Space comics and in the Alpha Control reference manual. The Jupiter-2 itself was described as a "super spaceship" in The Reluctant Stowaway. The ship also had artificial gravity which was only switched off temporarily in the first episode. The ship is the most sophisticated piece of hardware yet devised by the mind of human beings at the time of launch. Bold in concept and brilliant in execution, this most delicate yet most colossal of instruments makes possible travel to other worlds beyond our solar system. It is shown to take five and a half years for it to reach Alpha Centauri, although in later episodes it can travel through an entire galaxy within a day or less though the show's use of the term 'galaxy' often does not match real life. In the comic, the ship has movable walls and they can be removed to make more room in the ship. The spacecraft is propelled by atomic propulsion, using the substance deutronium as a power source. It also appeared to have an ion drive, and a magnetic drive. Small rockets came from unknown locations along the rim of the ship. the Jupiter-2 is also equipt with an all terrain chariot vehicle.

The spaceship stands two storeys tall. The upper deck contains a sophisticated automated guidance system and a set of freezing tubes capable of placing the six member crew into a state of suspended animation for the duration of their five and half year journey. It also contains storage lockers, a communications system, and cabin pressure control. Located at the center of the upper deck is the astrogator. The astrogator is commonly seen replaced by a table and chairs when on a planet, as it is not required when not in flight. An electronic glide tube elevator and fixed ladder are used to connect both decks. In the third season, one of the storage rooms is seen to house a staircase leading to the lower deck, and other parts of the ship. The space pod was also added and accessed from the upper deck. There are several inconsistencies in where characters access parts of the ship. In the episode "Space Creature" we see a huge third deck that contains the power core, but it is unclear whether or not its on a seperate deck or not. The ship constantly changes. The controls also frequently change and there appears to be many buttons that activate the force field. Another constant change was the positioning of the fire extinguishers, which made the ship appear to have hundreds. Small communication transmitters also appear to be in many places.

The ship became Lost in Space as a result of sabotage by Dr. Zachary Smith, acting as an agent of a foreign government. Dr. Smith was inadvertently trapped aboard the ship at launch. The ship is the home of the Robinson family, Major Don West, Dr. Smith and their General Utility Non Therorising Enviormental Control Robot class M3, Model B9, known as The Robot in their journeys through the universe in search of Alpha Centauri.