Updated: January 17, 2023

The Jupiter-2 is the main spaceship on Lost in Space. It resembles a flying saucer on the exterior, with a dome on top, and a large viewport. 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. 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 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 Centuari, although in later episodes it can travel through an entire galaxy within a day or less. 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.