Professor Robinson discovers that the planet's orbit will bring immense heat on the spaceship. With that knowledge, the Robinsons take off in the Chariot and head south. Dr. Smith stays behind because he believes them to be lying, but soon realizes the orbit is odd. There are periods of extreme cold followed by equally extreme heat. The Robot is sent to tell the Robinsons and they try to return to the Jupiter 2. They must brave various geographical areas and the strange weather before returning to the Jupiter 2 where they are most safe.moreless
Professor Robinson attempts to explore a planet that the family is planning to land on. Dr. Smith has sabotaged his para-jet propulsion system, causing it to fail. Smith has also sabotaged the propulsion system of the Jupiter 2. Major West crash lands the ship on the planet so that he and the family can rescue the Professor.moreless
The Robinson family banishes Smith from the Jupiter 2. He takes refuge in an abandoned spaceship where he finds a machine that can materialize anything. In an attempt to get back into the Robinson's good standing, he gives them the machine, which plays on the family's greed.
John Robinson becomes possessed by an alien creature who forces the family to prepare to return to the creature's home world, even if it requires that he sacrifice Will to keep his secret from the rest of the family.
Penny and Judy stumble upon a mirror on the planet. But it's not an ordinary mirror as it seems that there is someone on the "other side". Before they know it they are transported to the mirror universe that is occupied by only one person, a boy who is lonesome for companionship.moreless
Professor Robinson discovers that the planet they are on will travel further from the sun. In an attempt to survive, the Robinsons pack up and head south. Dr. Smith stays at the Jupiter 2 site while the Robinson family encounter a terrifying Cyclops and an ancient deserted city.
A zoo keeper who travels the universe wants to take Will and Penny and add them to his vast collection of celestial animals.
The Robinson family and Major West are imprisoned in their camp after being indicted to appear before a court for space crimes. As the trial begins, Dr. Smith's name begins to appear and it is not long before everyone realizes that all of the Robinson's "crimes" should be attributed to Smith, and he is indicted to appear before the court.moreless
The Robinsons are given the option to turn Penny and Will over to The Keeper or face certain death.
Will uses an alien transporter to send himself back to Earth. However, many people believe the Robinson family to be dead after hearing the ship went off course. Nobody on Earth believes him, and they lock him up with the intention of sending him to a boys' home.
Will Robinson meets a man in a cave who may hold the solution to helping them get to Alpha Centauri.
Penny is given a gift by a thief on the run, who tells her to protect it for him. She and Dr. Smith discover that it leads them to a ring which, when worn, allows the person to turn anything to platinum, which Dr. Smith does. Unfortunately, the ring also turns their food into the metal too and food is always in short supply.moreless
While the men are away, an alien creature stalks the Robinson women from the shadows. The girls just think it's a small dog that is to blame for raids on food and other mischief.
Luminous aliens capture Dr. Smith with the plan to replace their burnt out computer with his brain. Smith bargains with them, and they decide to use Will's brain instead.
Will Robinson and Dr. Smith stumble upon another robot on the planet that is even more capable than their own. The alien robot sets out to gain the confidence of the Robinson family because, at a future critical point, he plans to transport them to his home planet as slaves.
The Jupiter 2 is pulled into a giant alien spaceship where there are advanced rock-like creatures. John and Don look for maps and equipment while Dr. Smith and Will look for trouble.
Before leaving their planet, the Robinsons meet a boy alien called J-5. They take him with them to return him to his home planet. They meet a strange ship, which turns out to be an Earth "lighthouse" for lost ships. Thinking this ship will help them with extra fuel and star charts they celebrate. However, when J-5 learns that they don't have enough fuel to take him home, he angrily sets about to destroy them all with a creation of his imagination.moreless
A visiting family of aliens, called Taurons, have decided to use the Robinsons' planet as a new colony. Although the Robinsons cannot understand the language of a visiting family they welcome them to live in peace and harmony. However, as usual, Dr. Smith causes problems when he panics and draws a gun on the alien family.moreless
The space pod lands on a planet that is inhabited by creatures who all look alike but aspire to be different. They capture the Robinsons and make duplicates of them with the objective of using the duplicates to fly theJupiter 2 back to Earth. Only Will is not duplicated and attempts to thwart their plan.moreless
The Robinson family discover a large alien plant that can duplicate whatever it is fed. Dr. Smith steals the ship's remaining fuel with the intention of feeding it to the alien plant, hoping to double the fuel supply.
In the year 1997, the Robinson family is cryogenically suspended before their launch into space in the space-saucer Gemini 12 on man's first mission to colonize a planet orbiting Alpha Centauri.
Soon after leaving Earth, a meteor swarm sends the Gemini 12 spiraling out of control, ending in a crash landing on an unknown planet. The Robinsons survive the crash and set up camp, but their preparations to head south to avoid the sudden onset of the cold season are hampered by One-Eye, the giant cyclops, trapping John and Don in a cave.
After Will saves the men, and Penny is recovered after a turtle ride, the travellers journey to the tropics encountering along the way, the One-Eye again, fierce electrical storms, an underground city and a stormy sea crossing where they become caught in a whirlpool.
The Robinsons' power source drops to critical levels, leaving them unable to recharge the Robot. Rather than endanger them, the Robot leaves the group. The crew looks for it and Will and Dr. Smith discover that the Robot has grown to be bigger than a house after exposure to strange gasses.moreless
The Intergalactic Delivery Service comes to Priplanus. Once again Dr. Smith seeks transportation and has Will "test drive" the spaceship. Will returns much smarter than when he left. Smith, realizing the same increase of intellect could happen to him, boards the spaceship. His trip, however, ends in his rapid aging and subsequent impending death.moreless
An alien boy is sent to Priplanis to validate his prince status. Will Robinson is drawn into a battle to the death, unbeknown to his father. Once his real intentions are known, John Robinson substitutes himself in the challenge and the alien ruler substitutes himself for his son.
Don West and Dr. Smith are installing some equipment when Dr. Smith comes across an alien prison escapee. The prisoner alien makes Dr. Smith change jackets and then runs away. When the prison guards catch up with Smith and West, they arrest them for aiding the escape of a prisoner.
Dr. Smith and Penny are entrusted with a valuable amulet after saving an alien's life. However, trouble soon arrives in the form of space thugs, and they want the amulet.
After leaving their planet, Dr. Smith manages to plot a course back to Earth.
Dr. Smith disposes of a plant that has grown out of control. However, the plant manages to attach itself to the Jupiter 2, apparently believing that Smith is its mother. Meanwhile, the ship comes under attack by a space warrior.
The Jupiter 2 lands on a planet which apparently serves space as a junkyard. The Robinson's food supply is dwindling, so Dr. Smith tries to sell the robot and the ship in order to get food.
Dr. Smith holds a seance to contact his Uncle Thaddeus. Instead a "spirit" creature is contacted and creates havoc for the Robinsons.
Dr. Smith eats some alien fruit, which turns him into a giant. He becomes convinced that giving him the fruit was the Robinsons trying to kill him. So he plots to take them out.
Due to Dr. Smith's actions, the crew of the Jupiter II has had to land their ship on a alien planet which is run by cyborgs. The crew must rescue their crippled robot and then try to break free from the captors, even though the cyborgs promise them power and luxury for the rest of their lifes.moreless
Astronaut Jimmy Hapgood lands on the planet and the Robinsons befriend him. After Jimmy fixes his spaceship, the Robinsons try and convince him to take Will and Penny back to Earth with him. However, Dr. Smith tries to get aboard the ship to get back to Earth instead.
The galactic showman, Farnum B, returns, this time as the producer of the Miss Galaxy Beauty Pageant. And he wants Judy to be in the contest, only she wants no part of it. Dr. Smith submits her anyway by forging her name to the contest roster.
The Robinsons' communications system is knocked out, and they discover that the culprit is a female warrior, who is planing on making their planet a colony for her people.
A crew led by Captain Kraspo is searching for the missing Princess Alpha. They bring Will Robinson on board their ship, and he makes them think that Penny might be the Princess they are looking for.
Dr. Smith discovers another android machine in the middle of a dangerous fissure. When he tries to order something, he is trapped inside the machine. Later when Will tries to get him out, he too is sucked in. Zumdish arrives on the planet in order to destroy the faulty, forgotten machine. Meanwhile, Will and Dr. Smith discover the magical Toymaker's world, as they are mistaken for toys.moreless
Rocketing through space, the Robot suddenly announces that the Jupiter 2 is approaching Alpha Centauri. Everyone is surprised, and the ship lands on a planet, where they are greeted by a group of people who appear to be teenagers from Earth. It turns out that they are aliens who live like Earth-style hippies, and they are incapable of growing old.moreless
The Robinsons come across a group of space hippies who are trying to destroy the planet the Robinsons currently inhabit. It is up to the Robinsons and Dr. Smith to stop them or they will all be doomed.
Doctor Smith uses the space pod to land on a planet that the Jupiter 2 is passing by. It turns out that on this planet, plants are the highest form of life and some of them are quite intelligent. One of these plants, a large carrot, captures Smith and tries to change him into a plant.moreless