I first discovered Lost In Space 20 years after it had finished its original TV run, and it has remained a firm favourite ever since. A recent purchase of the complete series on DVD - all 83 episodes across 23 DVDs - has kept me entertained for many an evening, and also bought home just how much the series changed across its three years.September 15th 1965 saw the first episode broadcast on US network CBS. Set in the year 1997, the Robinson family leave Earth in the Jupiter 2 space ship to colonise Alpha Centauri, but they have a "Reluctant Stowaway" (the title of the episode) in the form of Dr. Zachary Smith. He is working as a saboteur for a foreign government and rigs the environmental control robot to destroy the ship's control systems hours after take off. After the 'doomed' ship encounters a meteor storm it veers light years off course, and soon the robot becomes active and does further damage before it can be stopped. Later, Professor John Robinson tries to fix the ship's sensor systems but must go outside the craft to perform the repairs. The excitement factor is high throughout this episode, and when John Robinson becomes untethered, and his wife Maureen must go out to help him, we're left with a fantastic cliffhanger ensuring viewers will return for episode 2.In fact the first 5 episodes of Season 1 are very suspenseful, the kind of television to rival any sci-fi / adventure stories out there. While the story isn't exactly hard science, it is fun, and on the whole the first half of Season 1 is very dramatic in its impact. The family had to find food, shelter and water, and at the same time battle the unknown and sometimes hostile creatures.Episode 18 (The Sky Pirate) takes a sudden turn in direction. From that point onwards the focus of Lost In Space was more "comedic villain" of the week, and how Will Robinson, Dr. Zachary Smith and Robby the Robot would deal with plot. Despite the format change, all of the first season has a lot of charm and excitement about it, and now is easily my favourite.Season 2 continues mainly in the "comedic villain" of the week format, but also adds in an element of farce. This may be why this was my favourite season whilst a kid. There are moments when you can feel a return to pure adventure, especially in the opening episode (Blast off Into Space). The villain is disposed of early in the story and the focus is on the plight of their situation. This is followed with an episode titled Wild Adventure, which is easily the best of Season 2 and one of the strongest of the entire series. It's a great space bound adventure with the crew of Jupiter 2 getting close to finding Earth.The back half of Season 2 is a little hit and miss, some episodes are just absurd (The Questing Beat and The Space Vikings especially), and some are essential viewing (Trip Through The Robot and The Mechanical Man as examples), but once Season 3 begins you can really feel the excitement bought in by another new direction for the series.Season 3 is more action packed, with more trips into space, and include some of the most ambitious stories the show attempted. Condemned In Space is an action packed season opener, where we see the Robinson's lift off in Jupiter 2, dodge a comet, loose the Robot in space and come across a frozen prison. This is followed up with A Visit to a Hostile Planet, and although logic is thrown out of the window it really is one of the best of the series. The crew return to Earth of the past, 1947 to be exact, and the townsfolk of the small Michigan town where they land believe they have been invaded by aliens.This style of action/adventure episodes would continue for most of the first half of Season 3, but toward the middle it starts to feel as if the writers had milked all they could out of the format and decide to return to farcical fantasy, and the results are not very good. Starting with A Day At The Zoo you can almost hear the death knell ringing. There are still some exciting stories to be told (The Anti-Matter Man and Target: Earth), and when originally broadcast the ratings remained strong, but possibly the series had run its course. My only wish is that they'd been given the chance to wrap things up properly.March 6th 1968 saw the transmission of Junkyard In Space, not the greatest of stories but considering it followed The Great Vegetable Rebellion (which features a talking carrot) it's almost Shakespeare! Whilst this final story was in production the cast and crew were informally made to believe the series had been renewed for Season 4, and scripts were being prepared. However, less than two months later, in May 1968, CBS announced they had cancelled Lost In Space, and so the Robinsons would never find Earth.So, like any long running series, there are episodes that aren't so great, but with Lost In Space the good far outweighs the bad. The different styles appeal to me at different times, as they likely do to the different age groups of viewers watching the series. It's a brilliant concept for a show, and I admit to having a soft spot for the 1998 movie (more of a guilty pleasure than anything), but watching it again you can't help but think it is ripe for a small screen remake. With the right writers there are almost unlimited stories to tell, and countless "Danger, Will Robinson" could find himself in.