Lost In Space was originally envisaged as a serious (or at least semi-serious) science fiction adventure series rather than the campfest it quickly became. The original concept can be seen pretty clearly in the first episode, The Reluctant Stowaway. The preparations for the launch of the Jupiter II are handled in a straightforward manner. Dr Zachary Smith is introduced to us as a US Air Force officer who has turned traitor and plans to sabotage the mission. His sabotage plans encounter one hitch - he had intended to be well clear of the spacecraft before its launch but he miscalculates the timing and ends up still aboard when the spaceship lifts off.
This is a Dr Smith who is certain scheming and cowardly but he’s not a mere figure of fun. He is a genuinely sinister villain. The role is not really played for laughs at all in The Reluctant Stowaway. The robot also has a sinister aspect, being the tool Dr Smith has chosen to wreck the spacecraft (and thereby cause the deaths of all its crew members).
This opening episode actually works quite well as science fiction. In fact in some ways it’s more realistic than most television science fiction programs. The Jupiter II’s destination is the closest star system to Earth, Alpha Centauri, just over four light years away. We are told that the Robinsons will be in suspended animation for five years, which means the spacecraft will be traveling at something below light speed. So far the series scores surprisingly high for scientific plausibility. The assumption that spacecraft in 1997 would be powered by atomic motors must have seemed well within the bounds of probability in 1965. OK, towards the end it enters the world of television sci-fi pseudoscience but it’s remarkable that it maintains at least a degree of scientific plausibility for most of the first episode - that’s more than can be said for many other sci-fi series.
Episode two, The Derelict, has a similar feel. Dr Smith remains sinister and menacing. The Jupiter II continues on its journey through space, narrowly dodging a comet and then encountering a very large and very strange spacecraft. Dr Smith has his own ideas about the origins of this spacecraft and is rather taken aback to discover that it really is an alien spaceship. The set design is quite imaginative and the aliens and much more interesting and more truly alien than most of the aliens we will encounter in later episodes. And they look rather cool. The Derelict, like The Reluctant Stowaway, is a pretty decent space adventure.
In episode three, Island in the Sky, we can see the formula starting to fall into place. The Jupiter II crash lands on an unknown planet which brings the spaceflight adventure element of the series to an abrupt halt. For the first time we see the relationship between Dr Smith and the robot start to take on the comedic aspect that would come to dominate more and more. On the other hand Dr Smith (who is still referred to at times as Colonel Smith) is still pretty villainous in a fairly straightforwardly murderous way, and the robot is still more frightening than amusing. At this stage in the series it could have gone either way, either continuing as a relatively serious space adventure or making the switch to high camp comedy. We all know which way the series did in fact go.
What we can be fairly sure of is that sooner or later there would have been pressure from the network to lighten things up and play the situations for comedy rather than thrills. That seems to have been the almost inescapable pattern in 1960s American network television. Voyage to the Bottom of the Sea and The Man from U.N.C.L.E. are notable examples of series that changed midway through their runs as a result of network interference and the obsession of the networks with treating science fiction and action adventure themes as lightheartedly as possibly. It was not a great strategy but no-one was able to convince the suits at the networks but maybe they were wrong.
By episode four, There Were Giants in the Earth, the formula has been pretty much locked in. Jonathan Harris is playing Dr Smith more for laughs than menace. The robot is becoming a comic relief character rather than a deadly menace. It’s becoming obvious that there’s going to be a monster in just about every episode and that the monsters will be somewhat on the silly side. There would still be the occasional more ambitious episode that tried to deal with relatively serious science fictional themes but the emphasis was going to be on light-hearted fun and monsters. Fortunately it would be a great deal of fun indeed and there’s no point in regretting the slightly more serious Lost in Space that was never to be.