In the first Lost in Space episode of the original series (not the pilot, but "The Reluctant Stowaway"), Don warns the rest of the crew when they are woken up that "we're going into a hyperdrive - it's out of control!" Now, the distance from Earth to Alpha Centauri is 4.93 light years, and it is announced at the beginning the mission will take 5 years, hence they were traveling at sub-light speed (although not far off light speed).

Assuming that a hyperdrive is what we today understand it as (i.e. a drive that allows faster than light speeds), that means that at that point in time, Earth had the ability to travel at faster-than-light speeds (unless they somehow were able to go faster than light by their sub-light drive during the chaos, which seems unlikely to me). Why, then would they travel below the speed of light for five years when they could easily get to Alpha Centauri faster than that?

The only answer I can think of is that the hyperdrive was not quite working yet, which then begs the question - why did they have hyperdrive abilities in the first place?

6 Answers 6


Because the Jupiter's hyperdrive works in leaps

From the books we get a little more detail as to how the Jupiter 2's hyperdrive works and it doesn't seem to be the "continuously FTL speed" that we think of when it comes to traveling in hyperspace or Star Trek's warp speed:

Page 10 explains that the Jupiter 2's hyperdrive warps space to make its immense leaps. It also distorts time so that the trip might take seconds, minutes, or hours.

And the leaps may require a period of rest:

Page 17 reveals that it can take several weeks to regenerate the ship's hyperdrive core material after some jumps. How the core material is regenerated is not explained.

So the ship is moving at FTL at some times, and sub-FTL at other times. Since the range of the 'drive is not known ... it is hard to tell how much faster vs slower than light speed the ship is actually travelling, but it seems for Alpha Centauri it measures out to just be old "lightspeed".


There was an episode where the Jupiter Two crossed the galaxy in a day, I don't remember if it did this under its own power, or from an outside source. I believe it made Hyper Jumps much like the Battlestar Galactica ships in the 2004 version. However its normal flight time to Alpha Centauri was said to be 5.5 years. So its capabilities contradicted themselves from season to season. I do not think the writers put much effort into getting any propulsion science somewhat believable like in Star Trek.

  • 1
    Great answer and welcome to the site!
    – Wad Cheber
    Commented Jul 18, 2015 at 5:41
  • Having only re-watched about half of the first season (I last watched it during its initial run, of which I now have only vague recollections) it seems that the ship's capabilities are contradicted episode to episode not just season to season. They are lost on an unknown planet - they don't know where they are, yet they somehow know exactly the way home ("The Raft") - unless I missed something.
    – Anthony X
    Commented Oct 14, 2018 at 16:00

If you were a consistent watcher of the series, it shows that the Jupiter 2 does NOT regularly travel at FTL--in one episode, major west tells smith that the ship is traveling at About half" the speed of light.As most know, no ships that we know travel with their engines constantly running. And we also know that The Jupiter 2 ran out of fuel early on in the first season due to the robots running amok and causing them to go into a hyper drive. Therefore, from those observations, The Jupiter 2 was not actually designed to travel FTL.


To go 4.25 light years in 5.5 years you would have to average about 144,000 miles per second. One would assume that the acceleration and deceleration process is not instant and that navigating the Oort Cloud might require some maneuvering that would extend the miles traveled. I agree that the ship and the fact that hyperdrive seems to be an accident, not a cruising speed, means that the ship was built to do around 80% of Light Speed. That being said, the terms "Galaxy", "Solar System", and, early on, the reference to having traveled "two" verses "one million miles" several days into the trip when the ship was built to travel that distance in under 14 seconds adds to the theory that this all was written from Penny's more fanciful and delightful perspective and not the Professor or Will's. AND that the writers truly didn't take much interest in science.


I'll throw in my two cents worth on this one....

In its original inception, I doubt that anyone ever conceived of the J2 traveling at faster than light speeds - had they that capability then why put the Robinsons into cold storage?

Based on the "Alpha Control Manual", which has its flaws but is overall quite well done, the J2's flight to Alpha Centauri, a distance of 4.32 light years, would have occurred at relativistic speeds only, approximately 60% of light speed, which would have lasted 7.2 years. Allowing for time dilation at relativistic velocities, for the Robinsons, the trip would have seemed as if only 5.76 years... better, but still too long without the 'freezing tubes'.

Clearly, the 'hyperdrive' was a systems upgrade that was made to the J2 at some point after their initial launch, something that they picked up and jury-rigged along the way.

And, as long as we're speculating on that, then the inevitable questions arrives of 'how, at only 60% of light-speed, could they have become so lost so quickly?'.

Turns out, I've got an explanation for that (no surprise there)...

The first thing that happened to them once they awoke was encountering the 'derelict' craft, which essentially swallowed them whole. If you'll recall the scene where John Robinson is fiddling with an alien dial in what he concluded was their control room (a really stupid thing to do, under the circumstances), when he and Don West start seeing viewer images of different locations... Robinson presumes (in my opinion, incorrectly) the images to be some sort of star-chart, showing pictures of various nebulae and constellations and so forth. But, what if he were wrong?

Suppose, instead, that they were looking not at places to go but, as he turns the dial, they're looking at places that they now are? He could easily have been accessing the ship's jump-drive system and not have been aware of it. We never did see the outside of the derelict so, if we're imagining that the J2 could pick up hyper-drive along the way then its not too much more implausible to conclude that other races already have such technologies. By the time that they exited the derelict, they were hundreds and thousands of light years away from their original location. In essence, the reason that they were 'lost' is that they got that caused it themselves, even if only inadvertently.


I believe that the original Jupiter 2 was designed to reach light speed but lacked the fuel capacity to continually reach light speed. This was demonstrated in the movie version, where the Jupiter 2 was forced to “jump” in to light speed to travel through the sun to avoid being burned up.

Edit: To follow up the above, in the movie version, J2 appears to be generating a “warp” bubble around the ship as the “hyper drive engine is “deploying. As well as it also appears to be deploying “warp nacelles”. The story line implies that in order to “fly through the sun” the hyper drive engine can allow J2 to drive fly right through.

  • Is there any specific evidence regarding the point about fuel capacity, or that just an assumption? Commented Apr 11, 2021 at 5:15

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