Home Fun The Science of UFO: The Interceptor

The Science of UFO: The Interceptor

8 min read

The S.H.A.D.O Interceptor is one of the most Iconic designs from UFO.

UFO InterceptorsOriginally designed by Mike Trim and then revised by Derek Meddings. It is a small one seater fighter that forms SHADO’s first line of defence against the alien aggressors. Its most striking feature being the single missile that protrudes from the front of the craft.

When brought up this aspect of the designs generally attracts a lot of criticism, after all, why is there only one, why couldn’t they laden in with missile batteries and machine guns, after all anything goes in space, right?

Personally I find that the original idea for the interceptor is a lot smarter than people think, and is probably one of the most realistic interpretations of a space fighter in sci-fi, allow me to put my “Fake scientist” hat on and explain why…

You only get one shot

The series spends a lot of time pointing out that the Alien’s technology is way ahead of our own, the only real saving grace we have is that our atmosphere hampers their craft forcing them to move slower and disintegrate over time.

In space they have no such problems and can travel far in excess of the speed of light. From when SID detects them, Interceptor pilots literally have minutes to slide into their craft, get airborne and achieve optimal firing position. By then the UFO is nearly out of range.

Because UFO’s move so fast, engaging them normally is pointless, a dogfight would be like trying to chase a jet fighter with a mobility scooter, however by using some maths you can calculate roughly where the UFO will be at a particular time. This way the interceptors fire nuclear missiles (To cover the most area) to intersect with the UFO’s path.

UFO Interceptor missile path


So why not carry a second if it doesn’t work?

Nukes are big and heavy, the added mass would slow the Interceptors down, also if you missed the first time, the UFO’s would already have reached the upper atmosphere and firing nuclear missiles at the Earth would probably spoil someones day.

So why not have more interceptors?

One of the core elements that UFO based itself round was realism, unlike other top secret world protecting organisations like Spectrum or the Terrahawks, stuff costs money and SHADO has very limited resources. Nuclear warheads cost millions, delivering a stack of them to the Moon would cost billions. If they blew their entire stack of warheads on one group of UFO’s then there would be nothing to stop the next set.

The bitter truth is they only send 3 Interceptors because thats probably all they can afford, If they miss a few then thats when Skydiver comes in.

Aren’t you thinking a little too much about this? After all it’s fiction.

Admittedly yes, and having such an unreliable defence system helped contribute to many really good UFO episodes. In fact a lot of the above thinking is ignored in the latter half of the series when the interceptors are seen fighting with the UFO’s in close quarters and magically reloading their missiles. Understandably sometimes science can take a back seat to whats exciting and i’m ok with that.

I do think however that it is nice to put a spotlight on what is a very interesting and for the time, quite different way of thinking in regards to space combat. There are plenty of flaws with it but it really highlights how stretched an organisation like SHADO would be in that kind of situation. For me personally this level of thinking is one of the things that makes UFO unique in regards to similar series.

So what do you reckon?

So what do you guys think? How would you defend the planet in a similar situation.


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A freelance Artist and Film-maker based on a not so secret island in the East Atlantic. Grew up up on the Anderson series reruns in the 90s and have always strived to create works that are as interesting and exciting.
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  • Gary Hawkins

    Makes sense. I always did wondwr why the aliens didnt jiat approach earth from the side furthest away from tge moon though. There’s no way tge intrceptors would cover half a million miles in the short time they had to react

  • Nick Evetts

    I think it was stated in many episodes “Thank God for the atmosphere it’s the best defence we have ” as to sourcing Nukes for Moonbase well since the the worlds super powers fund SHADO I’m sure handing over warheads would not be a problem, As to reaction time The Interceptors would be mostly engine, fuel and weapon and your only lifting from the Lunar gravity well not Earth’s . It was also hinted that SHADO had at least 4 Skydivers with at least 2 at sea at any given time and would have had at least 2 shifts of Combat Astronauts . How much would I change? not much .I agree with the comments about loosing a Nuke towards the Earth – a bad idea the EMP would deafen and blind us – just what the Aliens would like …….

  • Griff Wason


    A little more research may have uncovered the following:-

    Memo from Derek Meddings to the production personnel, dated January 10th 1969:

    “When the Interceptors have been launched, appropriate time should be allowed for them to be flown into the estimated path of the UFO (this may be many hundreds of thousands of miles ahead of it). When in position, an order should be given to release the atomic warheads/missiles from the noses of the Interceptors. These missiles would then quickly and automatically break up into ten smaller parts (similar to the way in which a 12-bore cartridge breaks up) and then, after about ten seconds (allowing time for the Interceptor to reach a safe distance) these parts would erupt into a blanket atomic explosion. If the right calculations have been made, the UFO would either be destroyed as it flew into the explosion or be caused to divert.” – Derek Meddings – Special Effects Director UFO

    Extract from Chris Bentley’s excellent book, “The COMPLETE book of Gerry Anderson’s UFO.

    Hope this helps,


  • Rob Schofield

    Nicely argued, and the simplest explanation is usually the best.

    Orbital dynamics dictates the approach path of the UFOs – they can’t come in from out of the plane of the ecliptic, or from the opposite of the Earth’s orbital direction and expect to be able to brake sufficiently from SOL down to earth orbit traverse speeds (think about the immense quantity of energy needed to decelerate!). Hence, the moon is the best proximal launch point to the Earth for an intercept as UFOs manoeuvre to get into the Earth’s atmosphere.

    A closing intercept trajectory from behind the UFO is the only possible way to place a “shotgun blast” into the Alien’s path: the UFO is decelerating and the missile is accelerating to catch up. So the missile only has to converge at a closing speed close to that of the approaching UFO. Entirely feasible, even with current technology. The RAF and Army used the Bloodhound (Bristol Dynamics/BAC) and Thunderbird (English Electric) respectively for this right up to the time of the Falklands, at least for interceptions at supersonic, atmospheric speeds (up to Mach 3, I believe).

    I was always under the impression that the Interceptors had 3 cannons in front of the pilot’s cockpit, but this was never used on screen. Given that the Interceptor was essentially just the first stage of a launch platform for the missiles, it is hardly likely they would ever have achieved sufficient speed to even come within shooting range of a target in any case, so it would be pointless to have secondary armament. The only scenario I could think of quickly would be strafing a stationary target on the moon’s surface, and given the position of the cannons they would be firing along the top of a long missile body giving limited forward vision: they’d have to get rid of the missile first.

    A good little article!

  • Nick Evetts

    I always thought they were thrusters on the Interceptors

  • Simon Fay

    A plausible explanation for the use of such a lop-sided platform. I’d still love to know how the pilots transferred from the chute into the cockpit and what the post-flight procedure was for landing and disembarkation.

  • Stephen Koehler

    They did th best with 60’s tech the best they could. In a contemporary context interceptors would be based in space either in lunar orbit or at the Lagrange points. SID would be based there as well dince neing outside Earth’s gravity well would improve detection. Orbital bases should be at each Earth-Moon Lagrange point if finances allow. Lunar basing alone opened up a significant gap in derences as well as detection. It was a major miracle SID caught as many UFO’s as he did based in Low Earth Orbit. A second layer of automated defences would be bases ib Geosynchronous orbit.

    • Stephen Koehler

      I know my spelling is atrocious, but i hope you get the idea. Also Skydiver would probably resemble contemporary SLBM launched in that fashion looking something like the Seaplane based fighter the US was developing in the 60’s. Ya can tell I have given this a lot of thought.

      • Stephen Koehler

        Our updated space based interceptors would probably be the Space 1999 Hawks equipped with SDI derived railguns, lasers, and missles.

  • Timothy W Smith

    We noticed taht right in front of the copit are three indentions, which could be stearing jets, as on the space shuttle, or gun ports. In the second episode of our fan film, UFO:1999, we brought back the interseptors upgraded and used thos indentions as laser ports, Thus the big missile was not the only defense. I still wonder if on UFO those were emean to be guns ports.

  • dejudicibus

    Mines. In Van Allen belt.

  • Spanner1960

    One other factor nobody has ever reasonably explained is how you get in, (as the chutes are never seen connected), and more to the point, out of one.

  • Qui Quai Duod

    I know this is a bit of an older discussion, but the question posed above about the Interceptors and their weaponry, and why they don’t have “machine guns”. Well, according to the Manual (or at least the diagram in the book), in that black square on top of the nose, right below the cockpit, there are three “high-velocity machine guns”. So even though they were never shown in use in the series, the Interceptors did have alternate weaponry at their disposal once the missile had been fired. (And while we didn’t see those guns in use, perhaps those Interceptors used them in “Reflections in the Water” when the UFOs launched that massive attack?) Either that, or there ARE more than three Interceptors, but only three are on immediate standby, and others are in reserve (and it was those in reserve that were called out in that “Reflections” invasion). After all, we know Interceptors were lost in at least two episodes I can think of, and they were replaced rather quickly, so I’m guessing that SHADO does have more than just three, and keeps them in another underground hangar on Moonbase.

  • Ed Brault

    I remember a Fanzine story that had a Space 19999/UFO crossover where an Eagle gets thrown back to 1971 and is intercepted by SHADO and forced to land on the pre-Moonbase Alpha Moon. At the end, Cdr Straker remarks that he was looking over some design proposals from Lockheed Space, and while he was more interested in the Hawk fighter, the Eagle looked just like their vanished mystery visitor…

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