Killer probes of movies past…
‘Killer probes’ are an old science fiction concept. The idea is an imperialist interstellar culture uses an indirect means of expansion. Rather than waste effort and resources ‘conquering’ another solar system, the aggressor species simply eliminates other potential rivals before those races reach the star-faring stage.
Typically, this means detecting a species at just the right point of technological development: evolved enough to be a noticed as a potential threat (by listening for their early radio broadcasts, etc.) but not to the same level as the aggressors.
Then send a killer probe: some kind of self-guided weapon or destructive phenomenon the target culture can’t resist. They’re overwhelmed and wiped out. No muss, no fuss. When the aggressor’s ships eventually arrive, they have an empty world to colonize.
The theory was originally proposed in light of the lack of communication from “out there” (aka the Fermi Paradox); as one possible reason we haven’t encountered intelligent aliens.
More recently even Stephen Hawking said “Such advanced aliens would perhaps become nomads, looking to conquer and colonize whatever planets they could reach[…] Who knows what the limits would be?”
I mainly started reading this in science fiction novels and short stories in the 1980s-1990s. Killer probe ideas ranged from biological agents to inserting a destructive mechanism in the planet’s core (the premise of Greg Bear’s The Forge of God.)
But how old is this concept really?
I know it goes at least as far back as the machine intelligence “Berserker” stories Fred Saberhagen wrote in the 60s.
The Berserkers aren’t a classic killer probe, though, but the end results are pretty similar.
They’re AI machines, designed as the ultimate weapon in a war between two biological species. The Berserkers go off the rails and decide to destroy all intelligent life, beginning with the two combatant species.
The artifact in the Star Trek:TOS episode “The Doomsday Machine” is also arguably a killer probe (although somewhat inspired by the Berserker concept.)
However, could the idea be even older? I was surprised by one old 50s scifi film, and then started looking around for more…
I’ve always been a big fan of science fiction films, whether with serious concepts, or campy 1950s scifi and Japanese kaiju films.
So I was a little shocked as I rewatched The Monolith Monsters recently – a movie I hadn’t seen since I was a child. The ‘monsters’ were a perfect idea for a killer probe!
For those who missed this cinematic gem or need a refresher – a meteor crashes in a California desert, strewing what looks like obsidian rocks:
The local government geologist picks up samples. These get activated accidentally by water – causing them to multiply and kill the geologist. How? They’re not alive per se, but it’s later determined they use water as a catalyst to start absorbing silicon from the desert. They also literally absorb the silicon from the human body, causing people to stiffen up and die.
(Well… okay you’ll have to bear with the “science” here. There’s truth to our bodies using miniscule amounts of silicon in connective tissues, but this is really a stretch!)
As the movie progresses this rock gets all the water it needs in the form of sudden desert rains, and the crystals begin growing exponentially. But they can only reach a certain height before they collapse, destroying whatever’s underneath them, and shatter into dozens of smaller crystals, which each grow in turn... The growth progresses unabated, following a clear path along sources of water.
How does this tie in with killer probes?
Suppose, as an alien, you want to settle worlds where physiologies similar to yours might thrive. If you’re oxygen-breathers who developed in a water-rich environment, then Earth’s perfect! It’s not much of a leap that your societies might have developed along common water-ways, like ours did: rivers, lakes, etc. Towns would spring up there, grow into cities, and eventually into civilizations. (It happened in Sumer, Egypt, etc.)
Now introduce something that replicates uncontrollably and destructively in those circumstances. Place near a source of civilization, aka a fresh water source. And let it go about its business…
The crystals would absorb a useful element from the target beings (silicon), grow, collapse, grow again, and keep expanding. They’d simply follow the same waterways along which the cultures developed… The cycle of destruction continues as long as they encounter fresh water, destroying much of the civilization’s infrastructure.
However, in typical 1950s monster movie fashion, our heroic scientists discover the monoliths can’t survive in salt water. They blow a dam, which soaks the local salt flats, then flooding and destroying the monsters. Plain old salt water destroys them. (Must be related to triffids… 😉)
So the analogy breaks down a little… Or does it? Let’s think about this for a second – assuming our killer probe aliens are from a similar ecosystem and evolutionary background (after all, why destroy/invade a place you can’t live?) they’d want to clear the viable land masses – not salty oceans. And aliens would realize how unlikely humans would be to live in the oceans. (Similar physiology, right?) So you make your killer probe stop working when it hits the sea.
Another point: you’re saying not all human societies live along waterways, right? So how much impact would the monoliths really have? Well, actually a significant number of people live near water. (See also How Close Do We Live to Water? & Water and Population Centers)
Even destroying the portion of humanity living adjacent to waterways would be enough to cause havoc. And wiping out those fresh water sources, at least temporarily, could lead to mass drought/crop failure/starvation. Even if some people survived, as was likely, the remainder would have to rebuild their society – and remain ripe for conquest by the enroute aliens when they arrived.
I got to thinking, were there other scifi films that hid killer probe ideas? I knew of at least one other movie I was pretty sure of (see the end of my list below😉), but some others popped up too!
Kronos (1957)
Enter another killer probe concept, albeit from a different perspective – energy. In our modern world energy is key. Witness the chaos that results from power outages, like the planned outages during California’s wildfires. This film plays on that vulnerability…
An alien craft arrives near earth, is mistaken for an asteroid at first, and shot with a nuclear missile (man they had piles of those things lying around in the 50s!) The result triggers a response to land. Thus, the ‘probe’ recognizes a potential civilization to destroy, lands and gives rise to the real threat: KRONOS.
KRONOS appears and begins hoovering up all energy sources. Much the same with other energy-absorbing scifi concepts, the more it absorbs, the larger KRONOS gets. (An atom bomb used on it only serves to make it monstrous in size.)
Rather than destroying physical people and structures, like The Monolith Monsters, KRONOS assumes an alien race is siphoning off all of Earth’s energy resources to replace its own depleted stores. This isn’t really a 100% unguided killer probe concept then, since technically the alien race wants to steal our energy, not destroy us outright (one might argue the effect would be the same.) And furthermore, the main monster – a giant, energy-sucking robot – is actually guided by an alien intelligence which took over the mind of a scientist early in the film.
When all seems lost the scientist figures out a way to kill himself despite the alien intelligence, eliminating the control source. Simultaneously the other scientists determine that (sigh) reversing polarity on KRONOS will cause it to feed on its own energy and be destroyed. (Reversing polarity is an old chestnut…)
Is this a killer probe then? Hmmmm… answer a little hazy, try back later. Arguably it follows the killer probe plan: from the get-go this device is keyed to check for a pre-space, but post-atomic, civilization. Had it not been attacked by the right type of technology (atomic bomb) it may never have landed. Its efforts will severely curtail, if not destroy, humanity by stealing all of its energy resources.
But, the need for active control makes it less automatic then the classic killer probe. Remember, the idea is to send such a thing out and let it act with no back-up or remote support. Still, given the exploitation of a vulnerability and the ability to bring a pre-space-faring culture to its knees, this is a decent killer probe scenario…
The Lost Missile (1958)
It could be argued this is perhaps the most perfect killer probe story I ran across!
A mysterious “missile”/spaceship approaches Earth. In panic, an Eastern European country fires a rocket at it. This in turn forces the missile into a close-Earth orbit, where its hydrogen-powered drive literally burns up the countryside from 5 miles up (outputting heat described as over a million degrees!) It burns a swath of destruction across the Earth in its path, as it approaches the ultimate destruction of New York City. Nothing can touch it either, because the heat it generates destroys any aircraft or missile making the attempt. (Makes you wonder how the first missile got through? Shhhh…)
“No nation on Earth would fire such a missile; it would have to be a nation of homicidal maniacs!” quips our scientist protagonist towards the end of the film. (There’s even a montage explaining the missile will continue in an endless orbit, destroying swathes of the planet on each circuit: England, Stockholm, etc.)
Sounds like a killer probe to me! Aliens send a ship to a potential rival planet. Again, the post-industrial, yet pre-space-flight, natives pay it undue attention. The ship descends to do its business of destruction…
Had Earth simply not reacted, the ship would probably have continued on its way. Instead it sniffed out a potential rival civilization and attempted to destroy it. (The powerful drive is also interesting: I ran across some theories online that any starship drive capable of sending a ship across the empty reaches of space could produce enough energy to destroy worlds.)
50’s scientists were always compensating…
But much like in KRONOS, Earth’s 1950’s science heroes happen to have a solution. In this case a special project - the Jove missile, which can survive the heat near the Lost Missile and deliver a hydrogen bomb warhead to destroy it.
The day’s saved! Too bad about Ottawa and our hero (radiation poisoning), though… ☹
Gamera 2 (1996)
Finally turning to the modern era (1990s), we have an unusual entry in the killer probe arena, due to its distinctly kaiju flair…
Gamera movies traditionally feature the giant fire-breathing turtle beating up monsters and saving kids. Even for a kaiju fan like me, the 60s originals have pretty poor special effects and cheesy, kids-show plots. The 90s Gamera films, though, are arguably some of the best kaiju of the era, and gave Godzilla a serious run for his money.
This film is no exception. Much better special effects, good characters, and excellent giant monster battles. We have a plot straight out of killer probes, and unlike the 50s films I’ve discussed, is likely a conscious decision on the part of the film makers. Gamera’s new foe is a planet-hopping alien plant, which comes with its own defense mechanisms, in the form of ‘Legion’ (smaller, crab-like monsters which attack anyone attempting to harm the plant) and a large “queen” form, which can go toe-to-toe with any military or kaiju threat.
So why is this a killer probe plot? Well, for starters the plant becomes a giant flower which grows a giant seed pod, releasing massive amounts of oxygen in the process, and when the oxygen reaches saturation point – blam! – explodes to hurtle the seed into space. The smaller Legion creatures are attracted to electromagnetic radiation (aka radio) and use silicon to replicate. This means they seek out supplies of glass, near radio sources (principally cities, a major source of civilization…)
Gamera is able to stop the first seed pod launch, though he’s hurt by the smaller Legion aliens. But the second time the queen Legion manages to hold him off long enough for the pod to fire. And though it doesn’t make it to space (Gamera has changed the flower’s angle) – it still destroys another city and severely wounds Gamera in the process.
But all is not lost! Since the smaller Legion creatures are attracted to electromagnetic radiation, humans are able to distract and destroy that swarm by luring them into a trap. Thanks to some pseudo-psychic shenanigans by a human girl, Gamera is revived. He has another fighting battle with the queen Legion and, using what comes totally out of left field, and can only be described as the Gamera wave motion gun, destroys her…
So the kaiju battle is solved in the usual “beat ‘em up” way, but this could easily be considered a killer probe story – we have an organism designed to seek out cities (great sources of electromagnetic radiation) and destroy them in the process of reproducing more killer probes. Coupled with a defense mechanism to prevent any interference, you have a very effective killer probe that goes around destroying major outposts of civilization.
There the argument starts to falter a little, though: the Legion doesn’t launch a pod from every city (though it destroys two) and some reviews I’ve read say it’s just trying to launch one successful pod into space as part of it’s reproductive cycle. But still, it’s a unique plot for a kaiju film, and offers a very different take on an enemy.
Are there other killer probe movies I may have missed? I’ve seen a lot of science fiction films, but its impossible to see them all! If you know of any please add them to the comments!
Some interesting further reading if you’re so inclined:
Killer probes in Earth in Human Hands: Shaping Our Planet's Future
Would E.Ts try to kill us off? (Nope. They’d be deterred.)
Beyond “Fermi’s Paradox” VI: What is the Berserker Hypothesis?