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Ask Slashdot: How Could We Actually Detect an Alien Invasion From Outer Space?
First time accepted submitter defiant.challenged writes As I was watching another sci-fi blockbuster about aliens wanting to harvest the life stock population on earth for their energy since we are such a robust species, I was wondering how likely and easy/difficult it would be currently to actually detect an outer space invasion (fleet). I am a firm believer that if we would be invaded, we would not stand a chance and would probably not even hit a single ship when it comes to fighting them. The aliens in the movie had the capability to space-jump right into our solar system and even very close to earth. My question is how good are we at the moment in detecting an alien ship/fleet that jumps into our solar system. Do we have radio dishes around the globe such that we can detect objects in space in all longitude and latitude degrees? I know we have dishes pointing to the skies but how far can they reach? Do we have blindspots perhaps on the poles? I also wonder if our current means, ie radio signals, are relatively easy to be compromised with our current stealth technology? To formulate it in more sci-fi terms, how large is our outer space detection grid, and what kind of time window can they give us?
Email Elon, see what he thinks.
Any race advanced enough to travel here to invade will have capabilities way beyond anything we could hope to combat or detect. I would imagine the first sign you would have would be if you were one of the lucky ones to see half the world wiped out a few seconds before you yourself were removed from this mortal realm.
Do you expect any other answer than "we would be fucked"?
Frankly, any aliens able to travel here from another world are so far ahead of us, it wouldn't make any difference if we detected them or not.
However, you asked the question... so...
Our space detection system is largely aimed at Earth. For example, to warn of us of ICBM launches the first system put into space was called MIDAS between 1960 and 1966.
http://en.wikipedia.org/wiki/M...
The GPS satellites have nuclear detonation detectors, which doesn't do any good, but it another example of how our systems are aimed at Earth.
All the stuff pointed out into space, like the Hubble Space Telescope, are designed to see VERY far away and aren't looking for ships. Given the small likely size of any ships compared to planets and moons, we aren't likely to be able to see them even if we're looking for them, until they are on top of us.
After all, we still don't have a telescope that can see the moon landing sights. Pictures taken from sats in lunar orbit have gotten some pictures, but they aren't as good as you'd expect.
http://en.wikipedia.org/wiki/T...
This is the best image I could find of Apollo 11's landing site, and this was after the LRO was moved into a lower orbit:
http://featured-sites.lroc.asu...
Yea, you can tell what it is, because you know what you're looking at, but if you didn't even know where to look? You could stare at the moon for a month with such a camera and see nothing.
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TL;DR - We likely would have no notice whatsoever of aliens until they entered orbit of Earth, and even then, it is just as likely to be a random person with a telescope who spots them as anyone from the government.
Unless of course they can be seen with the naked eye, if their ships are big enough and they are in low orbit, that is possible.
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The usual example given to illustrate an Outside Context Problem was imagining you were a tribe on a largish, fertile island; you'd tamed the land, invented the wheel or writing or whatever, the neighbors were cooperative or enslaved but at any rate peaceful and you were busy raising temples to yourself with all the excess productive capacity you had, you were in a position of near-absolute power and control which your hallowed ancestors could hardly have dreamed of and the whole situation was just running along nicely like a canoe on wet grass... when suddenly this bristling lump of iron appears sailless and trailing steam in the bay and these guys carrying long funny-looking sticks come ashore and announce you've just been discovered, you're all subjects of the Emperor now, he's keen on presents called tax and these bright-eyed holy men would like a word with your priests.
Banks goes on to note that most civilisations tend to encounter an Outside Context Problem only once, at the point where that particular civilisation ends or is subsumed into the more powerful one. (Incidentally this is also the title of a series of eBooks by Christopher Nuttall which are satisfyingly geeky.)
Of course, there are plenty of fictional examples of invasion, I guess ranging from the barely-competent aliens in Niven & Pournelle's "Footfall" (who were easily detected) and the almost-Gods of Arthur C Clarke's "Childhood's End" who basically just turned up without warning. It's too varied a field to come up with an idea of how we could detect them.
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If Sony knows, then North Korea will be the first to know!
They still have to match orbital velocity on the same ecliptic, even at 0.1c they would show up from a long ways away. There's no "stealth" in space, plain and simple. Spaceships produce too much everything, heat, radiation, gas etc.
Orbital insertion would be pretty obvious as well, even at the L1 behind the moon we would notice them coming in.
moox. for a new generation.
I once had two ducks. I wondered what I looked like to my ducks. I decided that I look like a duck. All the extra powers that make me more than a duck - speech, thinking, telphones, etc. - are beyond the duck's imagination. To a duck, I look like a duck.
Then I wondered what an alian would look like to me, a human. I decided that an alien would look just like another human. So I began to wonder what advanced characteristics I couild watch out for. Successful businessman, good luck, healthy long life, mysterious origin, that sort of thing.
I found one. At the time he was my boss. He pretends to be Chinese, but hey, what westerner really knows what Chinese people look like?
They have landed already; and they are friendly. I was friendly to my ducks, and that Chinese family is friendly to me.
I don't think the question is stupid. Dismissing it out of hand seems more so.
1. Asking questions such as this, where we have limited information, often spawns interesting approaches to solving them
2. Any method for detecting 'unwanted visitors' may also be effective in detecting unintelligent (but still unwanted) visitors like significant lumps of fast moving rock which if unencumbered may cause an extinction event
3. It is an opportunity to involve people across national, political, tribal and ethnic divides in pursuit of something important to all of us.
(I'm sure there are many more advantages to at least contemplating what our civilisation could do in this 'hypothetical' situation but this lot should do for demonstrating that the question is at least worth asking...)
We actually have quite many detectors pointing in every direction and these are for detecting different kinds of interesting stuff. Gamma rays, radio, gravity waves, neutrinos, asteroids, and so forth. There are satellites and ground based detectors to make sure that there is essentially no blind spot, not even behind the Moon or the Sun, and the detectors are very very sensitive. These are all automatic and will report anomalies quite fast. Most of these are even linked to other detectors that would try to capture events in another medium. For instance, when we detect a gamma day burst, we want to detect it in optical and gravity as soon as possible. We also have an army of amateur astronomers with very good telescopes (with wide fields of view) trying to hunt asteroids, comets, and by all means.. aliens too (we've found none yet, in case you were wondering). So, in an event of an alien fleet would suddenly appear in our solar system, I'd guess that such an agent would register as an anomaly in all kinds of different detectors, and turn pretty much the world's eyes towards it within hours. Astronomers are very keen of detecting new and strange phenomena. I think the alien technology would be pretty advanced to cloak it from detection in such different mediums as broad spectrum electro magnetic (gamma, optical and radio), neutrino and gravity. I think such technology would have to be so utterly alien that we probably would detect an innovation, even in progress.. we might already be invaded and exploited. And what would be the point of fending off such innovation, if we wouldn't even take notice of it?
- Henrik
- when the Shadows descend -
They still have to match orbital velocity on the same ecliptic, even at 0.1c they would show up from a long ways away. There's no "stealth" in space, plain and simple. Spaceships produce too much everything, heat, radiation, gas etc.
Orbital insertion would be pretty obvious as well, even at the L1 behind the moon we would notice them coming in.
We would? You mean like we notice all those asteroids flying by that we get a few days notice of, or sometimes get notice of AFTER they have passed us?
What makes you think there is no stealth in space? Anyone who can come up with a FTL drive likely can come up with stealth in space.
How does it work? I haven't a clue, but I don't know how FTL works either, just like someone from 400 years ago couldn't tell you how a modern turbofan engine works.
My thoughts exactly. The environments we've physically checked so far are:
Earth: High degree of confidence that there is life here.
Moon: A couple spots on the surface, moderate degree of confidence that there is no life there. Surface in general, low degree of confidence, based only on comparing the few places we've checked with how the geology looks from orbit, with no data from many types of terrain. Elsewhere: no degree of confidence.
Mars: Same.
Elsewhere in the solar system: no degree of confidence (no other probes to other bodies have returned samples or returned data that would allow us to have any sort of confidence in determining whether life was present or not)
Elsewhere in the universe: no degree of confidence.
Many people gladly make assumptions about where life would or wouldn't be, but that's of course highly anthropocentric. "We need water, a solid rocky surface, a low radiation environment, temperatures in the 273-330 kelvin range, and these building blocks..." - you have no idea what you actually need, you have a sample size of "1". That's why people obsess over, say, Europa, despite us having absolutely zero evidence that there's any sort of life there. Heck, the best direct evidence currently on hand for life outside of Earth is probably Titan's "acetylene / ethane, hydrogen, and methane problem" (acetylene and ethane seem to be highly deficient at the surface compared to what should be there; there's some evidence that hydrogen may be disappearing at the surface; and Titan's methane persistence over geological times has long baffled; before the data on acetylene, ethane, and hydrogen was even known, it had been theorized that any life on Titan would most likely metabolize acetylene and ethane with hydrogen into methane). Plus, we know that there's extensive organic chemistry making all kinds of complex CHN "building blocks" in the upper atmosphere. But any life on Titan would have to be utterly different than LAWKI to survive the radically different environment.
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To me the best argument against an invasion is this (not mine, of course): with all the incredible technology they would have, they would find what they need in millions best places in the galaxy. Why should they chose one little planet among billions ones, and just the rare one that's hosting life? Unless they are sadist and enjoy killing living beings, of course, but that would be a too much expensive hobby even for them, I guess...
We have problems spotting and tracking 1km-long rocks in space beyond the Earth's orbit. We literally get taken by surprise by large rocks and their orbits all the time, whizzing around our solar system without us knowing they're there.
We're also not looking for those kinds of things, as such. A ship of some description able to sense us from afar and come into the system probably wouldn't jump in at the third planet out by default. They'd probably jump in off-axis, far away, and we'd be hard pushed to spot anything of space ship size (http://io9.com/nasa-spots-a-po...
That wasn't spotted for ages, discovered only in 2013, when it was only 10 times the moon's distance away (nearly a Mars distance). It was spotted only by something looking for near-earth objects and only because it looked like its natural trajectory may bring it close to Earth in the next 100 or so years. It's 650 metres long, orbits every three years and could weigh tens or hundreds of thousands of tons.
We can't see this kind of stuff. The angles and chances are just too small and anything that settles into a natural orbit is basically indistinguishable from a rock. It wouldn't take much for something to jump in just outside the outer planets and settle, say, a Saturn distance away, probably off-axis (hiding in-axis may well give shadows etc. that give it away and we likely look at the planets and other things in our axis more than elsewhere) and we'd never spot it. Never. If we did, we'd think it was a rock.
From there, a basic telescope (or a pair of binoculars) would be able to light us up like a Christmas tree, show us to be particularly interesting, and a simple radio antenna would be able to prove that their was life on here, while at the same time being basically invisible to us without even trying.
Any civilisation with a 1km intra-system space-ship capability likely has much better tech than a $200 telescope and a satellite dish connected to a radio scanner, They'd know we were here, and be able to observe us for centuries, long before we ever would know they were there - and we'd probably NOT know they were anything other than a rock.
The distances are too immense, the angles involved far too tiny once you get out past the moon, and there's just too much stuff moving about if you have a sensitive instrument. Hell, we don't even reliably know what everything in EARTH ORBIT is, let alone trying to go out to even a Moon-distance or Mars-distance or Neptune-distance.
Basically, we would never know. The only way to get to the point we would know would be to colonise enough of the solar systems to provide mapping and triangulation of the entire space in-between, And even then, you probably could still hide if you were at all careful.
How did the American Indians detect the Europeans?
I suggest we *not* do that...
Also how did the Poles detect the Mongols?
Let's *not* do that, either...
No, that doesn't make any sense, and I'd like a citation to that theory. Something is stealthed if you don't see it. To not see it requires no more than not looking at it. It is certainly allowable by the laws of physics that we don't look at something.
In fact, to suggest an old theory that says stealth of any kind is impossible not only imagines a theory that doesn't exist, but it violates the very principles of empiricism, thereby undermining the entirety of Physics with every other science to follow.
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Nice try advanced scout party. You slipped through but I doubt the armada will fair as well.
"Sometimes I think the surest sign that intelligent life exists elsewhere in the universe is that none of it has tried to contact us."
Sanity is the trademark of a weak mind. -- Mark Harrold
Life is pretty rare in the Universe Source? I'd be shocked if we didn't find life in the oceans of Jupiter's moons, if we ever bothered to go there.
Direct observation. Anything other than evidence based science is just you daydreaming. Besides, even if life was found elsewhere in this solar system that wouldn't be enough to change the general premise that life is pretty rare in the Universe. When all is said and done, as of 2015, life has only been observed on one planet, in one system, in one galaxy in the entirety of the Universe. You can't even point to evidence of past civilizations. But I guess it's only been 14 billion years give or take. Give them some time. They'll show. In all honesty though, if life was as common as you assert then shouldn't we see colonies and ships by now? It'd only take 1 civilization to decide to colonize our galaxy. Mathematically, they could have done it in 50 million years without FTL travel. So where are they?
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be glad that they're invading when they should simply destroy the entire solar system instead
If these aliens were intent on destroying us, they'd simply drop something large, fast and nasty into the sun and cause some sort of X-Ray eruption. Since there is a massive nuclear reactor so close, it would be silly not to leverage that to your goals. No need for ships or an invading force.
So we can assume that if aliens did arrive here, our destruction would not be their goal. They might, for example, just be neighbours popping over to ask politely if we'd mind turning down our electromagnetic emissions: TV, radar, etc.
If domination / subjugation / removal of humans to make way for their own settlers was their intent, then there's no reason to expect it would have to be done quickly. It could be a centuries long process. And, again, climate control or sunlight restriction would be a straightforward approach that would cause little permanent damage and wouldn't involve their actual presence in our system.
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Any race advanced enough to travel here to invade will have capabilities way beyond anything we could hope to combat or detect. I would imagine the first sign you would have would be if you were one of the lucky ones to see half the world wiped out a few seconds before you yourself were removed from this mortal realm.
Well, I think when they start posting on slashdot asking about the possibility of detection, that's a pretty good first sign.