One somewhat neglected until recently potential area for SETI searches was within the solar
system itself.
Much more favored has been searching the various sun-like stars in the Sun’s local area,
within about 100 light years.
This is mainly because the further out you go, in general the fainter the signal is likely
to be unless someone is really putting some massive energy into their beacon.
One problem with searching for radio signals in the solar system except by way of randomly
studying more distant stars is simply because you’d have to know exactly where to look
in targeted SETI searches, but also because any probe that might be transmitting back
to its place of origin almost certainly would not be pointing in the direction of earth.
That said, the idea of very close SETI targets has always been part of the alien life debate.
And the possibilities are far reaching.
It’s always been seen that interstellar space travel for biological beings is unfeasible
without essentially building mobile generational ships more like worlds in themselves to cross
the distance, perhaps containing miles of infrastructure and function as fully self-contained
megacities plying the fast ocean of space.
That could happen, but it seems unlikely anyone would do that, or ever has visited our star
system in that way.
What doesn’t seem likely is magic or Clarketech where the aliens have faster than light travel.
That’s a conjecture used all too often in science fiction to get past the barrier speed
limit that reality presents, but absolutely nothing in science points to it being possible.
On the contrary.
Not only do we have anything but a few very speculative ways to start thinking about faster
than light travel, any method of doing so requires exotic forms of matter we don't know
are actually possible, but there also doesn’t seem to be a physical framework that’s going
to allow for FTL in the universe.
Or if you will you can think about building a car and you might imagine how one might
be used, but you live on an ocean planet that has no land in which to build roads.
But accounting for the difficulties of biological life crossing between the stars, and the bottom
line that you’re confined to slower than light speeds, none of this applies to a machine.
Machines can be constructed to be robust and self-repairing, almost to the point of at
least functional immortality, using the raw materials in the universe.
As such, machines might not care about relativistic time dilation, or the passage of time.
Rather, an easy to imagine scenario is that someone somewhere in the galaxy noticed earth’s
odd oxygen and methane levels at some point in the last few billion years, sent a probe
out at say 1 percent the speed of light, and now maintains a silent presence in the solar
system to study our world.
It’s also possible that the solar system is littered with past and functioning probes
from many different civilizations in the galaxy.
It’s very unlikely however that we would ever detect one of these.
They would be needles in a haystack times ten, the solar system is enormous.
Except however in a few specific instances.
And they’re all a bit spooky.
The first is the notion of a sleeping communications probe.
In the 1960’s Ronald Bracewell envisioned that alien civilizations may not choose to
send radio signals from their home planets, but rather conclude that it’s more efficient,
and hides the location of your home world, better if you send the transmitter to the
star system you wish to communicate.
They may not know that there is a civilization here, but they might conclude from evidence
of our biosphere that it’s worth a shot to station a dormant probe in the solar system
just in case anyone ever arises on earth worth talking to.
As a result such a dormant probe might wake up periodically and take a look at earth and
record what’s going on.
Or it may simply remain dormant until we attempt to communicate with it by sending out signals
that it would recognize.
It might send a message of its own, or it might simply send our own signal back to us
in an altered way not possible in nature.
Weirdly, there is a candidate for this in the form of long delayed echoes in radio,
where you get an echo of your signal seconds after, which is somewhat of a tall order for
earth’s ionosphere to cause, though it does create shorter echoes in radio.
Other variants include von Neumann self-replicating probes and Benford probes deposited opportunistically
during stellar close encounters.
There are ideas that fully conform to the laws of physics that provide a fully plausible
way for an alien civilization to maintain a presence in the solar system.
But it’s the needle in a haystack problem, where do you look for such probes.
There are several things that could be done.
One is to look for defunct technology that’s been captured as it passed through as interstellar
objects.
The object Oumuamua for example exhibited behaviors that put it on the list of candidates
for just such a technology.
But there are also places where Jupiter can capture and collect interstellar objects conveniently
where you can search for anything artificial.
Indeed this is one of the aspects the Galileo Project is looking into pursuing.
But within the history of astrobiology and SETI there is one signature that isn’t often
mentioned.
If you presume that an alien civilization would send a probe, it’s going to need an
energy source.
The most logical energy source we can envision would be a probe powered by a fusion reactor,
and that may make a detectable technosignature if its active in your star system.
It’s tritium as a by-product of hydrogen fusion.
Tritium is rare in nature, and it only has a half life of just over 12 years.
So if a probe is giving it out as exhaust, it would imply that the probe is active.
Tritium in space is detectable, it emits radio at the frequency of 1516.701 megahertz.
In the 1980’s Valdez and Freitas looked in radio for tritium in some nearby star systems,
but found nothing, but no search for nearby tritium in space has been conducted.
If this is ever detected it would give at least a general area of where the location
the probe could be, and a strong indicator that an artificial probe is present in the
solar system.
It would almost be a smoking gun.
Another obvious place to look for evidence of alien probes intended to study earth is
in orbit.
This is rather difficult because right now we are in the process of filling orbit with
objects of human origin, both functioning and dead.
How do you tell the difference between something that acts just like a human satellite and
a human satellite?
The answer is that the world’s militaries know, because they track space junk very carefully.
So far, no one has reported the detection of an alien probe.
But would they all classify it if they found it.
Of course there are rumors about something having been detected.
I often get comments about the so-called black knight satellite, but that story is really
a myth that has built up on the internet over recent years.
In other words it’s an urban legend, and the infamous picture of it is a known photograph
of a shuttle era thermal blanket lost on the STS-88 mission.
But there are two other possibilities, one good and the other not so good.
The not so good one first.
In the 1950’s Major Donald Keyhoe reported that the US government had indeed detected
two objects of unknown origin in orbit of earth in the early days of the space age.
Nothing further about this claim has ever surfaced and Keyhoe died in 1988.
In short, this one can only be called a rumor from a single source we aren’t likely to
ever hear anymore about.
The second is much better.
This involves research being done by the VASCO project into transients captured in astronomical
photographic plates taken before the first satellites were launched, which started in
1957 with Sputnik.
Odd factoid about Sputnik, it reentered the earth’s atmosphere and burned up in 1958.
It was a huge success for the Soviet Union, but oddly there was nothing left of it to
put into a museum.
Except one piece.
An arming key that prevented contact between the satellites batteries and transmitter was
pulled out at the last minute before launch to activate the transmitter.
This key has survived, but sits in a rather unlikely place.
You’d think it would be somewhere in the former soviet union, but it now resides at
the Smithsonian in Washington DC.
I’d love to know the story of how that came about, so if anyone knows, tell me in the
comments below.
The search for transients and potential satellite tracks is ongoing and expanding with a new
project known as EXOPROBE which aims to use a network of earth based telescopes to search
for non-human objects near or in orbit of earth, but VASCO so far has already found
a surprising number of candidates and they do not appear to have been artifacts or defects
in the plates.
Some even appear to be the same object crossing the plate changing brightness during the exposure.
Lastly of course is searching the earth's atmosphere itself.
This has led to somewhat of a disparity due to a stigma.
This would by its nature be a UFO, and until recently remained a subject mostly tabooed
in science.
The reality however is that SETI at large has not shied away from the idea of von Neumann
probes and things that might be in the solar system.
Indeed, one possible explanation for the Wow!
Signal, SETI's most famous candidate, was that it originated within the solar system.
But it can’t have been from low earth orbit, as the signal fit the antenna pattern of the
telescope, which means it had to originate further than half the distance to the moon.
Humans had very little out there at that time.
It also appeared as a fixed point in the sky, further suggesting it was not close and was
not moving in any way similar to a satellite.
But one really puzzling aspect of it was that it was extremely strong, over 30 times the
background, and was the strongest unidentified signal the big ear telescope ever picked up
in its decades of operation.
That could mean a lot of things, but one is that it was simply close.
Another oddity was that it appeared to have a very slight blue shift, as though it were
very slowly traveling in our direction, though slower than some of our own probes move.
But the point is, the moment you mention anything in the atmosphere, out comes the stigma which
has thankfully been lessening of late.
But this was in the face of a hard bottom line, the moment you say von Neumann probe,
you are in close alien territory, and there is little fundamental difference between that
and a UFO of alien origin.
They are effectively the same thing.
You can’t say we’ll ponder ideas of Bracewell probes, but then leave those same probes off
the table if they dip into the atmosphere.
The big question is however if we did find actual evidence of an alien presence in the
solar system.
If it’s inactive junk, we’d have to ask the question of where’s it from.
After all, even if a close piece of alien technology were found, that’s a bad thing,
because then you run up against the Silurian hypothesis and past civilization on earth
we have no geologic record of.
And if we could determine it was truly of alien origin, then where did it come from?
if still active, we’d have to ask why it didn't announce itself.
Why is it studying us?
Why is it here?
Truth is, It would be under no obligation to ever tell us.
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently wondering what we’d
do if the von Neumann probe didn’t answer if we asked what it was doing.
We’d need a police force and a loitering ticket program in space to deal with unsavory
alien probes.
Not sure how I feel about that, imagine if an alien lawyer shows up and it would just
be a big fat legal mess and be sure to check out my books at your favorite online book
retailer and subscribe to my channels for regular, in-depth explorations into the interesting,
weird and unknown aspects of this amazing universe in which we live.