The Key to Spotting Advanced Alien Life May Be Space Junk
It's no secret humanity has a littering problem, nor is it a particularly recent development, but the problem is growing larger as we increase our travels beyond our home world, and increase the amount of garbage we leave lying around in space.
The problem of space junk is likely to affect humanity more and more over the coming years. While it's unlikely that much of this junk will cause harm to people below, it will make missions to outer space increasingly difficult, and spaceships and stations have to negotiate around a growing mess of man-made debris.
That said, while pondering the issue of our own space junk, scientists have come to an interesting conclusion: If alien species are as prone to littering as we are, then we might be able to use telltale signs of orbital junk as a method of detecting advanced alien life, according to a paper by astrophysicist Hector Socas-Navarro from the Canary Islands Institute of Astrophysics in Spain.
Of course, these aliens would only be visible from their junk if they have the same bad habits as us, and if they develop a space program that's analogous to our own, but if these conditions are met, we might now know exactly what to look for when scanning for distant lifebearing worlds.
In the paper, Socas-Navarro wrote:
This theory ties into a similar suggestion that Socas-Navarro has made previously, surrounding NASA's upcoming TESS (Transiting Exoplanet Survey Satellite) project.
According to Navarro, the TESS could be used to spot alien worlds that show off what's known as a Clarke exobelt; a layer of artificial satellites created by sentient life forms. This name comes from the science fiction novelist Arthur C Clarke, who suggested in one of his novels that humanity would develop a series of communication satellites, long before this technology was feasible.
The TESS would be able to spot a Clarke exobelt, or alternatively a layer of dust and debris, in orbit around any of the 3,000 exoplanets that are within 100 light years of our own star.
Unfortunately, this doesn't give us a particularly large sample, so if life is as uncommon in the galaxy as it appears to be, we might not be able to see much from any of these planets. Our efforts will also be dependent on these planets' native species having developed a Clarke exobelt or a whole load of space junk earlier than a hundred years ago, considering how long it takes light to travel to our world so that we're actually able to see these planets.
Nevertheless, while this is a longshot, the search for space junk would certainly give us an easy indicator of whether life exists on a foreign world close by, and whether these life forms are approximately as technologically advanced as we are.
Similarly, our own space junk will eventually make us visible to other advanced, stargazing aliens - although it might take a while for news to reach them, as light travels from our own star out into the cosmos.