Now, a team of scientists suggests that Earth should look out for similar probes in orbit around our planet — or at least what’s left of them. A recent study on the preprint server arXiv suggests looking for space debris leftover by alien probes sent to visit Earth.
The GEOs is an Earth-centered orbit that мคtches the planet’s rotation on its axis. It’s a low orbit around Earth, with a period of about 23 hours and 56 minutes.
The team of researchers behind the new study suggests that an advanced alien civilization мคy have sent over a space probe to observe the Earth within the past 100,000 years or so.
SETI (Search for ExtraTerrestrial Intelligence) is a series of interrelated programs looking for intelligent life beyond our solar system by scanning the skies for radio signals or technosignatures — signals emitted by any sort of technology from an alien civilization.
On September 5, 1977, the Voyager 1 space probe launched into space. As the mission was bound out of the Solar System, NASA packed Voyager 1 (and its companion, Voyager 2) with a golden phonographic record that contained sounds and sights from Earth that displayed the diversity of life on our planet.
The record included the sounds of birds and other animals, wind and thunder, greetings said in 55 different languages, a survey of music from Earth, a picture of street traffic in Thailand, and a woman breastfeeding, among different displays of human society.
Some of these alien probes мคy have remained in high-altitude orbits around Earth, หคмely the geosynchronous Earth orbits (GEOs).
Once the probe stops operating, it would dis¡หтεgяคтε into space debris. However, those pieces of debris can remain in orbit for м¡łł¡σหร of years before being crushed into tiny fragments by any future collisions.
If the light from the Sun hits those pieces of debris, they will give off a fast, transient glint. When the reflective surface of the alien space junk lines up with the Sun from the observer’s perspective, telescopes could observe this short-lived glint.
The authors of the recent study suggest the VASCO project would be ideal for this search. Because it contains archival images that predate 1957, when the first space probe, Sputnik, was launched into space. These images of the sky will be free of any space debris that came from human civilization.
Instead, any artificial debris detected pre-1957 might be leftover from an alien spacecraft that visited Earth in the past.