Shh. Did you hear that? You may not have, but one SETI (Search for Extraterrestrial Intelligence) scientist believes it’s possible an eavesdropping alien did … using listening gear secretly placed on a space rock that is in the same orbit around the Sun that Earth occupies. How did that happen? Should we be worried? Should we ask them for help? Should we speak louder?
“A recently discovered group of nearby co-orbital objects is an attractive location for extraterrestrial intelligence (ETI) to locate a probe to observe Earth while not being easily seen. These near-Earth objects provide an ideal way to watch our world from a secure natural object. That provides resources an ETI might need: materials, a firm anchor, and concealment.”
James Benford,a physicist and independent SETI (Search for Extraterrestrial Intelligence) researcher, told LiveScience he got the bug about ET bugs last year and it bugged him until he came up with the idea that co-orbitals might be a great place for aliens to send spaceships to plant solar-powered listening devices to spy on us. He expands on the theory in his paper published recently in The Astronomical Journal. Co-orbitals are asteroids or space rocks inhabiting roughly the same orbit as a planet – orbiting the Sun rather than the planet. The first Earth co-orbital found is 3753 Cruithne, discovered in 1986 in a photo taken in 1983. Its co-orbit wasn’t confirmed until 1997 and since then about 15 others have been identified. While occupying the same orbital space, their actual paths can vary -- 3753 Cruithne has a bean-shaped orbit while others are more like closed horseshoes. The closest one, 2016 HO3, is 38 times as far away from Earth as the moon. However, that seems to be close enough for Benford’s alien eavesdropping theory.
In “Looking for Lurkers: Co-orbiters as SETI Observables,” Benford proposes that an advanced civilization on a nearby star could have send robotic probes to the most likely planet in our star’s “Goldilocks zone” (or whatever they might call it), but rather than violating their version of the ‘prime directive’, they positioned the lurkers on co-orbitals where they could listen and replenish their power from the star or from mining the asteroid. While they may have arrived millions of years ago and only picked up the moans of dying bacteria, eventually humans arrived to make enough noise to convince the lurkers that Earth finally contains intelligent (at least according to some definitions) life.
It’s an interesting theory and certainly fits in with the Fermi Paradox – there has been no alien contact and we can’t detect them because they’re just quietly listening in. However, we may be able to find them or prove Benford wrong soon. China’s space program announced it will send a probe to 2016 HO3 in 2022 which will land, collect samples and send them back to Earth on a separate ship before continuing on to another asteroid. Since 2016 HO3 is so small (41 meters in diameter), Benford thinks there’s a good chance it could find evidence of a lurker from one of the many stars that have occasionally been less than a light year away from ours. If it were up to him, Benford might want to try communicating with them first using "Benford Beacons" – targeted short bursts of broadband signals in the 1-to-10-gigahertz range. Since they already know we’re here, this shouldn’t surprise the lurkers but may signal that we’re ready for contact.
Or maybe the beacons will act like a microwave dinger signalling we're done cooking and ready to be eaten.
Is that really a good idea? Who knows? Are there really lurkers listening to us on Earth’s co-orbitals? Who knows? If they can pick up the Internet and read this, maybe we’ll find out.