Looking for Lurkers: Co-orbiters as SETI Observables

Abstract

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, concealment. These have been little studied by astronomy and not at all by SETI or planetary radar observations. I describe these objects found thus far and propose both passive and active observations of them as possible sites for ET probes.A probe located nearby could bide its time while our civilization developed technology that could find it, and, once contacted, could undertake a conversation in

Interstellar Communication Network. I. Overview and Assumptions

“…The postulation of alien probes inside the solar system is interesting, but more is required to narrow down the most likely locations. Generic "Lurkers" have been proposed to be located on nearby co-orbital objects (Steel 1995(Steel , 1998Benford 2019) for surveillance, near the Earthmoon Lagrangian points (Freitas & Valdes 1980;Valdes & Freitas 1983), in geocentric, selenocentric, Earth-Moon libration, and Earth-Moon halo orbits (Freitas 1983), in a tight orbit around the Sun (Gertz 2018), in the asteroid belt (Papagiannis 1978;Forgan & Elvis 2011), the Kuiper belt (Loeb & Turner 2012), on the surface of the moon (Davies & Wagner 2013;Wagner et al 2017), on Earth (Davies 2012) or anywhere in the solar system (Gertz 2016a(Gertz , 2017.…”

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It has recently been suggested in this journal by Benford (2019) that "Lurkers" in the form of interstellar exploration probes could be present in the solar system. Similarly, extraterrestrial intelligence could send long-lived probes to many other stellar systems, to report back science and surveillance.

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SETI: the argument for artefact searches

“…Papagiannis (1978) urged a search for extraterrestrial mining operations in the asteroid belt. More recently, Benford (2019) noted that objects that are co-orbital with Earth would be useful reconnaissance bases for those who have an interest in developments on our planet.…”

Propulsion of Spacecrafts to Relativistic Speeds Using Natural Astrophysical Sources

“…Finally, it has been suggested since the 1960s that searches for probes and artifacts in our Solar system may represent a viable line of enquiry (Bracewell 1960;Sagan 1963). A number of targets have been proposed in this context such as: neighborhood of the Solar gravitational lens (Gillon 2014), Oort cloud and Kuiper belt objects (Gertz 2016), the asteroid belt (Papagiannis 1978(Papagiannis , 1983 (Freitas & Valdes 1980;Valdes & Freitas 1983), co-orbital near-Earth objects (Benford 2019), the upper atmosphere of the Earth (Teodorani 2001;Siraj & Loeb 2020) as well as its surface and subsurface environments (Arkhipov 1996;Davies 2012;Wright 2018b;Schmidt & Frank 2019). What remains unknown, however, is the probability of success for any of the aforementioned strategies, because it ultimately comes down to the question of how many technological species are extant in the Milky Way (Shklovskii & Sagan 1966;Vakoch & Dowd 2015;Cirkovic 2018;Lingam & Loeb 2019c).…”