Is ET Lurking in Our Cosmic Backyard?

Author: James Benford

Description: I argue that a strategy of exploring for alien artifacts near Earth is a credible alternate approach relative to the existing listening-to-stars SETI strategyStars come very close to our solar system frequently. About two stars per million years come within a light year. An extraterrestrial civilization that passes nearby can see there is an ecosystem here, due to the out-of-equilibrium atmosphere. They could send interstellar probes to investigate. I estimate how many probes could have come here from passing stars. And where could we find them now? The Moon and the Earth Trojans have the greatest probability of success. Close inspection of bodies in these regions, which may hold primordial remnants of our early solar system, yields concrete astronomical research. I suggest additional resources devoted to imaging of our Moon’s surface, the Earth Trojans and Earth co-orbitals, and for probe missions to the latter two. The Search for Extraterrestrial Artifacts (SETA) concept can be falsified: if we investigate these near-Earth objects and don’t find artifacts, the concept is disproven for this nearby region. I construct a ratio of a Drake Equation for alien artifacts to the conventional Drake Equation, so that most terms cancel out. This ratio is a good way to debate the efficacy of SETI vs. SETA. The ratio is the product of two terms: One is the ratio of the time Lurkers could be present in the solar system to the length of time extraterrestrial (ET) civilizations transmit electromagnetic signals. The second term is the ratio of the respective ‘origin volumes’: the volume from which Lurkers can come (which is affected by the long-term passage of stars nearby) to the volume of transmitting civilizations. This Drake Equation logic argues for emphasis on artifact searches, a strategy of ET archaeology.