The Search for Extraterrestrial Intelligence (SETI) has a low probability of success, but it
would have a high impact if successful. Therefore it makes sense to widen the search as
much as possible within the confines of the modest budget and limited resources
currently available. To date, SETI has been dominated by the paradigm of seeking
deliberately beamed radio messages.
However, indirect evidence for extraterrestrial intelligence could come from any
incontrovertible signatures of non-human technology. Existing searchable databases
from astronomy, biology, earth and planetary sciences all offer low-cost opportunities
to seek a footprint of extraterrestrial technology. In this paper we take as a case study
one particular new and rapidly-expanding database: the photographic mapping of the
Moon’s surface by the Lunar Reconnaissance Orbiter (LRO) to 0.5 m resolution.
Although there is only a tiny probability that alien technology would have left traces
on the moon in the form of an artifact or surface modification of lunar features, this
location has the virtue of being close, and of preserving traces for an immense duration.
Systematic scrutiny of the LRO photographic images is being routinely conducted
anyway for planetary science purposes, and this program could readily be expanded
and outsourced at little extra cost to accommodate SETI goals, after the fashion of the
SETI@home and Galaxy Zoo projects.