The most profound question asked by mankind is: are we alone? So the second most profound question must be: where should we look for life if we're not alone?
Now, two prominent scientists have published a paper suggesting that although we have an entire universe to seek out the proverbial alien needle in a haystack, perhaps looking in our own backyard would be a good place to start.
Paul Davies and Robert Wagner of Arizona State University have suggested a crowd-sourcing effort to find artificial structures on the moon. After all, lunar missions like NASA's Lunar Reconnaissance Orbiter are returning some dazzling, high-resolution imagery of the moon's surface. If aliens have been there, perhaps we could spot evidence of their presence.
"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," Davies and Wagner say in their paper published in the journal Acta Astronautica (doi:10.1016/j.actaastro.2011.10.022).
Indeed, due to the moon's pristine environment, any modification of lunar surface features will remain preserved for eons - the lack of an atmosphere means features are not eroded away. Unless intelligent aliens came, saw and then covered their tracks, perhaps they left something as basic as a footprint for us to find.
Alien-hunting programs like the Search for Extraterrestrial Intelligence (SETI) have primarily focused on looking for alien transmissions being beamed around the universe, but the probability of success is extremely low. Other methods of alien hunting are therefore being considered and the moon has just become the logical "intelligent alien hunting ground."
If these hypothetical aliens are advanced enough to traverse the vast distances between the stars, and if they decided to pay the Earth-moon system a visit over the past few million years, they may have used the lunar surface as an ideal observation post. Logical, right?.
The idea that some kind of alien artifact may have been left behind then makes sense. This "artifact" could be a footprint, spacecraft or structure - the LRO can spot the Apollo landers and astronauts' preserved footprints from orbit (pictured top), so it stands to reason that we have the technology to carry out this proposed lunar hunt.
"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," Davies and Wagner point out.
Although the probability for success is low, building a crowd-sourcing effort like the hugely popular SETI@home and Galaxy Zoo projects could be a very efficient and low-cost means to analyze the lunar surface.
Simply distribute images being beamed back from lunar satellites to participating members of the public - using PC idle time (like SETI@Home) or asking for voluntary participation (like Galaxy Zoo) - and see if any strange shapes in the lunar regolith need some follow-up investigation.
With a lot of search time using low cost crowd-sourcing techniques could result in a profound discovery if aliens did decide to camp out on our moon at some point in history. The moon may be keeping a record of their campsite.
Image: The LRO images the Apollo 17 landing site. Astronaut footprints from 1972 are preserved. Credit: NASA's Goddard Space Flight Center/ASU