Xenoarchaeology is a hypothetical form of archaeology that exists mainly in works of science fiction. The field is concerned with the study of material remains to reconstruct and interpret past life-ways of alien civilizations. Xenoarchaeology is not currently practiced by mainstream archaeologists due to the current lack of any material for the discipline to study.
Xenoarchaeology is sometimes called exoarchaeology, although some would argue that the prefix exo- would be more correctly applied to the study of human activities in a space environment.
Other names for xenoarchaeology, or specialised fields of interest, include Probe SETI (Search for Extra-Terrestrial Intelligence), extraterrestrial archaeology, space archaeology, SETA (Search for Extra-Terrestrial Artifacts), Dysonian SETI, Planetary SETI, SETT (Search for Extra-Terrestrial Technology), SETV (Search for Extra-Terrestrial Visitation), extraterrestrial anthropology, areoarchaeology and selenoarchaeology.
It is arguably the case that, due to the immense distances between stars, any evidence we discover of extraterrestrial intelligence, whether it be an artifact or an electromagnetic signal, may come from a long-vanished civilization. Thus the entire SETI project can be seen as a form of archaeology. Additionally, due to the extreme age of the universe, there may be a reasonable expectation for astrobiology research to produce evidence of extinct alien life prior to the discovery of alien life itself.
Vicky Walsh argued for the existence of "exo-artifacts" using the principle of mediocrity and the Drake equation. She proposed that a theoretical and speculative field of archaeology be established in order to test outlandish claims, and to prepare for a time when undeniably extraterrestrial artifacts needed to be analysed. "If it is possible to construct an abstract archaeology that can be tested and refined on earth and then applied to areas beyond our planet, then the claims for ETI remains on the moon and Mars may really be evaluated in light of established archaeological theory and analysis".
Ben McGee similarly proposed the creation of a set of interdisciplinary, proactive xenoarchaeological guidelines, arguing that identifying suspected artifacts of astrobiology is all that is required to justify establishing a methodology for xenoarchaeology. He emphasized the necessity of proactive xenoarchaeological work in order to avoid future bias, mischaracterization, and information mismanagement, and he cites three scenarios under which such a methodology or set of guidelines would be useful, those being "remote sensing" of a potential xenoarchaeologial artifact, encountering an artifact during "human exploration," and "terrestrial interception" of an artifact.
The origins of the field have been traced to theories about a hypothetical Martian civilization based on observations of what were perceived as canals on Mars. These theories, of which Percival Lowell was the most famous exponent, were apparently inspired by a mistranslation of a quote by Giovanni Schiaparelli.
The 1997 Theoretical Archaeology Group conference featured a session on "archaeology and science fiction".
Planetary SETI is concerned with the search for extraterrestrial structures on the surface of bodies in the Solar System. Claims for evidence of extraterrestrial artifacts can be divided into three groups, the Moon, Mars, and the other planets and their satellites.
Examples of sites of interest include the "bridge" sighted in the Mare Crisium in 1953, and the "Blair Cuspids", "an unusual arrangement of seven spirelike objects of varying heights" at the western edge of the Mare Tranquillitatis, photographed by in Lunar Orbiter 2 on November 20, 1966.  In 2006, Ian Crawford proposed that a search for alien artifacts be conducted on the Moon.
Percival Lowell's mistaken identification of Martian canals was an early attempt to detect and study an alien culture from its supposed physical remains. More recently, there was interest in the supposed Face on Mars.
The Society for Planetary SETI Research is a loose organization of researchers interested in this field. The organization does not endorse any particular conclusions drawn by its members on particular sites.
Probe SETI, or SETA
If so, a solarcentric Search for Extraterrestrial Artifacts (SETA) would seem to be favored over the more traditional radio or optical searches. Robert A. Freitas coined the Term SETA in the 1980s.
On the basis that the Earth-Moon or Sun-Earth libration orbits might constitute convenient parking places for automated extraterrestrial probes, unsuccessful searches were conducted by Freitas and Valdes.
In a 1960 paper, Freeman Dyson proposed the idea of a Dyson sphere, a type of extraterrestrial artifact able to be searched for and studied at interstellar distances. Following that paper, several searches have been conducted.
A subculture of enthusiasts studies purported structures on the Moon or Mars. These controversial "structures" (such as the Face on Mars) are not accepted as more than natural features by most scientists, examples of the pareidolia phenomenon.
Palaeocontact or ancient astronaut theories, espoused by Erich von Däniken and others, are further examples of fringe theories. These claim that the Earth was visited in prehistoric times by extraterrestrial beings.
Xenoarchaeological themes are common in science fiction. Works about the exploration of enigmatic extraterrestrial artifacts have been satirically categorized as Big Dumb Object stories.
Some of the more prominent examples of xenoarchaeological fiction include Arthur C. Clarke's novel Rendezvous with Rama, H. Beam Piper's short story Omnilingual, and Charles Sheffield's Heritage Universe series.
Jack McDevitt's science fiction novels often revolve around human or alien historical and archaeological mysteries.
Mass Effect's plot revolves around technologies in the form of structures, transportation, buildings and machines left behind by an extinct alien race.
The primary setting of Halo: Combat Evolved takes place on a massive structure created by an ancient, extinct alien super race. These structures feature prominently in the sequels Halo 2, Halo 3, and Halo 4.
In the video game "Borderlands", and its sequel "Borderlands 2", the Atlas corporation started mining the planet Pandora after finding evidence of an ancient material called Eridium. This material was supposedly created by extraterrestrial creatures or is a natural product of long-term planetary production.
- Gateway by Fred Pohl
- Noon Universe by Strugatsky brothers.
- 2001: A Space Odyssey by Arthur C. Clarke
- Rendezvous With Rama by Arthur C. Clarke
- Wasteland Of Flint by Thomas Harlan
- House of Reeds by Thomas Harlan
- The Season of Passage by Christopher Pike
- Broken Angels by Richard Morgan
- Strata by Terry Pratchett
- Revelation Space by Alastair Reynolds
- Grass by Sheri S. Tepper
- The Voyage of the Space Beagle by A. E. van Vogt
- The Engines of God by Jack McDevitt
- The Hercules Text by Jack McDevitt
- The novels in the Heritage Universe by Charles Sheffield
- The Past of Forever (Children of the Stars, Book 4) by Juanita Coulson
- Saga of Seven Suns (Most notably Book 1: Hidden Empire) by Kevin J. Anderson
- Heritage Trilogy by Ian Douglas
- Ringworld (and its sequels) by Larry Niven
- The Gaea Trilogy by John Varley
- "Omnilingual" by H. Beam Piper
- "The Sentinel" by Arthur C. Clarke
- "At the Mountains of Madness" by H. P. Lovecraft
- "The Vaults of Yoh-Vombis" by Clark Ashton Smith
Computer and video games
- Sid Meier's Alpha Centauri
- Alien Legacy
- Star Trek: A Final Unity
- RAMA (based on Clarke's novel)
- Wing Commander: Privateer
- The Dig
- Doom 3
- Halo series
- Mass Effect: Mysteries related to an extinct race known as the Protheans figure prominently in the plot and one of the characters you get in your party is a xenoarchaeologist. Also, it's a profitable business, giving rise to various "paleotechnological" companies recovering functioning devices, which are often superior to indigenous technology of the 22nd century.
- Civilization: Call to Power
- Star Wars: Knights of the Old Republic (Although the Star Wars saga doesn't take place in our Galaxy or the human timeframe; the game's main concept is discovering traces of an ancient stellar empire of unknown aliens that existed before the Galactic Republic)
- Aliens vs. Predator
- Aliens versus Predator
- Dead Space
- Metal Fatigue
- Marathon 2: Durandal
- The Lacuna Expanse: There are many buildings that were left behind on hundreds of thousands of planets by a mysterious species known only as "the Great Race".
- Indiana Jones and the Kingdom of the Crystal Skull
- Alien vs. Predator
- Destination: Outer Space features a robot that visited Earth over two thousand years ago.
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