In the pilot episode, a team of Zero-X astronauts investigate the surface of Mars in 2068 after unidentified radio signals emanating from the planet are detected on Earth. The source is discovered to be an extraterrestrial base, which is attacked and destroyed when the explorers mistake a harmless sensor device for a weapon. The inhabitants of the settlement, the Mysterons, are sentient computers that form a collective consciousness. They are the remnants of the original Mysteron race, extraterrestrial life forms that originated in a galaxy other than the Milky Way and maintained their colony on Mars for 3,500 years before abandoning the planet at the turn of the 20th century. Possessing partial control over matter, the Mysteron computers draw on their power of "reversing matter" to rebuild the complex before vowing revenge for the unwarranted aggression. Reversing matter, also described as "retro-metabolism", allows the Mysterons to re-create the likeness of a person or object in the form of a facsimile that is under their control. This ability is used to conduct a "war of nerves" against Earth, in which the Mysterons issue threats against specific targets (from world leaders and military installations to whole cities and continents) and then destroy and reconstruct whatever instruments are required (whether human or machine) to execute their plans. The presence of the Mysterons is indicated by two circles of green light (the "Mysteron rings") that trail across scenes of destruction and reconstruction. Although the Mysterons are able to manipulate events from Mars, their actions on Earth are usually performed by their replicated intermediaries.