One of the open questions of astrobiology is whether there is extant or extinct life elsewhere the Solar System. Astronomer Jason Wright at Penn State says that we are looking for microbial or, at best, unintelligent life, even though technological artifacts might be much easier to find. Searches for alien artifacts in the Solar System typically presumes that the origins such artifacts would be from beyond our Solar System, even though life is known to have existed in the Solar System, on Earth, for eons.

But if a prior technological, perhaps spacefaring, species ever arose in the Solar System, it might have produced artifacts or other technosignatures that have survived to present day.

The origins and possible locations for technosignatures of such a prior indigenous technological species might have arisen on ancient Earth or another body, such as a pre-greenhouse Venus (image shown above NASA’s Pioneer Venus Orbiter took this false color image of Venus’ clouds ) or a wet Mars. In the case of Venus, the arrival of its global greenhouse and potential resurfacing might have erased all evidence of its existence on the Venusian surface. In the case of Earth, erosion and, ultimately, plate tectonics may have erased most such evidence if the species lived a Gyr, a billion years, ago…