The most observable leakage radiation from an advanced civilization may well be from the use of power beaming to transfer energy and accelerate spacecraft. Applications suggested for power beaming involve Earth–to-space applications such as launching spacecraft to orbit, raising satellites to a higher orbit, and interplanetary concepts involving space–to–space transfers of cargo or passengers. We also quantify beam-driven launch to the outer solar system, interstellar precursors and ultimately starships. We estimate the principal observable parameters of power beaming leakage. Such beams would be visible over large interstellar distances. This implies a new approach to the SETI search: Instead of focusing on narrowband beacon transmissions generated by another civilization, look for more powerful beams with much wider bandwidth This requires a new approach for their discovery by telescopes on Earth. Further studies of power beaming applications should be done, which could broaden the parameter space of observable features we have discussed here. By observing leakage from power beams we may well find a message embedded on the beam.

The ultimate technosignature is an alien artifact. We should look for them near Earth. The great virtue of searching for artifacts is their lingering endurance in space, long after they go dead. I compare a Search for Extraterrestrial Artifacts (SETA) strategy of exploring near Earth for alien artifacts to the existing listening-to-stars SETI strategy. Stars come very close to Earth frequently. About two stars per million years come within a light year. An extraterrestrial civilization that passes nearby can see there’s an ecosystem here, due to the out-of-equilibrium atmosphere. They could send interstellar probes to investigate. The Moon and the Earth Trojans have the greatest probability of a successful search by us, ET archeology. I suggest resources devoted to imaging of our Moon’s surface, the Earth Trojans and Earth co-orbitals, and for probe missions to the latter two. The SETA concept can be falsified: if we investigate these near-Earth objects and don’t find artifacts, the concept is disproven for this region. Close inspection of bodies in these regions, which may hold primordial remnants of our early solar system, yields concrete astronomical research.