Opportunity Lost in Searching for Technosignatures

Abstract

The sensitivity of radio technosignature searches has improved dramatically over the last five decades; however, as the RFI environment from which these searches are conducted has become increasingly polluted, our advancements in telescope sensitivity have not necessarily been complemented by less ambiguous technosignature searches. In this work, we investigate the resulting loss of opportunity to conduct unambiguous technosignature searches from Earth. We introduce three new concepts, \textsf{opportunity lost}, \textsf{volume lost}, and \textsf{self-censorship}, to quantify the impact of orbiting RFI sources on Earth-based technosignature searches. Using publicly available orbital data between 2008 and 2025, we find an approximately two-fold increase in the spatial occupancy of satellites within representative telescope beams, with the exact magnitude of the loss strongly dependent on telescope pointing. We further demonstrate that the cumulative effect of faint emission from multiple satellites increase the effective system temperature and consequently reduce the volume over which a technosignature of a given intrinsic power can be detected. Using approximately 10,000 archival observations from the Murchison Widefield Array spanning 2014--2024, we find suggestive evidence for increasing RFI occupancy across most of the frequencies observed by the MWA. While other opportunities for terrestrial technosignature searches exist, we argue for the protection and utilisation of uniquely radio-quiet environments such as the lunar farside, which offers an opportunity to regain the ability to perform unambiguous technosignature searches that is being progressively lost on Earth.