Possible Photometric Signatures of Moderately Advanced Civilizations: The Clarke Exobelt

TL;DR

This paper proposes a new method to detect moderately advanced extraterrestrial civilizations by observing the light curve signatures of their potential geostationary satellite belts, called Clarke exobelts, around exoplanets.

Contribution

It introduces the concept of Clarke exobelts as an indicator of extraterrestrial civilizations and demonstrates their detectability through numerical simulations of light curves.

Findings

Clarke exobelts with opacity ~1E-4 are detectable with current instruments.

Light curve analysis can distinguish Clarke exobelts from natural rings.

Numerical simulations support the feasibility of this detection method.

Abstract

This paper puts forward a possible new indicator for the presence of moderately advanced civilizations on transiting exoplanets. The idea is to examine the region of space around a planet where potential geostationary or geosynchronous satellites would orbit (herafter, the Clarke exobelt). Civilizations with a high density of devices and/or space junk in that region, but otherwise similar to ours in terms of space technology (our working definition of "moderately advanced"), may leave a noticeable imprint on the light curve of the parent star. The main contribution to such signature comes from the exobelt edge, where its opacity is maximum due to geometrical projection. Numerical simulations have been conducted for a variety of possible scenarios. In some cases, a Clarke exobelt with a fractional face-on opacity of ~1E-4 would be easily observable with existing instrumentation. Simulations of Clarke exobelts and natural rings are used to quantify how they can be distinguished by their light curve.