  The development of civilisations like ours into spacefaring, multi-planet
entities requires significant raw materials to construct vehicles and habitats.
Interplanetary debris, including asteroids and comets, may provide such a
source of raw materials. In this article we present the hypothesis that
extraterrestrial intelligences (ETIs) engaged in asteroid mining may be
detectable from Earth. Considering the detected disc of debris around Vega as a
template, we explore the observational signatures of targeted asteroid mining
(TAM), such as unexplained deficits in chemical species, changes in the size
distribution of debris and other thermal signatures which may be detectable in
the spectral energy distribution (SED) of a debris disc. We find that
individual observational signatures of asteroid mining can be explained by
natural phenomena, and as such they cannot provide conclusive detections of
ETIs. But, it may be the case that several signatures appearing in the same
system will prove harder to model without extraterrestrial involvement.
Therefore signatures of TAM are not detections of ETI in their own right, but
as part of "piggy-back" studies carried out in tandem with conventional debris
disc research, they could provide a means of identifying unusual candidate
systems for further study using other SETI techniques.
