  Glints of light from specular reflection of the Sun are a technosignature of
artificial satellites. If extraterrestrial intelligences have left artifacts in
the Solar System, these may include flat mirror-like surfaces that also can
glint. I describe the characteristics of the resulting flashes. An
interplanetary mirror will appear illuminated for several hours, but if it is
rotating, its glint may appear as a train of optical pulses. The resulting
glints can be very bright, but they will be seen only if the mirror happens to
reflect sunlight to the Earth. The detection of large mirrors is limited mainly
by the fraction oriented to reflect sunlight toward Earth. I give rough
calculations for the expected reach of each exposure of Pan-STARRS1, LSST, and
Evryscope for mirror glints. A single exposure of Pan-STARRS1 has an effective
reach of 10^-9 - 10^-7 AU^3 for interplanetary mirrors with effective areas of
10 m^2, depending on rotation rate. Over several years, Pan-STARRS1 might
accumulate a reach ~10^5 times greater than this, as it tiles the sky and
different mirrors enter and exit a favorable geometry.
