  The formation of satellites is thought to be a natural by-product of planet
formation in our Solar System, and thus, moons of extrasolar planets (exomoons)
may be abundant in extrasolar planetary systems, as well. Exomoons have yet to
be discovered. However, moons larger than 0.1 Earth masses can be detected and
characterized using current transit techniques. Here, we show that collisions
between rocky planets with masses between a quarter to ten Earth masses can
create impact-generated debris disks that could accrete into moons. Collisions
between like-sized objects, at oblique impact angles, and velocities near
escape speed create disks massive enough to form satellites that are
dynamically stable against planetary tides. Impacts of this type onto a
superearth between 2 to 7 Earth masses can launch into orbit enough mass to
create a satellite large enough to be detected in Kepler transit data. Impact
velocity is a crucial controlling factor on disk mass, which has been
overlooked in all prior studies of moon formation via planetary collision.
