The Wikipedia page linked in @OrganicMarble's answer about the Air Force Space and Missile Museum contains the image below, of a (now retired) GPS monitoring station. To the right of the station itself is a sign that says
Monitor Station GPS Antenna 1984-2007
On Time, On Target
and shows three different emblems, each with a motto or other words on it.
Does anyone recognize these three symbols or can guess what organizations they are associated with?