Observing the Ultrahigh Energy Universe with OWL Eyes
  The goal of the Orbiting Wide-field Light-collectors (OWL) mission is to study the origin and physics of the highest energy particles known in nature, the ultrahigh energy cosmic rays (UHECRs). The OWL mission consists of telescopes with UV sensitive cameras on two satellites operating in tandem to view in stereo the development of the giant particle showers induced in the Earth's atmosphere by UHECRs. This paper discusses the characteristics of the OWL mission. 
F.W. Stecker, J.F. Krizmanic, L.M. Barbier, E. Loh, J.W. Mitchell, P.   Sokolsky, and R.E. Streitmatter