The Air Force is set to launch the fourth Global Positioning System (GPS) IIF satellite (GPS IIF-4) tonight between 5:35 p.m. and 5:58 p.m. EDT from Cape Canaveral Air Force Station, Fla.

Boeing’s GPS IIF satellite. Photo: Boeing.

GPS IIF-4 will launch upon one of United Launch Alliance’s (ULA) Atlas V rockets to lift the precision, navigation and timing (PNT) satellite into orbit. The Air Force successfully launched GPS IIF-3 in October, despite a launch anomaly that the service is still investigating. ULA is a joint venture between Lockheed Martin [LMT] and Boeing [BA] to ensure the federal government access to space.

GPS IIF-4 continues the Air Force’s effort to sustain and modernize the GPS constellation and ensure it provides precision PNT services to users around the globe.