WASHINGTON — Two high-orbiting U.S. Air Force space surveillance satellites that launched in July 2014 are expected to reach initial operational capability by the end of September, the service said.

In a response to questions from SpaceNews, Capt. Connie Dillon, an Air Force spokeswoman, said the Geosynchronous Space Situational Awareness Program (GSSAP) satellites are going through on-orbit initialization and checkout procedures as well as developmental and operational testing. Air Force Space Command expects to declare initial operational capability by the end of fiscal year 2015, she said in an Aug. 4 email.

Air Force officials publicly disclosed the previously classified space surveillance program in February 2014 and have acknowledged that the satellites would perform rendezvous and proximity maneuvers to allow close-up looks at spacecraft in geosynchronous orbits, some 36,000 kilometers above Earth’s surface.

According to an Air Force fact sheet, the two-satellite system will operate in a “near-geosynchrous orbit regime” to provide accurate tracking and characterization of man-made orbiting objects.  Built by Orbital ATK  of Dulles, Virginia, the GSSAP satellites, are controlled by operators at Schriever Air Force Base in Colorado Springs, Colorado.

Gen. John Hyten, the commander of Air Force Space Command, told SpaceNews in December that the service is taking it very slowly in testing the GSSAP satellites on orbit. “We’re taking a very deliberate approach to checking the satellites out to make sure we understand exactly how they work, exactly how the systems are characterized, exactly what we see and understand,” he said.

Experts have said the satellites must show “unprecedented” maneuvering accuracy given their potential to cause damage in a heavily used belt of Earth orbit, according to a professional journal published by the service.

Two additional GSSAP satellites are notionally scheduled to launch in 2016.

Mike Gruss covers military space issues, including the U.S. Air Force and Missile Defense Agency, for SpaceNews. He is a graduate of Miami University in Oxford, Ohio.