United Launch Alliance’s Delta IV launched a pair of monitoring satellites to be used by the U.S. Air Force’s Geosynchronous Space Situational Awareness Program.
Liftoff came at 12:52 a.m. EDT on Aug. 19 from Cape Canaveral Air Force Station in Florida.
The Delta IV employed two solid rocket boosters to place the relatively heavy monitoring satellites — built by military contractor Orbital ATK of Dulles, Va. — into geosynchronous orbit some 36,000 kilometers above the equator.
The constellation will serve to monitor objects in the belt of space used by the Pentagon for communications and defense satellites.
The launch of two additional GSSAP satellites brings to four the total number now in place and completes the program’s constellation. The first two satellites launched in 2014 and were confirmed as operational last October.
The latest GSSAP launch originally was scheduled for July 21 but was postponed first to Aug. 4 and then another 15 days. The launch — ULA’s seventh this year — marked the Centennial, Colo.-based company’s 110th mission since being formed in 2006 as a joint venture of Boeing and Lockheed Martin.