WASHINGTON — The U.S. Air Force has officially terminated its $2 billion contract with Lockheed Martin to develop the ground segment for the now-defunct Transformational Satellite (T-Sat) communications system, according to a June 8 Defense Department announcement.

U.S. Secretary of Defense Robert Gates terminated T-Sat in the Pentagon’s 2010 budget request, deciding the technology was too risky and its lifecycle cost of some $26 billion was too high. Instead, he directed the Air Force to buy two additional Advanced Extremely High Frequency satellites built by Lockheed Martin Space Systems of Sunnyvale, Calif., which along with Boeing Space and Intelligence Systems of Seal Beach, Calif., was competing to build the T-Sat constellation.

Lockheed Martin Information Systems and Global Services of San Jose, Calif., won the $2.02 billion, 10-year contract for the T-Sat ground segment, called the T-Sat Mission Operations System, in 2006. The company received a $336 million modification to that deal in 2008.

The Pentagon also announced June 8 it has terminated its $20.8 million T-Sat engineering and integration contract with Booz Allen Hamilton Inc. of McLean, Va.