The support services involve the Air Force's Satellite Control Network and Global Positioning System antenna sites.
Harris had earlier won a U.S. Air Force Network and Space Operations and Maintenance contract, which supports the Air Force Space Command's 50th Space Wing, which is responsible for the operation of Department of Defense satellites.
Under the contract modification, Harris and its industry team will continue to support both inbound and outbound data and communications for more than 150 Department of Defense satellites, operating and maintaining the Air Force Space Command Network's antenna and ground system infrastructure at 10 locations worldwide.
The network provides readiness, launch, early orbit/on-orbit support, and anomaly resolution for a variety of satellite constellations.
"The 50th Space Wing plays a vital role in our nation's defense by managing a complex system of satellites," said Harris IT Services President Wayne Lucernoni. "This requires extraordinary technological knowledge and management skill.
"Harris helps ensure that communications and critical data are properly managed. This contract modification expands our support at a reduced cost to the Air Force and U.S. taxpayers."