WASHINGTON — The U.S. Air Force awarded Boeing a $152 million contract modification June 18 to continue supporting one of the service’s primary space surveillance satellites.

Under the contract, announced June 19 on the Federal Business Opportunities website, Boeing will sustain and support the Space Based Space Surveillance (SBSS) Block 10 satellite for as many as seven years. The SBSS Block 10, built by Boeing Space and Intelligence Systems of El Segundo, California, was launched in 2010 and became operational in 2013.

The satellite watches the geostationary orbit arc 36,000 kilometers above the equator, where most military and civil communication satellites are stationed.

Space situational awareness has become a top priority for Air Force Space Command. U.S. defense and intelligence officials have said U.S. satellites are facing growing threats from China and Russia.

The Air Force intends to build additional space surveillance satellites for greater coverage and has budgeted $365 million for a SBSS follow on program for 2016-2019, with a launch expected in the early 2020s.

Jonathan Charlton is a SpaceNews.com editorial intern who has been logging a bunch of solo hours at the controls of Aviation.com. The Boston College senior is majoring in political science with a minor in hispanic studies.