SpaceX defeated the United Launch Alliance, a joint venture between Boeing and Lockheed Martin, who offered to use their Delta 4 rocket to send the military satellites into space.
One reason companies are pitted to compete for contracts from the US government is to keep costs down.
Missile System Center Commander, Lieutenant General Air Force Space, John Thompson said that SpaceX won the contract because they can ensure the government has access to space at an affordable price.
According to SpaceNews, the average shipping cost for Delta 4 reached the US $ 350 million. While heavy loader rockets from NASA have not been made.
By awarding this contract to SpaceX, the US Air Force showed their confidence in the newly launched SpaceX rocket once. Falcon Heavy was first launched in February. Although one of the booster's rockets failed to land, the launch process went smoothly.
"SpaceX is proud of the Air Force's decision to use Falcon Heavy to launch AFSPC-52," SpaceX president and COO Gwynne Shotwell said in an official statement.
"I want to thank the Air Force for its faith in Falcon Heavy, giving this important mission to us and for their trust in our company."