SpaceX will launch a secret Air Force space plane in August

This summer, Elon Musk's private spaceflight company will make its Air Force launch debut, and in a big way.

SpaceX won a contract to launch the Air Force's secret X-37B uncrewed space plane to orbit for another mission in August. This will mark SpaceX's first Falcon 9 launch for the Air Force, and the fifth mission to orbit for the X-37B.

"We are very excited for the next fifth X-37B mission," said Randy Walden, the director of the Air Force Rapid Capabilities Office, said in a statement. "We look forward to continued expansion of the vehicle's performance and are excited to continue hosting experimental payloads for the space community."

It's still not exactly clear what the X-37B does while in space, though it certainly spends a lot of time up there.

The last mission, which came to a close with a surprise landing in May, lasted a total of 718 days, setting a new record for the spacecraft.

The Air Force reportedly has two X-37B space planes, which are built by Boeing, though it's not clear which one with fly to orbit atop a Falcon 9.

The planes are about 29 feet long and 9 feet 6 inches high, weighing in at 11,000 pounds at launch.

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While we may not know the specifics of the X-37B's missions, the Air Force has released some general information about the program.

"The primary objectives of the X-37B are twofold; reusable spacecraft technologies for America’s future in space and operating experiments which can be returned to, and examined, on Earth," the Air Force said in a statement.

SpaceX has been attempting to break into the lucrative Air Force launch market for some time.

The company actually sued the government for a chance to compete with United Launch Alliance -- a joint rocket-building venture of Boeing and Lockheed Martin -- for Air Force launch contracts.

SpaceX settled with the government in 2015, and since then it has won multiple contracts to fly payloads to orbit for various government agencies.

In May, for example, the company launched its first satellite for the National Reconnaissance Office, the arm of the government that keeps U.S. spy satellites up and running.

Like other private space companies, SpaceX sees government contracts as a significant revenue source even as it earns publicity for more daring exploits, such as its goal to send humans to Mars