Featured image: The Air Force X-37B space plane (Boeing)

Back in May, the Air Force’s classified X-37B space plane touched down at Kennedy Space Center’s former Space Shuttle Landing Facility after a two-year mission. On Thursday, the mini fixed-wing spacecraft will be launched to orbit again atop a SpaceX Falcon 9 rocket.

Liftoff is scheduled for Thursday from the historic Launch Complex 39A on Florida’s space coast and SpaceX plans to recover the Falcon 9 booster on ground after delivering the X-37B to a preliminary orbit. Due to the classified nature of this mission, the launch window is still unknown.

This will be the 4th launch of the military’s secret space plane which is manufactured by Boeing’s Phantom Works program.

The Air Force previously contracted SpaceX competitor United Launch Alliance to launch the X-37B on its Atlas V rocket. The news of the change in launch providers came from Air Force Secretary Heather Wilson back in June. “SpaceX will be sending the next Air Force payload up into space in August,” said Wilson according to Reuters. “The X-37B will be going up again on top of a SpaceX launcher.”

A few minor delays pushed the launch into September. The launch contract is a result of SpaceX winning a legal case in 2015 to compete against veteran national security launch providers ULA in order to bid on military contracts. United Launch Alliance is a joint venture between Lockheed Martin and Boeing.

The X-37B is a reusable vehicle that can be launched vertically and land on a runway. The spacecraft’s cargo area has the same amount of space as a large pickup truck bed. Payloads are never revealed to the public. The space plane is 30 feet in length, about 10 feet in height with a wingspan of 15 feet. X-37B weighs over 11,000 pounds. The spacecraft has already spent a total of 2,085 days in low-Earth orbit.

On May 07, when the X-37B made its first touchdown in Florida (previous landings have been at Edwards Air Force base in California) it broke its own spaceflight time record with 718 days in orbit. The Air Force has decided to now facilitate both launches and landings at Kennedy Space Center––where an old Space Shuttle hangar is being used to refurbish the X-37B.

The encapsulated X-37B space plane before being mated to the SpaceX Falcon 9 (Boeing)

According to the Air Force, the X-37B Orbital Test Vehicle “is an experimental test program to demonstrate technologies for a reliable, reusable, unmanned space test platform for the U.S. Air Force. 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.”

Some of those experimental technologies include avionics, state-of-the-art guidance and navigation systems, thermal spacecraft protection for atmospheric re-entry, propulsion systems, and autonomous flight capability. “The X-37B is the first vehicle since NASA’s Shuttle Orbiter with the ability to return experiments to Earth for further inspection and analysis,” said the Air Force. “But with an on-orbit time of 270 days or greater, the X-37B can stay in space for much longer.”

“This mission carries small satellite ride shares and will demonstrate greater opportunities for rapid space access and on-orbit testing of emerging space technologies,” said a statement from the Air Force.

“Building upon the fourth mission and previous collaboration with experiment partners, this mission will host the Air Force Research Laboratory Advanced Structurally Embedded Thermal Spreader payload to test experimental electronics and oscillating heat pipe technologies in the long duration space environment.”

The X-37B is expected to come back to Earth at some point in 2019 and will mark the end of its secret mission with a startling sonic boom.

Featured image: The Air Force X-37B space plane (Boeing)

Robin Seemangal is a Space Reporter, with a focus on NASA and advocacy for space exploration for the New York Observer. He’s also written for Popular Science and Wired Magazine. He was born and raised in Brooklyn, where he currently resides. You can find him on Twitter and Instagram.