Inside the US Air Force's Top-Secret X-37B Space Plane

Inside the US Air Force's Top-Secret X-37B Space Plane

Inside the US Air Force's Top-Secret X-37B Space Plane


By Wes O’Donnell
Managing Editor, In Space News, In Military and InCyberDefense. Veteran, U.S. Army and Air Force.

The appearance of U.S. Department of Defense (DoD) visual information does not imply or constitute DoD endorsement.

Among the many secretive projects hidden beneath the redacted cover of the black budget, none serve to galvanize the public’s imagination quite as much as the Boeing X-37B space plane.

This orbital test vehicle (OTV) was originally developed by Boeing Aerospace for NASA in 1999. It was transferred to the Defense Advanced Research Projects Agency (DARPA) and the U.S. Air Force in 2004, where it transitioned to a classified project.

OTV-4 stationary at the Shuttle Landing Facility. Courtesy U.S. Air Force.

In a fact sheet, the U.S. Air Force states that this aircraft’s purpose was to test several bleeding-edge technologies, including:

  • Advanced guidance
  • Navigation and control
  • Thermal protection systems
  • Avionics
  • High temperature structures and seals
  • Conformal reusable insulation
  • Lightweight electromechanical flight systems
  • Advanced propulsion systems
  • Advanced materials and autonomous orbital flight, reentry and landing

Indeed, Spaceflight Now confirmed in 2015 that one of the primary missions of the X-37B that year was the test of experimental Hall thrusters, a propulsion system that uses electricity and xenon to produce thrust for maneuvering satellites in space.

X-37B: The Ultimate Unmanned Aerial Vehicle

The X-37B Orbital Test Vehicle (OTV) is a reusable, robotic spaceplane that can be controlled from the ground. After receiving the command from controllers, the X-37B lands automatically.

OTV-4, the fourth mission of the X-37B, stayed in space a staggering 717 days. It broke the program’s previous record for OTV-3, which stayed aloft for 674 days.

Previously, the first four missions of the X-37B were launched on Atlas V 501 rockets. But in September of 2017, the latest orbital test vehicle (OTV-5) was launched into space orbit by a SpaceX Falcon 9 rocket. That mission is still ongoing; the current X-37B has been in orbit for 668 days.

The sixth X-37B mission, OTV-6, is planned to fly on an Atlas V 501 rocket in December 2019.

General Characteristics of the X-37B

Primary Mission: Experimental test vehicle
Prime Contractor: Boeing
Height: 9 feet, 6 inches (2.9 meters)
Length: 29 feet, 3 inches (8.9 meters)
Wingspan: 14 feet, 11 inches (4.5 meters)
Launch Weight: 11,000 pounds (4,990 kilograms)
Power: Gallium Arsenide Solar Cells with lithium-Ion batteries
Launch Vehicles: United Launch Alliance Atlas V (501) and SpaceX Falcon 9

X-37B Caught on Camera by Civilian Skywatcher

The X-37B Orbital Test Vehicle in the encapsulation cell at the Astrotech facility April 13, 2010, in Titusville, Florida. Courtesy US Air Force.

In recent news, reported that skywatcher and satellite tracker Ralf Vandebergh of the Netherlands recently caught a rare glimpse of the secretive space plane, and was able to photograph it!

Vandebergh claimed to have been hunting for the top-secret vehicle for several months, and he finally tracked it down with the help of his amateur satellite observer’s network. When he went to view it again the next month, the space plane could not be found; it had maneuvered to another orbit.

Given that the military space plane is only 29 feet long with a 15-foot wingspan, Vandebergh’s accomplishment is impressive, especially since he states that he initially tracked it manually through a 6×30 finderscope.

Could the X-37B Become A Space Weapon for Trump’s New Space Force?

Some active-duty Air Force personnel, without direct knowledge of the X-37B program, speculate that the space plane could be weaponized, perhaps as an anti-satellite platform. However, even though the payload is often top secret, secret doesn’t always equate to offensive weapons.

In addition to the official Air Force missions of testing new technologies, it is likely that the X-37B serves some sort of intelligence, surveillance and reconnaissance (ISR) function.

Regardless, like other secret government programs, the very act of designating this spacecraft “Top Secret” makes it that much more interesting to the general public.

Perhaps the most important mission of the X-37B space plane is that it is getting people excited for space science again. Mission accomplished!

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This article appeared originally on



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