Mysterious X-37B military robotic space plane to fly again Wednesday

The United States Air Force’s mysterious X-37B, its reusable, robotic, unmanned space plane, will launch for a fourth test mission this week, according to a joint statement from the Air Force Research Laboratory, the Space and Missile Systems Center, and the Rapid Capabilities Office. The launch is scheduled for Wednesday at 10:45am ET from Cape Canaveral Air Force Station in Florida atop an Atlas V rocket. Since the first mission launched in 2010, two X-37Bs has racked up a total of 1,367 days of on-orbit experimentation — but it’s still unclear what exactly the plane is doing each time it’s up there.
The military itself doesn’t offer much in the way of clues. “Space is so vitally important to everything we do,” said Maj. Gen. Tom Masiello, AFRL commander, in a statement. “Secure comms, ISR, missile warning, weather prediction, precision navigation and timing all rely on it, and the domain is increasingly contested. A more efficient on-orbit thruster capability is huge. Less fuel burn lowers the cost to get up there, plus it enhances spacecraft operational flexibility, survivability and longevity.”


Here’s what we know so far: The 29-foot-long X-37B looks kind of like a small version of the old Space Shuttle. Each time it goes into orbit, it hitches a ride on the back of a rocket, just like the Shuttle did. This time, the experiment will fly with a new Hall thruster, an electric propulsion device that ionizes and accelerates a noble gas such as Xenon. The thruster is a modified version of what propelled earlier military communications spacecraft, and one with increased fuel economy compared with regular rocket engines. The new version should result in a higher payload carrying capacity and the ability to execute more maneuvers in orbit.
Beyond that, details are still sketchy. The X-37 was originally designed as a robotic spacecraft that would connect with satellites to repair or refuel them. But DARPA took over the project in 2004, and it’s been highly classified the entire time since. We know there are at least two X-37B planes, and that there have been three prior missions (OTV-1, OTV-2, and OTV-3). Each mission has lasted a long time — hundreds of days, in fact.
One thing is for sure: A lot of big-ticket vendors and acronyms are involved. “AFRL is proud to be able to contribute to this research teamed with our partners at SMC, RCO, NASA, Boeing, Lockheed Martin, and Aerojet-Rocketdyne,” said Dr. Greg Spanjers, the AFRL Space Capability Lead and Chief Scientist of the Space Vehicles Directorate. “It was great to see our Gov’t-Contractor team identify an opportunity and then quickly respond to implement a solution that will offer future Air Force spacecraft even greater capabilities.”
There’s been plenty of speculation, especially since the X-37B could reach speeds of Mach 25 on its return to Earth. It’s possible the X-37B holds prototypes of reconnaissance gear for spying on the Middle East and other geopolitical hotspots, as we’ve alluded to in the past. It’s also possible it’s a hedge against the possible and long-feared weaponization of space, in that it could carry a small thermonuclear payload. Really, it would be great if we could get some more details this time around, but I guess we’ll soon find out.
One nice side effect of this mission: The same rocket that’s launching the X-37B will also launch the Planetary Society’s Linux-powered LightSail probe. Carl Sagan would be proud.