What Is the Boeing X-37B? The Military's Secret Spaceplane Explained

The Boeing X-37B is a reusable, unmanned spaceplane operated by the U.S. Space Force, and it has been quietly circling Earth on classified missions since 2010. It looks like a miniature Space Shuttle, launches vertically on a rocket, spends months or sometimes years in orbit, and then glides back down to land on a runway by itself. Nobody outside a small circle of government officials knows exactly what it does up there. That combination of capability and secrecy is exactly why it keeps drawing so much attention.

This post breaks down what we actually know about the X-37B: what it is, how it works, what experiments it carries, how long it stays in orbit, and why the U.S. military keeps flying it. If you've been trying to separate fact from speculation, this is the place to start.

What the Boeing X-37B Actually Is

The X-37B is an unmanned, autonomous orbital test vehicle built by Boeing and operated as a partnership between the U.S. Air Force Rapid Capabilities Office and the U.S. Space Force. The program traces its roots back to 1999, when NASA and the Air Force started developing what was then just called the X-37. NASA originally wanted a craft that could spend up to 270 days in orbit. After the Columbia accident in 2003, the project was transferred first to DARPA and eventually handed over to the Air Force for military development.

The result is a vehicle that sits in an interesting middle ground. It's not a satellite, not a crewed spacecraft, and not a traditional robotic probe. It's a reusable space laboratory that can carry experiments into orbit, operate autonomously for extended periods, and bring hardware back to Earth for analysis. That last part matters a lot. Most satellites can't return anything physical. The X-37B can, and that makes it uniquely useful for testing materials and technologies under real spaceflight conditions.

Most satellites can't return anything physical. The X-37B can, and that makes it uniquely useful for testing technologies under real conditions.

How It Works: Launch, Orbit, and Landing

The X-37B launches vertically inside a rocket fairing, just like a satellite. It's been carried by the Atlas V, the Falcon 9, and the Falcon Heavy. Once in orbit, it deploys solar arrays to power its systems and begins whatever mission the Space Force has planned. The spacecraft uses a hypergolic propulsion system (nitrogen tetroxide and hydrazine) for maneuvering in orbit and for the deorbit burn that brings it home.

Landing is fully automatic. The X-37B glides back through the atmosphere and touches down on a runway without any human input at the controls, making it one of only a handful of spacecraft in history with that capability. For reference, the Soviet Buran shuttle and NASA's Space Shuttle both had automatic landing systems, though NASA never used theirs operationally. The X-37B uses it every single time.

Earlier missions landed at Kennedy Space Center in Florida. The seventh mission, OTV-7, touched down at Vandenberg Space Force Base in California in March 2025, the vehicle's first West Coast landing since 2014. The landing site choice depends on the orbital inclination the mission uses, which itself reflects the experiments being run.

The Eight Missions So Far

The X-37B has completed eight missions as of 2025 and 2026. The first flight launched in April 2010 and lasted about 225 days. From there, mission durations have grown steadily longer. OTV-6 holds the duration record at nearly 909 days in orbit. OTV-7 launched in December 2023, operated in a highly elliptical orbit (reaching as high as 38,838 km at apogee), demonstrated a series of aerobraking maneuvers, and landed in March 2025 after 434 days. OTV-8 launched in August 2025 aboard a SpaceX Falcon 9 from Kennedy Space Center and is currently on orbit.

Across those seven completed missions, the X-37B logged over 4,200 days in space total and traveled more than 1.3 billion miles. OTV-8 is still adding to that count right now.

What Experiments Does the X-37B Actually Carry?

This is where things get interesting, because the Space Force doesn't publicize most of what the X-37B does. But over the years, a few experiments have been officially confirmed, and they give you a sense of the vehicle's range.

OTV-6, which flew in 2020, was the first mission to include a service module, a ring attached to the rear of the vehicle that expanded payload capacity. That mission carried a Naval Research Laboratory experiment converting solar power into radio frequency microwave energy, with the goal of eventually beaming power down to Earth from orbit. It also carried NASA experiments studying how space radiation affects seeds and how select materials respond to the space environment over long durations.

OTV-7 operated in a highly elliptical orbit and demonstrated aerobraking, using atmospheric drag to gradually slow the vehicle and change its orbit without burning fuel. According to the Space Force, the mission also tested space domain awareness technologies. In February 2025, the DoD released a photo taken by an onboard camera showing Earth from deep space, the first time imagery from the X-37B itself had ever been publicly shared.

OTV-8, currently in orbit, is carrying a laser communications demonstration, the first in-space test of a strategic-grade quantum inertial sensor, and NASA material exposure research connected to inflatable heat shield technology. The laser communications work is particularly significant: if it succeeds, it could allow future spacecraft to move far more data across distributed orbital networks than current radio-frequency systems permit.

Why Is It So Secretive?

The short answer is that the X-37B is a national security asset, and most of what it tests has military relevance. The Space Force and Air Force Rapid Capabilities Office don't publicize classified payloads, orbital parameters beyond basic facts, or the specific results of experiments. That's not unusual for military space programs. What makes the X-37B notable is that its very existence is public, while its activities mostly aren't.

This has generated a lot of speculation over the years, including theories about it being a space weapon or a reconnaissance platform. In my reading of what's actually confirmed, the evidence points toward something more mundane but still important: it's a versatile testbed for technologies the military wants to validate in real orbital conditions before committing them to operational satellites. Think of it as a proving ground that flies.

The secrecy also reflects the competitive space environment. China has been developing its own reusable spaceplane, and what the U.S. learns from X-37B missions about maneuvering, propulsion, and long-duration operations has strategic value that goes beyond any single experiment.

How Big Is the X-37B?

If you picture the X-37B as a miniature Space Shuttle, you're on the right track. It's about 29 feet (9 meters) long with a wingspan of roughly 15 feet (4.5 meters). Its launch mass is around 11,000 pounds (5,000 kg). For scale, the Space Shuttle orbiter was about four times larger. The X-37B fits inside a standard rocket fairing, which is a big part of what makes it practical and reusable at a reasonable cost.

The vehicle has a small cargo bay for experiments and a solar array that deploys once on orbit to power its systems. The modular service module introduced on OTV-6 has expanded that payload capacity on more recent missions. Boeing designs, builds, and operates the vehicle out of facilities in Seal Beach, California, and Kennedy Space Center.

What Comes Next for the X-37B Program?

OTV-8 is currently in orbit with no announced return date. Given the pattern of missions getting progressively more ambitious, it's reasonable to expect this one to push new boundaries too. The experiments it's running, particularly the quantum inertial sensor and laser communications demo, are the kind of technologies that could show up in future military satellites if they prove out.

Boeing has also floated the idea of a scaled-up variant called the X-37C, which would be roughly 165 to 180 percent of the X-37B's size and could theoretically carry up to six astronauts. As of 2024, with NASA committed to Starliner and SpaceX Crew Dragon for crewed missions, there has been no further public announcement about developing the X-37C. But the X-37B platform itself is clearly maturing, not winding down. Each mission has added new capabilities, and the turnaround between OTV-7 and OTV-8 (less than six months) suggests the program is running at a higher operational tempo than ever before.

Each mission has added new capabilities, and the less-than-six-month turnaround from OTV-7 to OTV-8 suggests the program is running at a higher tempo than ever before.

If you want to stay current on what the X-37B is doing, the best primary sources are the U.S. Space Force's official press releases and Boeing's newsroom. Both publish updates when there's something the government has decided to share, which is more frequent now than it was in the early years of the program. Tracking sites maintained by amateur astronomers have also historically spotted the vehicle in orbit and published its approximate orbital parameters.

The Bottom Line on the Boeing X-37B

The X-37B is one of the most capable and least-understood spacecraft flying today. It's a fully reusable, autonomous spaceplane that has quietly accumulated more than a decade of operational experience across eight missions, testing technologies that range from solar power beaming to orbital maneuvering to laser communications. Most of what it does is classified, and that's not going to change. But the confirmed details alone are impressive enough.

If this got you curious and you want to go deeper, a good next step is reading through the U.S. Space Force's official mission summaries, which have gotten noticeably more detailed with each passing flight. You can also check out Boeing's X-37B program page for the engineering perspective. The program has been running for 15 years and is still actively flying, which tells you something about how well it works.