Boeing X-37B

📷 U.S. Air Force / Wikimedia Commons (Public domain)

The Boeing X-37B is the U.S. military’s reusable robotic space plane — a 8.9-metre mini-shuttle, about a quarter the length of the old orbiter, that flies years-long classified missions with nobody aboard. Since April 2010 it has flown seven Orbital Test Vehicle (OTV) missions, one lasting a record 908 days, each ending with a fully autonomous landing on a runway. Two vehicles exist, operated by the U.S. Space Force.

Officially it is a testbed for reusable-spacecraft technology and long-duration experiments. Unofficially, its payload bay’s contents are mostly secret, which has made the little white space plane one of the most discussed — and most speculated-about — objects in orbit.

Development History

The design began openly, as NASA’s X-37 program with Boeing in 1999 — a technology demonstrator descended from Shuttle research. Budget shifts pushed the project to DARPA in 2004, and in 2006 the Air Force announced its own orbital version, the X-37B, built by Boeing’s Phantom Works. From that point the program went largely quiet.

OTV-1 launched on an Atlas V on April 22, 2010, and landed itself at Vandenberg 224 days later — the first American vehicle to fly to orbit and land autonomously on a runway (the Soviet Buran shuttle had done it once, in 1988). A second airframe joined in 2011.

Mission durations then climbed relentlessly: 468 days, 675, 718, 780, and finally OTV-6’s 908 days from May 2020 to November 2022, aided by a new service module that added experiment capacity. OTV-7 broke the pattern instead of the record: launched December 28, 2023 on a Falcon Heavy, it flew in a highly elliptical orbit far beyond the vehicle’s usual neighborhood and landed at Vandenberg in March 2025 after 434 days. An eighth mission followed in 2025, carrying — according to the Space Force — laser-communications and quantum-sensor experiments.

Design & Capabilities

The X-37B looks like a Space Shuttle that shrank in the wash: 8.92 m long, 4.6 m wingspan, about 5 tonnes, with stubby delta wings and an angled V-tail. It launches folded inside a standard rocket fairing on an Atlas V, Falcon 9, or Falcon Heavy, and its payload bay is about the size of a pickup-truck bed — 2.1 by 1.2 m.

Long endurance comes from a deployable gallium-arsenide solar array that unfolds in orbit, something the fuel-cell-powered Shuttle never had. Improved silica tiles and tougher carbon composite leading edges handle reentry, and a storable-propellant engine lets it change orbits repeatedly — amateur trackers have watched it maneuver, vanish, and reappear throughout its missions.

Everything about the flight profile is automated: deorbit, hypersonic reentry, approach, and touchdown on the former Shuttle runways at Kennedy Space Center or Vandenberg, with no pilot and no ground joystick.

Notable Missions

OTV-4 (2015-2017) carried one of the program’s few announced payloads: a Hall-effect thruster test and a materials-exposure experiment. OTV-6 set the 908-day endurance record while hosting the Naval Research Laboratory’s PRAM experiment, which converted solar power to microwaves to explore beaming energy from space, and deployed the FalconSat-8 student satellite. It also flew NASA seed samples to study long-duration radiation exposure.

OTV-7 was the boldest departure: a Falcon Heavy launch to a highly elliptical, high-altitude orbit, and near the end of the mission a series of aerobraking passes — dipping into the upper atmosphere to change orbit while conserving fuel — before landing in March 2025. It demonstrated maneuvers the Space Force openly described as relevant to operating unpredictably in orbit.

Frequently Asked Questions

What does the X-37B actually do in orbit?

Most payloads are classified, but announced experiments include materials exposure, seed studies for NASA, a power-beaming demonstration, and navigation and sensing tests. Analysts generally read it as an orbital test rack: a way to fly new sensors and technologies for years, maneuver them, and — uniquely — bring them home for inspection instead of letting them burn up.

How long can the X-37B stay in space?

The record is 908 days — nearly two and a half years, set by OTV-6 between 2020 and 2022. Its deployable solar array supplies power indefinitely, and with no crew there is no food, water, or air constraint. Mission length is limited mainly by propellant and by how long its experiments remain useful.

Is the X-37B a space weapon?

There is no public evidence for that. At five tonnes with a small payload bay and well-tracked orbits, it is poorly suited to weapons delivery, and independent analysts consistently describe it as a reusable testbed. That said, its aerobraking and orbit-changing demonstrations clearly rehearse skills — maneuver, inspection, unpredictability — that matter militarily, which keeps the speculation alive.

How is the X-37B different from the Space Shuttle?

Scale and crew. The X-37B is about a quarter of the orbiter’s length, carries no people, launches sealed inside a rocket fairing rather than stacked openly, and stays up for years instead of two weeks. What it kept is the payoff idea: wings and wheels, so the vehicle and its cargo come home gently to a runway and fly again.