The X-37B Orbital Test Vehicle (OTV) is an experimental and highly classified reusable unmanned spacecraft operated by the United States Space Force. Since its first orbital flight in 2010, the X-37B has conducted a total of seven missions, setting new records for flight duration and demonstrating advanced technologies for long-duration spaceflight.
History and Development
The X-37 program originated at NASA in 1999 as a reusable spaceplane project envisioned to be a smaller, cheaper alternative to the Space Shuttle. After NASA transferred the X-37 project to the U.S. Department of Defense in 2004, the program became classified and was assigned to the Air Force’s Rapid Capabilities Office.
Boeing was selected to build prototype vehicles based on NASA’s initial X-37 design. Two operational X-37B spaceplanes have been built so far, each about 29 feet long with a wingspan of 15 feet and weighing approximately 11,000 pounds. The X-37B features a solar array power system, an advanced thermal protection system, and a unique autonomous guidance, navigation and control system that allows the spaceplane to land automatically without human intervention.
Missions and Capabilities
The primary objectives of the X-37B program are to operationally test and validate reusable spacecraft technologies while also conducting experiments that can be returned to and examined on Earth. However, most details about the spaceplane’s classified payloads and activities remain highly secret.
The first X-37B orbital test flight launched atop an Atlas V rocket in April 2010 and spent 224 days in orbit before autonomously landing at Vandenberg Air Force Base in California. Subsequent missions have utilized both Atlas V and SpaceX Falcon 9 rockets to deliver X-37B spacecraft into orbit.
Mission durations have steadily increased over time, culminating with the record-breaking 908 days spent in orbit by the X-37B during its sixth mission from 2020-2022. In total, the two X-37B vehicles have accrued over 10 years in space across their seven flights so far.
Although its missions and payloads are classified, the Department of Defense has revealed that X-37B flights have tested experimental electronics, oscillating heat pipe technologies, advanced guidance and navigation control systems, and materials science experiments.
Theories and Speculation
The secrecy surrounding the X-37B has fueled much speculation about its true purpose and capabilities. Some theorists have suggested the spaceplane could be a space weapon or may have the ability to capture enemy satellites. More extreme ideas propose it could deploy nuclear weapons or conduct surveillance on the Chinese space station.
However, space analysts largely dismiss such theories and maintain the X-37B is primarily used as a reusable testbed platform for evaluating advanced technologies over long-duration flights. Given its multi-year endurance, the spaceplane offers unique opportunities to conduct experiments and validate systems that could support future military and commercial space operations.
Ongoing Innovation
As the X-37B program continues flight testing, each new mission pushes the boundaries further with breakthrough capabilities. The seventh mission, launched in late 2023, is the first to use a SpaceX Falcon Heavy rocket to carry the X-37B into a higher initial orbit. This expanded flight envelope will enable additional experimentation and technology demonstrations over an extended duration flight.
With China also developing its own secretive reusable spaceplane and Russia expressing suspicions about U.S. motives, the X-37B program remains at the leading edge of space innovation while also being shrouded behind a veil of security classifications.
The X-37B’s accomplishments prove that reusable spaceflight technology provides unmatched advantages for affordable, reliable access to space and sustained presence in orbit. As the Space Force considers options for future spaceplanes, the X-37B continues blazing a trail forward as the world’s most advanced unmanned, reusable spacecraft.