The US military’s experimental X-37B space plane has returned to Earth, ending a mysterious 908-day mission. While we’ll likely never know everything that happened to the autonomous spacecraft while it was in space, it worked long enough to set a new record for time spent in orbit. Previously, the X-37B’s record was 719 days in orbit.
The unmanned ship took off more than two and a half years ago on a United Launch Alliance Atlas V rocket. It was the first mission for the Boeing-built X-37B to have a service module attached, allowing it to carry more experiments and satellites into orbit. After launching with a rocket, the X-37B maneuvers solo into orbit and then lands on a runway like an airplane — much like the beloved space shuttle.
Although this was the Air Force’s sixth mission of the X-37B, also known as the Orbital Test Vehicle (OTV), it surpassed the flight time for any other reusable spacecraft in space at 1.3 billion orbital miles and 3,774 days. The X-37B landed safely in the early hours of November 12, marking the end of its record-setting mission. However, we only know a fraction of what was done in those 908 days.
The service module, which put the OTV into orbit before landing, allowed the spacecraft to carry out a number of experiments and bring satellites into orbit. It carries a solar energy experiment designed by the Naval Research Lab, NASA’s Material Exposure and Technology Innovation in Space (METIS-2) experiment, and the FalconSat-8 satellite built by the Air Force Academy and the Air Force Research Laboratory. It organized a NASA experiment to study the effects of spaceflight on seeds.
Of course, it doesn’t take 908 days to launch a few satellites — the government is always concerned about discussing the full scope of the X-37B’s mission. Astronomers have confirmed that the space plane periodically releases satellites that are not registered with the United Nations Office for Outer Space Affairs, making them difficult to track. A former Air Force secretary also confirmed that the X-37B was designed to use close atmospheric passes to change its orbit, making it harder to track and providing cover to engage in covert activities.
There are currently no public plans for another X-37B launch, but it is only a matter of time. The Air Force typically launches an X-37B mission every few years, and each one lasts longer than the last.