The X-37B landed at NASA’s Kennedy Space Center in Florida on 12 November after 908 days in orbit Boeing/U.S. Space Force

The secretive X-37B space plane has beaten its previous flight duration record by staying in orbit for 908 days before landing. The autonomous craft, operated by the United States Space Force (USSF), is officially classified and therefore scant details about its purpose or missions are released, but officials say that the latest flight carried a host of scientific experiments.

The X-37 Orbital Test Vehicle (OTV) began life under the umbrella of NASA, but was passed to the US military, which created the X-37B variant. That model first flew in orbit in 2010 and the two vehicles constructed so far have carried out increasingly lengthy flights, including a 674-day mission that ended in 2014. Its latest 908-day mission sets a new record for the craft, although many other space missions, such as the International Space Station, have been in orbit for longer periods.

The Boeing-constructed X-37B spacecraft looks like a miniature space shuttle and functions similarly, but without a human crew. It launches vertically inside the nose of an Atlas V or Falcon 9 rocket, spends long periods in space at an orbit of around 400 kilometres and then lands like a traditional aircraft upon reentry to Earth’s atmosphere.

The landing at NASA’s Kennedy Space Center on 12 November marked the end of the mission known as OTV-6, which started in May 2020. Officials say that it carried out a range of scientific experiments, including a test designed by the US Naval Research Laboratory, in which energy was collected by solar panels and beamed back to Earth as microwaves. It also released a satellite designed by cadets at the United States Air Force Academy that featured an electromagnetic propulsion system. Other experiments were provided by NASA, including some designed to test the effects of space exposure on various materials and seeds.

There is speculation that X-37B has a military as well as scientific purpose, just as the space shuttle before it did. The then-head of Russia’s space agency Roscosmos, Dmitry Rogozin, said in an interview earlier this year that the craft could be “a carrier of some kind of reconnaissance apparatus, and a carrier of weapons of mass destruction”.

The USSF didn’t respond to a request for comment, but a statement issued by Joseph Fritschen at the organisation said: “The X-37B continues to push the boundaries of experimentation, enabled by an elite government and industry team behind the scenes. The ability to conduct on-orbit experiments and bring them home safely for in-depth analysis on the ground has proven valuable for the Department of the Air Force and scientific community. The addition of the service module on OTV-6 allowed us to host more experiments than ever before.” Fritschen didn’t respond to a request by New Scientist for interview.