The X-37B broke its previous record by returning to Earth after more than two years in space.
The X-37B space plane stayed in the air for more than 900 days before landing. The United States Space Force (USSF), which operates the craft, is classified and therefore little is known about its purpose or missions.
The US military created the X-37B variant of the X-37 after it was passed onto them by NASA. The two vehicles that have been constructed so far have carried out more lengthy flights than the model that first flew in 2010. Many other space missions, such as the International Space Station, have been in the air for longer periods.
The X-37B is similar to a space shuttle but without a crew. It launches vertically inside the nose of an Atlas V or Falcon 9 rocket, spends long periods in space at an altitude of around 400 kilometres and then lands like a traditional aircraft on the ground.
On November 12th, the end of the OTV6 mission was marked by the landing at NASA's Kennedy Space Center. The US Naval Research Laboratory designed a test in which energy was collected by solar panels and beamed back to Earth as microwaves, according to officials. Cadets at the United States Air Force Academy designed and built a satellite that featured an electric motor. NASA provided some experiments that tested the effects of space exposure on seeds and materials.
It is thought that X-37B has the same purpose as the space shuttle did. In an interview earlier this year, the head of Russia's space agency said that the craft could be used to carry 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 that the X-37B continues to push the boundaries of experimentation. The Department of the Air Force and the scientific community value the ability to conduct on-orbit experiments and bring them home safely. More experiments were hosted because of the addition of the service module on OTV. Fritschen didn't reply to a request for an interview.
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