While details about the plane's orbit are mostly kept from the public, Langbroek told Space.com that he's certain he captured the aircraft, as he works with a small band of skywatchers that track its path.
According to Langbroek, the aircraft was in very low orbit, flying at an altitude between 193 and 202 miles. "Basically, only one type of object fits this: X-37B. Previous X-37B missions we tracked also orbited at such very low altitudes. The object also has a similar brightness to previous OTV missions," he said.
The Air Force's miniature space plane, which is also known as the Orbital Test Vehicle-5, was launched into orbit atop a SpaceX Falcon 9 rocket on September 7, 2017, from NASA's Kennedy Space Center in Florida.
At the request of the US Air Force, SpaceX only aired the first few minutes of the shuttle's liftoff before cutting off the feed. The launch also broke new ground, as it was first time that an OTV was sent into orbit by a rocket provider that wasn't the United Launch Alliance.
With X-37B just two weeks shy of marking its one-year anniversary in orbit, officials have indicated that the latest mission will likely continue the trend of outlasting previous flight times, according to Space Flight Insider. OTV-1 spent 224 days in space; OTV-2, 468 days; OTV-3, 675 days; and OTV-4, 718 days.
Per the Insider, when OTV-5 does wrap up its mission, it's likely to land at the Shuttle Landing Facility at Florida's Kennedy Space Center. It added that despite the military's attempts to keep mum on the purpose of the project, information has leaked out, revealing that hardware stowed inside the vehicle was developed in order to test "a thermal management system optimized for the space environment."
The US Air Force is known to have two OTVs, both which were built by Boeing. According to Space.com, both vehicles measure in at 29 feet long and 9.6 feet tall, with a payload bay roughly the size of a pickup truck bed.