The United States Air Force's not-so-secret unmanned Space shuttle, called the X-37B, just landed at NASA's Kennedy Space Center in Florida after a two-year Mission in orbit. While Boeing and the Air Force have been quite open to the public about the existence of the robotic space plane, what exactly it is doing in orbit remains to be top secret.

An ongoing project

The return of the X-37B orbital spacecraft is the fourth successful mission of the Boeing-built shuttle. The mission is also marked as its longest classified mission ever after spending over 718 days in space. The X-37B was launched on top of a United Launch Alliance Atlas 5 Rocket back in 2015.

The reusable orbiter is a smaller version of the older NASA space shuttles and stands at just 2.9 meters. The craft is unmanned and is fully automated, which includes its computer-guided landings. NASA originally started the X-37B project in 1999 and was then transferred to the Defense Advanced Research Project Agency (DARPA) in 2004.

The secret mission

Despite being open about the craft, its launch dates, and several other details, the agencies involved in the project remain to be very secretive about the details of the orbiter's mission. The official statements from the different agencies are that they are "testing advanced technologies" and "operating experiments."

Shortly after the new landing, the Air Force released a statement and expressed their pride in yet another successful landing for the X-37B program and mentioned that the craft now holds the on-orbit endurance record.

Theories on its missions

Since the program began, there have been a lot of speculations about the true purpose of the unmanned orbiters. The three earlier missions were launched back in 2010, 2011, and 2012. All previous missions landed at the Vandenberg Air Force Base in California, which means that the recent one was the first landing in the state of Florida.

Earlier reports had claimed that the unmanned spacecraft might be some form of "orbital bombers." Other theories have claimed that the craft may be a new type of spy satellite that can monitor different areas across the globe. However, most of the claims have been downplayed by the agencies who have continued to claim that the project is simply to develop reusable spacecraft technologies further and to further conduct necessary experiments in space.