The unmanned Boeing X-37B landed at NASA's Kennedy Space Center in Florida on Sunday, after making a sonic boom that could be heard from miles away.
The space plane was launched from the nearby Cape Canaveral Air Force Station in May 2015, aboard an Atlas 5 rocket built by United Launch Alliance (ULA), a partnership between Lockheed Martin Corp and Boeing.
This was the spacecraft’s first landing in Florida. All the previous missions had landed in California’s Vandenberg Air Force Base.
The orbiter spent 718 days in the space, setting a new on-orbit endurance record. Overall, the two X-37Bs built so far have spent 2,085 days in space.
Also known as Orbital Test Vehicle (OTV), the 29-feet-long drone was first launched into space in April 2010 and returned after eight months. It was sent on a second mission in March 2011 and remained in space for 15 months. The spacecraft set on its third mission in December 2012 and returned after 22 months.
Brigadier General Wayne Monteith, commander of the 45th Space Wing, thanked his forces for conducting the last mission.
"Our team has been preparing for this event for several years, and I am extremely proud to see our hard work and dedication culminate in today's safe and successful landing of the X-37B,” he said in a statement.
According to the USAF, the reusable plane "performs risk reduction, experimentation and concept of operations development for reusable space vehicle technologies.”
This is while, military analysts say the spacecraft will be ultimately used for spying activities.
The Secure World Foundation, a nonprofit promoting the peaceful exploration of space, says the US military is using the platform to test intelligence-related hardware.
The USAF is planning to launch the fifth X-37B mission from Cape Canaveral air force station later this year.
"The ability to land, refurbish, and launch from the same location further enhances the OTV's ability to rapidly integrate and qualify new space technologies,” said Monteith.