A mysterious unmanned space secret plane stayed in orbit for 780 days – more than two years – before it landed on Sunday.
The robotic plane touched down at NASA’s Kennedy Space Center in Florida on Sunday.
The plane developed by Boeing and coded X-37B craft – also known as Orbital Test Vehicle 4 was on a classified mission, testing new technologies.
It took off for space to take start on its mission on September 7, 2017.
Experts believe the Spaceplane vehicle is designed to destroy satellites or spy on other countries.
The X37-B first went into space in 2010 and has completed five missions so far. The craft can carry cargo loads into space and return them to engineers on Earth.
The US Air Force has said it performs “risk reduction, experimentation, and concept of operations development for reusable space vehicle technologies”.
When the secret space plane landed from a previous mission, it was greeted by ground crew in biohazard suits staring rumours that there was something radioactive on board.
The aircraft’s wingspan is less than 15ft and flies into space attached to a rocket, but glides back to Earth like the space shuttle.
NASA has previously said that there is a materials experiment on board. But its main payload remains a mystery and a classified top secret.
During previous missions, amateur astronomers were able to detect the orbital pattern of the first X-37B which included flights over North Korea, Iraq, Iran, Pakistan and Afghanistan.
These flight patterns have brought about speculation of a top-secret attack mode as well as spying missions.