A SpaceX Falcon 9 rocket will blast into space tomorrow morning, carrying the US military's secretive X-37B drone on its eighth mission.
The rocket is due to launch at 5.50am Irish time, according to SpaceX, which said a backup window is available at the same time the following day.
The U Space Force has said the drone's mission will include "a wide range of test and experimentation objectives".
"These operational demonstrations and experiments comprise of next-generation technologies including laser communications and the highest performing quantum inertial sensor ever tested in space," the service said in a statement last month.
"Mission 8 will contribute to improving the resilience, efficiency and security of US space-based communications architectures," it added.
About the size of a small bus, the X-37B US space drone looks like a mini version of the manned space shuttles retired in 2011. On previous missions, the X-37B has carried out tests for US space agency NASA.
In operation since 2010, the X-37B Orbital Test Vehicle was designed for the Air Force by United Launch Alliance by Boeing.
It is 9 metres long, has a 4.5 metre wingspan and is powered by solar panels.
Accreditation: AFP
