The shuttle is an automated voice activated sub-orbital transport vehicle, that Adam Jensen uses to reach Panchaea in the Arctic Ocean. It is launched from Hangar 18 at the Omega Ranch facility in Singapore, utilizing an underground Electrodynamic Launch Assist System (a large Linear Accelerator) located directly below the hanger.
During the approach, the shuttle's chute malfunctions, and the vehicle crash lands in the ocean, just by the installation.
As its name implies, the LEO shuttle can also enter Low Earth Orbit on the way to destinations that would be impossible or impractical to reach via a sub-orbital trajectory.
Based on what is seen of the shuttle, it appears to use a dual cycle rocket/turbojet engine, with pop-out intakes on either side of the shuttle supplying the turbojet with air. While not actually seen in action, the turbojet portion of the engine would likely have been used in the last stage of a normal approach to an in-atmosphere destination, probably once the chute had deployed and reduced the speed of the vehicle to a point where the turbojet mode could be safely used. Since it is not clear if the LEO shuttle is actually equipped with any form of landing gear, it is unknown if the LEO shuttle was capable of landing by itself on a VTOL pad, or whether it would have needed a special landing cradle or else something along the lines of the old BAe (now BAE Systems) Skyhook system.
The LEO shuttle design appears to have been partly inspired by the real world Boeing X-34 robotic spaceplane, originally developed as an Orbital Test Vehicle for NASA in the late 1990s/early 2000s, of which at least two operational/test examples (X-35B) are currently [early 2012] in service with the USAF. Unlike the LEO shuttle, the X-35B uses an Atlas V booster to reach orbit, not necessarily a LEO one. The preceding (non-space capable) X-40A, which tested technologies for the X-35, may have had even more of a direct influence on the design of the LEO shuttle.
The code the computer speaks after Jensen activates the shuttle is similar to the code Captain Kirk enters to activate the self-destruct sequence of the U.S.S. Enterprise in Star Trek III: The Search For Spock.