CAPE CANAVERAL, Fla., April 11 (UPI) -- NASA's next major space observatory, the Gamma-ray Large Area Space Telescope, is moving closer to launch with a mission review this week in Arizona.

The observatory, called by its acronym "GLAST," is designed to explore the mysteries of the high-energy universe. Nearly all of the telescope's components have been assembled on the spacecraft, which is to begin testing by the primary contractor, General Dynamics Advanced Information Systems in Gilbert, Ariz.

GLAST's main instrument, the Large Area Telescope, operates more as a particle detector than a conventional telescope. It is designed to detect thousands of new gamma-ray sources while extending human knowledge of previously unidentified sources.

The other instrument, the GLAST Burst Monitor, will detect roughly 200 gamma-ray bursts annually.

The U.S. Department of Energy helped build the LAT in collaboration with other institutions in the United States, France, Italy, Japan and Sweden. NASA's Marshall Space Flight Center built the burst monitor in collaboration with institutes in Germany.

The mission review is expected to be completed later this week, with the spacecraft scheduled to be launched into a low-Earth circular orbit no earlier than Dec. 14.