Shuttle Expected to Carry Spy Satellite : Space: Experts say Discovery’s orbit suggests cargo is designed to search for troops, weapons sites. Mission will be last devoted to the military.

KENNEDY SPACE CENTER, Fla. —  The shuttle Discovery, set to lift off Wednesday with a satellite that experts believe will spy on hot spots in Europe, Asia and the Middle East, will mark the end of an 11-year partnership between the Pentagon and the National Aeronautics and Space Administration.

Although the identity of the satellite in Discovery’s cargo bay is being kept secret, the seven-day flight promises to be somewhat more open than previous military missions.

Defense analysts said the shuttle’s planned orbit far north of the Equator is appropriate for satellites that use digital optics or radar imagery to search for military camps, warhead factories and underground missile silos.

NASA officials say this mission, the 52nd for a U.S. shuttle, will be the 10th and last devoted to the military.

Jeffrey Richelson of the National Security Archives said the shuttle’s cargo is probably a large imager known by the code name Lacrosse, which also can detect troop movements at night. Lacrosses bounce radio signals off targets below and convert the returning signals into pictures, which are relayed back to Earth by secure communications satellites.

Two already in orbit complement digital telescopes called Keyholes, which are said to be powerful enough to read a newspaper headline from space.

“For postwar intelligence collection requirements, where you’re trying to track convoys in Yugoslavia or something, a Lacrosse would be useful,” said John Pike of the Federation of American Scientists.

Whatever the mission, Discovery will undo a union with the Pentagon that helped finance development of the orbiter fleet that debuted in 1981.

The Pentagon is about to exhaust a dowry of free shuttle flights it received in exchange for a share of the cost. After the shuttle Challenger exploded in 1986, the Pentagon decided to shift all of its crucial national security payloads to unmanned rockets that it deems cheaper and more dependable.

Citing high costs of $70 million a year and the end of the Cold War, defense officials also have relaxed security controls that were imposed for a decade on NASA launch and mission facilities.

The result is that details once closely guarded, such as the type of cargo and the shuttle’s orbital path, are no longer restricted. The launch time was published weeks in advance, unlike previous military missions, when it was announced only nine minutes before liftoff.