DISCOVERY FLIES FIRST OPEN MILITARY MISSION

The shuttle Discovery's seven-man crew thundered into orbit yesterday on a military research mission for the Strategic Defense Initiative (SDI) program. The successful launch came after two months of delays because of onboard technical problems. Discovery's flight is the 40th since shuttle launches began April 12, 1981.

The goal of Discovery's mission, the first unclassified military flight in shuttle history, is to gather data about how to locate and track enemy missiles in flight, a key element of the "star wars" missile defense plan.

While critics claim the controversial SDI system could not stop an all-out Soviet attack, supporters say it could protect the nation from attacks by smaller nations. They cite the success of Patriot missiles in shooting down Iraqi Scuds during the Persian Gulf war.

The astronauts plan to launch five small satellites during the course of the mission, including three that will release different rocket fuels into space and one that will photograph the shuttle from up to six miles away during scores of carefully orchestrated rocket firings.

Other instruments will gather data about the space environment and Earth's atmosphere to help scientists learn how to distinguish fast-moving missiles in flight against a variety of backdrops ranging from the deep black of space and the brilliant blues and whites of Earth.

Launch originally was scheduled for Feb. 26, but the flight was delayed to March 9 because of three leaking rocket thrusters. Launch was again delayed to April 23 due to cracks in the hinges of fuel line doors in the belly of the orbiter.

Last Tuesday, the flight was delayed once more because of a faulty main-engine fuel-pump sensor.