Left in Space

On April 7, 1984, soaring 257 nautical miles above the Earth, astronaut Terry Hart used the space shuttle Challenger's manipulator arm to float an experiment-laden, 12-sided satellite into proper orbital orientation and then surrendered it to the invisible tethers of Earth's gravitational field. There the laboratory-called the LongDuration Exposure Facility (LDEF) began its silent, vital task of just staying in space. More than 200 investigators from 70 companies, universities and research centers worldwide had loaded this orbiting techno-patchwork with 57 experiments, carried mostly on the 86 experimental trays covering the ends and the sides of the 14-foot diameter, 40-foot-long facility And LDEF did stay in space, stranded there more than four years longer than originally planned. For more than five years now, some of its experiments have probed, measured and monitored cosmic-ray nuclei and other space particles originating at the sun and at more distant stars. Others have studied particles trapped in Earth's magnetic field or collected micrometeoroids and other debris from the solar system's younger days. Many researchers hope to learn what happens to various materials including reinforced epoxy composites, reflective coatings and spacecraft components such as optical fibers and solar cells after long tours in the exotic environment of space. The health of human space travelers and the structural integrity of future spacecraft or space stations may depend on such knowledge. NASA's original plan called for LDEF to remain aloft for 12 to 18 months, after which shuttle astronauts would retrieve it. Lacking telemetry for radioing data Earthward, the voiceless laboratory would horde its ever-growing treasury of data until researchers on terra firma got LDEF's experiment-laden trays into their laboratories and started to determine how space conditions had affected their samples. As part of a tightly scheduled space program in which delays seem the norm, a postponement of LDEF's recovery until autumn of 1986 came as no surprise. But on Jan. 28, 1986, Challenger which not only carried LDEF to its high perch but was slated to recover it exploded over the Atlantic Ocean. Seven crew members died, and NASA postponed all future shuttle missions. Five and a half years after LDEF's launch, scientists still await its results. "The only information from LDEF so far is its orbital decay," says LDEF program manager E. Burton Lightener of NASA's Langley Research Center in Hampton, Va. Today, as NASA gears up for a year-end retrieval mission with the shuttle Columbia, anxiety runs high. The orbit of the powerless spacecraft has dropped so much that if the planned retrieval fails, scientists will lose all their experiments and the data they carry when LDEF instead returns to Earth the hard way by burning up as it tumbles through the atmosphere sometime in early February Such a loss would be especially wasteful now, researchers say, because the value of LDEF data has multiplied with each extra year in orbit.