With Spacelab back home, NASA readies Discovery for June flight

Challenger has scarcely returned to Earth, yet the shuttle team at the Kennedy Space Center already is moving swiftly toward the launch of the next mission June 12. This time it is Discovery, which will head toward orbit carrying three communications satellites. It will also release a research satellite designed to fly along side the shuttle until it is retrieved and returned at the end of the seven-day mission.

As they continue their busy launch schedule, officials of the National Aeronautics and Space Administration (NASA) and Hughes engineers are developing a plan to revive the ``dead'' Leasat on orbit. If this plan matures, Astronaut Joe H. Engle would wire in a new radio command system during shuttle mission scheduled for launch Aug. 10. This could enable engineers to recover control of the Leasat communications satellite, whose electric power failed to switch on when it was launched last month.

Meanwhile, mission manager Joseph Cremin calls the just-ended Spacelab 3 flight ``an excellent science mission'' with more than 90 percent of its objectives accomplished. The main disappointments during the seven-day flight -- which ended with Challenger's touchdown at Edwards Air Force Base, Calif., at 12:11 Eastern daylight time Monday -- were failure to release a small Navy satellite and inability to deploy a French wide-field camera due to a frozen airlock. The camera was to have made a survey of the heavens as seen in ultraviolet light.

The main surprise was the clouds of food particles and other debris that flowed out of the animal holding cages to float about the Spacelab cabin and even into Challenger's crew area. The animals -- two squirrel monkeys and 24 rats -- were unexpectedly active, as they adapted to weightlessness. The main purpose of carrying the animals was to test the animal holding facility to find any problems, such as the leaked debris, which need to be corrected.

Also, the animal and the human astronauts were subjects in NASA's continuing study of the ``space sickness,'' which partly incapacitates many astronauts as they adapt to the zero-gravity orbital environment. One monkey did have some problems. But the animals, reportedly, adapted more easily than did some of the crew. Now the rats are being dissected for detailed study of possible organ changes due to weightlessness.

The main Spacelab experiments and investigations, other than the French camera, were quite successful. Photos were made of the aurora over Earth's magnetic poles. The Atmos instrument of NASA's Jet Propulsion Laboratory measured concentrations of 40 different chemicals in the high atmosphere before it failed, providing ample data for studying high-altitude pollution.

Crystals grown under virtually gravity-free conditions have been brought back to see if they are superior to those grown on Earth. Techniques for growing them were further tested. And experiments that simulated the atmospheric circulations of Jupiter and the Sun produced photographs of patterns that may give atmospheric scientists new insights into such questions as what produces and maintains Jupiter's famous Red Spot.

In all, the mission produced 3 million pictures of various kinds and enough computer data to fill 50,000 books averaging 200 pages each, according Mr. Cremin.

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