World Flavor for US Space Work
Atlantis mission was largely a success, but tether needs attention
THIS has become a summer of international cooperation for the American space shuttle system.
Saturday, the shuttle Atlantis returned from its eight-day mission with a crew that included the first Swiss and Italian astronauts to enter space. Now another international crew is preparing for the next shuttle mission, by Endeavor.
The newest orbiter, Endeavor is to carry the United States-Japanese spacelab in September.
Japan's first professional astronaut - chemist Mamoru Mohri - will be part of the seven-member crew.
This is more than a guest appearance. Spacelab-J is a joint mission of Japan's National Space Development Agency (NASDA) and the US National Aeronautics and Space Administration (NASA). The spacelab, carried in the shuttle cargo bay, is a joint research laboratory with 24 materials experiments and 20 biological experiments.
This has required close collaboration of technical teams from both countries. Payload processing manager Glenn Snyder says that "the module was prepared for flight in record-setting time and everybody ... pooled all their resources and pulled together as a real team." This is useful experience as the two countries prepare to work together on the space station, for which Japan will supply a laboratory module.
Meanwhile, NASA has impounded records of the tethered satellite experiment from Atlantis.
A team will try to find out what caused the American-supplied tether mechanism to stick and prevent deployment of the Italian-supplied satellite. The satellite was to have moved about 20 kilometers (12 miles) from Atlantis but never got farther than about 230 meters (750 feet).
This was a major disappointment with an otherwise successful mission. NASA administrator Daniel Goldin told the astronauts they had done "wonderful work under difficult circumstances" when they landed at the Kennedy Space Center in Florida at 9:11 a.m. Aug. 8. In fact, this was only a partial failure for the $329 million tethered satellite package. The 500-kilogram (1,100-pound) satellite, which was equipped to study particles and electric and magnetic fields, worked well.
Speaking in Italian, Italian Space Agency astronaut Franco Malerba told Italy's prime minister, Giuliano Amato, that "we blew a tire in a Formula One Grand Prix, but the car is working fine," according to a translation provided by the Associated Press. The astronauts themselves took the tether snag in stride. NASA had warned in advance that it was impossible to predict how this untried technology would behave. "We still believe in the potentials of the Tethered Satellite system," astronaut payload comman der Jeffrey Hoffman said.
One of those potential applications is electric power generation. As the electrically conducting pencil-thin tether cuts across Earth's magnetic field, it should act as an electrical generator. It was expected to generate a difference of 5,000 volts between satellite and shuttle when extended to the full 20 kilometers. As it was, it generated 40 volts. This, at least, demonstrated that the generator concept works.
The mission's other major task - deployment of the European Space Agency (ESA) $213 million Eureca-1 satellite - seems to have been fully successful.
ESA's on-orbit representative - Swiss astronaut Claude Nicollier - helped release Eurica, only to have the satellite become disoriented. But engineers at ESA's control center at Darmstadt, Germany, found and fixed a computer program error in a sun sensor. By Friday, controllers had moved Eureca to its working circular orbit 506 kilometers (315 miles) high.
Eureca is to travel this orbit for about nine months. Then Darmstadt controllers will drop it to a lower orbit where Atlantis is expected to pick it up next June. Meanwhile, an assorted cargo of materials and biological experiments plus cosmic ray and radiation monitoring instruments will operate under remote control of ground-based scientists.
This is different from NASA's Long Duration Exposure Facility (LDEF) satellite, which can also be left in space for extended periods. Once released, LDEF is beyond Earth control until a shuttle retrieves it.
The 4,491-kilogram (9,900-pound) Eureca can carry a one-ton payload. It is the largest satellite ESA has yet built, measuring 20 meters by 3.5 meters (65.6 by 11.5 feet) when fully extended in space. ESA expects this to be the prototype for a family of free-flying laboratories for microgravity research.
Before Atlantis meets up with Eureca again, it will return to the Rockwell International orbiter facility in Palmdale, Calif., for maintenance and modifications. NASA announced this maintenance strategy last month. It allows the slimmed-down Kennedy center work force to concentrate on shuttle missions while Rockwell maintains a work force that can also supply shuttle spare parts.