LAST week's spectacular mission of the space shuttle Endeavour opened a new phase of manned spaceflight for the United States. It began the exploration of the kinds of challenges astronauts may face in building the space station.
Endeavour's crew had the first extensive practice in the space-walking work that station building may involve. Now the National Aeronautics and Space Administration (NASA) and its astronaut corps look forward to the second step in this new type of exploration - next month's mission of the shuttle Columbia.
Scheduled to last 13 days, it is to be the longest shuttle mission yet. This will begin to test the physiological and psychological effects on astronauts of carrying out a busy work schedule while orbiting in a confined space longer than any previous shuttle crew.
Columbia is returning to service after an extensive refitting. This has given it the capacity to stay on orbit for such extended periods and provide opportunities for studying the effect of longer orbital work assignments. The ability of crews to work efficiently and safely in space for periods ranging up to a few months will be important both in building and in operating the space station.
The seven-astronaut crew's main mission will be to carry out micro-gravity experiments in the Spacelab mounted in the shuttle's cargo bay. But, like Endeavour's crew, they will also be taking part in a space station related learning experience.
Last week, Endeavour's crew learned about the limitations of ground-based training. When their plan to capture the 9,000-pound spinning Intelsat-6 satellite with a grab bar failed, they had to improvise. Using three astronauts instead of two, they were able to capture the satellite by hand.
Astronaut Pierre Thuot, who had failed to catch Intelsat-6 with the 15-foot grab bar, noted that the task was "something we couldn't train for." He explained, "We don't have a simulator that can put all the components together."
Also, there is no simulator that enables astronauts to get the exact "feel" of handling massive or bulky objects in weightless conditions. Astronauts Kathryn Thornton and Thomas Akers discovered this when they practiced assembling a truss structure in Endeavour's cargo bay.
They reported that the bars they assembled handled somewhat differently than they did in underwater simulations on Earth.
Summing up last week's experience, flight director Al Pennington at the Johnson Space Center in Houston observed, "We've rewritten the book on a number of things."
Incoming NASA administrator Daniel Goldin emphasized the learning aspect of the mission in replying to criticism about the cost effectiveness of using an $800 million shuttle mission to rescue a $150 million satellite. He praised the astronauts' work as demonstrating "the wonderful brilliance of the human mind that was able to adapt and react and do things that machines just can't do."
Astronauts will likely run into such situations many times in building the space station. Mr. Goldin said that one of his agency's goals in manned missions now is to gain as much experience as it can in matters relevant for station construction.
When it comes to crew stamina and general effectiveness, NASA can draw on the experience of the 1973-74 American Skylab missions. The longest of these lasted 84 days. Also, the Russians have had extensive long-duration orbital experience, including the record-setting 366-day mission of 1987-88. However, these are of limited value. Work loads were lighter and crew sizes smaller than will be the case on shuttle station-building missions.
Next month, seven astronauts will work intensively in restricted quarters. The mental states of the crew members and their social interactions will be studied carefully. Exercise routines and food and liquid intake will be monitored in detail along with bodily changes.
Endeavour commander Daniel Brandenstein, speaking in his role as chief astronaut, observed that Endeavour's crew worked hard but came back in good shape. He says, "I feel comfortable" about stepping up to the 13-day challenge.