Time for a Power Boost at International Space Station ; the Arrival of the Space Shuttle Discovery Will Mark the Next Stage in Construction

Article excerpt

Imagine overhauling the electrical system of a transatlantic airliner in midflight, and you get an inkling of the challenge NASA faces this week as it takes the next major step in completing the International Space Station.

Saturday night, the shuttle Discovery and its seven-member crew arced into the sky, spraying a trail of fire that lit the night. Tuesday, astronauts Robert Curbeam and Sweden's Christer Fuglesang begin the first of three spacewalks to ensure that the orbiting outpost can provide the power and cooling needed to house six crew members and run European and Japanese labs, slated to arrive at the station beginning next October.

Astronauts will help install a new $11 million truss to the station's "backbone." And they will connect a set of solar panels, delivered in September, to the station's power grid.

These are not simple plug-and-play operations. Controllers in Houston will have to partially retract an existing solar array to give the new panels room to move as they track the sun. Then ground controllers must reroute the flow of electricity through the station so that astronauts don't handle live wires during their spacewalks. Vital life-support systems will be shut down in parts of the station, temporarily erasing the protective redundancy built into the station. Equipment that must be kept running to ensure redundancy will have to be "jumpered" to the powered half of the grid.

If all goes as planned "it won't be as complicated" as it could be, says Kirk Shireman, the space station's program manager. "But you have to prepare yourself for quite a number of ugly contingencies."

Some of the hardware the astronauts must activate have been dormant for years. "It's like storing a car in a garage for four years, then turning the key to see if it starts," he continues. This mission is important for the station's future, which itself is important as NASA plans to explore the moon and, perhaps, Mars.

"One of the things we're going to learn from the station is in fact how to work through failures or problems" during long-lived manned missions, acknowledges NASA Administrator Michael Griffin. Until the space station came along, he continues, US missions consisted of brief episodes on orbit or at the moon. "Even Skylab was 84 days, less than three months. When we go to Mars, we need three years. …


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