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."
If the station represents a step on the ladder that will ultimately allow humans to climb out of low-Earth orbit for long-term exploration, it also remains a test of Washington's reliability as a partner in global manned-spaceflight projects.
Last week, NASA unveiled a rough outline of its plans for a lunar outpost, whose evolution beyond a single dot on the lunar map will depend on international participation.
NASA's likens the effort to the history of exploring Antarctica. Some 50 years passed between the first successful round trip to the South Pole and the establishment of permanent bases there. Visits grew longer, and the bases expanded, until today, where many nations have year-round facilities there. The outlines of a lunar outpost bear the same gradualist features.
Yet NASA's vision for space explorationis the first set of goals set out by President Bush and endorsed by Congress that by design spans administrations and generations. Several science-policy analysts have noted that it's difficult to see how NASA will be able to do it with the money it's likely to receive from Congress. By one analysis, from the original Mercury flight in 1961 through the Apollo-Soyuz mission of 1975, NASA spent roughly $145 billion in 2005 dollars. The two-decade-old shuttle program carries a $150 billion price tag to date. And the station's costs have ballooned from an initial estimate of $8 billion to roughly $100 billion. Yet given its current budgets, NASA is likely to have only $75 billion available through 2020, when the current plan anticipates fresh human boot prints on the moon.
Dr. Griffin notes that the US is not the only spacefaring nation where political support for human space exploration ebbs and flows.
"There is nothing I can say that is in any way a guarantee," he adds. "We are going to meet our commitments and finish the space station." He says that this should serve to give international partners "some confidence in us for the long term. We want to have them with us when we take the next step. Enterprises of this magnitude must have a leader, and in this era of world history, the United States is that leader. But it needs to be an alliance. We hope that others will take the risk and go forward with us."