CAPE CANAVERAL: Now that space shuttle flights can border on the humdrum, it's easy to forget that an international effort to build a once-unthinkable space station is nearly underway. Monday, two astronauts from the shuttle Endeavour were put through the paces for just that purpose: working 200 miles above Earth, rookie Leroy Chiao and Dr. Daniel Barry had no trouble handling a 250-pound beam, laying cable and reading labels warning of "Electrical Hazard" and "Corrosive Hazard" in the dark. "The lessons we're learning here are going to be folded directly into the station design, so that we can make sure the station is a workable, maintainable facility," said Daryl Schuck, lead flight controller for the spacewalk and another one coming up Wednesday. "They felt better after we assured them there were no demons inside this box." Next up for the six shuttle astronauts: Tuesday's retrieval of a NASA science satellite that they dropped off Sunday. The nine-day mission ends Saturday.