astronauts take out the trash
   astronauts on sunday exchanged supplies for trash that has accumulated on the international space station since shuttles were grounded after the 2003 columbia tragedy. they also prepared for a second spacewalk set for monday.
space shuttle discovery, which docked at the orbiting outpost thursday, became the first shuttle to return to orbit last week. among the mission's goals: resupply the station and remove the mounds¹ of trash that have accumulated in recent years.

   "it is kind of just like working in your closets and your garage," station flight director mark ferring said. "it's a lot of work."

   the astronauts are unloading 15 tons of cargo². they expect to return to earth with 13 tons of trash and other items that are no longer needed on the station.

   when the station's two-man crew awoke sunday, they were told that their seven discovery guests would remain at the station for an additional day.

  "hopefully it is not going to be like the relatives who miss their flight and have to stay another day," charles hobaugh, who works in the station's mission control, told crew members by radio.

   a ninth day at the station was approved late saturday, days after nasa decided³ to ground future shuttle missions because an almost one-pound piece of foam⁴ broke free of discovery's external fuel tank. the piece of foam missed discovery, but was a haunting reminder⁵ of columbia.

   a 1.67 pound chunk⁶ of foam shed from columbia's external tank hit the shuttle's left wing and caused a hole that allowed the searing gases of re-entry to melt the wing from the inside out. the shuttle disintegrated⁷ over texas as it returned to florida. all seven astronauts died.

   nasa spent hundreds of millions of dollars over 2{ years redesigning the external tank, but said last week it did not solve the problem and more work is needed.

   bill gerstenmaier, the station's program manager, said discovery will leave the station in much better shape than when it arrived. water will be left behind, as well as laptops, wash cloths, a printer, dry wipes, floppy disks, food and nitrogen