The U.S. space agency is moving ahead with preparations for Thursday's scheduled launch of the space shuttle(航天飞机) Discovery on its mission to the International Space Station.
NASA said it was loading liquid oxygen and liquid hydrogen into the shuttle on Tuesday. The two chemical elements are used in the shuttle's three fuel cells to produce electricity and water in space and also pressurize（密封,增压） the crew's cabin.
This is the 39th and last flight for NASA's oldest surviving shuttleDuring the 11-day flight, the six astronauts aboard the orbiter will deliver cargo to the space station as well as a storage module and a humanoid robot, Robonaut 2. Two spacewalks are planned as well, along with science experiments.
Discovery's flying days should have been completed by now and preparations under way for its eventual museum display. Its last flight was scheduled for late last year, but a hydrogen leak was discovered in the shuttle's external fuel tank. Later, a NASA team discovered cracks in the tank.
One NASA official said the fuel tank is now "stronger than ever."Only two shuttle flights remain after Discovery's mission ends. The shuttles Endeavour and Atlantis also are being retired this year.（本文由在线英语听力室整理编辑） |