* Astronauts cannot free stuck cargo platform * Two former teachers paired for spacewalk * Spacewalk is last of three planned during shuttle flight (Updates with end of spacewalk) By Irene Klotz HOUSTON, March 23 (Reuters) - Two astronauts used pry bars and brute force but failed to free jammed equipment outside the International Space Station on Monday during a spacewalk to prepare the outpost for its last phase of construction. Visiting space shuttle Discovery astronauts Richard Arnold and Joseph Acaba ended up tying down the stuck cargo platform with tethers and left it for future spacewalkers to deal with. "I know it didn't turn out the way we wanted it to, but you guys did a great job," astronaut Steven Swanson radioed to Arnold and Acaba from inside Discovery's crew cabin. Soaring 220 miles (355 km) over northern China, former high school science teachers Arnold and Acaba floated outside the station's airlock just before noon EDT/1600 GMT for a day's work outside the complex, which ended at 6:04 p.m. EDT (2204 GMT). The spacewalk lasted just under 6 1/2 hours. "Thanks again for going outside today," station commander Mike Fincke radioed to the spacewalkers. "This is probably the last EVA (extravehicular activity, or spacewalk) for this Discovery mission. We just want to say take your time, enjoy it and do good work." It was the second spacewalk for the men. They also went on separate outings with lead spacewalker Swanson to upgrade the station's power system, loosen battery connections and complete other tasks. During Monday's spacewalk, the last of three planned during Discovery's eight-day stay at the station, Arnold and Acaba wrestled with a cargo platform attachment that defied spacewalkers' efforts on Saturday to slip it into position. 'NEED TO STUDY THIS THING SOME MORE'-NASA NASA believed the rotating mechanism needed more force to move into its proper latching position. But after several attempts to free the device, flight directors told the spacewalkers to tie it down and move on to other chores. The astronauts were able to hammer away a locking pin that was installed upside-down, but that didn't solve the problem. "We've ruled that out," Swanson told Mission Control in Houston. Arnold and Acaba then braced themselves against handrails and tried to pull the platform into position. "I didn't even feel it move," Arnold said. "It's really stuck." With that, NASA called off attempts to fix the problem. "We're going to need to study this thing some more," Mission Control's Rick Davis told the crew. The astronauts also moved one of the station's two rail carts about 62 feet (19 metres) from one end of the station's truss to the other, where it will be used by the next visiting shuttle crew in June to install an outdoor porch for experiments on a Japanese laboratory. Other works included lubricating a part of the space station's robot arm and rewiring a circuit breaker to separate the wiring for the station's gyroscopes. The shuttle is scheduled to depart the station on Wednesday and return to the Kennedy Space Center in Florida on Saturday. NASA has up to nine more missions to the space station, as well as a final servicing call to the Hubble Space Telescope, planned before it retires the shuttle fleet in 2010. (Additional reporting by Chris Baltimore, Editing by Jim Loney)
Russian special forces stand near the bodies of gunmen killed during fighting in the Karabudakhkentsky region, some 30 km (19 miles) south of the regional capital Makhachkala, March 21, 2009. The ...
