Updated at: 0925 PST, Tuesday, March 24, 2009
WASHINGTON: Discovery astronauts ended their third and final spacewalk on Monday on a slight down note, unable to fix a jammed cargo carrier system, NASA said. Richard Arnold and Joseph Acaba, two former science teachers turned astronauts, carried out a six-and-a-half hour walk in space, which included attempts to unblock the external cargo carrier. The carrier became stuck after Acaba and another astronaut inadvertently inserted a restraining pin upside down on Saturday. Although Arnold and Acaba managed to dislodge the pin, the cargo system remained stuck. The two emerged from the decompression chamber at 1537 GMT, six minutes earlier than planned, after mission control told them to stop trying. The astronauts secured the system with "long-duration tethers," which are to protect the hardware until another attempt can be made in the future.