NASA managers cut short Friday's spacewalk by two Endeavour astronauts because one of their carbon dioxide sensors stopped working, according to AP. The astronauts were nearly five hours into a routine planned six-and-a-half hour spacewalk at the International Space Station when mission controllers noticed that Gregory Chamitoff's spacesuit sensor wasn't working. NASA needs to know if levels of carbon dioxide _ expelled when you breathe _ get too high. The levels were probably not too high, but the decision was made because of the lack of information. Chamitoff and spacewalking partner Drew Feustel were about to start a 45-minute task to finish installing an antenna on the space station, but controllers figured that would take too much time. They started clean-up tasks instead.
