CAPE CANAVERAL, Fla. (AP)  — Two astronauts, who were teaching math and science to middle school students just five years ago, went on a spacewalk together Monday, their path cleared of dangerous orbiting junk that had threatened the space station and shuttle.On Sunday, the linked shuttle-station complex had to move out of the way of a 4-inch piece of debris that had been projected to come perilously close during the spacewalk. Astronauts Joseph Acaba and Richard Arnold II had no luck trying to free up a jammed equipment storage shelf at the international space station, one of their main tasks. Using a hammer, they managed to loosen a pin that Acaba and another astronaut accidentally inserted upside down on the platform during Saturday’s spacewalk.