NASA says it\'s looking at Saturday to launch its Radiation Belt Storm Probes mission after an intended Friday morning launch was canceled for technical reasons. A drift in the signal from a transponder aboard the Atlas V launch rocket led to the postponement of the launch from Cape Canaveral Air Force Station in Florida, the space agency reported. It is not yet known if the issue was in the transponder itself or in the ground-based range detection equipment meant to receive its signals, engineers said. The transponder is part of one of several systems used to track the vehicle after launch, and it is mandatory for it to operate prior to liftoff, they said. The next 20-minute launch window will start at 4:07 a.m. EDT Saturday. The Radiation Belt Storm Probes mission is intended to study the sun\'s influence on Earth and near-Earth space by studying the Earth\'s radiation belts on various scales of space and time, NASA said.