A privately funded team will attempt this year to break a 50-year-old record for the highest-altitude parachute jump, floating a balloon well into the stratosphere before its pilot leaps out for a supersonic free fall. The team behind the Red Bull Stratos mission announced details of the attempt here Friday morning in a media briefing. If all goes as planned, a towering helium balloon will loft Austrian-born skydiver and BASE jumper Felix Baumgartner, 40, roughly 37 kilometers into the air before he begins his descent. (BASE stands for "buildings, antennas, spans, Earth"—the places and structures from which a BASE parachutist...