China launched a new trio of reconnaissance satellites over the weekend on a mission that also marked the 500th Long March rocket launch. A Long March 2D rocket lifted off from Xichang Satellite Launch Center at 8:58 p.m. EST on Dec. 9 (0158 GMT, or 9:58 a.m. Beijing time, Dec. 10). The rocket rose into blue skies above the hills surrounding the spaceport , trailing a purple and orange exhaust plume produced by its hypergolic propellant mix. Aboard were a fifth group of three Yaogan-39 satellites. Like previous Yaogan-39 launches, the trio of spacecraft entered orbits with an altitude of…