By Rick Nathanson / Journal Staff Writer   Retiring Albuquerque pilot Elaine Thacher, 85, fires up the burners on her hot air balloon Saturday morning. For Thacher, the 50th Albuquerque International Balloon Fiesta will be her last. (Roberto E. Rosales/Albuquerque Journal) Nothing could dampen the spirit of balloon pilot Elaine Thacher — not the thick clouds blanketing the sky and obscuring the Sandias, not the 50-degree temperatures, not even the light mist that fell nonstop over Balloon Fiesta Park, making an already soggy launch field even wetter. It's was all good to Thacher, who at 85 was the oldest pilot...