Photo courtesy of Smithsonian Air and Space Museum So this is how we got to spy on Boris and Natasha. For today only, until 5:30 p.m., the Smithsonian Air and Space Museum will be hosting a free, public viewing of the newly declassified HEXAGON (KH-9) satellite in the parking lot of the Steven F. Udvar-Hazy Center. The now hefty, ten-foot in diameter relic of the cold war took pictures of the Soviet Union and…