J an. 28, 1986, was a day that changed Rashid Johnson. He remembers the TV set being rolled into his elementary-school classroom in Evanston, Ill.He remembers watching with his classmates as the space shuttle Challenger flew into the air and transformed into a stream of white cloud. “I remember how that affected my thinking, recognizing that failure was possible amongst adults, amongst folks who we were supposed to trust,” says the artist, sitting in his spacious Brooklyn studio, surrounded by