Could this be the sequel to Man on a Wire? Nik Wallenda, a 34-year-old high-wire artist, will attempt the impossible Sunday: crossing the Grand Canyon on a tightrope, 1,500 above Little Colorado River Gorge. Wallenda will be walking on a two-inch-thick cable, one that he's traveled on many times. The only catch: he won't be wearing a safety harness. "I give my wife and kids a hug and a kiss and tell them I'll see them in a bit," he told reporters of the moment before he starts a walk. If anyone can achieve the feat, it's Wallenda, who is a seventh-generation high-wire artist.