Columbia Gorge Discovery Center will open a new traveling exhibit this weekend that follows the 1843-44 travels of Lt. John Fremont on his expedition to map the Pacific Northwest.  Discovery Center Marketing Manager Susan Buce says Fremont was an unlikely hero and colorful character who eventually made a bid for President,  and he stopped in The Dalles along with Kit Carson at the Wascopam Mission.  The exhibit opens to the public on Saturday, and will be at the Center at least through the early summer.  Saturday’s opening will feature a 1 p.m. presentation by Bill Cossitt, who will talk about the search for Fremont’s howitzer believed abandoned in the Sierra Mountains in January 1844.