This is a 1 Troy Oz. .999 Fine Silver bar made by International Silver Ingot Co. in 1986 for J.P. Clark as a tribute bar to the Space Shuttle Challenger. Only 25 of this RARE serial number bar was made. This one is number 000.  It is listed in the silver art bar guidebook as number ISIC-44. Our research shows that other serial numbers are:  080, 131, 1000, 1003, 1040, 1084, 1109, 1117, 1179.