SAVANNAH, Ga.—The National Park Service is pushing back after a U.S. government report recommended approval of a launch pad for commercial rockets on the Georgia coast, saying a chance of explosive misfires over a federally protected island popular with tourists and campers poses an “unacceptable risk.” Camden County in Georgia’s coastal, southeast corner has spent nine years and $10 million seeking permission to build what would be the nation’s 13th licensed commercial spaceport. The proposed Spaceport Camden took a big step forward in June, when the Federal Aviation Administration issued a final environmental impact study that concluded building the spaceport would be its “preferred alternative.” Now the Park Service and its parent agency, the U.S. Department of the Interior, are disputing the FAA’s conclusion that the spaceport poses minimal risks or adverse impacts to Cumberland Island, a federally protected wilderness. The island, known for wild horses and nesting sea turtles, …