By Daniel Wiessner (Reuters) -SpaceX on Thursday sued a U.S. labor board that had accused the rocket and satellite maker of illegally firing employees who sent a letter to company executives calling CEO Elon Musk “a distraction and embarrassment.” SpaceX in the lawsuit filed in Brownsville, Texas federal court claims the structure of the National Labor Relations Board(NLRB), which issued a complaint against the company on Wednesday, violates the U.S. Constitution. The NLRB alleges SpaceX violated federal labor law by firing eight workers in 2022 for signing onto the letter, which accused Musk …