We pulled up outside the sloped, fire-scorched wall of a concrete launch bunker. The Mars rocket towered on its pad, surrounded by four twenty-story hinged gantries. Wisps of cloud poured down from the rocket’s liquid-oxygen ports. Dozens of technicians in white coats and hard-hats clambered on the skeletal gantry-ladders, or shouted through bullhorns around the rocket’s huge base.