Mixing powerful and deeply moving footage with telling forensic analysis, Horizon reveals what really went wrong on the Space Shuttle Columbia. The film's final revelation is telling. If NASA had acted differently, all seven astronauts could have been brought back to Earth alive. The film begins with the astronauts' final moments and shows the haunting scenes at Mission Control at the moment the disaster struck. What then follows is a disturbing detective story as the investigators gradually realise that the tragedy was caused by the failure of a small panel on the shuttle's left wing that had been built to be indestructible. No one had ever thought such an accident was possible. It has led to the shuttle being grounded for the foreseeable future. But that wasn't all. The film also shows that NASA had a number of options to bring the crew back safely - if only it had commandeered a spy telescope to visually inspect the damage. It could even have launched a rescue mission.