Apollo abort modes were procedures by which the nominal launch of an Apollo spacecraft, either the Saturn IB or Saturn V rocket, could be terminated. The abort of the flight allowed for the rescue of the crew if the rocket failed catastrophically. Depending on how far the flight had progressed, different procedure or modes would be used. In the history of the Apollo Program, none of the abort modes were ever used on any of the fifteen crewed Apollo spacecraft flights. Houston's announcements of the current abort mode and the spacecraft commander's acknowledgements were among the few things said on the radio link during the first minutes of flight. If the rocket failed during the first phases of the flight, the Emergency Detection System (EDS) would automatically give the command to abort. The reason is that life-threatening situations can develop too fast for humans to discuss and react to. In the later, less violent phases of the ascent, the EDS was turned off and an abort would have to be initiated manually. Overview Of the five abort modes, the modes up to three (III) are variations of jettisoning the entire rocket followed by an immediate landing in the sea (splashdown). Mode four (IV) and the Saturn V-specific modes are variations of jettisoning only the failing rocket stage, using the other stages to continue into Earth orbit. Once there, a backup Earth-orbit mission could be performed so that the flight was not entirely in vain. In all cases, the Command Module (CM) with the astronauts performs a splashdown by: Dumping the hypergolic fuel overboard since the toxic substance would be an unnecessary risk to recovery personnel. If high enough, deploying high-speed parachutes (drogue parachute). Jettisoning the drogues and deploying the main parachutes. Splashing down in the sea and waiting for recovery team to arrive Pad Abort If the rocket failed in the last five minutes before launch, the CM and the launch escape system (LES, see figure) would separate from the remainder of the rocket below with the LES propelling itself and the CM beneath it upward and eastward to the sea using a small solid-fueled motor (the launch escape motor) at the top of the tower on the launch escape system. The launch escape tower would then be jettisoned in anticipation of the parachute deployment and the CM would splash down. (Preparation for a pad abort is seen in Apollo