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Correct definition of Mode III, more detail specific to Saturn IB and V
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m →Details: clean up, typo(s) fixed: seperate → separate using AWB
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**'''Mode IC (one charlie):''' From 30.5 km (100,000 ft, or about 19 miles) until the LES is jettisoned, turning the CM-LES combination around into the CM-forward position would still be necessary, but in the now thin air the canards are useless. Instead, the small engines of the CM's reaction control system ([[Reaction control system|RCS]]) would do the job. During One-Charlie, the first staging occurs, that is the jettisoning of the spent first stage and ignition of the second stage. One-Charlie ceases about 30 seconds after the staging when the LES is jettisoned, at an altitude of about 90 km (295,000 ft or 55 miles). |
**'''Mode IC (one charlie):''' From 30.5 km (100,000 ft, or about 19 miles) until the LES is jettisoned, turning the CM-LES combination around into the CM-forward position would still be necessary, but in the now thin air the canards are useless. Instead, the small engines of the CM's reaction control system ([[Reaction control system|RCS]]) would do the job. During One-Charlie, the first staging occurs, that is the jettisoning of the spent first stage and ignition of the second stage. One-Charlie ceases about 30 seconds after the staging when the LES is jettisoned, at an altitude of about 90 km (295,000 ft or 55 miles). |
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*'''Mode II:''' With the LES gone, the [[Apollo Command/Service Module|Command/Service Module]] (CSM) would separate as a whole from the rocket and use its large engine and RCS engines to move clear of the rocket and align itself. The CM would then separate from the SM and splash down. |
*'''Mode II:''' With the LES gone, the [[Apollo Command/Service Module|Command/Service Module]] (CSM) would separate as a whole from the rocket and use its large engine and RCS engines to move clear of the rocket and align itself. The CM would then separate from the SM and splash down. |
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*'''Mode III:''' For use when a Mode II type abort would risk the spacecraft coming down over land, or landing in the cold waters of the North Atlantic. The CSM would |
*'''Mode III:''' For use when a Mode II type abort would risk the spacecraft coming down over land, or landing in the cold waters of the North Atlantic. The CSM would separate from the rocket in the same manner as a Mode II abort, but would additionally use the SPS engine to make either a posigrade burn (Mode IIIA) or retrograde burn (Mode IIIB) to land in a specific area on the eastern side of the Atlantic. Mode III was only available as a primary abort mode for 10–15 seconds during a Saturn IB launch, and was only used as a backup abort mode for Saturn V launches, in case of an abort requiring the immediate landing of the spacecraft. |
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*'''Mode IV:''' Abort during [[S-IVB]] burn. Should the S-IVB fail, the Service Module engine can place the CSM in Earth orbit to perform an Earth-orbit mission. |
*'''Mode IV:''' Abort during [[S-IVB]] burn. Should the S-IVB fail, the Service Module engine can place the CSM in Earth orbit to perform an Earth-orbit mission. |
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*'''Mode V:''' Only planned for the [[Apollo-Soyuz Test Project]] launch. In the event of an early S-IVB shutdown, the CSM RCS thrusters would be used to insert the entire stack (including the docking adapter) into orbit. The time window for a Mode V abort was only 1.5 seconds before nominal S-IVB cutoff. |
*'''Mode V:''' Only planned for the [[Apollo-Soyuz Test Project]] launch. In the event of an early S-IVB shutdown, the CSM RCS thrusters would be used to insert the entire stack (including the docking adapter) into orbit. The time window for a Mode V abort was only 1.5 seconds before nominal S-IVB cutoff. |
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During the launch of an Apollo spacecraft by the Saturn IBorSaturn V rocket, the flight could be aborted to rescue the crew if the rocket failed catastrophically. Depending on how far the flight had progressed, they would use different procedures or modes. None of these launch abort modes was ever used on any of the fifteen manned 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.
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:
Apollo's planned-for abort modes were, in chronological order:
For Saturn V launches, two additional abort modes were available:
During orbital abort phases (S-IVB to COI, S-IVB to orbit and Mode IV), modes II and III were available as backup modes in the event of further problems.
The EDS is enabled for the pad abort (beginning 5 minutes prior to launch) through abort mode IB phases. Beginning in mode IC, the EDS is switched off and aborts must be commanded manually.
