The propulsion systems available for abort during the launch phase are as follows:
Figure 1 shows a summary of the abort modes for the launch phase and through what region of the launch burn they apply. These modes are shown as a function of the burn time as well as the respective launch vehicle stage. The black bar des- ignates the prime mode while the striped bar represents the optional or backup modes of abort.
Note that the first mode is the LES or launch escape system mode which is prime from the pad throughout the S-I stage and extending on for a few seconds into the S-II burn before LES, jettison. As shown in figure 2, a LES abort consists of the LES propulsion system separating the Commnand Module from the stacked launch vehicle configuration and providing an adequate altitude and downrange translation. This is followed by the orientation of the Command Module with heat shield for- ward for reentry. Landing occurs in a continuous Atlantic recovery area along the flight azimuth up to a maximum down range of approximately 400 nautical miles.
The next mode is the suborbital free-fall abort. This mode, as shown in the summary chart, begins where the LES is jettsoned and remains available until approximately halfway through the S-IVB burn. Note that this mode is prime through approximately the first half of the S-II burn and through half of the S-IVB burn. It is considered an optional mode through the second half of the S-II burn because of the availability of a contingency; orbit insertion with the S-IVB, which will be discussed below.
As shown in figure 3, the suborbital free-fall mode consists of CSM separation from the launch vehicle using Service Module RCS, a 10-second SPS burn to gain further separation from the launch vehicle, Service Module jettison, and Command Module orientation (heat shield forward) for re entry. Landing would be in the continuous Atlantic recovery area along the flight azimuth up to 3,200 nautical miles downrange.
An extension of the suborbital abort mode can be achieved by addition of another SPS burn for landing area control, as shown in the summary of abort modes in figure 1. This mode is available as an option during the second half of the S-IVB burn when the suborbital free-fall mode is no longer available.
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