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Flying the Shuttle - Abort Procedures Overview: Difference between revisions
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Flying the Shuttle - Abort Procedures Overview (view source)
Revision as of 14:27, 14 May 2016
, 14 May 2016→Abort once Around
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== Abort once Around == | == Abort once Around == | ||
Requiring more energy than a TAL but slightly less than is needed to reach a safe orbit, the Abort once Around ( | Requiring more energy than a TAL but slightly less than is needed to reach a safe orbit, the Abort once Around (AOA) would typically be used if there is a systems problem during ascent that requires to get the Shuttle down in a relatively short time or if there is a problem with the OMS engines in addition to an underspeed due to engine loss prior to MECO that means maneuvering is severely limited. | ||
During the AoA, the Shuttle flies a depressed ballistic trajectory around the whole Earth, including a normal de-orbit burn and entry to land at the launch site. The decision to abort to ground rather than to orbit does not have to be made until the OMS-1 burn. | During the AoA, the Shuttle flies a depressed ballistic trajectory around the whole Earth, including a normal de-orbit burn and entry to land at the launch site. The decision to abort to ground rather than to orbit does not have to be made until the OMS-1 burn. | ||
Once the OMS-1 burn is done, the AOA can be selected on OPS 105 via item 35 as value 4 or 5 and executing the resulting maneuver. Here, item 4 calls a burn target for a nominal entry trajectory and should be chosen if OMS propellant is not limited, item 5 calls a target for a shallow entry trajectory and should be chosen if OMS fuel is limited. Such a shallow entry might require pre-bank to ensure atmospheric capture and is in general difficult to target (see the Shuttle operations manual for details). | |||
Technically, the AOA target should be called in OPS 1, then the OPS transition to OPS 3 should be made, then the de-orbit burn should be computed and executed using OPS 3 software. | |||
During an AOA, the APUs keep running till touchdown and rollout to minimize problems with re-starting APUs - however to minimize fuel consumption the 'pressure select' switch is set to low during the orbital flight phase when the hydraulic system is not needed and only switched back to 'high' in preparation for entry. | |||
An AOA gets the Shuttle back on the ground about one hour and 45 minutes after liftoff. | |||
== We're going to Africa! - a TAL tutorial == | == We're going to Africa! - a TAL tutorial == | ||