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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 14:19, 14 May 2016
, 14 May 2016→Abort to Orbit
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An ATO follows a relatively late loss of an engine during ascent. Dependent on payload and target inclination, a <i>partial</i> OMS fuel dump is initiated early on to reduce the weight that is accelerated and thus gain extra velocity.At MECO, the Shuttle is typically delivered into an unstable orbit with the periapsis inside the atmosphere, thus an immediate OMS-1 burn is executed to push the Shuttle onto a rising orbit with a 105 mile periapsis, followed by a circularization OMS-2 burn at the periapsis. | An ATO follows a relatively late loss of an engine during ascent. Dependent on payload and target inclination, a <i>partial</i> OMS fuel dump is initiated early on to reduce the weight that is accelerated and thus gain extra velocity.At MECO, the Shuttle is typically delivered into an unstable orbit with the periapsis inside the atmosphere, thus an immediate OMS-1 burn is executed to push the Shuttle onto a rising orbit with a 105 mile periapsis, followed by a circularization OMS-2 burn at the periapsis. | ||
The ATO is declared using item 2 and 3 of SPEC 51, and the fuel dump is programmed using items 6, 7 and 9. Item 50 allows to throttle the remaining engines up to 109% of nominal power which further reduces the expected underspeed at MECO. | |||
[[File:Shuttle avionics spec51.jpg|600px|OVERRIDE display of the Space Shuttle]] | |||
Following MECO, the OMS-1 burn can be quickly called up setting item 35 (abort target) to a value of 1 and loading and executing the resulting target. | |||
[[File:Shuttle avionics mnvr exec.jpg|600px|MNVR EXEC display of the Space Shuttle]] | |||
Dependent on the state afterwards, selecting item 35 again with a value of 3 calls up the circularization burn target whereas values of 4 and 5 are used to quickly program the Abort once Around. | |||
All in all, ATO is considerably less hectic than either RTLS or TAL and the workload resembles that of a nominal arrival in orbit. | |||
== Abort once Around == | == Abort once Around == | ||