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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Apollo abort modes | 2/2 | https://en.wikipedia.org/wiki/Apollo_abort_modes | reference | science, encyclopedia | 2026-05-05T12:32:59.476103+00:00 | kb-cron |
== Mode IV == Mode IV was an abort mode that occurred during the S-IVB burn. Should the S-IVB fail, the Service Module engine can place the CSM into Earth orbit to perform an Earth-orbit mission.
== Mode V == A Mode V abort was only planned for use during 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.
== Saturn V specific abort modes == 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 was enabled for the pad abort (beginning 5 minutes prior to launch) through abort mode IB phases. Beginning in mode IC, the EDS was switched off and aborts would have had to be commanded manually.
=== S-IVB to COI === ("Saturn IV-B (NASA's designation for the Saturn V's third stage burn) To Contingency Orbit Insertion") In case of a failure of the S-II second stage, the stage would be jettisoned, and the rocket is high and fast enough that the S-IVB third stage, followed by the Service Module (SM) engine, has enough propellant to place the spacecraft in Earth orbit. There would not be enough propellant to perform trans-lunar injection, so only an Earth-orbit mission would be performed.
=== S-IVB to Orbit === The failing S-II would again be jettisoned, but Earth orbit insertion is now possible by the S-IVB alone. Other than not using the SM engine, this is identical to an S-IVB to COI abort.
== See also == Apollo pre-launch abort modes Space Shuttle abort modes Orion abort modes Soyuz abort modes
== Notes ==
== References == ASTP Recovery Requirements - NASA History Office NASA TN D-7083: Launch Escape Propulsion Subsystem NASA TN D-6847: Apollo Experience Report—Abort Planning Apollo 11 Glossary - spacelog.org Archived 2019-05-13 at the Wayback Machine