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{{short description|Soyuz spacecraft emergency crew rescue systems}}
[[File:Jsc2006e11326.jpg|thumb|right|alt=Upper section of Soyuz TMA-8 during assembly|The capsule and escape system of the [[Soyuz TMA-8]] mission during assembly]]
In the event of catastrophic failure, the [[Soyuz (spacecraft)|Soyuz spacecraft]] has a series of automated and semi-automated abort modes (Rus. Система аварийного спасения (САС)) (literally - System for Emergency Rescue (SER)) to rescue the crew. The abort systems have been refined since the first
==Launch abort modes==
The Soyuz abort systems are especially complicated because of the modular design of the vehicle; only the middle descent module is designed to survive reentry, so in an emergency, the orbital module and the descent module must be separated together (sometimes with the service module also attached) before the descent module can be separated and orient itself for reentry. Other Soviet spacecraft, like the [[TKS (spacecraft)|TKS]], attempted similar modular designs with a hatch through the heat shield to resolve this issue.<ref name="astronautix">{{cite web|title=Soyuz|url=http://www.astronautix.com/s/soyuz.html|archive-url=https://web.archive.org/web/20160820153043/http://www.astronautix.com/s/soyuz.html|url-status=dead|archive-date=August 20, 2016|publisher=www.astronautix.com|
===Jettisonable emergency escape head section===
[[File:Soyuz launch pad abort sequence.svg|thumb|right|alt=image showing stages of Soyuz pad abort, refer to caption|The Soyuz pad abort procedure. The Image shows from left to right: 1) The firing of the SAS carrying the orbital module, descent module and a portion of the payload fairing from the launch vehicle 2) The separation of the descent module from the rest of the assembly 3) The deployment of parachutes and separation of heat shield 4) The firing of landing engines]]
The primary abort system for use early in the flight is the Jettisonable Emergency Escape Head Section, known by its Russian abbreviation OGB SAS or just SAS. It is a [[launch escape system]] designed by a team from [[OKB|OKB-1]] under [[Sergei Korolev]]'s leadership.<ref name = zak>{{cite web|last1=Zak|first1=Anatoly|title=Emergency escape system of the Soyuz spacecraft|url=http://www.russianspaceweb.com/soyuz_sas.html|website=www.russianspaceweb.com|
The SAS can be used to separate the Soyuz capsule from the launch vehicle up to about two anda half minutes into powered flight. The launch escape system can be triggered by onboard computers or by radio communication from ground crews. The onboard computers use instruments to detect several possible failures including premature separation of stages, loss of pressure in combustion chambers, and loss of control of the launch vehicle.<ref name = zak/> Once triggered, struts are deployed to secure the descent module to the orbital module until after the escape motors are burnt out and jettisoned. After this, the descent module is separated, its heat shield is jettisoned, and its parachutes are deployed.<ref name = 'spaceflight 101'/>
Beginning with the [[Apollo-Soyuz Test Project]], the Soyuz spacecraft also has a secondary set of four rocket motors at the top of the fairing that can propel the escape head section away from the rocket during the period between the jettisoning of the SAS at T+115s until fairing deployment at T+157s. In contrast to the SAS these rockets only move the escape head section a small distance away from the rocket, as at these altitudes there is enough time for the landing system to deploy.<ref name="hall & shayler"/>
===Other abort procedures===
In early Soyuz models, there were two abort modes in the time ranging from the ejection of the launch escape system until orbit. One called for separation of only the upper two modules and a controlled descent and could be initiated before about T+522s, the other separated all three and underwent a ballistic descent after T+522.<ref name = 'hall & shayler'>{{cite book|last1=Hall|first1=Rex|last2=Shayler|first2=David J.|title=Soyuz: A Universal Spacecraft|date=2003|publisher=Praxis Publishing Ltd.|location=Chichester, UK|isbn=1-85233-657-9|page=70|url=https://books.google.com/books?id=dbGchpi1HP8C&pg=PA67}}</ref>
Unlike the [[
==Reliability==
An analysis of the overall reliability of the Soyuz capsule was published in the years leading up to the [[retirement of the Space Shuttle]] in 2010 by individuals from [[Johnson Space Center|NASA JSC]] and the [[ARES Corporation]]. The report concluded that the current
Following a malfunction in the central thrust chamber of the launch escape system when it was routinely jettisoned during the 2009 [[Soyuz TMA-15]] launch, concerns were raised by officials with NASA and Russian organizations (including the [[TsNIIMash|Machine Building Central Research Institute]]) about the quality control and reliability of Soyuz emergency systems.<ref>{{cite news|last1=Oberg|first1=James|title=Russians report snag in space safety system|url=http://www.nbcnews.com/id/36119843/ns/technology_and_science-space/#.Vy4ao2OMCCQ|
==Soyuz abort history==
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| 5 April 1975 || [[Soyuz 7K-T No.39|Soyuz 18a]] || Second stage separation failed prior to third stage ignition. The flight control computer detected a trajectory deviation and triggered an automated abort. Since the escape tower had already been jettisoned, the service module engines were used for the abort.<ref name="shayler" >{{cite book | title= Disasters and Accidents in Manned Space Flight | last= Shayler | first= David | year= 2000 | page= 159 | publisher= Springer Praxis| isbn= 1-85233-225-5}}</ref>
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| 26 September 1983 || [[Soyuz 7K-ST No.16L|Soyuz T-10-1]] || The rocket caught fire on the pad. The launch escape system was fired, pulling the spacecraft free two seconds before the rocket exploded. This is, to date, the only successful
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| 11 October 2018 || [[Soyuz MS-10]] || The [[Soyuz-FG]] rocket experienced an anomaly during staging, when one of the boosters hit the core stage and damaged the second stage. The launch escape system pulled the spacecraft free of the rocket.<ref>{{cite news |last1=Bodner |first1=Matthew |title=Soyuz investigators {{sic|hone|hide=y}} in on booster separation, promise conclusions Oct. 20 |url=https://spacenews.com/soyuz-investigators-hone-in-on-booster-separation-promise-conclusions-oct-20/ |work=Space News |date=12 October 2018}}</ref>
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| 10 April 1979
| [[Soyuz 33]]
| The [[
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[[Category:Soyuz program]]
[[Category:Abort modes]]
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