Many manned spacecraft have had an "escape tower" to propel the crew capsule safely beyond the booster, if an abort is needed. What prevents the booster from simply continuing into the path of the crew capsule? Is there some form of lateral propulsion that moves the crew capsule out of the way of the booster?

  • $\begingroup$ A faster acceleration is needed for the separation of the launch escape system from the booster anyway. But a booster malfunction requiring the escape would not necessarily continue the desired trajectory of the booster. The probability is low, but with bad luck both the booster and the escape system will turn to the same direction. Increasing the distance fast between both is essential. $\endgroup$
    – Uwe
    Commented Nov 6, 2018 at 13:25

2 Answers 2


Is there some form of lateral propulsion that moves the crew capsule out of the way of the booster?


The Saturn-Apollo LES, for instance, has a solid rocket mounted sideways at the tip, the “pitch control motor”.

In abort mode Ia, used for low altitude aborts when the booster is still flying nearly vertically, this fires briefly along with the main solid rocket motors to turn the LES/command module stack away from the booster’s path.

Once the launcher has tilted sufficently off the vertical, starting at around 3km altitude, other abort modes are used, that don’t use the pitch motor; gravity instead does the job of separating the booster trajectory from the LES trajectory.

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    $\begingroup$ It also had canards $\endgroup$
    – user20636
    Commented Nov 7, 2018 at 6:44
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    $\begingroup$ The canards don’t deploy until after the escape motors burn out; they flip the LES-CM stack to fly blunt-end first, in preparation for LES jettison and parachute deployment. $\endgroup$ Commented Nov 7, 2018 at 10:28
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    $\begingroup$ Detailed functional description of the LES here: hq.nasa.gov/alsj/CSM15_Launch_Escape_Subsystem_pp137-146.pdf $\endgroup$ Commented Nov 7, 2018 at 10:33

The escape system is specifically designed to get away from the booster, and the key is to get away from it initially, and while still under thrust move to the side such that the booster will pass right by you. You can see this in the flight test of escape systems, some included below.


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