Getting to space requires ruthlessly eliminating weight from launch vehicles. Older spacecraft like Apollo carried big Launch Escape towers. For an Apollo mission flying on a Saturn V, the LES meant carrying an extra 8,000 pounds to an altitude of 295,000 feet, at which point it was jettisoned by firing the Tower Jettison Motor (source). Did NASA ever consider using the main Launch Escape Motor for added boost once the spacecraft was above the abort altitude instead of just throwing away the launch escape rockets?

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    $\begingroup$ I don't know if it was ever contemplated. It would produce 650kN of force trying to pull the CM away from the service module that would have to be designed for, which is about 12 times the weight of the CM; at all other times in the mission, the CM/SM interface would be in compression from 0g to about 4g. $\endgroup$ – Russell Borogove Apr 22 at 0:00
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    $\begingroup$ The CM weighs about 5 1/2 tons. At the point of tower jettison, the stack still consists of at lest the S_II, S-IVB and full CSM. The S-IVB and CSM wheigh 150 tons, the S-II comes in at 480tons. not much delta-v to get from the tower. You'd need to keep it until after trans-lunar injection to get any appreciable delta-v (after the S-IVB is gone). And at that pint, when you are already on the wa to the moon, the usefulness of additional thrust/delta-v seems questionable. $\endgroup$ – Polygnome Apr 23 at 13:04

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