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APOLLO EARTH RETURN ABORT CAPABILITIES

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Introduction

It has always been a stated desire, as regards Project Apollo, to have continuous abort-to-earth capability throughout the entire lunar landing mission. This paper will examine the capability of the spacecraft to satisfy this objective through each mission phase of the lunar landing mission. The abort capability will be discussed primarily from a performance standpoint. In other words examining whether or not the spacecraft has the necessary performance required for continuous abort capability through— out the mission, Portions of the mission where redundancy exists will be pointed out as well as portions of the mis- sion which are critical or marginal as regards abort capa- bility. The primary ground rules for this discussion are as follows;

a.

The only objective considered as regards earth return aborts is the safe return of the Crew. No alternate mission objectives are considered.

b.

Only spacecraft abort capability after an abort decision has been made will be dismissed. In other words, an assessment or the spacecraft capability to recognize an abort situation will not be included.

c.

Only one, or at the most two, burn abort maneuvers will be considered since more sophisticated multiple burn maneuver sequences are not required to provide adequate abort capability.

The items which will be discussed for each mission phase are as follows:

a.

The characteristics of the trajectories from which aborts could be required will be described. This includes any trajectory which might result from an underburn or an overburn during any of the major power flight maneuvers.

b.

The basic abort modes or procedures will also be briefly described. Where possible, the mode considered prime will be pointed out along with the modes which are optional or backup, The computer logic required to provide all of these abort modes and procedures are currently

beinq imlemented in the real time ground computer system.

c.

The capability of the spacecraft of actually performing abort maneuvers will be disscussed. Included here will

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