Introduction

Apollo Mission Techniques books contain all the necessary wisdom and knowledge to handle trajectory control of a given mission, providing decisional inputs and guidance to a number of documents, including Crew Procedures, Checklists, Flight Plans, Flight Control Procedures and Mission Rules.

In the words of Bill Tindall, the main architect behind the huge effort that led to the development of Apollo Mission Techniques, defining trajectory control means "to figure out how the various components of the guidance, navigation and control ( GNC) systems and, to some extent, the engines, are to be used during all phases of each of the manned Apollo missions". Also, "activities associated with trajectory control constitute by far the largest piece of operational overhead in any Apollo mission" and "the manner of conducting them has an impact on almost every other facet of the mission". Therefore Mission Techniques were born "to consider all of these things in the development of the overall trajectory-control procedures" [1].

Mission Tecniques are mainly abort-oriented, in the sense that they not limit the scope on the nominal execution of each mission phase. They readily extend to cover all the possible not-nominal cases, defining what 'not-nominal' is applicable to each phase. Also, it is noted that "operation planning on all manned space flights so far has been based on a philospophy of cross-checking and monitoring every critical system and operation to make sure that the systems are performing properly". This of course applies even more so during during critical mission phases (like the execution of maneuvres). And the monitoring task is compounded by the availability of multiple data sources to compare and select, introducing in the scheme also a data prioritization job. Planning therefore does not limit itself to the availability of primary GNC systems, but extends to backups or other components that can be used to accomplish a given task within limits and constraints. 

Definition of limits and constraints is also part of the Mission Techniques payload, and these definitions may change according to mission requirements (this is one of the reasons why in general Mission Techniques books were subject to update after every mission, or at other interval). In addition, the fact that ground-based control and tracking are an integral part of the mission, means that many data exchanges between ground and spacecraft have to be coordinated in the overall techniques scheme. Again, in the words of Tindall, "a tremendous amount of data must be relayed back and forth between the spacecraft and the ground, and the content and format of these data have to be complete and precisely compatible". Defining requirements of data and procedures to control their exchange is another part of the Mission Techniques content.

To conclude with Tindall's words, "Mission Technique documents describe precisely how all of this is done and the reason for doing it that way". For this reason we think that Mission Techniques Books are one of the greatest testaments of the Apollo program as they explain how, using Apollo hardware and software, to land a man on the moon and return him safely to the Earth.

Disclaimer

This short guide is limited to the Mission Techniques published from the beginning up to Apollo 17 (mission J-3). Additional books were published for Skylab and ASTP but they are not treated here (for now).

Mission Techniques Books

Mission Techniques books are arranged according to mission phases basically coincident with the major phases of a lunar landing mission flight plan. The books are arranged in such a way as to provide a precise breakpoint between each phase with a clear definition and, of course, a stable situation at the beginning and ending of each phase.

In general, Apollo planning deals with a mission divided into the following phases:

Pre-launch

Earth Launch and Earth orbit insertion

Earth parking orbit

TransLunar Injection burn

Transposition and docking

TransLunar Coast (includes MidCourse Corrections)

Lunar Orbit Insertion (two different burns)

Lunar Orbit, which includes LM activities:

	Descent Orbit Injection

	Lunar Landing

	Lunar Ascent

	Rendezvous

TransEarth Injection burn

TransEarth Coast (includes MidCourse Corrections)

Entry, with two possible scenarios:

	Entry from Earth parking orbit

	Entry from transearth coast

As Mission Techniques books are concerned more with trajectory control, static phases are not described or discussed (it is noticeable, for instance, any reference in the nominal techniques about the transposition and docking maneuver is lacking).

What follows is a list of the Mission Techniques phases, according to trajectory control procedures and with reference to each of the relevant Mission Techniques books.

Launch phase

Book title: Apollo Mission Techniques, Launch Phase Aborts

This phase starts at Saturn booster ignition and ends with a successful Earth orbit insertion (i.e. engine cut-off upon achievement of target orbital speed, or propellants depletion). 

This book includes also all the possible abort modes, many of them leading to a Earth landing instead of orbit insertion. This is a rather unique instance because for the other mission phases all the contingencies are collected in a separate book.

Please note that there are two separate editions for the book, one for Saturn IVB boosters and one for Saturn V boosters.

Earth orbit and TLI

This phase starts after a successful Earth orbit insertion and deals with both the preparatory work and the execution of the TLI burn. It ends with TLI burn cutoff.

TransLunar Coast and LOI

Book title: Apollo Mission Techniques, Translunar Midcourse Corrections and Lunar Orbit Insertion

This phase starts after a successful TLI burn and includes the planning and execution of the midcourse maneuvres and the targeting and execution of both lunar orbit insertion burns. It ends with the LOI-2 burn cutoff.

Lunar Orbit

Book title: Apollo Mission Techniques, Lunar Orbit Activities

This phase includes four main sub-phases concerned with trajectory control of the CSM+LM ensemble or the CSM alone.

The first sub-phase includes the Descent Orbit Injection (LM only for missions G and H-1, CSM/LM for missions H-2 and subsequent). The second sub-phase starts with the CSM/LM undocking and ends with the beginning of the LM powered descent (for LM), including CSM circularization, if applicable, and powered descent following (for CSM). The third sub-phase includes all the activities related to LM rendezvous and docking. The fourth sub-phase starts after CSM/LM docking and includes LM jettisoning and preparation for TEI burn.

Lunar Descent

Book Title: Apollo Mission Techniques, Lunar Descent

This phase starts after CSM/LM undocking and more precisely at activation of program P63 (Powered Descent). It ends 2 minutes after a successful touchdown (TD+2) with the selection of program P68.

Abort from Lunar Descent

Book Title: Apollo Mission Techniques, Abort from Lunar Powered Descent and Subsequent Rendezvous

This phase applies from DOI + 10 minutes (Missions F, G, H-1), or after CSM circularization (missions H-2 and subsequent) and ends after landing at time T2 (about touchdown + 10 minutes). The phase ends with rendezvous procedures with both LM-active and CSM-active cases.

Lunar Surface

Book Title: Apollo Mission Techniques, Lunar Surface Phase

This phase starts after selecting program P68, at lunar touchdown + 2 minutes, and include the pre-launch activities performed in the LM and also the CSM.

Lunar Ascent

Book Title: Apollo Mission Techniques, (Lunar) Powered Ascent

This phase starts with a nominal lunar launch (see also Manual Ascent) and ends with the insertion into lunar orbit, from which a standard rendezvous with CSM (LM-active) will be performed.

Lunar Manual Ascent

Book Title: Apollo Mission Techniques, Manual Ascent

This phase provides a contingency plan for the manual execution of the lunar ascent with degraded/failed PGNCS/AGS. It starts from the lunar launch and ends with the insertion into lunar orbit. The book also provide details about the execution of rendezvous (in general CSM-active, with PGNCS/AGS assumed failed).

TEI and TransEarth Coast

Book title: Apollo Mission Techniques, Transearth Injection Midcourse Corrections and Entry

This phase starts with the execution of the TEI burn and includes the planning and execution of the midcourse maneuvres for the targeting of a correct atmospheric entry. It ends with the Earth landing.

EPO, Retrofire and Entry

Book title: Apollo Mission Techniques, Earth Parking Orbit, Retrofire and Entry Procedures

This phase deals with a CSM in Earth orbit and the activities leading to the planning and execution of a retrofire burn and the subsequent entry and Earth landing. The book never appears in the official list of Mission Techniques books for a lunar landing mission, but it is evidently used for other missions or for the Earth orbit alternate missions (planned, but never performed).

Contingency procedures

Book Title: Apollo Mission Techniques, Contingency Procedures

This books deals with all the phases for which contingency situations management has not already been provided. In more detail, it provides procedures for the following phases: Earth parking orbit, TLI and Transposition and Docking, TransLunar Coast, LOI and Lunar orbit, TEI and TransEarth Coast. It also provides procedures for navigation in loss of communications conditions.

Auxiliary Books

Book Title: Apollo Mission Techniques, Tracking Data Selection Controllers Procedures

This book provides details about the logic behind the selection of the right tracking information among those that are available to flight controllers.

Book Title: Apollo Mission Techniques, Attitude Reference Inizialization

This book provides details about the different attitude reference matrixes (REFSMMAT) selectable according to the different flight phase.