Manned Lunar Landing Via Rendezvous

In any mission description, the vehicles, the
flight profiles, and the astrionics hardware to im-
plement the mission are all tightly interwoven
things. A final result evolves only after many
iterations to the solution are made. This paper
will describe one of these iterations in the Saturn
C-5 Earth Orbit Rendezvous approach to the
Manned Lunar Landing Program. Since the iter-
ation to be described in an nthone, there exists
some basis for the hope that the perturbation from
the final solution is small.
This paper is not concerned with the landing
itself, but only with those operations leading to
injection of the space craft into the lunar trans-
fer trajectory. However, as is to be expected,
it is the target conditions which set the pace for
the overall operation. The entire operation must
be sized to culminate at a time and place which
places the lunar target in an attainable position.
The procedure would call for a burst of activity
lasting over a relatively short time as compared
to the long and extensive preparations leading up
to it.
The activity must be aimed at the opening of
the lunar "launch window". Figure 1 illustrates
the variation in the velocity increment required
to launch a vehicle into a lunar transfer trajectory
from a 485 kilometer earth orbit. The minima
are at irregularly spaced intervals and are a func-
tion of the inclination of the lunar and the earth
satellite planes and of the position of the moon in
its orbit around the earth (i. e. , the day of the
month). In an operations analysis these spacings
will influence the number of vehicles on the launch
pad (primary and back-up) , their state of readi-
ness, the firing rate, and also the flight profile to
be chosen. Whether it is decided to go by "con-
necting" or by "tanking" mode, the objective must
be to get the spacecraft in the launch ready state
at the opening of one of these launch windows. It
may be desired that the first vehicle be capable of
remaining in a functionally capable state even after
bridging one or more of the gaps between the
windows. This consideration will influence the
design of the vehicles as well as the operational
modes to be designed into the flight control hard-
ware. For example, a sleep switch may be de-
sirable from the standpoint of savings in battery
we ight.