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5
AMS Models
The Apollo Mission Simulator models manned Lunar exploration. It postulates a
Lunar Orbiting Laboratory in a low equatorial orbit about the Moon and a
reusable Ascent Stage/expendable Descent Stage Lunar Module. Many of the
models used in the Apollo Mission Simulator are described in this document.
Topics include:
Moon Model
Pilot Model
Lunar Orbiting Laboratory Model
Lunar Module Model
Portable Life Support System Model
Lunar Rover Model
Moon Model
The Moon is modeled as a perfect sphere with a 90° NORTH
radius of 1738.3 km. The gravitational field ............... ┌────┐
is a simple inverse square law with a ...: s | :... │MOON│
surface acceleration of 1.624 m/s². .: u | :.└────┘
Latitude and longitude reference points .: b | :.
are defined in the figure to the .: E | :
right. The Lunar solar rotation : A | :
period is 29.53 days. : R | :
: T | :
The modeled surface has constant : H | equator :
altitude but is covered with -90°:------------------+- 0° -------------: 90°
many features such as craters, WEST: m | :EAST
mountains, and rilles. LM : e 0° :
landing safety factors are reduced : r | :
in rugged lurrain. Movement on the : i | :
Lunar surface is more difficult as : d | :
well. The value of samples collected :. i | .: view
during EVA increases in proportion to the :. a | .: from
ruggedness of the lurrain. :... n | ...: EARTH
:.............:
-90° SOUTH
Moon Model (continued)
A list of lurrain features is given below in increasing order of ruggedness.
Manmade objects and special targets are assigned other symbols listed in the
"LUNARMAP" document. These objects, visible only on Level 2 maps, are
hazardous in landing or during movement but valuable to visit and sample. The
dark side of the Moon is indicated by a field of "▓" symbols.
SYMBOL RUGGEDNESS MEANING
------ ---------- ----------------------------------------------------------
" " 1.0 Featureless
∙ 1.1 Smooth, rocky
° 1.2 Small, subdued crater
+ 1.3 Moderate, rocky
* 1.4 Rugged, rocky
o 1.5 Medium crater
≈ 1.7 Rolling hills
O 1.8 Large crater
\ 2.2 Rille
/ 2.5 Rille
∩ 2.9 Mountainous
U 3.3 Valley
# 5.0 Major rille
Pilot Model
Parameters included in the AMS for modeling the Pilot are location,
environment, equilibrium, efficiency, metabolic rate, and injury.
Location/Environment: The Pilot may be located in the LOL, LM, or LRV, or on
the Lunar surface (EVA). Environments are shirtsleeves, spacesuit, and PLSS.
A comfort factor is calculated, based on location, environment, and injury, to
determine how rapidly the Pilot equilibrium factor decreases.
Equilibrium: The equilibrium factor is the limit of Pilot efficiency after an
extended period of idleness. It decreases with time depending on location,
environment, and injury, and is substantially restored after a rest/meal
period ("REST" command). It also varies with time-of-day, reaching a maximum
around UT 15:00 (3:00pm) and a minimum around UT 03:00 (3:00am). This
parameter is not displayed.
Efficiency: The efficiency parameter determines what fraction of keyboard
commands are executed correctly. Pilot efficiency approaches the equilibrium
factor when no activity is taking place and the Pilot metabolism approaches
30%. Avoid efficiencies of less than 60%.
Pilot Model (continued)
Metabolic Rate: The Pilot metabolic rate is a measure of short-term strenuous
activity. It is affected by keyboard commands and activities such as
movement, sample collection, etc. Avoid metabolic rates over 60%.
Injury: Injury to the Pilot may occur during landing, docking, or movement
on the Lunar surface, or due to lack of oxygen or battery supply. The injury
parameter also increases slowly while the Pilot is awake. Injuries affect
the rate at which the Pilot equilibrium factor decreases and are substantially
restored after a sleep period ("SLEEP" command).
Lunar Orbiting Laboratory Model
The Lunar Orbiting Laboratory is 30m in
diameter and is in a 100 km circular NORTH ┌───┐ DOCKING PORT
orbit about the Lunar equator. Body │ ┌──┬─┴───┴─┬──┐
axes are defined as Face (pointing ╔╤╤╤╤╤╤╤╤╤╤╗ │··│· · · ·│··│ ╔╤╤╤╤╤╤╤╤╤╤╗
north), Left (pointing toward the ╟┼┼┼┼┼┼┼┼┼┼╢ │··│· · · ·│··│ ╟┼┼┼┼┼┼┼┼┼┼╢
Earth), and Up. The LOL has a ╟┼┼┼┼┼┼┼┼┼┼╫─┤··│· · · ·│··├─╢┼┼┼┼┼┼┼┼┼┼╫
docking port on the north side. ╟┼┼┼┼┼┼┼┼┼┼╢ │··│· · · ·│··│ ╟┼┼┼┼┼┼┼┼┼┼╢
╚╧╧╧╧╧╧╧╧╧╧╝ │··│· · · ·│··│ ╚╧╧╧╧╧╧╧╧╧╧╝
The position and velocity of the LOL are known └──┴───┬───┴──┘ view from
with high accuracy. The LOL has a tracking system ┌─┴─┐ SUN
that can be used to determine the relative │═╬═│
position of the LM. └───┘
SUN ┌─────────┐
The LOL may be damaged during docking. │ ┌─┘· · · · ·└─┐
If damage is too great, docking may not │· · ┌───┐ · ·│
be possible. To avoid damage, ════════════─┤· · │ + │ · ·├─════════════
approach the LOL with caution. Do not │· · └───┘ · ·│ view from
ignite LM main engines within 2 km of the LOL and └─┐· · · · ·┌─┘ NORTH
set the RCS throttle to "LOW" when within 100 m. └─────────┘
Avoid thrusting directly away from the LOL within 50 m except in an emergency.
Lunar Module Model
The AMS Lunar Module is modeled after DOCKING╔═══════╗ ASCENT
those used during the last three PORT║│·│·│·│║ │ UP STAGE
Apollo Lunar exploration ╔══════════╩╤═════╤╩══════════╗
missions. Major components ╔═╝ · · · · │· · ·│ · · · · · ╚═╗ RCS
are the Ascent Stage, the ┌─┴─╢ · ╔═════╗ · │· · ·│ · ╔═════╗ · ╟─┴─┐ QUAD
Descent Stage, the Reaction ┤ O ║ · ║ ║ · │· · ·│ · ║ ║ · ║ O ├
Control System, the Guidance └───╢ · ╚══╧══╝ · │· · ·│ · ╚══╧══╝ · ╟───┘
System, and the Consumables. ║ · · · · │· · ·│ · · · · · ║ LEFT
Several features have been added ╟────────┬────┴─────┴────┬────────╢ ───
or enhanced to improve safety ┌───╢::::::::│· · ┌─────┐ EVA│::::::::╟───┐
margins, allow a greater ┤ O ║::::::::│ · ·│ └─┘ │EXIT│::::::::║ O ├
variety of targets, and └─┬─╢::::::::│· · └─────┘ · ·│::::::::╟─┬─┘
ease the task of docking. ╠════════╧═══════╤═══════╧════════╣
Propellant supplies and thrusts ║ · · · · · · ·├─┼─┤· · · · · · · ║
have been increased by 10%. /┼║ · · · · · · ·├─┼─┤· · · · · · · ║┼\
Extra RCS thruster quads have /┼┼┼║ · · · · · · ·├─┼─┤· · · · · · · ║┼┼┼\
been added to allow the LM /┼┼┼┼╢ · · · · · · ·├─┼─┤· · · · · · · ║┼┼┼┼\
to move in any direction. /┼┼┼┼┼╢ · · · · · · ·├─┼─┤· · · · · · · ║┼┼┼┼┼\
The original could only /┼┼┼/ ╚══════════════╪═╧═╪══════════════╝ \┼┼┼\
apply thrust up or down. /┼┼┼/ ├───┤ DESCENT \┼┼┼\
═╧════╧═ ═╧═════╧═ STAGE ═╧════╧═
Lunar Module Model (continued)
Ascent Stage: The Ascent Stage carries the Pilot to the Lunar surface and
back to the LOL. It stands 3.8 m tall, has a dry mass of 2234 kg, and carries
2615 kg of propellant. The Ascent Engine has a thrust of 16,890 nt and uses
propellant at a rate of 5 kg/s.
Descent Stage: The Descent Stage carries the bulk of the supplies required to
carry out a Lunar exploration mission. It is 3.3 m tall, has a dry mass of
2346 kg, and carries 9720 kg of propellant. The Descent Engine can be
throttled between 10% and 100% of its rated force. It has a thrust of 49,215
nt and uses propellant at a rate of 15 kg/s at full throttle. The Descent
Stage remains on the Lunar surface after liftoff.
Reaction Control System: The RCS consists of eight modules of three thrusters
each (quads) and is used to orient the LM and provide small changes in
velocity. "PITCH", "ROLL", and "YAW" commands cause short bursts that change
the spin of the LM by 1°/s. "FORWARD/BACK", "LEFT/RIGHT", and "UP/DOWN"
commands turn on sets of thrusters to make small velocity changes. The
translation thrusters have three throttle settings -- "LOW" (1%), "MEDIUM"
(10%), and "HIGH" (100%). The RCS has a thrust of 1970 nt and uses 0.5 kg/s
at full throttle. Total propellant is 316 kg at undocking.
Lunar Module Model (continued)
Guidance System: The AMS Lunar Module has an Inertial Guidance System that
provides estimates of position, velocity, and acceleration. Orbital
parameters may also be displayed. Major components of the guidance system
are the accelerometers, DSN and LOL transponders, and the Landing Radar.
Accelerometers are used to measure the acceleration of the LM during main
engine and RCS burns.
The DSN transponder, when activated, provides the INS with a rough measurement
of the position of the LM. It is used when the LOL transponder and Landing
Radar are not capable of providing updates.
The LOL transponder/Docking Radar, when activated, provides the INS with an
accurate measurement of the LM position. It has a maximum range (from the
LOL) of 100 km. Docking is not possible unless the LOL transponder is ON.
The Landing Radar, when activated, provides the INS with accurate measurements
of altitude and velocity. It has a maximum altitude of 18 km. It is located
behind the Pilot, so the LM Face body axis must be pointing within 95° of the
local vertical to lock onto a signal. The signal is lost if the LM Face body
axis points down more than 120°.
Lunar Module Model (continued)
Consumables: The AMS Lunar Module is designed to provide sufficient oxygen
and battery power for a 120hr mission. A 50% margin (surplus) of battery
power and a 100% margin of oxygen is added for emergency use. Damage to the
LM increases oxygen and battery consumption rates. Damage may occur during
docking or landing. If the LM becomes damaged, additional damage can occur,
especially during main engine burns. The Ascent Stage carries 10 hr of the
120hr supply.
Portable Life Support System Model
The Portable Life Support System allows the Pilot to move about on the Lunar
surface. The LM has four oxygen/battery packs used to replenish the PLSS
supply. Each pack contains oxygen and battery power to support an 8-10hr EVA
with plenty of margin. PLSS packs are designed to last 10 hr with 100% margin
provided in oxygen supply and 50% margin in battery power. Damage to the
spacesuit or PLSS increases consumable depletion rates as does a high Pilot
metabolic rate. Injury and rugged lurrain reduce the speed at which the Pilot
can move about on the Lunar surface. Damage can occur during landing,
docking, or movement about on the Lunar surface. To avoid damage, move slowly
over rugged lurrain. The PLSS has no reverse but can be turned in place.
Lunar Rover Model
The Lunar Rover allows the ┌┬┬┬┬┬┬┬┬┬┬┬┐ ┌┬┬┬┬┬┬┬┬┬┬┬┐
Pilot to move about more │ │ PILOT │ │
quickly and easily than on └┴┴┴┴┴┼┴┴┴┴┴┘ SEAT └┴┴┴┴┴┼┴┴┴┴┴┘
foot. It has a range of ╔╧══════════════════════════════════╧╗
200 km and a maximum speed ║ ┌────────┬──┐ ┌──┬──┐║
of 6 m/s over smooth FACE ║ ├────────┼──┤ ├──┼──┤║ LRV
lurrain. Damage and ─── ║ ├────────┼──┤ ├──┼──┤║SAMPLE
rugged lurrain make the ║ ├────────┼──┤ ├──┼──┤║ BOX
LRV run less efficiently. ║ └────────┴──┘ └──┴──┘║
Damage may occur during ╚╤══════════════════════════════════╤╝
landing, docking, or ┌┬┬┬┬┬┼┬┬┬┬┬┐ │ ┌┬┬┬┬┬┼┬┬┬┬┬┐
movement about on the │ │ LEFT │ │
Lunar surface. To avoid └┴┴┴┴┴┴┴┴┴┴┴┘ └┴┴┴┴┴┴┴┴┴┴┴┘
damage, move slowly over rugged lurrain. Avoid very rugged areas and manmade
objects. The LRV has no reverse but can be turned in place. The LRV has
a box for storing Lunar samples that can hold up to 30 kg. Eight sample boxes
are carried on the LM.