Several types of manned Mars surface missions, including sorties, fixed-base, and hybrid missions, which can be envisioned as potentially desirable approaches to the exploration and utilization of Mars are identified and discussed. Some of the advantages and disadvantages of each type are discussed briefly. Also, some of the implications of the types of missions on the surface elements' design are discussed briefly. Typical sets of surface elements are identified for each type of mission, and weights are provided for each element and set

Butler, J.

Mcdaniel, S. G.

English

NASA Technical Reports Server

N87-17755
MISSION AND _AC! INfrASTRUCTURE CON_
J. Butler and S. G. McDantel
Marshall Space Flight Center
Marshall Space Flight Center, AL
ABSTRACT
This paper
surface missions,
identifies and discusses several types of manned Mars
including sorties, flxed-base, and hybrid missions,
which can be envisioned as potentially desirable approaches to the
exploratlon and utllizatlon of Mars. Some of the advantages and
disadvantages of each type are discussed briefly. Also, some of the
implications of the types of missions on the surface elements' designs
are discussed briefly. Typical sets of surface elements are identified
for each type of mission, and weights are provided for each element and
set.
INTRODUCTION
The types of surface infrastructure elements which are needed are
heavily dependent on the nature, duration, and tlmeframe of the mission.
For manned Mars flyby missions or manned Mars orbiter missions, no
habitable surface elements would be necessary, but unmanned probes and/or
robotic surface explorer vehlcies would no doubt be required.
For manned landings (on Phobos, Deimos, or Mars), the types of
required infrastructure elements can vary significantly with several
factors. One is the timeframe of the mission. For early missions, there
is likely to be less emphasis on "permanent*' types of infrastructure
elements and more emphasis on the elements which are "bare essentials"
for landing men and returning them safely. Technology levels will be
lower on early missions, and hence equipment on early missions wlll be
less efficient than that on later missions. Hence, weight, volume,
power, and other resources will be more critical, which will allow less
infrastructure equipment to be taken per flight than on later missions.
The only practical types of manned Mars landing missions are those which
can be done during favorable planetary alignment periods. The favorable
alignments (reference 6) are of either the conjunction or opposition
type, and occur about every 2 years. The conjunctlon-type opportunities
require about a l-year stopover time at Mars, and the opposition-type
missions require about a 60-day stopover. The energy requirements for
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longer or shorter stopover times increase severely for even a few days'
change from the optimum times stated. The Initial manned Mars landing
mission may be of the type having a 60-day stopover, to minimize cost,
risk, and complexity of the mission. The opposition-type missions
usually have a Space Vehicle (SV) weight penalty compared to the
conjunctlon-type missions, but this is not too great for all-aerobraklng
concepts.
SURFACE MISSION OPTIONS
There are at least three types of surface exploratlon/utillzatlon
options which are possible (Figure 1): (1) sortie; (2) moving-base; and
(3) flxed-base options. In the sortie approach, each mission is directed
to a different landing site, with short-distance, llmited-round-trip
surface traverses being made in that general vicinity for exploration and
science investigation purposes. In the flxed-base mode, successive mis-
sions are directed to the same site, with fairly extensive round-trip
surface traverses being made from the base. The moving-base mode is a
hybrid of the other two modes, wherein two or more missions may be
directed to one location, then the entire base is moved to another
location, etc.
The sortie approach provides flexibility for exploration of surface
areas having widely different terrain, climate, etc., on different
missions, since widely separated landing locations can be chosen each
time. Sortie missions would be more limited in scope and duration than
the other missions, since each mission must furnish all its own equipment
and resources (no carry-overs from previous missions). The variety of
surface features which can be explored during each sortie mission is
limited by the landing location, the range and capability of the surface
traverse vehicle, and the duration of the mission. The mission
complexity of sortie-type missions is probably lower than the others
(especially if the scope and duration of the mission is more limited),
and the equipment complement is smaller.
The fixed-base concept provides the least variety of surface
features across missions (unless surface traverse distances can be
extremely great). It does offer significant advantages, however, in the
buildup and re-use of equipment from mission-to-mlssion. It would be
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necessary to use this mode for any long-term construction or
manufacturing activity.
The moving-base mode lies somewhere between the other two modes in
almost every respect, having some of the advantages and disadvantages of
both.
In actual practice, the missions Bay shift from one option to
another, and occasionally back again. For example, the earliest missions
will probably be of the sortie variety, with later missions trending
towards the moving-base or fixed-base variety. It is likely, however,
that an occasional sortie mission to a different location might be
desired, even after a fixed-base was established at one location. This
might be desirable for science/exploration reasons, or to begin
establishment of another base.
Many factors will help determine the selection of the surface
options to be used. The total number of missions In the program and the
flight frequency will have a significant bearing on this. The
availability of systems and resources (e.g., flying vehicles and tn-sttu-
manufactured propellants) to allow rapid and easy movement of equipment
over great distances would strongly Influence selection of surface
options. For cases where there ls a gap between successive habitation or
use of surface equipment previously landed, the advantage of buildup and
reuse of such equipment must be traded against the possibility that the
equipment might have become damaged or otherwise become Inoperable during
the interim period.
SURFACE INFRASTRUCTURE ELENENTS
Design of the surface infrastructure elements must be closely
coupled to design of the other elements of the SV (e.g., Ntsslon Module)
in some cases. This Is strongly dependent on Nars surface stopover
duration. For example, on a mission which only has a 60-day stopover, If
the lander (e.g., Nars Excursion Nodule (NEN)) equipment were designed
Independently from the orbiter (e.g., NN equipment), the lander would
only operate for 60 days out of a total mission time of 2 years. It
would be a much better use of the lander systems to utilize them for a
greater part of the 2-year mission. If, however, the mission were one
having a 1-year stopover, there might be more concern about the lifetime
426
of the lander systems if they were operated for the full mission
duration.
The division of the crew between Mars surface and Mars orbit
operations will be a factor in design of the lander. On an early sortie
mission of the 60-day-stopover variety, half the crew may be sent to the
surface in the lander and the other half may stay in the orbiter. On a
1-year-stopover mission, the entire crew may be sent to the surface.
Obviously, the split of the crew accommodations equipment between lander
and orbiter would vary significantly between these two types of missions.
An artist's concept of a Mars base is shown in Figure 2. Some of
the infrastructure elements shown here (greenhouses, Habitability
Modules, etc.) are more applicable to the fixed-base surface option, but
other equipment (rover, lander/departure stages, etc.), are applicable to
any of the surface options. More discussion is provided on this subject
in later paragraphs. Several of the infrastructure elements are depicted
with the large-dlameter aerobraklng shells still attached, but these
shells could be removed if necessary. It might be desirable to remove
these large structures for potential use as living quarters, storage
shelters, etc. An artist's concept of living quarters made from such
structures is shown in Figure 3.
Table I identifies a set of typical surface elements for each type
of surface option. As shown, the sortie concept would be the most
simplistic of the three, the flxed-base concept would be the most
complex, and the moving base concept would lie somewhere between the
other two concepts in terms of the amount and complexity of equipment
required. Where items have checkmarks enclosed in parentheses, an early
version of the item would probably be needed or desired as an elemeI_t of
that type of surface option.
The lander/departure element would be the MEM, or a growth version
of it. A number of different concepts of the MEM have been defined in
past studies, including Apollo Command Module derivatives, biconic
vehicles, etc. Data for some of these are shown, along with the MEM
defined in this study, in references 1, 7, and 8. In the flxed-base mode
of operation (and posslbly the movlng-base mode), the spent MEM descent
stages could be used as storage areas, or could possibly be joined
together to serve as a habitabillty volume.
427

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The early habitability and laboratory facilities might be modules
derived from Space Station (SS) modules, but later ones may be made from
other elements such as the large aerobraktng shells as previously noted
(Figure 3) or from in-sltu-produced materials ("concrete", etc.) The
power facility Item might be a nuclear reactor or nuclear isotope power
generator; other possibilities would include fuel cells operated from
ln-situ-produced reactants and some sort of solar-energy system.
Reference 2 describes some of these options in more detail.
The greenhouse would be an element only of the fixed-base surface
option. A definition of it is provided in reference 3. For the
greenhouse, an inflatable plastic structure on a pad could be used. The
structure would be optically transparent with a UV fllter. It would be
pressurized and would require a night-time cover. Due to the thin atmos-
phere, no support structure would be required, even during high winds.
The In-sltu Resource Production Units (IRPU's) are elements which
would produce such products as propellants, breathable gases, fuel cell
reactants, or water. Typical units have been defined in references 2 and
3. The small rover is an upgraded version of the NSFC-developed Lunar
Roving Vehicle (LRV) which was used on several Apollo missions. It Is
discussed in reference 4. This vehicle requires the passengers to wear
space suits, and it has a limited traverse range and cargo capacity.
The large rover is essentially a small Hab/Lab Module on a tracked
undercarriage. It has a traverse capability on the order of 100 km and
30 days, and is piloted by the crew from within the module. The Molab
was a vehicle of thls sort, which is discussed In reference 4. The
"pogo" vehicles are propulslvely-powered vehicles which can vary in size
from a 1-man backpack to a platform capable of transporting modules or
other large elements. These are discussed in reference 4. These
elements have the advantages of being insensitive to obstacle size during
traverses, require no horizontal takeoff and landing strip, and can
traverse great distances In a short time. They wlll require a large
amount of propellant, however, and are thus more practical if a local
source of propellant can be utilized.
The airplane is a remotely-piloted vehicle which will contain
science equipment and wlll be used to explore regions which would be
difficult or impossible for man to explore directly. One disadvantage it
431
has is the requirement for a takeoff and landing strip. The airplane is
discussed in references 4 and 9.
The "drills/minlng" equipment item listed in Table 1 is intended to
include only the larger size equipment of this nature. Smaller drills
are included under the "portable science" item. The larger equipment
would be used for taking deep core samples, for implanting deep seismic
charges and sensors, etc. The mining equipment would be used for
digging tunnels, for extracting minerals, etc.
The construction item includes equipment necessary to manufacture
building materials as well as equipment needed for erecting or emplacing
structures. A soil-mover of some sort will be needed for the flxed-base
missions, to support habitability element emplacement, construction
activities, road-buildlng, trench digging and filling, etc. A limited-
capability version would be desired on movlng-base missions. Types of
equipment which have been suggested in past studies for this category are
draglines, road-graders, backhoes, etc. A crane could be used to lift
and emplace any of the larger elements (Hab Modules, etc.) delivered to
the surface and would be used in the construction activity, as required.
The crane would be used on flxed-base missions, with smaller versions
used on other missions.
The portable science equipment includes a myriad of small items of
equipment which might be carried in the small rover vehicle or used in
the vicinity of the lander, to gather and analyze geological samples, to
make weather or environment measurements, etc.
The communications relay is not really a surface element, but is an
element which may be required in orbit to support the surface activities.
In manned missions to the surface, some elements will be left in Mars
orbit for the return trip to Earth. These elements will have communica-
tions equipment built in, and can serve as the communications relay for
the surface activities when needed. Unmanned missions may or may not
have such equipment left in Mars orbit, and so may require that a
separate element be provided.
432
WEIGHTS
In order to estimate weights for the total complements of equipment
for the various surface options, assumptions were necessary in a few key
areas, and are listed below:
(1) Sortie: 3 men/60 days surface stay/lO kw elect, power
(2) Moving-base: 6 men/1 year surface stay/25 kw elect, power
(3) Fixed-base: 12 men/1 year surface stay/lO0-200 kw elect, power
Table 2 provides weight data for some of the key elements previously
discussed. The top part of the table summarizes the portable science
equipment items, some of which might be taken along on surface traverses.
The bottom part of this table lists weights for miscellaneous larger
elements.
Table
delivered
options.
equipment
cumulative
3 provides a weight summary of the equipment necessary to be
to the surface of Mars for each of the three surface mission
Reference 5 uses these weights as requirements for delivery of
to the Martian surface, and shows the rates of buildup of
delivered weight to the Martian surface and to LEO as a
function of time, for various SV options.
433
4586--85
TABLE 2. EQUIPMENT WEIGHTS
PORTABLE SCIENCE EQUIPMENT
GRAVIMETER
X-RAY DIF/X-RAY FL
ELECTRON MICROSCOPE
GAS CHROMATOGRAPH
SPECTROMETER
MAGNETOMETER
SMALL DRILL
CENTRIFUGE
POLARIMETER
pH METER & REAGENTS
REFRACTOMETER
THERMOMETERS
SCALES
REFRIGERATOR
INCUBATOR
OVEN/STERILIZER
WORK BENCH
MICROMANIPULATOR
ULTRASONIC CLEANER & SOLVENTS
AGITATORS & BLENDORS
HAND TOOLS
SAMPLE HOLDERS & CONTAINERS
ANEMOMETER
EXPLOSIVES
MICROTOME
RTG POWER SUPPLY
BAROMETER
SEISMOMETER
SOIL BEARING STRENGTH
POWDERING, DISSOLUTION, OPTICAL ANAL
EM PROPERTIES
THERMAL PROPERTIES OF SOIL
IONOSPHERE STRUCTURE PROPERTIES
SOIL SAMPLE BOX
TOTAL
WT (LBS)
26
99
115
33
33
64
81
32
13
32
9
2
12
27
21
42
55
19
106
8
22
49
15
344
19
87
15
8
25
7O
52
24
88
17
1664
MISCELLANEOUS ITEMS
LARGE DRILL
ROVER
AIRPLANE
MOLAB
CRANE
EARTH MOVER
910
60O
66O
3400
450
450
434
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REFERENCES
1. Tucker,
2,
.
4o
D
6,
7.
8,
,
M., Meredith, 0., and Brothers, B.; "Space
Vehicle Concepts", NSFC Paper in Section III.
Gludici, R.; "Power Issues, Options, and Trades"; MSFC
Paper in Section VII.
French, J.; "The Case for Mars Concept"; JPL paper Jn
Section III.
McDaniel, S.G.; "Surface Transportation Elements", MSFC
Paper in Section IV.
Butler, J. and Brothers, B.; "Mission and Space Vehicle
Sizing Data", MSFC Paper in Section III.
Young, A.; "Mars Mission Concepts and Opportunities";
MSFC paper in Section II.
Butler, J.; "Mission and Space Vehicle Concepts; MSFC
paper in Sectlon III.
Stump, G., Babb, W., and Davis, H.; "Mars Lander
Survey"; paper in Section III.
French, J.; "The Mars Airplane"; JPL paper In Section
IV.
436


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