The Case for Mars workshops conducted in 1984 dealt with a program to establish a permanent scientific research base at Mars. The participants, viewed a Mars base as the much needed long-term focus for the space program. A permanent base was chosen rather than the more conventional concept of a series of individual missions to different sites became the permanent base offers much greater scientific return plus greater crew safety and the potential for growth into a true colony. The results of the workshops are summarized

French, J. R.

English

NASA Technical Reports Server

N87-17748
THE *CASE FOR NARS" CONCEPT
J.R. French
Jet Propulsion Laboratory
Pasadena, California
ABSTRACT
The Case for Mars workshops conducted in 1984 (Ref.1) dealt with a
program to establish a permanent scientific research base at Mars. The
participants, some of whom are listed in Appendix A, viewed a Mars base
as the much needed long-term focus for the space program. A permanent
base was chosen rather than the more conventional concept of a series of
individual missions to different sites because the permanent base offers
much greater scientific return plus greater crew safety and the potential
for growth into a true colony. This paper summarizes the results of the
workshops.
The Mars base will strive for self-sufficiency and autonomy from
Earth. Martian resources will be used to provide life support materials
and consumables. The Martian atmosphere will provide a convenient source
of volatiles: C02, N2, and water. Rocket propellant, fuels for surface
and air vehicles and possibly power plants, breathable air, and ferti-
lizers will be manufactured from the Mars atmosphere. Food will be grown
on Mars using Martian regolith as a growth substrate.
A permanent human presence will be maintained on Mars beginning with
the first manned landing via a strategy of crew overlap. This permanent
presence will ensure safety and reliabltty of systems through continuous
tending, maintenance, and expansion of the base's equipment and systems.
A permanent base will allow the development of a substantial facility
on Mars for the same cost (in terms of Earth departure mass) as a series
of temporary camps. A base equipped with surface rovers, airplanes, and
the ability to manufacture consumables and propellant will provide far
more extensive planetary exploration over a given period of years than
would an Apollo-style approach.
SCIENCE AND EXPLORATION
A human presence on Mars will accelerate and enhance scientific
exploration of the planet. Humans have unique capabilities which are
difficult or Impossible to automate. These features, along with the
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inherent flexibility of people, make the ln-situ human the best possible
tool for Mars science.
Prior to a manned landing, automated precursor missions are required
to Investigate the Mars environment and select an optimal location for
the permanent base. The base must be located in an accessible area
suitable for a landing field, and must be near areas of scientific
interest. Martian resources will be used for base operations. Thus the
chemistry, mineralogy, and the state and distribution of volatlles on the
Martian surface, particularly water, must be assessed globally and local-
ly. The meteorological environment of Mars must be studied to forecast
the likelihood of dust storms in the base location, and characterize the
local, regional and global weather.
A precursor program to accomplish these objectives includes the
planned Mars Geosctence Climatology Orbiter (NGCO). An orbiter mission
to provide hlgh resolution images of candidate base site areas is also
needed. A network of surface weather stations supported by lo_ resolu-
tion orbital imaging of cloud features ls desirable for several Mars
years in advance of the manned mission. A series of unmanned rover and
sample return missions is needed to collect samples of Mars materials
from prospective base sites and bring them to Earth for analysis.
An alternative possibility ls for the precursor missions to be man-
ned. The crew for the first few (say three) landings would evaluate the
most promising sites and bring back samples. The next mission (fourth?)
would then return to the best site to begin base establishment. In this
scenario, unmanned rover/sample return would probably be unnecessary
since the manned missions would do the same thing. A high resolution
orbital precursor might be sufficient to choose the first landing sites.
Assuming unmanned precursor missions, the Initial human landing at
the base site will certify the safety and habitability of the base loca-
tion, provide ground truth about the presence of water and other raw
materials for base operations, set up resource extraction equipment, and
establish meteorological stations in support of future manned landings.
Permanent scientific research facilities will be the next priority, after
these survival technologies are deployed. Facilities for research in
atmospheric science will provide weather observation and reporting as
well as climate, atmospheric dynamics, and atmospheric chemistry studies.
343
Geosclence research capabilities will include surface exploration, seis-
mic and drilling equipment, manned and teleoperated rover vehicles, and
laboratory equipment for geochemical and petrological study of samples.
Life science research on Mars will search for present or past life,
supported by appropriate laboratory capabilities.
MISSION STRATEGY
The mission strategy is directed toward support of a permanently
inhabited Mars base with crew rotatlon and resupply at each Earth-to-Mars
launch opportunity. In order to minimize the total mass departing Earth
orbit to support the base and to provide Earth return capability for the
crew being rotated home, a Mars powered flyby and return to Earth is
performed by the Deep Space Habitat vehlcle (Flffures la and lb).
Arriving crew members separate from the habitat in Mars Shuttle vehicles
(Flgure 2) while on the approach leg. The Shuttles proceed to Mars and
land at the base using a combination of aerodynamic braking and rocket
thrust (Figure 3). To get into an Earth - return trajectory, the deep
space habitat vehicle performs (unmanned) a propulsive maneuver as it
flies by the planet. Returning crewmembers depart Mars In their Shuttles
which rendezvous with the Habitat vehicle on the outbound leg departing
Mars. In preparation for the next habitat flyby (two years later), the
Mars Shuttles at the base are refueled using CO-O 2 propellant
manufactured from Mars CO2 (Figure 4).
While the newly arrived crew takes up its duties at the base, the
returning crew rides back to Earth in the Deep Space Habitat. Arriving
at Earth, the crew enters the Mars Shuttles and aerobrakes down to the
Space Station, and the Habitat vehicle makes a final use of its propul-
sion system to enter a loose elliptical orbit around Earth from which it
is later recovered for refurbishment and reuse.
Each mission of the Habitat/Mars Shuttle assembly delivers fifteen
crew members to Mars. In the early stages of the program, a lesser number
(say nine) of the base crew will return to Earth. This will not only
provide growth but also a highly desirable continuity In base operation.
VEHICLES
Three new major vehicles are involved in execution of the mission
strategy developed In this paper. These are: Mars Shuttle, the Deep
Space Habitat, and the Earth Departure Stage.
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The Mars Shuttle vehicles, as the name implies, are used to tran-
sport arriving crew members to the Martian surface from the Deep Space
Habitat and to bring homeward bound crew members from Mars to the Habi-
tat. At the end of the return journey, they are also used to bring the
crew to the Space Station. For the descent to Mars, the Shuttles depend
upon aerodynamic braking to slow them from an entry velocity of 5 to 6
km/sec down to a velocity suitable for parachutes. To provide the re-
quired accuracy and control, a relatively high lift - to - drag ratio is
needed. A biconic airframe (shaped like a slightly crooked cone) pro-
vides this capability. Two versions of the Mars Shuttle are needed; one
is a one - way unmanned cargo vehicle (Figure 5) the other a manned
version which can be reloaded with propellant on Mars for the return
(Figure 6). The initial manned version will be a two stage vehicle,
since the CO-O 2 propellant manufactured on Mars Is of low performance.
Later in the program, higher Isp propellants may allow a single stage
vehicle. Protection from aerodynamic heating would be provided by a
reusable heat shield similar to that used for the Space Shuttle.
The Deep Space Habitat (Figure 7) is composed of three identical
sections. Each section is assembled at the Space Station, and consists
of two Space Station modules, life support system, consumable storage,
and a propulsion system. All this is attached to a boom and tunnel
assembly, terminating in a docking adapter which allows the three sec-
tions to dock into a pinwheel configuration that is rotated to provide
artificial gravity. A crew - type Mars Shuttle is docked along each
boom, Each section (with its Mars Shuttle) is boosted separately on a
Mars-bound trajectory from low Earth orbit. The three sections rendez-
vous and dock on the way to Mars, remaining linked for the remainder of
the mission.
The Trans-ffars injection stage (Figure 8) Is used to boost the
Habltat/Mars Shuttle assemblies out of Earth orbit and into the Mars
transfer trajectory. It uses adaptations of the Space Shuttle Main
Engine for thrust. Tankage for the liquid oxygen/liquid hydrogen propel-
lant is modular to allow each tank to be launched in the Space Shuttle
for on-orbit assembly of the stage.
Cargo versions of the Mars Shuttle travel to Mars without being
attached to the Habitat. To provide power and other services to the
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FIGURE 8
TRANS-.MARS INJECTION STAGE
LH&
354
vehicle during interplanetary flight, a Jetttsonable service module will
be attached. Appendix B provides some characteristics of the vehicles.
HUMAN FACTORS
Human factors encompasses those facts of mission planning and design
which affect the physiological and psychological condition and the per-
formance of the Mars Base crewmembers.
Life support facilities must be provided for long-duration space-
flight with primary considerations being mass, volume and rellablltty.
Recycling of water and breathable gases is essential. Food Is primarily
transported, with possibly some supplementary food production in flight.
Organic waste can be stored for later use as an agricultural commodity at
the Mars Base. Development of long - duration life support is seriously
lagging behind other technologies relevant to human missions to Mars.
Life support at the Mars Base involves a program of gradually ex-
panding food production and gas recycling capability. Martian water,
gases, _nd possibly regolith will provide most of the raw consumable
materials. Greenhouses are used to provide the basic foodstuffs for the
Mars Base food chain. Optimum use of organic recycling is encouraged, and
the feasibility of microbial processing to provide a variety of biologi-
cal products and enhance nutritional value and palatabllty of food is
suggested. The overall facility is envisioned as a managed ecological
system relying on biological cycling of materials when possible. This is
augmented with chemical and physical subsystems to provide buffering
capability against system oscillations. Emergency food supplies are
cached in case of system failure.
Medical care must provide for the normal needs of crewmembers over
5 years' mission duration plus the ability to address a variety of fore-
seeable problems In unknown and hazardous environments of space and the
Martian surface. The likelihood of accidents requires the capability to
perform at least limited surgical procedures. A carefully selected
pharmacopoeia must be included to cover a reasonable range of disease and
accident treatments. All crewmembers must be trained In basic rescue and
emergency medicine. At least one physician must be included in the crew.
Relevant medical questions to be pursued prior to a Mars mission include
effects of zero and fractional gravity over long periods of time and
355
ameliorating drugs or techniques, and development of medical devices and
techniques appropriate to the space extraterrestrial environments.
Psychological considerations are involved at all stages of mission
planning including crew selection and training, selection of command
protocols, scheduling of work loads, provision of recreational facili-
ties, ergonomics and the Mars Base design, rotation of crews from mission
to mission, mission continuity with changing personnel, and Interpersonal
relationships.
MARS BASE
The primary function of the Mars Base is to support a continued
human presence on the surface and to achieve self - sufficiency through
the use of Martian resources. This provides the security and home base
from which to conduct the scientific exploration that will become the
main thrust of activities on the surface.
The major components and requirements for the Mars Base are shown in
Figure 9. The Initial crew size is 15 people, with incremental growth
over time. Major components include: Habitats derived from cargo ves-
sels; air shells/greenhouses which are lightweight erectable structures
which can be pressurized with Mars air; power supplies to provide power
to the base and to the resource extraction equipment (the largest power
user); rovers, trucks, and other mobility units for construction and
field experiments; habitat life support systems which can have consider-
able inheritance from Space Station Systems and from the resources avail-
able on the Martian surface; gas extractors which would obtain
breathable air and water from the Mars atmosphere or surface.
Breathable air could include an Ar/N 2 buffer gas mixture. These
elements together comprise over 5% of the Martian atmosphere and can be
obtained by condensing out the CO2. Oxygen can be obtained by reducing
the atmospheric CO2. The Mars atmosphere contains water (nearly at satu-
ration), which can be extracted with compression and cooling equipment.
Water may also be available from the Mars regollth. Rocket fuel can be
made from the CO2 itself (CO and O) or in combination with water (CH 4 and
02). An active research program must be established to look at the use
of gases and minerals available on Mars in support of the exploration ef-
fort.
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357
The initial focus of activities at the Mars base must be the devel-
opment of resource utilization technologies, since the continued presence
of the base and the long range science goals are contingent on estab-
lishing the resource base.
Some areas that need development in connection with the Mars base
include: 1) Power supply suitable to provide the approxlmately 200 - 400
kwatts needed; 2) Mars sult design; 3) small engines to run on fuel
made In-sltu; 4) the study of llfe support and resource utilization.
REFERENCES
1. Preliminary draft report " The Case for Mars: Concept
Development for a Mars Research Station " 5 December
1984.
358
APPENDIX A
AUTHORS OF
THE CASE FOR MARS:
CONCEPT DEVELOPMENT FOR A MARS RESEARCH STATION
PROGRAM JUSTIFICATION
DESIGN
S. N. Welch
C. R. Stoker
R. B. Wilson
T. R. Meyer
EDITOR
S. M. Welch
MARS
SCIENCE
C. R. Stoker
R. L. Grossman
P. J. Boston
MISSION/PROFILE
SPACECRAFT
J. R. French
R. L. Staehle
S. M. Welch
HUMAN FACTORS/
LIFE SUPPORT
P. J. Boston
T. R. Meyer
MARS BASE
DESIGN
C. P. Mcgay
D. Jones
PHOBOS/DEIMOS
MISSIONS
T. Caudlll
ARTIST
C. Emmart
359
APPENDIX B
VEHICLE CHARACTERISTICS
MARS SHUTTLES:
LENGTH: 23m
BASE DIAN: 5.75m
MASS AT EARTH DEPARTURE: 50 TONNES
(includes landing propellant)
MASS AT TOUCHDOWN: 30 TONNES
MANNED VERSION:
CARGO - CREW OF 5 and 5 - 6 TONNES EQUIPMENT
LIFT-OFF MASS: 215 TONNES (PROPELLANT C0/02, Isp = 260 sec)
CARGO VERSION:
CARGO - 24 TONNES
DEEP SPACE HABITAT:
EACH MODULE SUPPORTS 5 CREW (10 EMERGENCY)
DEPARTURE MASS PER MODULE 100 TONNES (220,000 lbs.) PLUS 50
TONNES MARS SHUTTLE NORMAL ASSEMBLY THREE COMPLETE MODULES
EARTH DEPARTURE STAGE:
LOADED MASS: 300 TONNES (660,000 LB.) LO2/LH 2 Isp=465 sec
EMPTY MASS: 20 TONNES (44,000 LB.)
PAYLOAD - ONE MODULE OF DEEP SPACE HABITAT OR 3 CARGO
SHUTTLE DELTA V CAPABILITY: 4.4 km/sec
360


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