Planning for the Scientific Exploration

of Mars by Humans

**By the MEPAG Human Exploration of Mars Science Analysis Group**

**MEPAG Human Exploration of Mars Science Analysis Group (HEM-SAG)**

James B. Garvin (co-chair), Joel S. Levine (co-chair), David W. Beaty,
Ariel D. Anbar, Mary Sue Bell, R. Todd Clancy, Charles S. Cockrell, Jack
E. Connerney, Peter T. Doran, Gregory Delory, Jay T. Dickson, Richard C.
Elphic, Dean B. Eppler, David C. Fernandez-Remolar, John E. Gruener,
James W. Head, Mark Helper, Jennifer Heldmann, Victoria Hipkin, Melissa
D. Lane, Joseph Levy, Jeff Moersch, Gain Gabriele Ori, Lewis Peach,
Francois Poulet, James W. Rice, Kelly J. Snook, Steven W. Squyres and
James R. Zimbelman

**January 31, 2008**

Review Copy

Recommended bibliographic citation:

MEPAG HEM-SAG (2008). Planning for the Scientific Exploration of Mars by
Humans,

Unpublished white paper, TBD p, posted March 2008 by the Mars
Exploration

Program Analysis Group (MEPAG) at
<http://mepag.jpl.nasa.gov/reports/index.html>.

Correspondence authors:

Inquiries should be directed to James B. Garvin
([**james.b.garvin@nasa.gov**](mailto:james.b.garvin@nasa.gov),
301-286-5154),

Joel S. Levine
([**joel.s.levine@nasa.gov**](mailto:joel.s.levine@nasa.gov),
757-864-5692),

or David W. Beaty
([**David.Beaty@jpl.nasa.gov**](mailto:David.Beaty@jpl.nasa.gov),
818-354-7968)

**Contents**

Executive Summary 1

Introduction 2

Why Mars? 3

Why Humans? 3

General Conclusions 5

Geology: Human Exploration Goals and Objectives 6

Geophysics: Human Exploration Goals and Objectives 18

Atmosphere/Climate: Human Exploration Goals and Objectives 30

Biology/Life: Human Exploration Goals and Objectives 42

Conclusions 58

Appendices 61

A. Candidate Human Exploration Sites 61

B. Atmosphere/Climate: Human Exploration Goals and Objectives 68

C. The Human Exploration of Mars: Lessons Learned from Apollo (James W.
Head) 83

References 85

# Executive Summary

Mars will remain an attractive destination for science for decades to
come and the pace of discoveries about the workings of the Red Planet
could be dramatically accelerated by means of human-based exploration at
any time it becomes possible. In the context of a set of three initial
human expeditions to Mars at some time beyond the current event horizon
(i.e., in \~25 years, meaning 2030s or 2040s), a team of experienced
planetary scientists with diverse scientific backgrounds has analyzed
scientific priorities and scenarios for such missions, under the
overarching precept that scientific discovery is a major aspect of such
missions. The Human Exploration of Mars Scientific Analysis Group
(HEM-SAG) derived human science reference missions using constraints
provided by engineers affiliated with the 2007 Mars Architecture Team
(B. Drake et al., NASA JSC) as well as the current scientific priorities
for Mars exploration summarized in the 2007 MEPAG Goals and Objectives
reference document as well as recent National Academy of Sciences Solar
System Decadal Survey recommendations (New Frontiers, NRC, 2003). After
initial evaluation of the state of knowledge about Mars today (circa
2007), the HEM-SAG projected this state of knowledge forward to \~2030,
under the assumption that a robotic Mars sample return mission must be
accomplished prior to Human scientific activities on the martian
surface. The HEM-SAG concluded that in any science-driven or
science-guided program of human exploration, each of three baselined
human missions must visit independent and distinct "exploration sites"
for maximal periods of time, as dictated by the realities of flight
dynamics and celestial mechanics. Thus, the overarching conclusion of
the HEM-SAG is for three human exploration missions to scientifically
(i.e, in terms of surface age of materials and scientific problem focus)
target different regions for periods of up to 500 days on the surface,
enabled by means of moderate-to-long range human mobility (100's of km)
and multi-100m scale subsurface access. Scientific priorities at the
time of the first HEM missions (2030s or 2040s) would likely remain
similar to those of today, in spite of major progress underway from the
current US and International robotic Mars programs (NASA's MEP, ESA's
science programme). In addition, there are "pass-backs" from what we
need to be able to accomplish on Mars for science that could be
validated and optimized via human exploration activities on the Moon,
including unique aspects of sample acquisition and handling, in situ
characterization, deep subsurface access, and long-range surface
mobility, potentially with pressurized human roving vehicles. Mars, in
the view of the HEM-SAG, represents an ideal target for intensive
human-based and enabled surface scientific operations for the next 50
years.

# HEM-SAG Introduction

To prepare for the exploration of Mars by humans, as outlined in the new
national Vision for Space Exploration (VSE), the Mars Exploration
Program Analysis Group (MEPAG), formed a Human Exploration of Mars
Science Analysis Group (HEM-SAG) in March 2007. The goal of HEM-SAG is
to develop the scientific goals and objectives for the scientific
exploration of Mars by humans. The HEM-SAG is one several parallel NASA
humans to Mars scientific, engineering and mission architecture studies
going on in 2007 to support NASA's planning for the VSE. The HEM-SAG
consists of about 30 Mars scientists representing the disciplines of
Mars geology, geophysics, atmospheric/climate science and biology/life
science from the U.S., Canada, England, France, Italy and Spain (It was
decided very early that the international Mars community should be
represented on HEM-SAG). Drs. James B. Garvin (NASA Goddard) and Joel S.
Levine (NASA Langley) were appointed co-chairs of HEM-SAG. The HEM-SAG
team conducted 20 telecons beginning on March 21, 2007. HEM-SAG convened
three face-to-face meetings: 1. May 3-4, 2007, at USRA Headquarters,
Columbia, MD, 2. July 8, 2007 at the Pasadena Hilton, and 3. October
23-24, 2007, at USRA Headquarters, Columbia, MD, On May 17, the interim
HEM-SAG interim findings were reported to MEPAG management (Drs. Ray
Arvidson, past MEPAG Chair and Jack Mustard, MEPAG Chair) and MEP
management (Drs. Michael Meyer, MEP, NASA Headquarters and Rich Zurek,
MEP, JPL) via telecon.

The scientific goals and objectives for the human exploration of Mars
discussed in this report are based on the Mars Scientific Goals,
Objectives, and Priorities: 2006, (MEPAG, 2006) (J. Grant, editor, 31
page white paper posted February, 2006, by the Mars Exploration Program
Analysis Group (MEPAG) at
<http://mepag.jpl.nasa.gov/reports/index.html>.

## HEM-SAG Starting Assumptions

1.  The first human mission to Mars may be scheduled for launch as early
    as 2030, and as late as 2040. In this study, only consider the first
    three human missions to Mars.

2.  Assume that the scientific objectives for the first human mission to
    Mars would be set based on cumulative knowledge and priorities as of
    about 5 years before launch.

3.  Assume that the robotic exploration of Mars would continuously
    operate from now until the first human mission.

4.  Because the timing of the second human mission to Mars relative to
    the first is subject to large uncertainties, for the purpose of this
    planning exercise, the HEM-SAG should focus on to develop inputs
    into the planning the baseline architecture for the first, and
    possibly subsequent, human missions to the Martian surface.

## HEM-SAG Requested Tasks

5.  Starting from the current version of the MEPAG (2006), develop an
    analysis of the probable/possible evolution of our scientific goals
    and objectives for Mars over the next three decades. The scientific
    goals and objectives of a future human mission would need to be
    based on this projection, not on today's list.

    a.  Which of MEPAG's current scientific goals, objectives and
        investigations would have been met, all or in part?

    b.  Since the nature of science is that investigations not only
        answer questions, but almost always also raise new ones, how are
        the current objectives and investigations likely to evolve into
        future ones?

6.  Develop an analysis of the spectrum of possible scientific
    objectives that would be appropriate for a future human mission to
    Mars.

    a.  Evaluate the advantage to an implementation involving humans for
        different kinds of scientific investigations

    b.  Analyze the opportunity to take scientific advantage of the
        engineering aspects of a human mission.

7.  Based on the above considerations, develop an analysis of the
    probable/possible relative priority of the identified candidate
    scientific objectives.

# Why Mars?

Mars is a unique and complex world. Many of the same
processes/mechanisms operate/operated on both Earth and Mars, e.g.,
early heavy bombardment, impact craters, planetary dipole magnetic
field, widespread and extensive volcanism, the presence of liquid water
on the surface, geochemical cycles, the condensation of atmospheric
gases forming polar caps, etc. Mars, like the Earth, is a terrestrial
planet with a very diverse and complex surface features and processes.
Like the Earth, Mars is also a possible abode for past and/or present
life. The geological record suggests that the atmosphere/climate of Mars
has changed significantly over its history. Early Mars may have
possessed a denser atmosphere, perhaps with a surface atmospheric
pressure in excess of 1000 millibars, the surface pressure of the
Earth's atmosphere. A denser atmosphere on Mars would have permitted
liquid water on its surface. Present-day Mars has a thin (6 millibars)
cold atmosphere, devoid of any surface liquid water. Why has Mars
changed so drastically over its history? How and why has the
habitability of Mars changed over its history? Is there a message in the
history of Mars to better understand the future of the Earth?

# Why Humans?

Humans have unique capabilities for performing scientific measurements,
observations and sample collecting. Human attributes to exploration
include: intelligence, adaptability, agility, dexterity, cognition,
patience, problem solving in real-time, in situ analyses - more science
in less time!

Humans are unique scientific explorers. Humans could obtain previously
unobtainable scientific measurements on the surface of Mars. Humans
possess the abilities to adapt to new and unexpected situations in new
and strange environments, they can make real-time decisions, have strong
recognition abilities and are intelligent. Humans could perform detailed
and precise measurements of the surface, subsurface and atmosphere while
on the surface of Mars with state-of--the-art scientific equipment and
instrumentation brought from Earth. The increased laboratory ability on
Mars that humans offer, would allow for dramatically more scientific
return within the established sample return limits. The HEM-SAG
envisions that the scientific exploration of Mars by humans would be
performed as a synergistic partnership between humans and robotic
probes, controlled by the human explorers on the surface of Mars.
Robotic probes could explore terrains and features not suitable or too
risky for human exploration. Under human control, robotic probes could
traverse great distances from the human habitat covering
distances/terrain too risky for human exploration and return rock and
dust samples to the habitat from great distances.

An important element of the HEM-SAG study has been to identity the
unique capabilities that humans would bring to the process of exploring
Mars. As a result, a common set of human traits emerged that would apply
to exploration relating to the MEPAG Goal III science disciplines which
include Geology, Geophysics, Atmosphere/Climate, and Biology/Life,.
These characteristics include: speed and efficiency to optimize field
work; agility and dexterity to go places difficult for robotic access
and to exceed currently limited degrees-of-freedom robotic manipulation
capabilities; and most importantly the innate intelligence, ingenuity,
and adaptability to evaluate real-time and improvise to overcome
surprises while ensuring that the correct sampling strategy is in place
to acquire the appropriate sample set.

The unique capabilities that humans would provide for each of the MEPAG
Goal III science disciplines mentioned above are summarized as follows:

### Geology

Intelligent sample selection, real time assessment of site sampling
progress and strategy development to optimize science return.

Drilling in environments difficult for core recovery (ice, sediments,
other unconsolidated materials) without human involvement.

Rapid assessment of subsurface and sampling/trenching (efficiency
factor).

### Geophysics

Humans are likely to be far more efficient and skilled than robots in
carrying out the careful emplacement of instruments, networks, and site
surveys required to meet geophysical investigation goals and objectives.
Even if rover-borne instrumentation is deployed tele-robotically, that
would require human oversight from the habitat. Some geophysics
instrumentation must be deployed and then recovered following
measurements (e.g., active seismic systems, or EM sensors). Humans would
make this deployment/recovery process more efficient and perhaps even
more carefully done, as well as providing instant gratification on the
health and performance of the instruments.

### Atmosphere/Climate

Human enabled investigations on Mars would benefit atmospheric, polar
cap, and ancient climate science objectives in a variety of ways. Human
dexterity and efficiency would be important qualities for
micrometeorological investigations where activities such as radiosonde
preparation and release are not yet automated on Earth due to the
dynamic interaction with surface turbulence and winds. Cognitive
ability, dexterity and efficiency would be necessary attributes in the
search for relevant rock outcrops and samples, providing the ability to
identify sources of trace gases for studies of current climate on Mars
as well as locating pristine impact glasses containing trapped gasses
for the study of ancient Mars climate. These unique human capabilities
would be vital to deep drilling and coring activities. Touch and sound
would be used to monitor the drill performance and respond rapidly to
changing subsurface conditions.

### Biology/Life 

Earth-based investigations into the purported evidence for life in
Martian meteorite ALH84001 have involved a great number of scientists
utilizing many sophisticated instruments and techniques but remain
controversial. Evidence of life on Mars, both past and present may be
quite subtle. The selection of relevant samples and sampling
environments would require the unique capabilities of humans (e.g.,
ingenuity, flexibility, efficiency) to interpret available clues in real
time and to strategically execute a plan for investigation of hypotheses
in situ. Humans bring to planetary exploration the ability to quickly
analyze and assess samples before they degrade locally or on return.
Samples should still be returned to Earth because of the advanced
analytical capabilities of terrestrial laboratories, but the increased
capabilities humans would provide on Mars, and the remarkable advances
that have and would continue to be made in lab instrument
miniaturization mean more science reaped without the restrictions of
sample weight on return and a greater likelihood of satisfying the goals
and objectives of the mission.

We believe that the human element is value added to all aspects of the
MEPAG Goals and Objectives. Technology development in the decades
leading up to a human mission to Mars would determine the best
synergistic fit between human and robotic exploration and perhaps
technology challenges would be overcome to shift the balance of physical
activity toward robotic assignment. However, certain uniquely human
attributes could not be duplicated by or relegated to robots or to
operations remotely operated by humans on a planet substantially
separated in time and space from Earth. Only a human presence in Mars
mission surface operations activities could facilitate and achieve the
ambitious scientific goals and objectives of MEPAG.

# some HEM-SAG General Conclusions

**For the first three human missions: three different sites or the same
site?**

Three independent sites.

**For the first three human missions should they be: "short stay (\~30
days)" or "long Stay (\~500 days)"?**

Three long-stay (\~500 days) missions to maximize scientific return.

**How much surface mobility, in terms of radial distance from landing
site, would be required to perform the required science?**

Human mobility (horizontal)/pressurized human rover \>200 km radial
(Perhaps \>500 km).

**What would be the subsurface access requirements?**

Vertical subsurface access (drilling) \~300 m at one site for access to
subsurface liquid water zones, if available; less (5-50 m) at multiple
sites on traverses. Selective recoverable coring, e.g., polar climate
coring to depth of 300 m.

**How would we implement a search for extant life vs. a search for
fossil life? (Assessing the human of human explorers on the search for
extant life)**

Very carefully. The search for extant biology must be an important
scientific goal/objective of human exploration. Humans have a great deal
of experience in carrying out aseptic sampling of exteme environments on
Earth to carry forward in this endeavor

Human in-situ analyses on Mars vs. returning samples to Earth for
analyses (Mass of instrumentation/equipment transported from Earth to
Mars for in situ analyses on Mars versus amount of sample mass to be
returned to Earth)

Human habitat/work station: In situ sample analysis and cataloging:
Analyses that could not be performed on Earth, e.g., tests for extant
life.

Samples would include rocks, drill cores, surface/atmospheric dust, ice,
atmospheric gas.

Sample conditioning and preservation would be essential.

Human habitat LAB instruments for multiple objectives: Geology,
Atmosphere/Climate and Biology/Life.

Emplacement of network stations for Geophysics, Atmosphere/Climate and
even Biology/Life would be essential beyond initial landing site
(200-400 km radial from landing site) to be operated during and after
humans return to Earth.

**How much sample mass should be returned to Earth?**

Mass of samples returned to Earth \>250 kg.

# Geology: Human Exploration Goals and Objectives

## What Would Be the Key Scientific Goals and Objectives of Human Exploration of Mars In Geology and What Would be the Sample Human Science Reference Missions (HSRM) In Geology?

While current and future robotic Mars missions would provide insight
regarding the geology of Mars, HEM-SAG concluded that the fundamental
top-level questions with regard to Mars would likely remain broadly the
same over the next 20 years. Among those questions are:

1.  What is the volcanic history of the planet, and is Mars volcanically
    active today?

2.  What was the nature and evolution of the Martian magnetic field?

3.  What is the climate history of Mars?

4.  What is the hydrologic history of Mars?

5.  Is Mars hydrologically active at the present time?

These questions have wide-ranging implications with regard to the
evolution of the Solar System, the nature and evolution of Earth's
surface and climate, and the feasibility and likelihood of biology on
another planetary body. The complex history of the Mars, and the
evolution of Mars from the potentially "warm and wet" periods of its
early Noachian history to the later "cold and dry" period of the
Amazonian, strongly suggest that an exploration strategy that addresses
the characteristics and processes of the three major periods would be
required (Figure 1).

![](media/image1.jpeg){width="6.502777777777778in"
height="4.529861111111111in"}

Figure 1. Geological history of Mars with the major periods and
significant events and processes.

Thus, none of these questions could be answered by a focused study on
just one landing site. The diversity of surface morphology and
composition of the Martian surface demands an array of landing sites
that spans the geologic history of Mars. As a preliminary exercise, we
specified 58 distinct landing sites that would address these issues and
would specifically benefit from the presence of human explorers (Figure
2). A brief discussion of each of the 58 landing sites is found in
Appendix 1. From these 58 sites, we chose 3 sample sites for more
detailed examination and traverse selection, which we plan to use as
reference missions after further outlining the major questions with
regard to the geology of Mars.

![](media/image2.jpeg){width="6.502777777777778in"
height="3.370138888888889in"}

Figure 2. Location map for the 58 potential exploration sites on Mars.

The three proposed reference mission sites are indicated in red.

### Planetary-Scale Geologic Processes that Could be Addressed by Human Exploration

The absolute ages of surface units on Mars has been deciphered through
indirect methods; samples returned from the Moon in the Apollo Program
were used to provide constraints on the crater-size-frequency
distribution of the lunar surface, and this has been applied to Mars,
among other terrestrial planetary bodies. While this has provided a
general history of Martian surface processes (Figure 1), it does not
allow for detailed study of specific Martian periods, in particular the
Hesperian and Amazonian, when the impact flux greatly decreased. While
Martian meteorites have been analyzed and dated, not knowing their
geologic context makes their incorporation into the geologic history of
Mars difficult. And while a Mars Sample Return mission would yield
surface samples with known context, a robotic mission would not yield
the array of optimal samples that would address a wide range of
fundamental questions. A human mission would allow for greater access to
samples that a robotic rover might not get to, and the capacity for
real-time analysis and decision-making would ensure that the samples
obtained would be the optimal samples available.

Human explorers would also have greater access to the near-subsurface of
Mars, which would yield insights into climate and surface evolution,
geophysics, and potentially biology. Humans would be able to navigate
more effectively through blocky ejecta deposits that would provide
samples that were excavated from great depth and provide a window into
the deeper subsurface. Humans could trench in dozens of targeted
locations and operate sophisticated drilling equipment that could sample
the top \~1 km of the crust. Our current understanding of the crust of
Mars is limited to the top meter of the surface, so drilling experiments
would yield unprecedented and immediate data. Drilling in areas of gully
formation could also test the groundwater model by searching for a
confined aquifer at depth.

### Human Science Reference Mission (HSRM): Geology

We have analyzed three different exploration sites in detail as
potential reference missions for the first program of human Mars
exploration. The sites would span the geologic history of Mars (one site
for each period of Martian history; Figure 1) and allow for exploration
traverses that would examine a variety of surface morphologies, textures
and mineralogies to address the fundamental questions posed by MEPAG.

**Jezero Crater.** Jezero crater is a \~45 km impact crater on the
northwest margin of the Isidis impact basin, in the Nili Fossae region
of Mars (Figures 3 and 4). This region is a very important area for
understanding the formation of the Isidis basin, the alteration and
erosion of this Noachain basement, and subsequent volcanism and
modification (e.g., Mustard et al., 2007; Mangold et al., 2007). The rim
has been breached in three places: twice where channels from the
neighboring highlands to the west have drained into the crater from the
northwest (Figures 3, 4), and once on the eastern margin where the
crater has drained eastward towards the Isidis basin (Fassett and Head,
2005) (Figure 5). Each input channel deposited deltas on the crater
floor that have been preserved and reveal sedimentary structures (Figure
6) and clay deposits (Figure 7) in high-resolution images and spectral
data (Fassett et al., 2007; Ehlmann et al., 2007). Other parts of the
crater floor appear to have been resurfaced by lava.

![](media/image3.jpeg){width="6.502083333333333in"
height="4.941666666666666in"}

Figure 3. Potential traverses for human explorers in and around Jezero
Crater.

![](media/image4.jpeg){width="6.502083333333333in"
height="2.002083333333333in"}

Figure 4. Jezero Crater in perspective view showing Isidis Basin rim and
watershed area.

![](media/image5.jpeg){width="6.502083333333333in"
height="1.7784722222222222in"}

Figure 5. Topography of Jezero Crater.

![](media/image6.jpeg){width="6.502083333333333in"
height="4.447916666666667in"}

Figure 6. HiRISE image of delta deposit and layering in scroll bar.

![](media/image7.jpeg){width="2.9993055555555554in" height="4.1in"}

Figure 7. CRISM multi-spectral map of delta:

Green, phyllosilicates; Orange, olivine; Purple, neutral or weak bands.

A 500-day mission at this site would reveal considerable data regarding
the early Martian environment. Jezero crater itself is Noachian in age
and the preserved rim would provide access to ancient bedrock material
(rich in low-calcium pyroxene) exposed by the impact. The delta deposits
are likely to be Noachian in age and HiRISE data show that the
sedimentary record in the deposit has been preserved as a series of thin
layers (Figure 6). On the basis of the fact that a standing body of
water existed within the crater for an extended period of time, this
would be an ideal site to search for extinct biology. Humans would also
be able to examine the structure and deposits within the channels
associated with the deltas, which would be applicable to the other vast
valley networks on Mars.

Extended traverses would be able to access and study the entire Jezero
crater system (Figure 3). To the southwest of Jezero are Hesperian lava
flows from Syrtis Major, a principle volcano in the northern hemisphere
of Mars providing a key constraint on the geological timescale of the
region. This would also shed light on the evolution of magma composition
on Mars. To the east of Jezero is the floor of Isidis basin, which is
topographically connected to the northern plains and which would allow
for detailed study of major impact events. Samples collected from all of
these sites would allow for enhanced geochronology and a more detailed
understanding of the hydrology, sedimetology, volcanology, and
habitablity of the region.

**Mangala Valles.** Mangala Valles is an Hesperian-aged outflow channel
which has received considerable attention on account of its role in
global cryosphere/hydrosphere interactions, as well as the possibility
that it contains icy near-surface deposits (Levy and Head, 2005; Leask
et al., 2007a,b; Hanna and Phillips, 2006; Ghatan et al., 2005; Wilson
and Head, 2004; Head et al., 2004; Hanna and Phillips, 2007; Leask et
al., 2007). Mangala Valles emanates from a graben that is radial to the
Tharsis volcanic complex (Figure 8). Massive release of water from the
ground at the graben was accompanied by phreatomagmatic eruptions
(Wilson and Head, 2004) and caused catastrophic flow of water to the
north, carving streamlined islands. There are also young glacial
deposits along the rim of the graben (Head et al., 2004) and evidence
for glacial scour having modified the surface of the outflow channel.

This site shows evidence for fluvial, volcanic, tectonic and glacial
activity and complicated interactions among them. A landing site in the
smooth terrain at the center of the outflow channel would provide access
to a variety of sites of interest. Traverses to the channel head and the
graben would allow direct observation of cryosphere-breaching geological
activity. Traverses along the floor of the outflow channel, as well as
on the scoured plains would provide insight into outflow flood hydrology
and erosion processes, as well as provide an opportunity for sampling
ice-rich deposits which may contain ancient flood residue. A traverse to
the vent-rim glacial deposits would provide access to landforms created
by volcano-ice interactions, as well as to samples of distal Tharsis
volcanic deposits. On the basis of the likelihood that if life exists on
Mars, it is most likely to inhabit the subsurface, a site such as
Mangala would offer a unique opportunity to sample for evidence of such
activity.

![](media/image8.jpeg){width="6.502083333333333in"
height="4.888888888888889in"}

Figure 8. Potential traverses for human explorers in and around Mangala
Valles.

**Arsia Mons Graben.** All three of the major Tharsis Montes shield
volcanoes and Olympus Mons exhibit expansive late-Amazonian glacial
deposits on their northwestern flanks. The broadest of these deposits
are the ones found on Arsia Mons, which show glacial deposits \~400 km
to the west of the accumulation zone and cover an area of about 170,000
km^3^ (Head and Marchant, 2003). These glacial deposits are found among
classic volcanic and tectonic structures, so an extended mission at this
location would provide a wealth of information concerning several of the
fundamental questions of Martian geology during the Amazonian period.

We designed several traverses from a potential base camp set up at 8°S,
124°W (Figure 9) that would analyze the glacial and volcanic deposits,
and the complicated relationship between them. Using extended rovers
human explorers would be able to ascend the western flank of the shield
and systematically obtain targeted samples that elucidate the recent
volcanic history of Arsia. Another traverse from the same base camp
would provide access to a \~5 km wide graben that appears to have been a
major accumulation zone for much of the observed glacial deposits (Shean
et al., 2007). A systematic sampling strategy at this location would
provide a history of the flow regime at this site, and drilling at
targeted locations could provide the recent climate record for Mars.

![](media/image9.jpeg){width="6.502083333333333in"
height="4.922916666666667in"}

Figure 9. Potential traverses for human explorers in and around the
Arsia Mons glacial deposits.

Recent General Circulation Models (GCMs) based upon global topography
have revealed the Tharsis Montes to be significant cold traps for the
accumulation of volatiles on the surface (Forget et al., 2006).
Fieldwork at this site used in conjunction with remote sensing data
would have global implications for recent climate change on Mars.

Below we assess the detailed activities that might be undertaken during
these extended exploration periods, and show how they might link to
MEPAG Goals and Objectives.

### Graben and Surrounding Smooth Plains --- 5 months

**Geological Analysis.** Analysis of glacial landforms and glacial and
climatic history. Analyze the multiple drop moraines and assess
sedimentary fabric, lithologic variations, search for erratics from
further up the volcano. Study the processes producing drop moraines and
assess similarities and differences between moraines. Dig for buried ice
for ancient ice samples, and assess for ice cores for climate history.
Examine the relationship to any exposed bedrock, searching for any
evidence that the glacier was ever wet-based (scou in rock, drumlins,
etc.). Examine thickness and fabrics of sublimation tills. Enter the
major graben from the north, and traverse the ridges to the apparent
base of the accumulation zone. Sample the volcanic rock suite and look
for diversity and evidence of different eruption styles. Assess wall
stratigraphy and gather representative samples in sequence for
radiometric dating. (MEPAG investigations IA1, IA2, IA3, IIA2, IIB4,
IIB5, IIIA1, IIIA3, IIIA4, IIIA5, IIIA6).

**Shallow Seismic Survey.** Measure thickness of sublimation tills and
graben fill deposit at distal and proximal locations; assess presence of
ice beneath till on graben floor. (MEPAG investigations IA1, IA2, IIB5,
IIIA1, IIIA2).

**Sediment Drilling.** Analyze contributions from Arsia (tephra and
bedrock) and from regional climate system (dust and ice) (MEPAG
investigations IA1, IA2, IIB5, IIIA1, IIIA2).

**GPR Ice-sounding.** Determine high-resolution layering of valley-ill
deposit, and document lenses of near-surface ice. (MEPAG investigations
IA1, IA2, IIB5, IIIA1, IIIA2).

**Shallow Excavations.** Sample near-surface ice and permafrost
deposits. (MEPAG investigations IA1, IA2, IIB5, IIIA1, IIIA2).

**Electrical Resistivity.** Determine permafrost depth in valley fill
deposit and on surrounding plains. (MEPAG investigations IA1, IA2, IIB5,
IIIA1, IIIA2)

**Rock Sampling.** Systematic sampling to provide constraints on flow
rates and evolution with implications for recent climate change. (MEPAG
investigations IA3, IIIA2)

**Mapping.** Features of interest would include accumulation zone at the
south-eastern extent of the graben and parallel ridges throughout the
graben. Detailed maps of the extent of each of the major drop moraines.
(MEPAG investigations IA1, IA2, IIB5, IIIA1, IIIA2)

### Eastern Flank of Arsia Mons --- 3 months

**Geological Investigations of the Flank of a Major Shield Volcano on
Mars.** Anaysis of mineralogy and petrology of lava flows, pyroclastic
edifices and tephra deposits. Examine evidence for volcano-ice
interactions and document geologic effects and chemical/mineralogic
alterations. Look for evidence of the highest topographic levels of ice
accumulation on the edifice and document the nature of such deposits.
(MEPAG investigations IIIA4)

Mapping of the Flanks of a Representative Tharsis Volcano. (MEPAG
investigations IA1, IA2, IIB5, IIIA1, IIIA2)

Installation of sensitive seismometers to detect current magmatic and
deeper subsurface activity and to study the internal structure of the
volcanic edifice. (MEPAG investigations IA1, IA2, IIB5, IIIA1, IIIA2)

**Rock Sampling.** Systematic sampling of Amazonian volcanic units to
provide insight into present Mars composition. (MEPAG investigations
IA3, IIIA2)

### Southern Young Glacial Deposits --- 3 months

**Geological Analysis.** Study the nature of the youngest glacial
deposits in and around the small graben and assess the drop moraines and
their stratigraphic relationships. Assess the ages of these in relation
to the rest of the Arsia tropical mountain glacier deposits. Traverse
the broad Arsia lava flows that appear to be superposed on the glacial
deposit and assess their ages in detail, sampling for radiometric ages.
Look for evidence for volcano-ice interactions and document these
effects, including generation and fate of any meltwater. Assess impact
craters for deeper material and subglacial deposits. (MEPAG
investigations IIIA3, IIIA4).

**Shallow Seismic Survey.** Determine relative contributions of glacial
and volcanic deposits. (MEPAG investigations IA1, IA2, IIB5, IIIA1,
IIIA2).

**Sediment Drilling.** Examine sediment for compositional analysis.
(MEPAG investigations IA1, IA2, IIB5, IIIA1, IIIA2).

**GPR Ice-sounding.** Determine high-resolution layering of smooth
glacial units, and document lenses of near-surface ice. (MEPAG
investigations IA1, IA2, IIB5, IIIA1, IIIA2).

**Shallow Excavations.** Sample near-surface ice and permafrost
deposits. (MEPAG investigations IA1, IA2, IIB5, IIIA1, IIIA2).

**Electrical Resistivity.** Determine permafrost depth in young glacial
deposits. (MEPAG investigations IA1, IA2, IIB5, IIIA1, IIIA2).

**Ice Coring.** Drill to reveal ice composition and trapped atmosphere
for recent climate change analysis.

### Western Deposits --- 4 months

**Geologic Analysis.** Traverse to major graben within the fan-shaped
tropical mountain glacier deposit. Compare these glacial deposits to
relatively younger deposits higher on the edifice. Assess proportions of
sediment sources and determine depth to ice. Look for evidence of
wet-based glacial activity. Traverse to graben: Analyze theories of
origin. Compare evidence for simple glacial-passive graben interaction
and the possibility of dike intrusion into the ice and phreatomagmatic
explosions and eruptions. Look for country rock blocks and juvenile
magmatic material on the rim and floor of the graben. Assess wall
stratigraphy. (MEPAG investigations IA1, IIIA4, IIIA7).

Detailed Mapping of Glacial/Volcanic Interactions. (MEPAG investigations
IIIA4, IIIA6, IIIA7).

**Shallow Seismic.** Record depth measurements of distal smooth facies.
(MEPAG investigations IIIA4, IIIA5, IIIA6, IIIA7).

**Rock Sampling.** Dating of distal units to provide context for
duration of glacial flow. (MEPAG investigations IIIA4, IIIA5, IIIA6,
IIIA7).

**Application to MEPAG Goal III.** Determine the evolution of the
surface and interior of Mars.

All of the investigations outlined by MEPAG Goal III could be addressed
by human exploration at carefully chosen exploration sites, such as
those at the here proposed reference missions outlined above. The
following table shows the methods and instrumentation that would be used
at the various exploration sites.

Table 1. Objective: Determine the Nature and Evolution of the Geologic
Processes that Have Created and Modified the Martian Crust and Surface
(Investigations In Priority Order)

+-------------------------------------+--------------------------------+
| Investigation                       | Geology Approaches             |
+-------------------------------------+--------------------------------+
| 1\. Determine the present state,    | \- Drilling                    |
| 3-dimensional distribution, and     |                                |
| cycling of water on Mars.           | \- Surveying for groundwater   |
|                                     | seeps                          |
|                                     |                                |
|                                     | \- GPR                         |
|                                     |                                |
|                                     | \- MET Stations                |
+-------------------------------------+--------------------------------+
| 2\. Evaluate fluvial, subaqueous,   | \- Sampling along traverses    |
| pyroclastic, subaerial, and other   |                                |
| sedimentary processes and their     | \- MET stations                |
| evolution and distribution through  |                                |
| time, up to and including the       | \- In-situ composition         |
| present.                            | analysis                       |
+-------------------------------------+--------------------------------+
| 3\. Calibrate the cratering record  | \- Thorough sampling of        |
| and absolute ages for Mars.         | diverse rocks                  |
|                                     |                                |
|                                     | \- Cosmogenic age dating of    |
|                                     | samples                        |
+-------------------------------------+--------------------------------+
| 4\. Evaluate igneous processes and  | \- Extensive sampling          |
| their evolution through time,       | traverses                      |
| including the present.              |                                |
|                                     | \- In-situ composition         |
|                                     | analysis                       |
+-------------------------------------+--------------------------------+
| 5\. Characterize surface-atmosphere | \- MET stations                |
| interactions on Mars, including     |                                |
| polar, Aeolian, chemical,           | \- Traverse sampling along     |
| weathering, mass-wasting and other  | glaciers                       |
| processes.                          |                                |
|                                     | \- Sampling of diverse         |
|                                     | mineralogy                     |
+-------------------------------------+--------------------------------+
| 6\. Determine the large-scale       | \- Drilling.                   |
| vertical structure and chemical and |                                |
| mineralogical composition of the    | \- Seismic stations            |
| crust and its regional variations.  |                                |
| This includes, for example, the     | \- GPR                         |
| structure and origin of hemispheric |                                |
| dichotomy.                          | \- Compositional comparison of |
|                                     | fresh/weathered samples        |
+-------------------------------------+--------------------------------+
| 7\. Document the tectonic history   | \- Seismic stations            |
| of the Martian crust, including     |                                |
| present activity.                   | \- Observations of graben and  |
|                                     | other tectonic features        |
+-------------------------------------+--------------------------------+
| 8\. Evaluate the distribution and   | \- Stratigraphic sample        |
| intensity of hydrothermal processes | collection                     |
| through time, up to and including   |                                |
| the present.                        | \- Compositional analysis at   |
|                                     | multiple sites                 |
+-------------------------------------+--------------------------------+
| 9\. Determine the processes of      | \- Sample collection at        |
| regolith formation and subsequent   | multiple                       |
| modification, including weathering  | latitudes/environments         |
| and diagenetic processes.           |                                |
|                                     | \- MET stations                |
+-------------------------------------+--------------------------------+
| 10\. Determine the nature of        | \- In-situ magnetometer        |
| crustal magnetization and its       | analysis.                      |
| origin.                             |                                |
|                                     | \- Traverses in areas of       |
|                                     | magnetic anomalies             |
+-------------------------------------+--------------------------------+
| 11\. Evaluate the effect of impacts | \- Ejecta sampling             |
| on the evolution of the Martian     |                                |
| crust.                              | \- Mapping of crater-wall      |
|                                     | outcrops                       |
+-------------------------------------+--------------------------------+