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Unpublished white paper, TBD p, posted March 2008 by the Mars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                       |
+-------------------------------------+--------------------------------+

**GEOPHYSICS: HUMAN EXPLORATION GOALS AND OBJECTIVES**

## What are the key scientific goals and objectives of human exploration of Mars in geophysics and what are sample Human Science Reference Missions (HSRM) in geophysics?

Mars geophysics science objectives fall into two broad categories:
planetary scale geophysics (1000s of km), and what might be called
"exploration geophysics," which addresses regional (10s-100s km) or
local scales (\<10 km). The first involves characterizing the structure,
composition, dynamics and evolution of the Martian interior, while the
second addresses the structure, composition and state of the crust,
cryosphere, hydrologic systems, and upper mantle. Here we describe how
these objectives could be met through investigations carried out on
human missions. The MEPAG Goal III science investigations relevant to
Mars geophysics are listed in Tables 2 and 3.

Table 2. Proposed Planetary Scale Geophysics: Investigations &
Approaches

+----------------------------+-----------------------------------------+
| Investigation              | Geophysics approaches                   |
+----------------------------+-----------------------------------------+
| 1\. Characterize the       | \- Seismology                           |
| structure and dynamics of  |                                         |
| the interior.              | \- Heat flow                            |
|                            |                                         |
|                            | \- Gravity                              |
|                            |                                         |
|                            | \- ULF EM induction (conductivity       |
|                            | profile)                                |
|                            |                                         |
|                            | \- High-precision geodesy               |
+----------------------------+-----------------------------------------+
| 2\. Determine the origin   | \- High-precision, high-resolution      |
| and history of the         | magnetic field measurements             |
| magnetic field.            |                                         |
|                            | \- Measurements of the magnetic         |
|                            | properties of samples                   |
+----------------------------+-----------------------------------------+
| 3\. Determine the chemical | \- Seismology                           |
| and thermal evolution of   |                                         |
| the planet.                | \- Heat flow                            |
|                            |                                         |
|                            | \- ULF EM induction (conductivity       |
|                            | profile)                                |
|                            |                                         |
|                            | \- Gravity                              |
|                            |                                         |
|                            | \- High-precision geodesy               |
|                            |                                         |
|                            | \- High-precision, high-resolution      |
|                            | magnetic field measurements             |
+----------------------------+-----------------------------------------+

Table 3. Proposed Regional and Local Scale Geophysics: Investigations &
Approaches

+---------------------------------+------------------------------------+
| Investigation                   | Geophysics approaches              |
+---------------------------------+------------------------------------+
| 1\. Evaluate fluvial,           | \- Reflection seismology           |
| subaqueous, pyroclastic,        |                                    |
| subaerial, and other            | \- Ground Penetrating Radar        |
| sedimentary processes and their |                                    |
| evolution and distribution      | \- Gravity                         |
| through time, up to and         |                                    |
| including the present.          | \- EM induction (conductivity      |
|                                 | profile)                           |
|                                 |                                    |
|                                 | \- Neutron spectroscopy            |
+---------------------------------+------------------------------------+
| 2\. Characterize the            | \- Reflection seismology           |
| composition and dynamics of the |                                    |
| polar layered deposits.         | \- Ground Penetrating Radar        |
|                                 |                                    |
|                                 | \- Gravity                         |
|                                 |                                    |
|                                 | \- EM sounding (conductivity       |
|                                 | profile)                           |
+---------------------------------+------------------------------------+
| 3\. Evaluate igneous processes  | \- Reflection seismology           |
| and their evolution through     |                                    |
| time.                           | \- Ground Penetrating Radar        |
|                                 |                                    |
|                                 | \- Gravity                         |
|                                 |                                    |
|                                 | \- EM induction (conductivity      |
|                                 | profile)                           |
+---------------------------------+------------------------------------+
| 4\. Characterize                | Requires active seismic, EM, NS    |
| surface-atmosphere interactions |                                    |
| on Mars, including polar,       |                                    |
| aeolian, chemical, weathering,  |                                    |
| mass-wasting and other          |                                    |
| processes.                      |                                    |
+---------------------------------+------------------------------------+
| 5\. Determine the large-scale   | Requires passive, active seismic,  |
| vertical and horizontal         | gravity, active EM, passive        |
| structure and chemical and      | low-frequency EM, what else.       |
| mineralogical composition of    |                                    |
| the crust. This includes, for   |                                    |
| example, the structure and      |                                    |
| origin of hemispheric           |                                    |
| dichotomy.                      |                                    |
+---------------------------------+------------------------------------+
| 6\. Determine the present       | Requires active seismic, active    |
| state, 3-dimensional            | EM, passive low-frequency EM,      |
| distribution, and cycling of    | instrumented drilling or wireline  |
| water on Mars.                  | sensors.                           |
+---------------------------------+------------------------------------+
| 7\. Document the tectonic       | Requires gravity, passive and      |
| history of the Martian crust,   | active seismic, active EM, passive |
| including present activity.     | low-frequency EM, instrumented     |
|                                 | drilling or wireline sensors.      |
+---------------------------------+------------------------------------+
| 8\. Evaluate the distribution   | Requires passive and active        |
| and intensity of hydrothermal   | seismic, active EM, passive        |
| processes through time, up to   | low-frequency EM, instrumented     |
| and including the present.      | drilling or wireline sensors       |
|                                 | (maybe robotic since there is      |
|                                 | astrobiological potential in       |
|                                 | hydrothermal systems).             |
+---------------------------------+------------------------------------+
| 9\. Determine the processes of  | Requires passive, active seismic,  |
| regolith formation and          | active EM, passive low-frequency   |
| subsequent modification,        | EM, NS for hydrogen?               |
| including weathering and        |                                    |
| diagenetic processes.           |                                    |
+---------------------------------+------------------------------------+
| 10\. Determine the nature of    | Requires mobile magnetometry, heat |
| crustal magnetization and its   | flow, passive low-frequency EM     |
| origin.                         | (multi-point? A network?). Does    |
|                                 | this require a borehole, so we\'d  |
|                                 | need drilling capability?          |
+---------------------------------+------------------------------------+
| 11\. Evaluate the effect of     | Subsurface mapping via active      |
| impacts on the evolution of the | seismic, EM sounding, other?       |
| Martian crust.                  |                                    |
+---------------------------------+------------------------------------+

We assume here that no robotic missions to Mars before 2025 address the
science issues in a complete way. For example, we assume that no network
mission such as ML3N would be flown. We do this to be conservative, in
order to make as complete a set of human exploration-related geoscience
investigations and activities as possible. Clearly if future robotic
missions address Mars geophysics topics, the human mission activities
must be revisited.

In general, Mars geophysics would be well served by landing sites and
traverses identified by the Geology panel. Figure 10 shows four of the
58 sites considered by the HEM-SAG. These sites would span the planet,
and offer a sampling of Mars' remarkable geologic diversity. The Chasma
Boreale site (CB) offers access to an immense stratigraphic column of
polar layered deposits presumably stretching far back into the
Amazonian. The Nili Fossae site (NF) sits on the edge of the hemispheric
dichotomy boundary and provides access to Noachian/Hesperian-age fluvial
features. The Centauri Montes site (CM), on the eastern rim of the giant
Hellas impact basin, contains features ranging from Noachian basin rim
materials to Amazonian/Hesperian outflow channels to Amazonian debris
aprons and recent gully changes, hinting at the possibility of
near-surface water. The Arsia Mons site (AM) sits on the western flank
of the volcano and provides access to putative Amazonian-age glacial
deposits and comparatively young lava flows. Each site offers the
opportunity to address multiple geophysics investigations. We will
revisit these sites and plausible geophysical exploration strategies
later.

### Planetary Scale Geophysics: Structure, Composition, Dynamics, and Evolution of the Martian Interior.

To characterize the structure and dynamics of Mars' interior and
determine the chemical and thermal evolution of the planet, physical
quantities such as density and temperature with depth, composition and
phase changes within the mantle, the core/mantle boundary location,
thermal conductivity profile and the three-dimensional mass distribution
of the planet must be determined. To determine the origin and history of
the planet's magnetic field, we must discover the mineralogy responsible
for today's observed remanent magnetization, and understand how and
*when* the rocks bearing these minerals were emplaced.

The measurement requirements for planetary scale geophysics present some
drivers for Mars Exploration architectures. A key driver is the need to
instrument the planet at appropriate scales: for example, global seismic
studies rely on widely separated stations so that seismic ray paths
passing through the deep mantle and core could be observed. This need
would translate into multiple, widely separated landing sites for the
first human missions. If only a single landing site would be selected
and revisited, then far less information about the planet's interior
would be obtained. As can be seen in Figure 10, the three low-latitude
sites would provide a reasonable planetary-scale network, and would also
enable heat flow measurements in diverse crustal/lithospheric settings:
the volcanic Tharsis rise, the Isidis wall/dichotomy boundary, and the
rim of the Hellas basin. However, these sites do not fall into the
region of intense remnant crustal magnetization, so it is important to
consider a location in the mid- to high latitudes of the southern
hemisphere near 180E longitude.

![](media/image10.jpeg){width="6.497222222222222in"
height="3.232638888888889in"}

Figure 10. Map of MOLA topography, with possible human exploration
landing sites indicated: Chasma Boreale (CB), Nili Fossae/Isidis (NF),
Centauri Montes (CM), and Arsia Mons (AM) sites. Also indicated is a
broad region spanning Terra Cimmeria and Terra Sirenum with intense
remnant crustal magnetization.

### Exploration Geophysics: Structure, Composition, State of Near-Surface Crust

To characterize the structure, composition, and state of Mars'
near-surface crust both local and regional subsurface information must
be obtained. A wide variety of exploration geophysics techniques exist
that provide such information. For example, sounding for aquifers could
be accomplished through electromagnetic techniques, and layering in
sedimentary units could be determined through reflection seismology.
Magnetic surveys carried out at landing sites tell us about the spatial
scales of crustal magnetization, and tie in to local and regional
geology for context.

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

Geophysics measurement requirements span three disparate spatial scales,
depending on the science to be done. At the largest scales (1000s of
km), characterizing the interior of Mars would require a widely spaced
network of at least 3 emplaced central geophysics stations, one at each
landing site. At regional scales (10s-100s km), characterizing crustal
structure, magnetism, and other objectives require mobility to emplace
local networks around a landing site. Finally, at local scales (\~10
km), mobility is key to performing traverse geophysics, and in carrying
out investigations (such as seismic or EM sounding) at specific stations
along a traverse. The central geophysics stations and the regional scale
networks would be emplaced and left to operate autonomously after the
human crew departs. Traverse and station geophysics would be carried out
only during the human mission, unless this can be done robotically after
completion of the human mission.

Central geophysical stations at each landing site would include passive
broadband seismic, heat flow, precision geodesy, and passive
low-frequency electromagnetic instrumentation. Satellite geophysics
stations would include the nodes of a regional seismic array and vector
magnetometers. Along the traverses, experiments would be performed at
sites of interest. These would include active EM sounding for subsurface
aquifers, active seismic profiling to establish structure with depth,
and gravity measurements. Ground penetrating radar and neutron
spectroscopy along the traverse track would help map out subsurface
structure and hydration state/ice content for the near-subsurface.

Based on the geophysics science objectives, multiple sites would meet
the investigation needs and geologic settings. A list of these sites is
captured in Table 4; three sites at widely separated locations would be
required to address global questions concerning the interior of Mars.
Table 5 lists instrumentation relevant to geophysics investigations, and
provides estimates of mass and power.

Table 4. Suggested Combinations for 3-site Visit Scenarios

+---------------------+------------------------+----------------------+
| *Site 1*            | *Site 2*               | *Site 3 (Antipodal)* |
+---------------------+------------------------+----------------------+
| *19. Arsia Mons     | *23. Chryse Planitia:  | *1. Impact Crater    |
| Glacial/ Volcanism: | (27.0°N, 41.0°W)*      | Near Nili Fossae     |
| (4.8°S, 126.3°W)*   |                        | (18.4°N, 77.7°E)*    |
|                     | *24. Medusae Fossae    |                      |
| *26. Northeast      | Formation:*            | *14. Nili Fossae:*   |
| flanks of Arsia     |                        |                      |
| Mons: (7.4°S,       | *(1.6°N, 173.2°W)*     | *(24.2°N, 79.4°E)*   |
| 121.2°W)*           |                        |                      |
|                     | *28. Terra Sirenum:    | *25. Hellas Basin    |
| *34. Arsia lobate   | (39.3°S, 161.7°W) or   | Floor:*              |
| glacial deposit:    | location near          |                      |
| (7.4°S, 123.8°W)*   | magnetization          | *(41.9°S, 69.6°E)*   |
|                     | reversal*              |                      |
|                     |                        | *27. Walls of Dao    |
|                     | *38. Mangala Valles:   | Vallis: (33.7°S,     |
|                     | (18.0°S, 149.4°W)*     | 92.5°E)*             |
|                     |                        |                      |
|                     |                        | *29. Centauri        |
|                     |                        | Montes:*             |
|                     |                        |                      |
|                     |                        | *(38.7°S, 96.7°E)*   |
|                     |                        |                      |
|                     |                        | *37. Syrtis Major    |
|                     |                        | Planum: (7.0°N,      |
|                     |                        | 69.0°E)*             |
|                     |                        |                      |
|                     |                        | *45. Isidis Basin    |
|                     |                        | Floor:*              |
|                     |                        |                      |
|                     |                        | *(12.0°N, 88.5°E)*   |
|                     |                        |                      |
|                     |                        | *46. Utopia Basin    |
|                     |                        | Floor:*              |
|                     |                        |                      |
|                     |                        | *(43.8°N, 117.0°E)*  |
+---------------------+------------------------+----------------------+

Notes:

For a single site stay, regions near Arsia Mons are of high priority
(listed under Site 1).

Restricting Site 2 to 38 and Site 3 to 14, 37, 45 may yield better
combinations of geophysical diversity (tectonic activity, heat flow,
crustal magnetization).

Sites 23, 25-29, and 46 may have higher probability of near-surface
recent activity and thus of high priority for groundwater studies.

Table 5. Proposed Geophysics Instrumentation

+-------------+-----+-----+-------------------------+-----------------+
| Instru      | M   | Po  | Capabilities/details    | Heritage        |
| ment/system | ass | wer |                         |                 |
+-------------+-----+-----+-------------------------+-----------------+
| Seismometer | 1   | 0.3 | 3-axis system, two      | NetLander       |
|             | .75 | W   | long-period and 1       |                 |
|             | kg  |     | MEMS-based short period |                 |
+-------------+-----+-----+-------------------------+-----------------+
| Geophones   | 0.2 | 0   | High frequency          | Apollo,         |
|             | kg  | .01 | magnetic-coil based     |                 |
|             |     | W   | seismometers (3-4       | commercial      |
|             |     |     | units)                  | systems         |
+-------------+-----+-----+-------------------------+-----------------+
| Active      | \   | N/A | Various explosive       | Apollo,         |
| seismic     | ~20 |     | sources and assemblies  |                 |
| sources     | kg  |     | (thumper, mortars,      | commercial      |
|             |     |     | bombs)                  | systems         |
+-------------+-----+-----+-------------------------+-----------------+
| Ground-     | 0.4 | 0   | Monopole 2-6 MHz.       | NetLander, MIDP |
| Penetrating | kg  | .15 | Bi-static modes         |                 |
| Radar (GPR) |     | W   | possible with           |                 |
|             |     |     | additional GPRs.        |                 |
+-------------+-----+-----+-------------------------+-----------------+
| Fluxgate    | 0.3 | 0.1 | Range ±10^4^ nT with    | MGS, NetLander, |
| M           | kg  | W   | 0.02 nT resolution,     | countless       |
| agnetometer |     |     | noise \~10 pT (0.01 to  | terrestrial     |
|             |     |     | 10 Hz)                  | space and       |
|             |     |     |                         | commercial      |
|             |     |     |                         | systems         |
+-------------+-----+-----+-------------------------+-----------------+
| Searchcoil  | 0.6 | 0.1 | Broadband 10^-2^ Hz to  | Terrestrial     |
| M           | kg  | W   | 100 kHz, sensitivity    | space and       |
| agnetometer |     |     | 10^-4^ to 10^-6^        | commercial      |
|             |     |     | nT/Hz^1/2^              | systems, MIDP   |
+-------------+-----+-----+-------------------------+-----------------+
| Electric    | 0.5 | 0.1 | Set of 4 Broadband      | MIDP and        |
| Field       | kg  | W   | 10^-4^ Hz to 10 kHz,    | commercial      |
| Probes      |     |     | sensitivity \>0.01      | systems         |
|             |     |     | uV/m/Hz^1/2^            |                 |
+-------------+-----+-----+-------------------------+-----------------+
| Active EM   | \   | 40  | Various flexible        | Commercial      |
| source      | ~20 | A   | loops/dipoles deployed  | systems         |
|             | kg  | -hr | 5m-100m baselines       |                 |
|             |     | b   |                         |                 |
|             |     | att |                         |                 |
|             |     | ery |                         |                 |
+-------------+-----+-----+-------------------------+-----------------+
| Precision   | 0.5 | 5   | Doppler measurements    | NetLander Niege |
| radio       | kg  | -35 | accurate to 0.1 mm/s.   | experiment      |
| receiver/   |     | W   | UHF and X-band          |                 |
| transmitter |     |     | transceiver.            |                 |
+-------------+-----+-----+-------------------------+-----------------+
| Temperature | 5   | 50  | Small (cm) to large     | NetLander,      |
| Probes      | kg  | mW  | (1m) temperature probes | Phoenix, MVACS, |
|             |     |     |                         | Apollo          |
+-------------+-----+-----+-------------------------+-----------------+
| Neutron     | 1   | 2 W | Continuous hydrogen     | Mars Odyssey,   |
| S           | kg  |     | assessment along        | Lunar           |
| pectrometer |     |     | traverses.              | Prospector,     |
|             |     |     |                         | MIDP            |
+-------------+-----+-----+-------------------------+-----------------+
| Data        | 1   | 1 W | 8, 12, and 24 bit       | FAST, THEMIS    |
| handl       | kg  |     | precision ADCs, digital | and various     |
| ing/storage |     |     | interfaces and 1-2      | commercial      |
|             |     |     | Gbyte memory storage    | equivalents     |
+-------------+-----+-----+-------------------------+-----------------+

### Centauri Montes Site

Figure 11 shows the Centauri Montes mission landing site and traverses.
The permanent, autonomous, central landing site geophysics station is
shown by the green square. During traverses, permanent satellite
geophysics stations (red triangles) are emplaced. The active gully
location is denoted by the cyan diamond. At selected points along a
traverse, gravity, EM sounding, active seismic experiments would be done
(crosses).

![](media/image11.jpeg){width="4.998611111111111in"
height="5.580555555555556in"}

Figure 11. Centauri Montes mission landing site and traverses.

The Centauri Montes site would provide a location for addressing
multiple geophysics objectives. First, it is one of three sites for
global seismic monitoring. Heat flow measurements for this highlands
site could be compared to, for example, such measurements in the large
volcanic Tharsis province, if the Arsia site is also chosen.

Figure 12 shows the Centauri Montes site geologic traverse plan with
superposed symbols denoting geophysics central station (green square),
and satellite stations (red triangles) forming part of the
local/regional seismic network and locations of electromagnetic
observatories. Exploration targets at this site would include recent
gullies (possibly liquid water), ancient Noachian Hellas basin rim
constructs, Amazonian debris aprons, and other features associated with
geologically recent climate change. The figure shows several traverses,
each requiring an extended period of exploration. During these
traverses, specific sites would be selected for in-depth geophysical
exploration. The right panel zooms in on one part of the blue traverse,
showing two stations (red crosses) where detailed geophysical
exploration could be done. Active reflection seismology and EM sounding,
for example, might be carried out to explore in detail the subsurface
structure of these lobate debris aprons.

![](media/image11.jpeg){width="2.4618055555555554in"
height="4.085416666666666in"}

Figure 12. Centauri Montes site geologic traverse plan.

While traversing, some kinds of measurements could be made to map out
subsurface structure and state. For example, ground penetrating radar
and neutron spectroscopy would provide cuts of near surface layering
(with sufficient dielectric contrast) and bulk hydrogen estimates as a
function of position along the traverse. Perhaps most important,
geophysical methods could be used to sound the subsurface along the rim
of the gullied crater, thus providing information about the presence or
absence of an aquifer as a potential gully source. This combination of
surface prospecting during traverse and fixed, temporary sounding sites
is illustrated in Figure 13. Here the rover team first would explore the
crater rim, stopping at promising sites to temporarily emplace
geophysics instrumentation such as EM sounding and active seismic
systems to characterize the subsurface. Results from these surveys would
help determine the most promising location(s) to drill.

![](media/image12.jpeg){width="4.997222222222222in"
height="4.714583333333334in"}

Figure 13. Exploration of the rim and interior of the gullied crater
near Centauri Montes.

Crosses show geophysical sounding station sites along the traverse
(yellow).

### Nili Fossae --- Isidis Site

The Nili Fossae site would be another location for addressing multiple
geophysics objectives. Again, it is one of three sites for global
seismic monitoring. Heat flow measurements for this dichotomy boundary
site, far from late Amazonian volcanic activity, provide another
important tie-point for interior structure, composition and dynamics.
The stratigraphy of depositional fans, possible lake-bottom deposits,
shoreline breaches and other features could be explored.

![](media/image13.jpeg){width="6.502083333333333in"
height="4.4527777777777775in"}

Figure 14. The Nili Fossae site on the western wall of Isidis basin.
Base (green square) and satellite (red triangle) geophysics stations are
shown. Possible local sites for detailed subsurface exploration are also
shown (crosses).

### Arsia Mons Site

The Arsia Mons site would open the exploration of the most important
volcanic province on Mars. Again, it would be one of three sites for
global seismic monitoring. Heat flow measurements for this Tharsis rise
site, where extensive volcanism has occurred since the Noachian, would
certainly improve our knowledge of interior structure, composition and
dynamics. Figure 15 shows the proposed locations of the base and
satellite stations for geophysics investigations. In this case the
satellite stations may include additional heat flow experiments,
searching for evidence of late stage dike intrusion, if cooling time is
not too short (\<10^5^ yr). With a local seismic network, identify
seismic velocity anomalies associated with deep magmatic bodies. Active
(reflection) seismic studies at many local sites along the traverses
would help reveal the history of ash deposits and lava flows. They may
also reveal the presence of ice at depths consistent with Late Amazonian
deposition and subsequent sublimation in current obliquity and climate
conditions.

![](media/image14.jpeg){width="6.504861111111111in"
height="4.842361111111111in"}

Figure 15. The Arsia Mons site.

### Crustal Magnetism Site

The most intense remnant crustal magnetic fields are found in the region
between Terra Sirenum and Terra Cimmeria, at mid- to high southern
latitudes centered on 180E. This region is thus a prime target for
shedding light on the history of an early Mars dynamo, the nature of the
crustal magnetization process, and attendant implications for Mars'
early thermal history. The left panel of Figure 16 shows the filtered
radial magnetic field component observed by Mars Global Surveyor at the
mapping altitude of 400 km. Superposed on this map are the locations of
gullies identified in MGS/MOC and MRO/HiRISE images by HEM-SAG member
Jennifer Heldmann. The right panel shows a HiRISE image of one of these
gullies (outlined by a black circle in the left panel, 47.2S 176.8E), on
a south-facing interior crater wall. This crater is within \~100 km of a
radial magnetic field reversal seen in MGS/MAG-ER aerobraking data. The
region of intense crustal magnetization contains many gullies; like the
Centauri Montes site, it affords many opportunities for study of
plausibly ice-cored formations and episodic surface water flow (if this
is the operative gully formation mechanism). Thus, a landing site in the
vicinity of these features would permit investigation of diverse science
areas: crustal magnetism (including possibly the identification of
magnetic minerals in ancient Noachian rocks), gullies and their
relationship to a (once) ice-rich mantle or subsurface aquifer, a record
of Amazonian climate change in the mantle deposits, and the
astrobiological potential of subsurface habitats.

![](media/image15.jpeg){width="6.488194444444445in"
height="4.228472222222222in"}

Figure 16. (Left) Map of MGS/MAG-ER radial magnetic field measured at
400-km altitude, with locations of gullies found in MGS/MOC (squares)
and MRO/HiRISE (crosses) images. (Right) HiRISE image of an interior
crater wall gully (located at black circle in left panel). (Inset)
Detail of the gully headwall, with suncup-like texture in the superposed
mantle deposit possibly indicating a once-ice-rich composition.

### Landing Site Prioritization

Table 4 indicates some combinations of landing sites that would serve
geophysics objectives, both global and regional/local.

### MEPAG Geophysics Investigations 

In the following table, the first column lists the MEPAG Goal III
investigations, the second column identifies the relevant geophysics
techniques (in no particular order) used to address the objectives of
each investigation. For example, a seismic network provides S and P wave
travel times, from which ray paths and velocities are determined. Models
of interior composition and structure must be consistent with these
measurables.

# Atmosphere/Climate: Human Exploration Goals and Objectives

## What are the key scientific goals and objectives of human exploration of Mars atmosphere/climate and what are sample Human Science Reference Missions (HSRM) in atmosphere/climate?

### Summary

Atmosphere and Climate goals and objectives are less site-specific than
geology or biology, with the notable exception of climate studies
associated with polar ice cap drilling.

In Appendix B, we emphasize updated atmospheric and climate objectives
and the degree to which they may be advanced by general rather than
site-specific human exploration activities on Mars.

Key scientific goals and objectives of Human Exploration for Mars (HEM)
for the atmosphere/climate are summarized in Table 6.

Table 6. Proposed MEPAG Atmospheric Goals and Objectives

  ---------------- ------------------------------------------------------
  MEPAG 2030 Goal  Key objectives for human missions
  II               

  Atmospheric      Surface-atmosphere interactions: dynamics, heat and
  objectives       mass balance, non-equilibrium trace gases

                   Search for sources of volatiles and trace gases

  Polar Cap        Baseline chronology and charactersation of the climate
  objectives       history of the north polar dome (deep core)

                   Horizontal sampling of the NPLD

  Early climate    Long-term climatic evolution of the planet
  evolution        (billion-year temporal scale); implications of early
                   climatic conditions in the emergence of early
                   potential habitats and/or Life, which includes
                   inference in the atmosphere chemical state

                   Sampling of Noachian to Amazonian deposits through
                   soft drilling (around 1 meter deep) along outcrops or
                   deep drilling to capture information in the
                   sedimentary record
  ---------------- ------------------------------------------------------

HEM Atmospheric Objectives focus on processes within the Planetary
Boundary Layer (PBL, surface to \~10 km), where surface-atmosphere
interactions impart fundamental influences on the dynamical, chemical,
and aerosol characters of the global Mars atmosphere. Orbital remote
sensing for this region remains difficult and lander/rover atmospheric
payloads limited such that sufficiently detailed measurements of the PBL
are unlikely to be returned from Mars science missions prior to 2030.
Field study of the PBL on Earth remains the preferred method of
advancing understanding, with intensive campaigns using combinations of
automatic weather stations, mobile surface-based atmospheric sounders,
and balloon borne sonde platforms. HEM atmospheric observations could
provide optimum in situ and remote access to the PBL important not only
to the understanding of global Mars Atmosphere and Climate, but also to
the support of HEM operations and as environmental characterization
essential to the interpretation of many biology and geology objectives.

HEM Polar Cap objectives are included as of high scientific value, but
are understood to be challenging due to polar night considerations.

A third class of activity is associated with the early evolution of
climate and would benefit from the return of samples containing gas
inclusions to Earth.

In the following sections two nominal reference missions are identified:
an atmospheric reference mission and a reference mission to the north
polar dome for deep drilling, in order to define the more site-specific
human-enabled mission activities necessary to sample the critical
volatile records contained within the polar ice caps. Atmospheric
reference mission activities are anticipated to be included in all human
missions.

## Nominal Atmospheric Human Science Reference Mission (HSRM)

### Science Goals And Approach

The nominal atmospheric reference mission would address the goals
described in Appendix B: "Quantitative understanding of atmospheric
processes" and "Microclimates." These goals would require similar
investigations, however a microclimate objective would be more specific,
requiring additional planning to optimize site selection for
meteorological stations, and time-phasing of investigations relative to
relevant seasonal cycles. Site selection considerations are described
under "location" below.

A proposed baseline is one central station (could be close to hab, but
see constraints on fetch under location section) plus remote stations
either to broadly characterize the region (co-sited with major
geology/biology investigations) or arranged to give three-dimensional
information on specific flows associated with microclimate. The
microclimate objective would also require (a) reference meteorological
station(s) to provide regional context.

The HSRM scientific capabilities are summarized in Table 7.

Table 7. Proposed HSRM Atmospheric/Climate Goals and Approach

+--------------+------+------------------------------------------------+
| Quantitative | Mi   | Approach                                       |
| U            | cro- |                                                |
| nderstanding | clim |                                                |
| of           | ates |                                                |
| Atmospheric  |      |                                                |
| Dynamics     |      |                                                |
+--------------+------+------------------------------------------------+
| Surfac       |      | 1\. Monitor basic atmospheric state            |
| e-atmosphere |      | (temperature, wind vector, pressure, humidity, |
| i            |      | radiation) at reference height above surface   |
| nteractions: |      | (2 m?)                                         |
| D            |      |                                                |
| ynamics/heat |      | 2\. Monitor temperature, wind, dust and cloud  |
| and mass     |      | through the depth of the boundary layer (2     |
| balance      |      | scale heights \~ 20 km)                        |
|              |      |                                                |
|              |      | 3\. Monitor the radiation and heat balance for |
|              |      | surface-atmospheric exchange and solar forcing |
|              |      |                                                |
|              |      | 4\. Monitor the mass balance for dust and      |
|              |      | volatile components, especially considering    |
|              |      | dust lifting processes and also considering    |
|              |      | electrical effects                             |
|              |      |                                                |
|              |      | 5\. Assess the impact of latitude, longitude,  |
|              |      | season and local time                          |
+--------------+------+------------------------------------------------+
| Search for   |      | 1\. Measure atmospheric composition            |
| sources of   |      | (trace,isotopes)                               |
| volatiles    |      |                                                |
| and trace    |      | 2\. Measure physical and chemical properties   |
| gases        |      | of the regolith                                |
|              |      |                                                |
|              |      | 3\. Measure the deposition of                  |
|              |      | chemically-active gases, such as ozone and     |
|              |      | hydrogen peroxide, to the Mars surface.        |
|              |      |                                                |
|              |      | 4\. Search for gases of biogenic (methane,     |
|              |      | ammonia, etc.) and volcanic (sulfur dioxide,   |
|              |      | hydrogen sulfide, etc.) origin and determine   |
|              |      | their source(s).                               |
|              |      |                                                |
|              |      | 5\. Search for sources of atmospheric water    |
|              |      | vapor.                                         |
|              |      |                                                |
|              |      | 6\. Assess the impact of latitude, longitude,  |
|              |      | season and local time on atmospheric           |
|              |      | composition and on the photochemistry of trace |
|              |      | atmospheric gases.                             |
+--------------+------+------------------------------------------------+

### Location

Siting of a meteorological station as part of a global network or for
regional context should consider an unobscured fetch in the direction of
the prevailing wind. For boundary layer studies on Earth, 1km is
considered the upwind requirement that would ensure the met station is
representative of its surroundings. Booms holding sensors should be
directed into the wind in order that the boom doesn\'t interfere with
measurements. As the prevailing wind may not be known at the specific
site, adjustment may be needed during the mission.

Siting with respect to topography should take into consideration
phenomena such as katabatic flows, gravity waves, and cloud base height.
Downslope evolution is generally of interest, but cross slope
information is useful for 3d information on eg gravity wave direction.
Horizontal thermal gradients through eg albedo differences, can also
drive local atmospheric circulations.

## Research Plan and Schedule 

Atmospheric reference mission activities would take place as part of a
multi-disciplinary mission. Frequency and timing of atmospheric
activities would be important. Activities would be scheduled at regular
intervals in order to sample diurnal and seasonal cycles usefully, but
some flexibility is required for response to interesting weather
conditions or results.

The estimates below are given for atmospheric activities only, and
assume that general site acclimatization and survey and traverse
activities are planned in addition. For example, if a crew would be
investigating a site of biological interest, 1 sol/2 people would be
added to the plan in order to install a met station installed in the
vicinity, 2 sols/2 people may be added to the plan to perform campaigns
at the site using portable instrumentation.

Site characterization and planning --- 2 people @ 10 sols

Installation of met stations --- 2 people @ 1 sol per site --- assume
minimum of 5 sites

Maintenance --- 1 person @ 1 sol per 30 sols

6 times over course of 500 sol mission -- once per season + 2 to respond
to weather events:

-   2 people @ 3 sols

-   Tethered balloon campaigns (3 sols, one profile per two hours)

-   Radiosonde releases (1 sol, midnight, midday)

-   Campaigns with portable lidar instrumentation --- 3 sols

6 times over course of 500 sol mission, 2 people @ 3 sols:

-   Chemistry campaign --- collection of samples for study of seasonal
    change, traverse activities to search for sources

### Vertical Mobility Requirements

There are requirements to access both the subsurface and the atmosphere.
Subsurface requirements are modest, with depths to \<2 m to install heat
flow, temperature and conductivity probes. Atmospheric vertical access
would be required for detailed profiles of the bottom two scale heights
(\~20 km) of the atmosphere. The lower boundary layer may be accessed by
tethered balloon (a balloon and winch system \<1 km), the higher levels
would require release of balloons with a radio-tracking system. These
systems are outlined under science capabilities required.

### Horizontal Mobility Requirements

For microclimate reasons, there would be high value in atmospheric
investigations taking place at many sites of biological and geological
interest. Access to those sites would follow the same mobility
requirements as biology/geology. Additional mobility around the site
would be required for atmospheric studies to follow topography, for
topography-related and upwind/downwind types of investigations, or
following gradients in trace species. This additional mobility
requirement is of order 1-10 km, and would be required to transport
equipment including for example a balloon winch, or a met station, and 2
people.

### Science Capabilities Required 

The HSRM Atmosphere/Climate Scientific Capabilities are summarized in
Table 8.

Table 8. Proposed HSRM Atmosphere/Climate Scientific Capabilities

+---+--------------------------+---------+----------------------------+
| 1 |                          |         |                            |
| \ |                          |         |                            |
| . |                          |         |                            |
| A |                          |         |                            |
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| c |                          |         |                            |
| e |                          |         |                            |
+---+--------------------------+---------+----------------------------+
| 1 | Monitor basic            | MET     |                            |
| . | atmospheric state at     | s       |                            |
| 1 | reference height above   | tation: |                            |
|   | surface ( 2m?)           |         |                            |
|   |                          | Instr   |                            |
|   |                          | umented |                            |
|   |                          | mast    |                            |
|   |                          | --sonic |                            |
|   |                          | ane     |                            |
|   |                          | mometer |                            |
|   |                          | (3      |                            |
|   |                          | he      |                            |
|   |                          | ights), |                            |
|   |                          | temp    |                            |
|   |                          | erature |                            |
|   |                          | (3      |                            |
|   |                          | he      |                            |
|   |                          | ights), |                            |
|   |                          | pr      |                            |
|   |                          | essure, |                            |
|   |                          | hu      |                            |
|   |                          | midity, |                            |
|   |                          | ra      |                            |
|   |                          | diation |                            |
|   |                          | (net,   |                            |
|   |                          | LW,SW), |                            |
|   |                          | dust    |                            |
|   |                          | p       |                            |
|   |                          | article |                            |
|   |                          | counter |                            |
|   |                          |         |                            |
|   |                          | Soil    |                            |
|   |                          | heat    |                            |
|   |                          | and     |                            |
|   |                          | condu   |                            |
|   |                          | ctivity |                            |
|   |                          | probes  |                            |
|   |                          |         |                            |
|   |                          | Soil    |                            |
|   |                          | temp    |                            |
|   |                          | erature |                            |
|   |                          | profile |                            |
+---+--------------------------+---------+----------------------------+
| 1 | Monitor the radiation    |         |                            |
| . | and heat balance for     |         |                            |
| 2 | surface-atmospheric      |         |                            |
|   | exchange and solar       |         |                            |
|   | forcing                  |         |                            |
+---+--------------------------+---------+----------------------------+
| 1 | Monitor temperature,     | Upward  |                            |
| . | wind, dust and cloud     | looking |                            |
| 3 | through the depth of the | thermal |                            |
|   | boundary layer (2 scale  | IR      |                            |
|   | heights \~20 km)         | spectr  |                            |
|   |                          | oscopic |                            |
|   |                          | sounder |                            |
|   |                          | (water  |                            |
|   |                          | vapor,  |                            |
|   |                          | dust,   |                            |
|   |                          | tempe   |                            |
|   |                          | rature) |                            |
|   |                          |         |                            |
|   |                          | T       |                            |
|   |                          | ethered |                            |
|   |                          | balloon |                            |
|   |                          | & winch |                            |
|   |                          | &       |                            |
|   |                          | gondola |                            |
|   |                          | --      |                            |
|   |                          | sonic   |                            |
|   |                          | anem    |                            |
|   |                          | ometer, |                            |
|   |                          | tempe   |                            |
|   |                          | rature, |                            |
|   |                          | pr      |                            |
|   |                          | essure, |                            |
|   |                          | hu      |                            |
|   |                          | midity, |                            |
|   |                          | camera  |                            |
|   |                          |         |                            |
|   |                          | Rad     |                            |
|   |                          | iosonde |                            |
|   |                          | balloon |                            |
|   |                          | --      |                            |
|   |                          | tempe   |                            |
|   |                          | rature, |                            |
|   |                          | pr      |                            |
|   |                          | essure, |                            |
|   |                          | wind,   |                            |
|   |                          | h       |                            |
|   |                          | umidity |                            |
|   |                          |         |                            |
|   |                          | P       |                            |
|   |                          | ortable |                            |
|   |                          | doppler |                            |
|   |                          | lidar   |                            |
|   |                          | (wind)  |                            |
|   |                          |         |                            |
|   |                          | P       |                            |
|   |                          | ortable |                            |
|   |                          | Raman/  |                            |
|   |                          | imaging |                            |
|   |                          | lidar   |                            |
|   |                          | (dust)  |                            |
|   |                          |         |                            |
|   |                          | DC      |                            |
|   |                          | e       |                            |
|   |                          | lectric |                            |
|   |                          | field   |                            |
|   |                          | sensors |                            |
|   |                          |         |                            |
|   |                          | P       |                            |
|   |                          | ortable |                            |
|   |                          | DIAL    |                            |
|   |                          | (water  |                            |
|   |                          | vapour) |                            |
|   |                          |         |                            |
|   |                          | Surface |                            |
|   |                          | accum   |                            |
|   |                          | ulation |                            |
|   |                          | measu   |                            |
|   |                          | rements |                            |
|   |                          | (du     |                            |
|   |                          | st/ice) |                            |
|   |                          |         |                            |
|   |                          | Mic     |                            |
|   |                          | roscope |                            |
|   |                          | a       |                            |
|   |                          | nalysis |                            |
|   |                          | of dust |                            |
+---+--------------------------+---------+----------------------------+
| 1 | Monitor the mass balance |         |                            |
| . | for dust and volatile    |         |                            |
| 4 | components               |         |                            |
+---+--------------------------+---------+----------------------------+
| 1 | Investigate processes    |         |                            |
| . | that influence the mass  |         |                            |
| 5 | balance for dust and     |         |                            |
|   | volatile components      |         |                            |
+---+--------------------------+---------+----------------------------+
| 1 | Assess the impact of     | Diurnal |                            |
| . | latitude, longitude,     | cycle   |                            |
| 5 | season and local time    | ca      |                            |
|   |                          | mpaign: |                            |
|   |                          | t       |                            |
|   |                          | ethered |                            |
|   |                          | balloon |                            |
|   |                          | s       |                            |
|   |                          | ounding |                            |
|   |                          | each    |                            |
|   |                          | two     |                            |
|   |                          | hours,  |                            |
|   |                          | p       |                            |
|   |                          | ortable |                            |
|   |                          | i       |                            |
|   |                          | nstrume |                            |
|   |                          | ntation |                            |
|   |                          | dep     |                            |
|   |                          | loyment |                            |
|   |                          |         |                            |
|   |                          | S       |                            |
|   |                          | easonal |                            |
|   |                          | cycle   |                            |
|   |                          | ca      |                            |
|   |                          | mpaign: |                            |
|   |                          | 3 days  |                            |
|   |                          | of      |                            |
|   |                          | diurnal |                            |
|   |                          | cycle   |                            |
|   |                          | cam     |                            |
|   |                          | paigns, |                            |
|   |                          | 6 times |                            |
|   |                          | over    |                            |
|   |                          | m       |                            |
|   |                          | ission, |                            |
|   |                          | rad     |                            |
|   |                          | iosonde |                            |
|   |                          | release |                            |
|   |                          | m       |                            |
|   |                          | idday/m |                            |
|   |                          | idnight |                            |
+---+--------------------------+---------+----------------------------+
| 2 |                          |         |                            |
| \ |                          |         |                            |
| . |                          |         |                            |
| A |                          |         |                            |
| t |                          |         |                            |
| m |                          |         |                            |
| o |                          |         |                            |
| s |                          |         |                            |
| p |                          |         |                            |
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| - |                          |         |                            |
| s |                          |         |                            |
| u |                          |         |                            |
| r |                          |         |                            |
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| n |                          |         |                            |
| s |                          |         |                            |
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| A |                          |         |                            |
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| m |                          |         |                            |
| o |                          |         |                            |
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| p |                          |         |                            |
| h |                          |         |                            |
| e |                          |         |                            |
| r |                          |         |                            |
| i |                          |         |                            |
| c |                          |         |                            |
| v |                          |         |                            |
| o |                          |         |                            |
| l |                          |         |                            |
| a |                          |         |                            |
| t |                          |         |                            |
| i |                          |         |                            |
| l |                          |         |                            |
| e |                          |         |                            |
| s |                          |         |                            |
| & |                          |         |                            |
| c |                          |         |                            |
| h |                          |         |                            |
| e |                          |         |                            |
| m |                          |         |                            |
| i |                          |         |                            |
| s |                          |         |                            |
| t |                          |         |                            |
| r |                          |         |                            |
| y |                          |         |                            |
+---+--------------------------+---------+----------------------------+
| 2 | Measure atmospheric      |         | Isotope mass spectrometer  |
| . | composition              |         | (2-10 0amu)                |
| 1 | (trace,isotopes)         |         |                            |
|   |                          |         | Sample processing system   |
|   |                          |         |                            |
|   |                          |         | pH, wet chemistry,         |
|   |                          |         | microscope                 |
+---+--------------------------+---------+----------------------------+
| 2 | Measure physical and     |         |                            |
| . | chemical properties of   |         |                            |
| 2 | the regolith             |         |                            |
+---+--------------------------+---------+----------------------------+
| 2 | Measure the deposition   |         |                            |
| . | of chemically-active     |         |                            |
| 3 | gases, such as ozone and |         |                            |
|   | hydrogen peroxide, to    |         |                            |
|   | the Mars surface.        |         |                            |
+---+--------------------------+---------+----------------------------+
| 2 | Search for gases of      |         | Portable laser diode       |
| . | biogenic (methane,       |         | system or FTIR for \~100   |
| 4 | ammonia, etc.) and       |         | pptv detection limits      |
|   | volcanic (sulfur         |         |                            |
|   | dioxide, hydrogen        |         |                            |
|   | sulfide, etc.) origin    |         |                            |
|   | and determine their      |         |                            |
|   | source(s).               |         |                            |
+---+--------------------------+---------+----------------------------+
| 2 | Search for sources of    |         |                            |
| . | atmospheric water vapor. |         |                            |
| 5 |                          |         |                            |
+---+--------------------------+---------+----------------------------+
| 2 | Assess the impact of     |         | Chemistry campaign: 3      |
| . | latitude, longitude,     |         | days, 6 times over mission |
| 6 | season and local time on |         |                            |
|   | atmospheric composition  |         |                            |
|   | and on the               |         |                            |
|   | photochemistry of trace  |         |                            |
|   | atmospheric gases.       |         |                            |
+---+--------------------------+---------+----------------------------+

### In Rover 

Meteorological sounding equipment would be deployed at specific
locations/grids during initial roving operations (deployed MET station
and upward looking spectroscopic remote sounders). These stations would
be self-operating once positioned. Requirements would be of order 5
sites at \<10 kg each.

### With Astronauts on Eva

In addition to the autonomous meteorological stations indicate above (IN
ROVER), a program of tethered balloon campaigns and radiosondes are
envisioned to be released at the landing site with a specific frequency.
Tethered balloons + winch system \~15 kg. On the earth, radiosonde
balloon and sonde packages are of order several kg each for
stratospheric sounding.With the Marian low atmospheric pressure, larger
balloons may be necessary to reach desired 5-10 km altitudes (although
lower gravity and higher CO~2~ mass density help). Of order 12 such
released balloon sondes would be desired, with two releases (midday,
midnight) each on 6 days spaced throughout the mission.

## HAB "lab" Capabilities

Atmospheric gas/subsurface volatile laboratory capabilities include
isotopic and trace gas analysis. Microscope for dust size, shape and
mineralogy.

Capability to receive and process daily meteorological data from
concurrent orbiters.

## Issues Identified That Would Require Handling Prior to Human Arrival

Design of easy-to-assemble mast equipment.

Miniaturisation of instrumentation.

Radiosonde balloon design, gas fill, and communications infrastructure.

Planetary protection considerations for released radiosonde balloons.

## Nominal Deep Drilling Polar Reference Mission

The high scientific value of a mission to the polar regions of Mars is
outlined in section 1.3. The polar regions pose unique technical
challenges due to cold temperatures and polar night which may be
somewhat offset by access to a ready supply of water and radiation
shielding material (ice).

The north polar dome is the proposed target for a first human polar
mission. A deep drilling phase is described followed by traverse to
lower latitudes for launch at the onset of polar night. This reference
mission does not include explicit biology investigations related to
access to ancient ice, or geology investigations related to crossing the
NPLD, both of which are anticipated to be of high interest.

### Scientific Goals and Approach

Scientific Goals and Approaches for Deep Drilling Polar Reference
Mission are shown in\
Table 9.

Table 9. Proposed Scientific Goals and Approach for Deep Drilling Polar
Reference Mission

  ------------------------ ----------------------------------------------
  Scientific goal          Approach

  Baseline chronology and  Deep core preferably to bedrock and baseline
  characterization of the  chronology
  climate history of the   
  north polar dome         

                           Polar cap mass and energy balance for current
                           climate state and seasonal cap formation
                           processes

                           Shallow cores to investigate heterogenuity

                           Emplacement of geophysical sensors (heat probe
                           and seismic sensors)
  ------------------------ ----------------------------------------------

### Location

Selecting a bore site would follow common practice on Earth where remote
sensing and local surveys are used to investigate a site before a drill
site is chosen. Important parameters are depth of bedrock, topography of
bedrock (a drill site should be close to a divide to minimize flow
effects), thickness of ice layers (thicker gives more sensitivity for a
chronology), quality of ice layers (distortion, density, temperature),
and accumulation rate and local meteorology (want to minimize highly
variable locales and local effects in selecting a site for a baseline
chronology). High resolution gridded aerogeophysical surveys are used to
map these parameters on Earth (e.g., Morse et al, 2002).

For Mars north polar dome site selection, extensive precursor orbital
geophysical and laser altimeter survey would be required to localize the
drill site as far as possible to make most efficient use of the human
team once they land. High-resolution orbiter laser altimeter
measurements over several seasons would aid in understanding surface
accumulation. On arrival, limited in situ geophysical survey could be
used to pinpoint a drill site, to avoid small-scale distortions and
embedded pebbles, as far as these can be detected.

### Research Plan and Schedule 

The Research Plan and Schedule is driven by the limitations imposed by
polar night. In the worst case of a site at the geographical north pole,
the sun will be at or above horizon at cap dome for only 372 sols
(vernal equinox: autumnal equinox Ls 0:180). For a 500 sol mission this
would infer that landing or launch are either done in darkness or
migration of the team to a lower latitude rendezvous with the launch
vehicle would b required. In the schedule below, a traverse to lower
latitudes is described on the understanding that it presents additional
risk and challenge.

### First phase: set up/test (40 sols)

Land on cap dome within 2 km of bore site as selected from precursor
orbital surveys

Site selection: 30 sols

-   Set up local network of 5 met stations to capture initial season: 5
    traverses\<5 km @ 1 sol, 2 people

-   Geophysical survey: 5 traverses \< 2km @ 1 sol, 2 people \<2 km to
    pinpoint drill site

Set up and test of deep drill: 10 sols (4 people)

### Second phase: drilling (22 0sols) 

Figure 17 shows a timeline for EPICA deep drilling at Dome C.

Figure 18 shows a timeline for an EPICA associated surface campaign.

-   Drilling: goal of 12 m/sol

-   Lab analyses for climate and biology

-   Surface heat and mass balance campaigns

-   Local traverses \<10 km, shallow cores by hand auger, emplacement of
    heat probes and a seismic sensor for long term analysis

![](media/image16.png){width="6.003472222222222in" height="8.75625in"}

Figure 17. Depth days at Dome C (Augustin and Antonelli, 2002).

![](media/image17.png){width="5.364583333333333in" height="6.5in"}

Figure 18. Timeline for a 2-month campaign for in situ surface heat and
mass balance experiments associated with EPICA polar coring (Van de
Broeke et al, 2002).

### Third phase: grand traverse (200 sols)

Leave drill rig in situ and traverse NPD scarp southwards to rendezvous
with launch vehicle for depart. Emplacement of additional seismic
sensors with baseline of 500 km. Investigation of sites of biological
and geological interest.

### Vertical Mobility Requirements

Vertical mobility requirements for a Mars Polar dome core are:

-   Depth \~2 km (base of north polar dome).

-   Diameter of core such that enough mass is generated to meet
    sensitivity needs for in situ investigations TBD \>3 in.

-   Ability to drill through dirty ice and lag deposits. MARSIS data
    indicates that the dust content of the NPLD is \<2% (Picardi et al,
    2005).

-   Low contamination for biology purposes (ancient ice deposits).

Reviews of terrestrial deep drilling techniques can be found in NSF ICWG
(2003b) and Bentley and Koci (2006). Tethered mechanical deep drilling
remains the most popular technique on Earth (NSF ICWG, 2003b). These
systems have a Bottom Hole Assembly whose weight relates to length of
the core section and includes the weight of the core section to be
raised to the surface. For a 3.5 m section, the BHA mass is \~200 kg,
e.g., EPICA. Maintaining core quality still remains challenging (NSF
ICWG, 2003a). However, extraction of an ice core on Mars may not be
necessary from a science requirements perspective as Continuous Flow
Analysis (CFA) is becoming increasingly used for analysis of ice core
composition (Svensson et al, 2005). In this case the core is melted and
a continuous flow of meltwater is analysed, giving high spatial
resolution. Thermal drills can generate meltwater directly which could
be pumped out of the drill hole under pressure along heated tubing to
analysis instrumentation. Borehole instrumentation captures the
stratigraphy while isotope and dust grain analysis are done from the
meltwater. Atmospheric inclusions can be captured through control of
pressure in a surface reservoir to allow dissolved gases to collect.
Visual survey of the core stratigraphy can be achieved via a down
borehole multispectral imager/microscope (Carsey et al, 2003). Thermal
drill developments for Mars polar work have already begun (Cardell et
al, 2006). High power would be required for a deep drilling mission ---
of around 1Wm^-1^ to keep the tether from freezing, with potentially
multi-stage pumps to lift the meltwater from the hole. An insulated
tether would be around 100 kg/km. Power required to drill and heat flow
lines would be very challenging at depth --- one possibility would be an
RTG device in the bore-head. (personal communication, Michael Hecht and
CHRONOS team).

![](media/image18.png){width="3.6006944444444446in"
height="4.213888888888889in"}

Figure 19. Thermal drill from Chronos Scout mission concept (Hecht and
Chronos team, 2006).

### Horizontal Mobility Requirements

To site drill rig -- 2 km distance

-   For geophysical survey to select site and characterize local region;
    in situ investigations of current heat and mass balance and polar
    processes --- 2 person roving capability (\<10 km)

-   To traverse off cap to below polar circle launch site -- 1500 km,
    full crew.

### Science Capabilities Required 

Required scientific capabilities are shown in Table 10.

Table 10. Science Capabilities Required.

  -------------------------------- --------------------------------------
  Deep core to provide baseline    
  chronology and characterization  
  of major climatic events in past 
  5M years                         

  Deep core and baseline           Continuous Flow Analysis equipment
  chronology                       (see Hab capabilities) for dating and
                                   composition

                                   Borehole instrumentation:
                                   Multispectral imager \<0.1 mm
                                   resolution; Microscopic imager;
                                   Thermometer

                                   Returned samples of dust from
                                   signficant lag deposits

  Polar cap mass and energy        Requirements as for nominal
  balance for current climate      atmospheric mission
  state and seasonal cap formation 
  processes                        

  Shallow cores to investigate     Hand auger
  heterogenuity                    

  Emplacement of geophysical       Heat probes, seismic sensors
  sensors                          
  -------------------------------- --------------------------------------

### Hab "Lab" Capabilities

Continuous Flow Analysis equipment (pressurized and temperature
regulated)

-   Isotope mass spectrometer

-   Chromatograph

-   Particle size analyzer

-   Biology instrumentation

The laboratory would need to be sited in the near vicinity of the drill
to minimize the transport of cores or the distance of flow tubing to be
heated.

### Sample Return Requirements

Dust collected from within the core would be of high scientific value to
return to Earth for analysis. Could be subsampled, with samples only
returned from significant lag deposits.

### Issues Identified that Will Require Handling Prior to Human Arrival

Feasiblity of a mid-length mission at the north polar cap

-   Deep drilling capability

-   Planetary protection issues --- deep drilling meltwater would
    generate a special region under current definition.

# Biology/Life: Human Exploration Goals and Objectives

## What are the key scientific goals and objectives of human exploration of Mars in biology/life and what are sample Human Science Reference Missions (HSRM) in biology/life?

Human enabled biological investigations on Mars would focus on taking
samples and making measurements to **Determine if Life Ever Arose on
Mars**. This goal is consistent with the 2006 Mars Exploration Program
Analysis Group (MEPAG) goals and priorities, and we do not see this goal
changing in the next 30 year period.

The search for life on Mars can be generally broken into two broad
categories: 1) the search for past (extinct) life on Mars and 2) the
search for present (extant) life. Both have been, and will continue to
be based on a search for water, since all life on Earth requires water
for survival. Abundant evidence on the Martian surface of past water
activity (e.g. rivers, lakes, groundwater discharge) has lead to Mars
becoming a strong candidate as a second planet in our solar system with
a history of life. With increasing knowledge of the extremes under which
organisms can survive on Earth, especially in the deep subsurface,
whether Martian life is still present today has become a compelling and
legitimate scientific question.

The National Research Council (NRC) was recently commissioned to do a
study to develop "an up-to-date integrated astrobiology strategy for
Mars exploration that brings together all the threads of this diverse
topic into a single source for science mission planning" (Jakosky et al
2007). This report did not consider how to do science with humans, but
we rely heavily on it and earlier MEPAG documents here as snapshots of
the current community thinking on astrobiological investigations on
Mars.

As pointed out by Jakosky et al (2007), the search for life on Mars
requires a very broad understanding of Mars as an integrated planetary
system. Such an integrated understanding requires investigation of the
following:

-   The geological and geophysical evolution of Mars;

-   The history of Mars's volatiles and climate;

-   The nature of the surface and the subsurface environments;

-   The temporal and geographical distribution of liquid water;

-   The availability of other resources (e.g., energy) that are
    necessary to support life; and

-   An understanding of the processes that controlled each of the
    factors listed above.

Many of these investigations are well underway robotically and would be
much further advanced through further robotic missions and sample
return. However, a human presence would...

## The Search for Extant Life

Jakosky et al (2007) suggested a number of high priority targets based
on evidence for present-day or geologically recent water near the
surface:

-   The surface, interior, and margins of the polar caps;

-   Cold, warm, or hot springs or underground hydrothermal systems; and

-   Source or outflow regions associated with near-surface aquifers that
    might be responsible for the "gullies" that have been observed.

SR-SAG noted that sites where recent water may have occurred would also
include mid-latitude deposits indicative of shallow ground ice.

Conditions in the top 5 m of the Martian surface are considered
extremely limiting for life. Limiting conditions include high levels of
ultraviolet radiation and purported oxidants as well as most of the
surface being below the limits of water activity and temperature for
life on Earth For these reasons, finding evidence of extant life near
the surface would likely be difficult and the search would almost
certainly require subsurface access. This was also a key recommendation
of Jakosky et al (2007).

## The Search for Extinct Life

Jakosky et al (2007) list sites pertinent to geologically ancient water
(and by association past life) include the following:

-   Source or outflow regions for the catastrophic flood channels;

-   Ancient highlands that formed at a time when surface water might
    have been widespread (e.g., in the Noachian); and

-   Deposits of minerals that are associated with surface or subsurface
    water or with ancient

-   hydrothermal systems or cold, warm, or hot springs.

## Human Science Reference Mission to Address Biological Goals

As a demonstration of how HEM-SAG envisions carrying out the biological
goals, a human science reference mission was designed to the Centauri
Montes region. This region has drawn attention from astrobiologists as a
result of the discovery by Malin et al (2006) that a flow feature
(gully) inside a crater wall has apparently been active in the last
decade, thereby providing the intriguing prospect of liquid water at or
near the surface (Figure 20). This region has also been well documented
for its concentration of young, volatile-rich deposits and figures
prominently in recent GCM simulations at different obliquities, which
indicate that the eastern-Hellas region should be receiving significant
amounts of water-ice from the south pole (Forget et al, 2006). Centauri
Montes is also at the head of major Amazonian/Hesperian outflow
channels.

![](media/image19.png){width="6.504861111111111in"
height="3.9069444444444446in"}

Figure 20. Southeast wall of an unnamed crater in the Centauri Montes
region, as it appeared in August 1999, and later in September 2005 (MGS
MOC Release No. MOC2-1619, 6 December 2006).

The indicators of ice deposits and liquid water today, as well as the
region being associated with outflow channels, provide ample local
targets for the search for extant and extinct life. For geological
investigations, this region has the attraction of all three epochs being
represented in close proximity. We understand that the connection
between the active gully features and liquid water is controversial
(e.g. McEwen et al. 2007). This site was chosen because at the time of
writing, it was one of the two most promising sites on the planet for
finding liquid water near the surface. If other more promising sites are
discovered, site selection for addressing biological goals should follow
these new discoveries.

## Science Goals To Be Addressed

Research at Centauri Montes would be focused on MEPAG goal number 1:
"Determine If Life Ever Arose on Mars." Specific investigations are
summarized in Table 11.

Table 11. Proposed MEPAG Investigations at Centauri Montes and Approach.

+------------------------------+---------------------------------------+
| Investigations               | Approach                              |
+------------------------------+---------------------------------------+
| Characterize complex         | \- Use of raman and GC MS             |
| organics.                    |                                       |
|                              | \- Screening for biomolecules         |
|                              | (electron transport molecules,        |
|                              | various key proteins, phospholipids,  |
|                              | etc.) using life marker chips and     |
|                              | other lab on a chip assays            |
|                              |                                       |
|                              | \- Equipment for nucleic acid         |
|                              | extraction (assuming any life has     |
|                              | nucleic acids) and some sequencing    |
|                              | capability                            |
|                              |                                       |
|                              | \- Basic microscopic staining for     |
|                              | biomolecules                          |
+------------------------------+---------------------------------------+
| 2\. Characterize the spatial | \- Use of isotope mass specs and GC's |
| distribution of chemical     |                                       |
| and/or isotopic signatures.  | \- Tabletop SEM                       |
+------------------------------+---------------------------------------+
| 3\. Characterize the         | \- XRD, LIBS                          |
| morphology or morphological  |                                       |
| distribution of              | \- FTIR + Raman                       |
| mineralogical signatures.    |                                       |
|                              | \- Bright field microscopy            |
|                              |                                       |
|                              | \- SEM                                |
+------------------------------+---------------------------------------+
| 4\. Identify temporal        | \- Basic metabolic analysis (Viking   |
| chemical variations          | style experiments, but using          |
| requiring life.              | non-organic redox couples and other   |
|                              | anaerobic media)                      |
|                              |                                       |
|                              | \- Analysis of major cations and      |
|                              | anions and metals associated with     |
|                              | redox couples.                        |
+------------------------------+---------------------------------------+

## Other Disciplinary Science 

Besides the biological targets, a number of sites of interest exist from
a geological perspective within 100 km of the target crater. Of
particular note is that geological units from all three major epochs are
accessible from this site, including:

-   Noachian Hellas basin rim material

-   Hesperian Smooth Plains sedimentary deposits modified by fluvial,
    periglacial processes

-   Amazonian Debris Aprons (ice-rich material, rock glaciers)

-   Amazonian/Hesperian Pitted Plains deflated ice rich materials

-   Amazonian/Hesperian Outflow Channel material of Reull Vallis

Geophysical surveys could search for near surface liquid water. The
close proximity of active gullies within the Centauri Montes region is
suggestive of possible subsurface aqueous activity which should be
explored to provide a more complete understanding of the hydrologic
system in this area*.* Such data may allow for the detection of a
subsurface aquifer if it exists and we could map out its planar extent
(Antol et al. 2005). The size of the aquifer could place constraints on
the amount of water available to form the gullies. Such information is
valuable for understanding the nature and extent of the hydrological
cycle on Mars as well as selecting drill sites. This information would
also be used to compare the amount of water potentially available in an
aquifer (which is dependent upon the aquifer size) with combined
modeling and geomorphology of predicted amounts of water that have run
through the gullies to assess the consistency of such independent
estimates of water volumes.

Climate and meteorology studies focused at Centauri Montes would provide
insight into the unique process of water ice transport to this region
from the south pole. As the area shows a huge geological record spanning
from Noachian to Hesperian, a long-term climatic evolution of the planet
could be inferred through the integration of geological,
sedimentological and geochemical data recovered from these old deposits.
In addition, meteorology studies would likely be conducted at any site
of human investigation on Mars and thus are not intrinsically
site-specific.

## Location

Centauri Montes is located on the rim of Hellas Basin (Figures 21 and
22). The Centauri and Hellas Montes region is characterized by remnant
massifs interpreted to be crustal uplifts and ejecta from the Hellas
impact which occurred early in Mars' history (Lehmann et al.).
Subsequently, several geologic processes have worked to alter the
landscape. Lobate debris aprons formed which are characterized by
viscous creep and deformation and are attributed to the movement of rock
glaciers (Squyres 1978, 1979; Squyres and Carr 1986; Crown and Stewart
1995). Volcanic processes formed several volcanic edifices in the region
(Greeley and Crown 1990; Crown 1991). Outflow activity worked to move
large volumes of water and debris in association with Dao, Niger,
Harmakhis, and Reull Valles (Price 1992; Bleamaster and Crown 2004).
Therefore the Centauri Montes region has a rich and complex geologic
history.

> ![](media/image20.jpeg){width="4.0in" height="3.8256944444444443in"}
>
> Figure 21. Mola scene of Helles Basin showing location of Centauri
> Montes region (inside white square).
>
> ![](media/image21.png){width="3.998611111111111in"
> height="3.998611111111111in"}
>
> Figure 22. Viking context image of active gully crater (shown in
> Figure 1) at Centauri Montes (inside red square).

A crater within this region located near 38.7°S, 263.3°W is the site of
recent gully activity (Malin et al. 2006). This crater (hereforth
referred to as the active gully crater) is shown in Figure 23. Sometime
between August 1999 and September 2005, a light-toned material was
transported downslope through a gully channel and deposited along the
crater wall (Malin et al. 2006). The new deposit has extended branches,
a digitate terminus, diverts around obstacles, and has low relief. These
observations have been interpreted as suggestive of fluid (aqueous) flow
(Malin et al. 2006). Due to the scientific interest in studying this
site extensively with humans, the human landing site would be adjacent
to this active gully crater.

## Research Plan At Centauri Montes

Two modes of research would be carried out at CM:

### Mode 1 --- Active gully investigations and local drilling

This mode of research is primarily focused on assessing the recently
active gully and other fresh gullies as potential sites of recently
water activity, and hence extant life (Figure 23).

![](media/image22.jpeg){width="5.502083333333333in"
height="5.038194444444445in"}

Figure 23. Mosaic of MOC images M04-04175, M20-00028, R14-02285,
S10-00142, S11-00332, and S16-01250, colorized using a look-up table
derived from Mars Reconnaissance Orbiter HiRISE color data and overlain
on a sub-frame of Mars Odyssey Thermal Emission Imaging System (THEMIS)
image V16997005.To study the active Malin et al gully, we would: a)
Traverse to a site on the crater rim (red X) immediately above the gully
and use a deep drill to access the potential volatile reservoir, b)
Deploy a human or a "cliffbot" from above to repel to the gully site
(blur line) for direct excavation/sampling, and c)Traverse to a point in
the crater just below the gully and access the deposits by climbing up
to them for direct excavation/sampling. A second drill site on the
crater floor would be desirable.

1\. Drilling. For this activity horizontal mobility would be minimal,
largely dependent on how close to the active gully crater a suitable
landing ellipse could be placed. The drill rig would need to be portable
enough to be moved from the landing site, to the drill site.
Alternatively, it could be moved from the landing site on the rover in
pieces and assembled at the drill site. We envision the drill site and
landing site to be close enough together that daily commuting could
occur between the two. Drill samples (cores and or cuttings) would need
to be acquired without drilling fluids (or with clean and sterile
fluids) to protect against contamination and alteration and would
require suitable on-site storage to keep them protected (as close to
their ambient conditions as possible) until such time that they could be
moved back to base (presumably the end of each work shift). Once back at
base, cataloging, sub sampling and analyses would be done in the hab
lab. If there is suitable interest from other disciplines (e.g.,
geophysics, geology), other (not necessarily as deep) holes could be
drilled in the local area for specific goals of geology, geophysics and
climate studies. Drill cores would be processed on site for analysis of
organics or potential biota by subcoring the main core and maintaining
the subcores in sterile conditions. These subcoring methods are similar
to those used in deep biosphere research on Earth. Processing on site
would minimize the chances of contamination during the transfer of the
cores from the field site to the hab or rover lab.

2\. Direct measurements and sampling from the active gully. Based on
available data, this seems to be achieved most easily by descending to
the gully site from above. Samples would be gathered both inside and
outside the gully to assess potential for organic/biological enrichment
in and under the gully, particularly if it is determined that water was
involved in gully formation.

3\. Sampling of sediments on the crater floor. The available imagery of
the active gully crater (Figure 23) suggests a history of fluid flow
through this crater, possibly associated with the gullies. Drilling on
the crater floor into some of these sediments, even to shallow depths
would be useful for seeking out evidence of past life. Multiple samples
would be collected from promising locations.

### Mode 2 --- Sampling Traverses

The second half of the expedition would be spent traversing out to a
radius of 50 km away from the landing site to access materials from the
three different epochs and collect samples for investigation of past
life. Samples would include short cores or grab samples of sediment or
rock. For the astrobiology work we would only do minimal analysis in the
field and would return many samples to the hab lab for detailed
analysis. The main focus is to look for samples which may have preserved
biosignatures (e.g., old ice, evaporites, etc.)

## Horizontal Mobility Requirements

A comparison was done in the region of CM between the scientific
benefits of traversing 50 km to a 100 km radial distance from the
landing site (Figure 24). In this region, 50 km horizontal mobility
seems to be an adequate range given the great diversity of sample sites
within this distance. Increasing the horizontal mobility to 100 km does
not provide a dramatic increase in new types of terrain. The most
significant new terrain type that could be accessed by extending the
traverse distance greater than 50 km is the Hesperian Ridged Plains
(HRPs). These materials outcrop north of the rim massifs shown in Figure
24 and to access the HRPs the astronauts would likely need to drive
around the massif blocks, requiring greater than 50 km driving distance.
In addition, the preferred landing site shown in Figure 24 is purposely
centrally located. If this landing site is shifted in any direction, a
traverse distance of greater than 50 km may be required to access the
highest priority science sites. Nonetheless, due to the high
concentration of scientifically compelling sites within the 50 km
radius, this degree of horizontal mobility would be sufficient for this
mission. Furthermore, only half of the mission would be dedicated to
traversing, and so a 50 km range should provide ample sampling targets
in the limited time. We also recognize a safety constraint on the
distance of the traverse. If there are no additional terrain types that
are of high priority beyond 50 km then rescue and safety considerations
make a 100 km traverse less desirable.

![](media/image23.jpeg){width="3.2375in"
height="3.4270833333333335in"}![](media/image24.jpeg){width="3.2375in"
height="3.4402777777777778in"}

Figure 24. Comparison of possible traverses with a 50 km (left) and 100
km (right) radius from base camp. Both provide access to numerous
deposits/features associated with water (e.g. debris aprons and outflow
channels). Both provide access to a similar diversity of terrain types
of interest, and most importantly, to deposits from all three major
epochs of Martian geology.

## Vertical Mobility Requirements

For biological investigations we would need vertical mobility to:

a\) Investigate the groundwater hypothesis for recently reported active
gullies on Mars (Malin et al. 2006). Several researchers have suggested
that a shallow subsurface aquifer may be the source of the liquid water
feeding the martian gullies (Malin and Edgett 2000; Mellon and Phillips
2002; Heldmann and Mellon 2004; Heldmann et al. 2007). In this scenario,
a liquid water aquifer exists beneath the upslope plateau behind the
gullies at a depth coincident with (or near to) the gully alcove base
depth. The average alcove base depth in the southern hemisphere is \~200
meters poleward of \~40° and thus a drill capable of reaching several
hundred meters depth would be required in order to reach the subsurface
aquifer. To account for any uncertainties and/or heterogeneities in the
subsurface as well as the natural variation in alcove depths within
different gully systems, a drill capable of reaching greater than 250 m
depth (preferably 400-500 m) would be desirable.

b\) Investigate other fresh gully sites (Heldmann unpublished) near the
landing site. Likely the same penetration depths as a) are required
here.

c\) Drill directly into gully sites to 5 m.

d\) Drill (5-50 m) while doing longer traverses to collect samples from
below the high radiation and oxidant surface region for ancient or
dormant life in ground ice and other water lain deposits.

We envision two drills to achieve these goals. One would be heavy and
not very portable (for a and b). The second would be more portable and
lightweight with the option to be mounted on the rover for the deeper
penetrations, and detached and manipulated directly by astronauts for
the shallower work in rough terrain. Examples of this type of
arrangement already exist for terrestrial prospecting (Figure 25).

![](media/image25.png){width="2.8694444444444445in"
height="2.484027777777778in"}

> Figure 25. Image of ARGO vehicle that can be equipped with either a
> hydraulic or pneumatic drill mast that can drill 2-4 in. diameter
> holes up to 60 m deep in rock formations ranging from sedimentary to
> metamorphic. And for further flexibility, the drill can be detached
> from the ARGO and used in man-portable mode. From
> [http://argoatv.com](http://argoatv.com/).

## Science Capabilities Required

The investigation of field samples can be split broadly into two levels
of analysis: 1) basic analyses in the field and measurements that need
to be accomplished in-situ, and 2) more detailed analysis using a full
suite of laboratory equipment.

To accomplish level 1 the rover should offer basic mobile laboratory
capabilities. However, the logistics of operation in a confined rover
space in the field probably militate against including large quantities
of equipment. Further, from a purely logistical standpoint, field
experiments should be limited to those required on site to select
samples etc. Considerations of safety and limited time in the field mean
that carrying out detailed laboratory investigations in a rover would
likely to be undesirable.

Level 2 should be accomplished at the habitat. In a fixed location free
of the constraints of EVA activity much more detailed and painstaking
analysis of samples could be accomplished. For example, precise dating
of samples, which wouldl be extremely helpful in determining the
geological and environment history of sampling sites and hence guiding
sample selection, would be best done on isolated mineral phases
physically separated from hand specimens. Such separation would be most
efficiently done by astronauts. The quality of data for some isotope
systems would also be enhanced by sample preparation procedures that
couild be difficult to automate and package for robotic exploration.

Two laboratories would likely be needed. A medical/planetary protection
laboratory would be used for human health monitoring and medical
treatment as well as monitoring of the microbial ecology of the habitat
and the region around it as part of a general planetary protection
protocol/survey. However, to minimize the chances of cross-contamination
this lab should be separated from a second laboratory used for
extant/extinct life investigations. Separating the two laboratories
would help prevent false positive detection of martian life and it would
reduce the chances of astronauts coming into contact with organic
material from Mars.

The human laboratory could either be physically separated from the
science laboratory within the habitat or alternatively a science
laboratory might be erected separately from the habitat and accessed
either in EVA suit or airlocked pressurized walkway. From a back
contamination point of view this option may be attractive to reduce
contact between Martian materials and people. Additionally, samples of
interest should be subdivided so that a portion of each sample could be
brought into the examination facility and the other portion could be
stored outside or in the "shed" and not brought into an area where
contamination may occur. These stored samples could then be reserved for
return to Earth and further detailed examination.

### Rover

-   Rover mounted drill

-   Seismic sounding equipment (to facilitate local sounding and locate
    the most promising drill targets)

-   Field microscope

-   LIBs and field tele-raman (if a portable package could be made for
    rovers to carry this would be better)

-   Ability to monitor the effectiveness of separation between humans
    and the environment

-   Ability to monitor bioload --- contamination of the environment or
    tools to ensure sample integrity. Basic biological 'dipstick' tests
    for major groups of human-derived organisms

-   GPR

-   Equipment to measure major cations and anions in water extracts.

-   Portable XRF and XRD

-   Radiation measurement tools (UV-Vis spectrometers and dosimeters)

-   pH and Eh meters (to examine water extracts of soils and rocks)

-   Sample containers and handling tools

-   Basic meteorology equipment (temp, pressure, light)

**Carried by astronauts (location)**

-   Multispectral imager

-   Rock hammer and sample bags

-   Hand lens and/or lens imager

-   Digital camera

-   Handheld XRF/XRD

-   Portable field microscope with camera

-   Hand-held spectrometer --- Raman (available at the moment)

-   Soil water/ice content measurement device

-   Sample logging equipment --- preferably automated in some fashion.

-   A portable microarray system

-   Shovel

**Down hole instruments (borehole inspection tools and sampling tools
with the optimistic assumption that we will encounter a brine at
depth):**

-   Panoramic camera

-   Microscopic camera

-   Raman spectrometer for mineralogy logging

-   Magnetic susceptibility detector

-   Environment physicochemical subsurface probes (pH, eH, T, C, ions)

-   Gas-meter in subsurface

-   Subsurface water sampler (is important to maintain the water sample
    under the original P conditions)

**Hab "lab" capabilities**

-   Lab isolation unit to allow astronauts to work on samples (probably
    separate from hab) --- ability to sterilize certain work areas I.e.
    laminar flow hoods for biological investigations

-   Basic lab equipment for planned and spontaneous research (drying
    oven, furnace, scales, etc.)

-   High-end raman spectrometer with mapping capability ---
    multiwavelength perhaps combined with same spot laser induced
    fluorescence or FTIR

-   Tabletop SEM

-   High precision mass spectrometers for isotopic analyses of possible
    biosignatures, environmental indicators and for geochronology

-   GC and GC mass spec (plus auto-extraction system) and laser ablation
    ToF

-   Bright field and fluorescence microscopy

-   Confocal raman microscopy

-   XRD/XRF eventually coupled to SEM

-   Equipment for sample prep (rock saws, mills, etc.)

-   General chemistry equipment for sample preperation and analysis.

-   Equipment for nucleic acid extraction (assuming any Martian life
    have nucleic acids) and some sequencing capability (note this same
    equipment is need for human health monitoring and microbial ecology
    analysis of habitat)

-   Screening for biomolecules (electron transport molecules, various
    key proteins, phospholipids, etc.) using microarray assays and other
    lab on a chip/miniaturized biomolecule detection instruments

-   Basic metabolic analysis/culturing equipment (Viking style
    experiments, but using non-organic redox couples)

-   Basic and fluorescence staining for biomolecules

We note that the equipment required for the investigation of extant and
extinct Martian life wouldl be similar to that required for human
medical analysis (microscopes, scales, molecular biology, etc.) as well
as some geological investigations. Although we recommend that the human
health and science laboratories should be kept separate there should be
redundancy in the consumables required for both labs thus reducing the
total mass penalty in having two labs. Furthermore, in the worst case
equipment (e.g., microscopes) could be cleaned and transferred between
labs for redundancy in the case of equipment failure.

## Benefits of Maximizing Lab Work on Mars

Advantage of doing as much as possible in situ or in Mars lab:

-   There is a scientific advantage to being able to do as much science
    as possible on the planet and portable lab devices would be well
    advanced in the next 30 years

-   Reduces risk of sample loss on return.

-   From a biological perspective, best to keep sample at ambient
    conditions which would be tough to do on sample return. As organics
    and biological material is subject to degradation over time, real
    time analysis would increase the chances of successful detection and
    characterization

-   Could include separation facilities to remove e.g. solids, dissolved
    substances and gases from ice (after thorough characterization) to
    process on site and then send the different factions home for more
    sophisticated analysis

-   Respond to discoveries made in real-time by carrying out a second
    round of more detailed and thorough collection in areas that show
    high potential

-   Could monitor environmental effects of inhabitation.

-   Ensure sample sterility and integrity

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
contentious. 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 (i.e., on Mars). Samples should still be returned to Earth
because of the advanced analytical capabilities of terrestrial
laboratories, but the more ability we have on Mars means more science
done without the restrictions of sample weight on return and a greater
likelihood of satisfying the goals and objectives of the mission.

## Planetary Protection Issues at the HSRM Locality and Potential Mitigation

To achieve the biology goals, especially the search for extant life, we
would almost certainly need to enter special regions (e.g., gully sites
and the subsurface) with humans. We feel that a biologically focused
mission would need to include a search for extant life, so technological
developments would be needed to prevent forward contamination and
provide a safe barrier for astronauts working on samples. Other
potential mitigation:

-   Carry out repeated analysis of microbial populations in soils to
    quantify contamination around station for planetary protection
    analysis. This might be undertaken every 100 days, but this time
    period could be changed in response to detection of contaminants
    and/or during periods of intense EVA activity.

-   Monitor microbial presence in an ever increasing perimeter around
    the station, or a set of perimeters to ascertain spread. Same tools
    used for microbial identification could be used for health
    monitoring and to check sterility of sampling tools if techniques to
    verify cleanliness and contamination control protocols are robust.

-   Any rover that would be developed needs a compartment which would be
    open to the outside only and not to inside contamination. This
    compartment could be used to store samples for their return to the
    habitat base, thus minimizing the escape of microbial contaminants
    from the habitat

-   The Hab lab should also be environmentally separate from crew
    habitation spaces

-   The possible development or designation of special EVA suits with
    high biological containment specification and cleanliness protocols
    that would only be used to access special regions.

## Precursor Science Measurements Needed to Maximize Value of This Site

-   High resolution visible coverage of region, especially crater and
    valley walls for scientific evaluation as well as traverse planning

-   Radar sounding to understand the subsurface and facilitate planning
    of drilling operations (depth and location). Transient
    ElectroMagnetic Sounding (TEM) or Vertical Electrical Sounding (VES)
    should provide additional information on the subsurface relevant to
    this mission

-   High resolution altimetry to evaluate traverse challenges

-   Continued repeat observations of gullies to monitor for additional
    changes within the gully system indicative of ongoing activity

## Issues Identified That Will Require Handling Prior To Human Arrival

-   Feasibility of drilling several hundred meters without fluids and
    within reasonable weight and size limits

-   Blow out protection when drilling into potential aquifers

-   Feasibility of getting humans and/or robots doing science (including
    shallow drilling) on scree slopes

-   Development of robust contamination control protocols for all sample
    handling systems.

## Biology Mission Timeline

A phased approach to the biology program is suggested with the following
key milestones/phases

### Phase I

A period of \~30 days at the beginning of the mission for acclimation
and operations around the station with no long-range vehicle mobility.
This early stage would be used for local sample acquisition, shallow
drilling and planetary protection surveys around the base (to gather
baseline data on soils). Familiarity with operations in the field site
would be gained. Safety would be maximized.

### Phase II

A second period where mobility is extended to \~5 km using
pressurized/unpressurized rovers. This would allow access to the drill
sites and the deep drilling can commence. This phase would last 200
days. Mobility could be extended over time for personnel not required on
the drill site so that they may set out caches and do some preliminary
reconnaissance for the Phase III traverses.

### Phase III

Phase III would lasts for the remainder of mission. Samples would be
collected from most promising sites and initial analysis undertaken in
the laboratory. Iterative process would begin of further sample
collection from most promising sites. The drill rig could be used during
this phase if time and personnel permit.

# Conclusions 

On the basis of about 12 months of scientific analyses and focused
discussions in partnership with Mars Architecture Team (MAT) engineers
and via the guidance of the Mars Architectural Working Group (MAWG), the
following "consensus findings," in bullet form, have been generated by
the HEM-SAG.

These initial "cross-cutting" findings related to specific attributes of
potential human missions required to enable the science priorities
described in detail above, can be listed as follows:

Sample mass to Earth and return mechanism

-   Sample conditioning and preservation essential for some

-   250 kg+ driver (Science) ...\[400 kg max\] → 250 EVA days at 1-1.5
    kg/EVA-sol vs *Apollo 17 threshold*

-   Biology requirements are subset of 250kg+ minima (must-have)

-   Biology hab-lab requirements on Mars are essential for sample
    selection (for in situ analysis)

-   Atmospheric/ice samples as well (subset of total for Earth return)

-   Independent robotic return path to Earth would be required for some
    samples

Horizontal Mobility: 100's km required (pressurized human rover)

-   Science theme dependent --- Biology deep drilling would be least
    horizontal mobility, but remains in \~100 km class

-   Geophysics station spacing requirements dictate (antipodal node
    emplaced): 200-400 km radial from initial landing position

-   Affects regional lithospheric structure, seismicity, thermal
    structure via geophyscial stations

-   Spacing from orbit of magnetic striations now 200 km --- rove to
    ensure high magnetization \> 200 km

-   Supports require atmosphere/climate network sampling

-   Biology/life requires geology-related context mobility (for
    sampling)

Vertical Subsurface Access (drilling)

-   Astrobiology (extant life): \~300 m for access to subsurface liquid
    water zones (if available)

-   5-50 m for traverse sampling

-   Ionizing radiation/super-oxidant zone is 2-5 m → minima is 2 m from
    neutron interaction path length

-   Geology/climate \> 100 m access is likely essential (site dependent)

-   Selective Coring (recoverable) vs pure drilling to depth z (cuttings
    recovered)

-   Polar climate coring-recovery also at 300 m depth (anywhere deep
    ice)

Hab-lab requirements (sample analysis requirements): \[all
multidisciplinary\]

-   Facilitates high-grading of Sample return to Earth mass

-   Enables biology-unique (and climate) measurements that cannot be
    done on Earth

-   Examples of key aspects include: i.e, extant life tests
    (productivity, labeled radio-C etc.)

-   Monitor environmental isolation (contamination and hab isolation,
    curation...)

-   Decisions on basis of samples analysis and directs future sample
    collections and science

Emplacement for network stations (geophysical-meteorological/climate
stations): requirement

-   Some to be left and operated after human departure (i.e.,
    ALSEP-like, LDEF-like, etc.)

Emplacement of short-lived monitoring assets

-   For critical climate/atmospheric sampling and analysis (human
    deployed)

Robotic assistants/adjuncts

-   "Science mule" for information capture and lugging and transport of
    samples, equipment, etc.

-   Next-generation versions ... UAVs, and others

Telecom support for science (getting the data back)

-   Navigation: This includes GPS-like or inertial reference...for
    science documentation: 10m x,y,z is baseline requirements

Ensure separation of biology experiments from human life sciences
biology for crew (hab-lab)

There are specific "pass-backs" to the Lunar human exploration program
that would enable the Mars-related science activities described above,
including validation of some of the cross-cutting findings listed above.

In addition, the following [generalized conclusions]{.underline} are
essential for any science-driven program of human exploration:

-   Multiple, independent sites for long-stay required for
    science-driven HEM missions (500 day, 250 day EVA)

-   Sample mass to Earth \> 250 kg, however achieved (could include
    robotic & human return approaches that separate the sample masses)

-   Human horizontal mobility is \> 200 km radial (may be up to 500 km
    radial)

-   Vertical mobility must be capable of \~ 300 m (at one site, less at
    multiple sites on traverses)

-   Extant biology is not off-limits (can go after it), including in
    situ analysis via special lab equipment

-   Habitat lab instruments for multiple objectives, including biology,
    geology, climate, etc.

-   Emplacement of network stations for interior, meteorological,
    climate and even biology essential beyond initial landing site (to
    be operated during HEM missions and after human return)

-   Science after humans return to Earth essential for monitoring
    climate and interior (and even biology if discovered)

-   Some key human science activities on Mars must be demonstrated on
    the Moon (validation, practice, science value), and maybe some on
    Earth in Mars analogue settings

-   Navigational and telecom infrastructure needed to support human
    science

-   Humans on site (on Mars) bring scientific improvisation,
    adaptability, agility, and increased cognition for solving major
    problems (more science in less time and ultimately results faster,
    better, cheaper)

-   Humans must have equipment to conduct analyses so they can iterate
    to perform well-adapted science to what they discover as they go

-   HEM missions to Mars are not apollo-like (less rush, more time to
    think and adapt) -- consider 500 day versions of Apollo missions as
    test cases

-   Careful consideration of contamination control and isolation for
    biology-relevant samples would be essential to prevent a "false
    positive" \[separate human life sciences from fundamental
    astrobiology investigations\]

-   There are HEM mission science precursors that would enable better,
    smarter, and less costly science that need to be developed \[some
    pragmatic knowledge of dust, radiation, sub-meter geo, terrain,
    etc.\]

-   Deep Drilling and long-range pressurized mobility are essential for
    science-driven HEM missions to Mars in the 2030s

-   Require use of robotic assistants on field traverse and short-lived
    monitoring assets (balloons, etc.)

-   There may be programmatic reasons for a sustained, stable MEP with
    related research and analysis, field analogues, etc. to keep HEM
    missions on track for the 2030s after an era of Human Lunar
    Exploration (20s)

-   The public must be engaged in the scientific exploration of Mars by
    humans! EPO strategy leading to humans on Mars (HEM missions) must
    start now

In summary, the HEM-SAG believe human exploration of the Martian surface
would be required (when possible in terms of space transportation, life
sciences and related engineering for human safety) to fully address the
range of science priorities currently summarized in the MEPAG goals and
objectives document.

# appendices

### Appendix A. Candidate Mars Human Exploration Sites: MEPAG Goal III: Determine the Evolution of the Surface and Interior

Compiled by HEM-SAG with specific site suggestions and contributions by
Jim Head, James Dickson, Caleb Fassett, Joseph Levy, Jim Rice, Francois
Poulet, Jeff Moersch, Jen Heldmann, Charles Cockell, Peter Doran, Ralph
Milliken and Rick Elphic. Initial biology prioritization also included:
(Score: 1- 5. EL = Extinct Life, PL = Present life. WG = biologist's
'wild guess'). See map for locations, separate entries at each site
description for GRS/NS data on hydrogen/water content. **\*\*RM\*\*** is
one of three Reference mission sites (red dots on map). All sites would
include full complement of geophysical instrumentation (active and
passive seismometers, magnetometers, heat flow probes, etc.) and the
selection of sites should consider how the selection would contribute to
the most effective seismic networks, obtaining heat flow measurements
from different terrains and terrains of different ages, and be sure to
sample the full range of known magnetic anomalies. Most sites contain
the average Water Equivalent Hydrogen (WEH) in weight %, courtesy of
Rick Elphic. Three reference mission sites provide seismic profile from
edge to middle of Tharsis (38 and 34) and opposite sides of the globe
for deep seismic structure (38/34 and 1). Primary goal maps and
suggested traverses are provided for the three reference mission sites
and a detailed exploration scenario is provided as an example for the
Mangala site (38).

**1. Impact Crater Near Nili Fossae:** (18.4°N, 77.7°E) (WEH wt% = 4.02)
Valley networks forming deltas and water-filled impact crater near edge
of Isidis Basin. Valley networks, layered sediments, ancient crater
walls, Isidis basin deposits, volcano or basin peak ring structure near
crater rim, mineralogical alteration revealed by OMEGA and CRISM
(phyllosilicates, olivine). EL 5 (valley network means water - and
ancient crater might have ponded water). PL1 (unless there is geological
activity there now, this looks like a place most promising for past
life). **\*\*RM\*\***

**2. Newton Crater gully sites:** (40.5°S, 157.9°W) (WEH wt% = 4.03)
Potentially ice-rich lineated valley fill on crater floor, gullies,
crater stratigraphy. Highest concentration of gullies in one region
anywhere on Mars. EL4 (crater hydrothermal systems?). Crater might have
hosted life in hydrothermal system. PL5 gullies might be sites of
present-day water seeps and therefore extant life.

**3. Meridiani Region:** (2.0°S, 5.5°W) (WEH wt% = 7.67) MER site to
investigate context and the nature of early water-rich deposits. Easily
traversable terrain would enhance regional study. Mineralogically unique
region of the planet. EL5 early sediments/water suggest site of high
priority for early life. PL1 Now dry and geologically inactive -- not so
likely to harbour present-day life

**4. Gusev Crater-Columbia Hills:** (14.6°S, 175.4°E) (WEH wt% = 8.42)
Complex stratigraphy and explosive volcanic deposits in Columbia Hills,
at the MER Gusev site. Lies on the crustal dichotomy, with fluvial input
from the southern highlands and volcanic deposits related to Hr
(Hesperian ridged plains). EL3 crater may have hosted hydrothermal
systems/ponded water for early life, although it is a large crater and
the site would have to be selected carefully. PL1 Doesn't look very
geologically active for present-day life.

**5. Chasma Boreale:** (82.6°N, 47.3°W) (WEH wt% = 41.45) North polar
layered deposits and pre-PLD basal unit. Assessment of polar
stratigraphy and relations to pre-polar deposits; orgin of Chasma
Boreale and relationship to the northern extent of Vastitas Borealis.
EL5 -- If chasma was formed by water flood may be site of potential
habitability early on and site of sustained water. Ice cap may have
provided water. PL4 Near water ice (polar cap). Changes in obliquity may
have created regions suitable for life even in recent times with oases
sustained today?

**6. South polar layered deposits and the Dorsa Argentea Formation:**
(71.8°S, 67.3°W) (WEH wt% = 35.71) Polar stratigraphy, comparison to
MARSIS radar data showing ice-like layering, exploration of Hesperian
DAF and possible ancient ice record. Close proximity to Amazonian ice
flow features along the margins of the present day polar cap. EL5 --
ancient terrains may have hosted water during the Noachian. PL4 Site of
ancient permafrost -- possible preservation/habitats of recent life?

**7. Gale Crater:** (5.1°S, 137.5°E) (WEH wt% = 6.48) Ancient crust,
valley networks, central mound of volatiles. Stratigraphic analyses of
crater wall material as well as sedimentary layers within the central
mound, possibly of fluvial origin. EL4 Crater may have hosted
hydrothermal systems/ponded water for life, particularly given evidence
for volatiles. PL1 If it's not geologically active now it's unlikely to
be a site for present life.

**8. Floor of Valles Marineris:** (7.0°S, 72.7W) (WEH wt% = 4.49)
Interior layered deposits, stratigraphy and mineralogy; VM wall talus
and stratigraphy. Examination of regional connection to circum-Chryse
outflow channels. EL3 May have layers of sediments with early biology?
PL3 Depth may create pressures suitable for transient liquid water even
today?

**9. Holden-Eberswalde Craters:** (24.0°S, 33.6°W) (WEH wt% = 2.47) Late
Noachian-Early Hesperian Valley network deltas and stratigraphy.
Well-preserved and accessible sedimentary deposits. Ancient crust
preserved along crater walls. EL4 See site 7 -- same rationale. PL1.

**10. Eastern Olympus Mons:** (17.7°N, 128.2°W) (WEH wt% = 4.34) Recent
volcanic, tectonic and fluvial activity, perhaps within the last few
tens of millions of years. EL3 Not clear what the potential is for
fossil life, but fluvial activity and volcanic activity would be
promising. PL4 recent tectonic activity may suggest geothermal hot spots
for present-day life?

**11. Elysium Planitia:** (5.0°N, 150°E) (WEH wt% = 3.05) Late Amazonian
volcanic lava flows and outflow channels deposits. High biological
interest. Testing of pack-ice hypothesis for platy units; could yield
recent ice activity in the equatorial region of Mars. EL5 Sustained
liquid water and lava, i.e. geochemically active and nutrients. PL2 Not
geologically/aqueous today.

**12. Western Olympus Mons Scarp:** (19.6°N, 139.7°W) (WEH wt% = 5.79)
Late Amazonian piedmont glacial deposits, stratigraphy of Olympus Mons
lava flows and talus deposits. Access to Olympus Mons aureole deposits.
EL4 Glacial deposits may be places for early life -- if they had melted
and provided liquid water. PL2 Not geologically active today to provide
habitats for extant life.

**13. Eastern Hellas Basin Massifs:** (38.7°S, 97.0°E) (WEH wt% = 4.21)
Hellas basin rim mountain rings for Noachian stratigraphy; Late
Amazonian ice-rich deposits. Late Amazonian gullies, including the
Centauri Montes "active gully" site (See 29), EL3 Ice and noachian
terrains may have been good for early life -- no obvious sustained
habitats though? PL2 Not geologically active today?

**14. Nili Fossae:** (24.2°N, 79.4°E) (WEH wt% = 3.75) Hesperian ridged
plains, OMEGA mineralogical anomalies (clays), possible ancient basin
impact melt and olivine deposits. EL5 clays and impact melts suggest
weathering/water/geochemical activity. May be good microenvironments for
life. PL1 Not geologically active today and not obvious where extant
life would be sustained.

**15. Lyot Crater central deposits:** (50.3°N, 29.1°E) (WEH wt% = 4.62)
Largest crater in the northern lowlands, crustal stratigraphy, evidence
for penetration of the cryosphere. Potential access to Late Amazonian
high-latitude volatile-rich mantling deposits. EL5 Penetration of
cryosphere may have provided conduit for liquid water into crater
hydrothermal system. Good habitat for life. PL2 Not geologically active
now, but the crater is in permafrost and contains ice -- may have basal
ice habitats for life?

**16. Coloe Fossae Dichotomy Boundary:** (41.3°N, 54.2°E) (WEH wt% =
3.86) Stratigraphy of dichotomy boundary scarp, Amazonian lobate debris
aprons and lineated valley fill. Accessing the plateaus that are
interspersed amongst the lineated valley fill can allow for testing as
to whether potential glaciation was local or regional. WG EL3 Not a site
of ancient water, but there was obviously geological activity, which may
benefit life?? PL1 Not geologically active/water rich now??

**17. Utopia Planitia:** (28.5°N, 134.4°E) (WEH wt% = 5.49) Examine the
deposits on the floor of Utopia, including the lahar-like deposits and
related materials. Access to volcanic and fluvial deposits; high
concentration of polygonally patterned ground in Utopia. EL2 Dead desert
in the past? May have been more water rich in the very early history of
Mars? PL1 Dead today

**18. Aram Chaos:** (2.6°N, 21°W) (WEH wt% = 4.35) Outflow channel
processes. Examine the nature of a range of mineralogical anomalies and
investigate the OMEGA-based mineralogy sequence, testing the
stratigraphic relationships. EL3 Outflow channels may have been good for
life, but probably very transient water availabilities? PL1 Not a
geologically active site today for life

**19. Arsia Mons Glacial/Volcanism:** (4.8°S, 126.3°W) (WEH wt% = 5..41)
Examine site of late stage volcanism extruded from dikes cutting Late
Amazonian glacial deposit on the northwest flank of Arsia Mons.
Meteorological analysis of local climate at high elevations. EL2 If the
volcanism wasn't in an environment of high water content maybe not
interesting? PL1 Not active today?

**20. Slope Streaks:** (14.4°N, 118.2°W) (WEH wt% = 4.31) Examine the
nature and origin of slopes streaks and their characteristics, including
searching for subsurface water, springs, landslide deposits, etc. EL4
Possible regions of past water, springs etc. PL4 Possible regions of
present-day water, springs etc?

**21. Atlantis Chaos:** (34.8°S, 177.4°W) (WEH wt% = 4.99) Examine the
nature of Atlantis Chaos and assess the large pluvial lake hypothesis.
Extended traverses to assess the major magnetic anomalies in this
area. Access to Noachian stratigraphy and fluvial processes, with
potential connection to deposition within Gusev Crater. EL4 Area of
water ponding??? PL1 Not very geologically active today?

**22. Central Alba Patera:** (40.7°N, 109.6°W) (WEH wt% = 6.85) Examine
the range of Hesperian and Amazonian volcanic activity associated with
Alba Patera, the young (Late Amazonian) latitude-dependent mantle
deposit, and ancient (Hesperian) valley networks on the northern flanks.
EL4 Valley networks and volcanism suggest strong potential for habitats
for life (water/mineral supplies). PL1 Geologically inactive today.

**23. Chryse Planitia:** (27.0°N, 41.0°W) (WEH wt% = 3.35) Examine over
a wide area the mineralogy, petrology and biology of outflow channel
effluent. Examine the \"oceans\" hypothesis. Study underlying Hesperian
ridged plains at impact craters. Provide greater context for the results
from Viking Lander 1 and Pathfinder. EL3 Outflow channels may provide
transient water availability, but not sustained for life. Impact craters
of potential biological interest. PL1 Geologically inactive today.

**24. Medusae Fossae Formation:** (1.6°N, 173.2°W) (WEH wt% = 6.39)
Examine the areas where interfingering of Tharsis lava flows and the MFF
are observed. Establish nature and origin of MFF and stratigraphy, age
and interactions with lava flows. WG EL4 Lava flows and past water? PL1
Geologically inactive today.

**25. Hellas Basin Floor:** (41.9°S, 69.6°E) (WEH wt% = 3.92) Study the
effluent of the Eastern Hellas outflow channels, and assess the Hellas
\"ocean\" hypothesis. Meteorologic analyses could address the unique
climate of Hellas at a low elevation and relatively high pressure. Very
important site for biology. EL5 depth of hellas and evidence of
sediments suggests sustained liquid water. PL3 May be a place where
transient liquid water (above triple point) could be sustained today at
bottom of basin?

**26. Northeast flanks of Arsia Mons:** (7.4°S, 121.2°W) Cave skylight
site (see Cushing et al., 2007 -- LPSC #1371). Site of high biologic
interest if subsurface water resources are available. Accessiblity to
Arsia lava flows. From Melissa Lane.

**27. Walls of Dao Vallis:** (33.7°S, 92.5°E) These are classic,
well-developed gully systems and also some of the gullies are associated
with the "pasted-on" terrain which Christensen (2003) has hypothesized
to be melting snowpacks. High relief throughout the valley could yield
excellent insight into local micro-climate-related surface processes.
From Jen Heldmann.

**28. Terra Sirenum:** (39.3°S, 161.7°W) Site of high-albedo deposit
that formed within the last decade in the proximity of gullies (Malin et
al., 2006). Classic Noachian highland terrain with Hesperian lava flows
and small-scale Amazonian fluvial activity.

**29. Centauri Montes:** (38.7°S, 96.7°E) Site of high-albedo deposit
that formed within the last decade in the proximity of gullies and more
extensive volatile-rich deposits (see site 13) (Malin et al., 2006).
Meteorologic stations could provide insight into the local climate of
eastern Hellas and the regional climate of Hellas as a whole.

**30. Terra Cimmeria:** (70.0°S, 180.0°E) A suggested drill target is at
180W between 60-80S which is a region of preserved crustal magnetism
(indicating old terrain) and ground ice (GRS measurement, but also
crater morphology indicative of underlying deeper ice). From Jen
Heldmann.

**31. Mawrth Vallis:** (25.3°N, 19.3°W) Fluvial geomorphology with heavy
weathering. Stratigraphic analysis and access to the northern lowlands.
From Francois Poulet.

**32. Olympia Planitia:** (75.0°N, 180.0°E) Sulfate-rich dunes around
the north pole (very recent alteration product(?)). Access to the
southern-most extent of the residual polar caps, and access to polar
troughs to reveal Amazonian climate history. From Francois Poulet.

**33. Valles Marineris:** (6.2°S, 70°W) Sulfate-rich deposits only
accessible by human operations. Extensive stratigraphic analysis and
access to landslides/talus piles. From Francois Poulet.

**34. Arsia lobate glacial deposit:** (7.4°S, 123.8°W) Evidence for
Late-Amazonian glacial activity. Assess the interaction of late-stage
glaciation and volcanism, analyze climate history and sample possible
residual ice. Assess various moraines, obtain ice cores, sample lava
flow stratigraphy to assess volcano and glacial chronology.
**\*\*RM\*\***

**35. North Polar Cap:** (86.0°N, 79.0°E) Accessibility to
Late-Amazonian ice deposits, through drilling and stratigraphic analysis
of polar troughs. From Joe Levy.

**36. South Polar Cap:** (88.0°S, 30.0°E) Accessibility to
Late-Amazonian ice deposits, through drilling and stratigraphic analysis
of polar troughs. From Joe Levy.

**37. Syrtis Major Planum:** (7.0°N, 69.0°E) Possible SNC-meteorite
ejection locale, Hesperian lava flows and silicate-rich deposits in
caldera. Interactions with Isidis and the northern lowlands. From Joe
Levy.

**38. Mangala Valles:** (18.0°S, 149.4°W) Outflow Channel Floor:
Residual ice-rich deposits remaining on the floor of an outflow channel.
Hesperian-aged (?) outflow channel. Dike-related vents; evidence for
phreatomagmatic eruption and rim glacial deposits at the graben. Examine
floor and evidence for multiple events and role of groundwater. Possible
residual ice on the floor of the channel. From Joe Levy. **\*\*RM\*\***

**39. Nilosyrtis Mensae:** (35.0°N, 71.0°E) Complex LVF/LDA stratigraphy
along the dichotomy boundary. Evidence for multi-stage formation of
extensive glacial deposits; sampling could provide chronology for recent
climate change and resulting glacial landforms. From Joe Levy.

**40. Olympus Mons Caldera Floor:** (18.3°N, 133.0°W) Age of Tharsis
volcanism; Caldera wall stratigraphy, chronology, atmospheric dust
stratigraphy, ash deposition. Landslide deposits along the caldera wall.
Seismic studies and mass spectrometer for possible gas venting.

**41. Milankovic Crater:** (55°N, 146.5°W) Rare large impact crater
within the northern lowlands (\> 40 km); Analysis of excavated material
from the northern lowlands and adjacent high-latitude volatile-rich
mantling and related deposits.

**42. Kasei Valles:** (21.0°N, 73.8°W) Massive streamlined morphology
gives access to Noachian/Hesperian fluvial deposits; Stratigraphic
analysis of channel walls; Channel is sourced from the northern extent
of Vallis Marineris, which could yield insight into more regional
processes. Evidence for fluvial activity, glacial scour, and subsequent
lava flows.

**43. Vastitas Borealis Formation:** (65.7°N, 20.2°E) Classic northern
lowlands terrain; Possible sublimation residue for outflow channel
effluent; extensive polygon development; Latitude-dependent mantling
deposits; Context for Mars Phoenix analysis.

**44. T-Shaped Valley:** (37.6°N, 24.0°E) Massive glacial deposits along
the dichotomy boundary; Multiple converging flows from various localized
sources; Meteorological study could address the recent conditions along
the dichotomy boundary; Possible Late Amazonian glacial ice preserved.

**45. Isidis Basin Floor:** (12.0°N, 88.5°E) Possible flooding remnants
from a Noachian and Hesperian northern ocean; Volcanic input from Syrtis
Major; Was this a major part of a northern lowlands ocean?

**46. Utopia Basin Floor:** (43.8°N, 117.0°E) Extensive access to
patterned ground and near-surface volatiles; Examine distal parts of the
Elysium lahar deposits; Corroborative studies to go along with VL2
analyses; Possible preserved ice from Early Amazonian.

**47. Hecates Tholus:** (32.0°N, 150.3°E) Unique concentration of young
(Hesperian/Amazonian) valley networks, in the proximity of extensive
Hesperian volcanic activity; Access to nearby northern lowlands; Some
volcanism may be Amazonian.

**48. Peak Magnetic Anomalies:** (60.0°S, 175.0°E) Geophysical analysis
could reveal details of an early Martian magnetic field; classic
Noachian cratered terrain could yield insight into the composition of
Mars in its first billion years; Major goal would be to link surface
geology to any evidence of subsurface magnetism and magnetic carriers.

**49. Hesperian Calderas:** (59.4°S, 60.7°E) Volcanic record for
middle-Mars history; Meteorological study could document interaction
between Hellas and South Pole; Examine key part of martian timeline;
understand Hesperian volcanic processes and related valley networks.

**50. Hesperia Planum:** (23.3°S, 110.6°E) Potential comparison with
classic lunar mare terrain; Structural investigation of wrinkle-ridge
formation; Examination of classic unit of the Mars timeline.

**51. Huygens Ridge:** (12.3°S, 66.3°E) Access to exhumed dike/Potential
Hesperian Ridged terrain; Geochemical analyses of intrusive volcanic
material; This dike system may be feeder for major Hesperian ridged
plains volcanism.

**52. Argyre floor deposits:** (51.5°S, 41°W) Potential analyses of
volatile deposits from south polar ice sheet; primary impact record for
large impact basin/large impact melt-sheet; Amazonian formation of
small-scale fluvial features. Possible eskers in southern part of basin;
Assess evidence for aqueous flooding and shorelines.

**53. Thaumasia Valley Networks (Warrego):** (38.6°S, 89.4°W)
Post-emplacement modification of classic Noachian valley networks;
Access to ice-rich crater-fill material; Geophysically probe classic
thrust-like structure at edge of Tharsis rise.

**54. Syria Planum:** (7.7°S, 100.5°W) Structural evolution of Tharsis;
Close proximity to western most extent of Valles Marineris; This region
is highest point on Tharsis and key to its early volcanic evolution.

**55. Proctor Crater:** (47.5°S, 30.2°E) Extensive dune field on crater
floor; Study of recent dune formation and migration and relation to
climate change; Stratigraphic analysis of Noachian crust.

**56. White Rock:** (8.0°S, 25.2°E) Field analysis of high-albedo crater
floor deposit; Eolian modification history of enigmatic surface unit;
Thought to be key to early mineralogy and resurfacing.

**57. Complex tectonic ridges:** (66.0°S, 140.0°E) Structural analysis
of Noachian terrain; Potential exposure of deep-crust from massive
faulting; Enigmatic part of Noachian crustal deformation; Geophysical
analyses.

**58. Mie Crater:** (48.5°N, 139.7°E) Rare large crater within the
northern lowlands provides vertical sampling and stratigraphy;
Fifty-year in-situ comparison of high-latitude present-day surface
processes and climatic activity; Examination of condition of Viking 2
lander after \~50 years; Ground truth for major mid-latitude site that
illustrates periglacial processes.

# Appendix B. Goal II (Climate): Objectives and Investigations for Human Exploration of Mars

## Overview of Updated Goals and Objectives

In the human era of exploration, atmospheric measurements at all sites
will be seen as important not only to the understanding Mars atmosphere
and climate, but also as environmental characterization essential to the
interpretation of many biology and geology objectives. The trend towards
system science called out in MEPAG 2006 Goal II Objective A
"ground-to-exosphere approach to monitoring the Martian atmospheric
structure and dynamics," will continue with more emphasis on the mass,
heat and momentum fluxes between the three Mars climate components:
atmosphere, cryosphere, and planetary surface.

This systems approach will be enabled by advances in Mars Global
Circulation Models (GCMs), a doubling in length of global time-series
derived from monitoring Mars surface and atmosphere from orbit, new
atmospheric vertical structure information from Mars Express and MRO,
new anticipated global data sets on aeronomy, atmospheric composition
and winds, and by network science and coordinated lander-orbiter
campaigns, such as that planned with Phoenix-MRO. In 2007, trends in
Mars GCM development are towards coupling of upper and lower atmosphere
(e.g., Angelats i Coll et al \[2005\]), coupling with regolith models
\[Bottger et al (2005)\], integrating models of atmospheric chemistry
and dynamics (Lefevre et al, 2004; Moudden and McConnell \[2007\]),
multiscale, nested models --- where small scale surface-atmosphere
interactions could be studied within the context of global transport
(Richardson et al \[2007\], Moudden and McConnell \[2005\]), and data
assimilation (Montabone et al \[2007\]). Models have not yet been
successful in reproducing the observed Martian dust cycle with active
dust transport \[Newman et al. (2002a, 2002b); Basu et al. (2004); Kahre
et al. (2006)\]. Temperature and wind profile information from heights
between the top of instrumented masts and the free atmosphere would
likely remain sparse or non-existent.

Understanding of Mars past climate (MEPAG 2006 Goal II Objective B),
will benefit from anticipated new knowledge of current atmospheric
escape rates from the 2011 Mars Aeronomy Scout. However, significant
advance in the key area of access to the polar stratigraphic record is
not expected in the decades before human exploration. In 2030, this will
remain one of the highest priorities for MEPAG Goal II. On the other
hand, the study of the paleoclimatic parameters imprinted in the ancient
geological record (e.g. Noachian to Amazonian) also concerns the high
priorities of the MEPAG Goal II Objective B, which directly relates to
unlock the ancient climatic conditions of Mars through the physical
(e.g., geomorphic and/or sedimentary), petrological, mineral and
geochemical (including isotopic) material characterization.

While recognizing that the MEPAG 2006 Goal II objectives are
sufficiently general that they will all remain largely valid, some
updating relevant to 2030 is captured in the following four subsections.

## Quantitative Understanding of Mars Atmospheric Processes

Characterizing the basic state and critical processes of the current
Martian atmosphere constitutes 2006 MEPAG Goal IIA. Here we describe
globally active physical processes that determine the basic state and
variability of the Mars atmosphere, and so are most important to
resolve. These processes are inherently global in character such that
relevant measurements might be obtained from HEM activities at all sites
visited, There are, however, large scale atmospheric provinces which
exhibit distinctive dynamical, aerosol (dust and clouds), surface and
potential subsurface volatile conditions. Consequently, although site
selection is unlikely to be driven by atmospheric science, the specific
complement of atmospheric experiments and measurement goals is likely to
vary according to site selection.

The emphasis of HEM atmospheric science would likely focus on processes
within the planetary boundary layer (PBL, surface to \~2 km), where
surface-atmosphere interactions impart fundamental influences on the
dynamical, chemical, and aerosol characters of the global Mars
atmosphere, Orbital remote sensing for this region remains difficult and
lander/rover atmospheric payloads limited such that sufficiently
detailed measurements of the PBL may not be returned from Mars science
missions prior to 2030. HEM atmospheric observations can provide optimum
in situ and remote access to the PBL and, in turn, characterize local
environmental conditions in support of HEM operations.

Atmospheric dynamics, in concert with radiative forcing, determines the
basic thermal structure of the Mars atmosphere, the global transport of
volatiles (CO~2~, water, dust), and the maintenance of Mars polar ice
caps, all of which vary on seasonal and interannual timescales. Current
understanding of Mars atmospheric dynamics is based to a large extent on
remotely sounded atmospheric temperature profiles, analyzed in the
context of Mars general circulation models (MGCM). Recent Mars missions
(MGS, MER, Mars Express, MCO) have extended the vertical, global, and
temporal coverages of atmospheric temperature and aerosol (cloud and
dust) distributions towards enhanced constraints on MGCM dynamical
simulations. The planned MSO mission would further complement improved
thermal and aerosol profiling with direct wind profile measurements for
the first time. The dynamical state of the upper Mars atmosphere
(altitudes above 80 km), which carries additional significance in terms
of spacecraft aerobraking and atmospheric escape rates, has been
inferred from in-situ density measurements associated with aerobraking
(e.g., Withers \[2006\]). Dedicated, global observations from the 2011
Mars Aeronomy Scout mission.would greatly expand our understanding of
Mars upper atmospheric dynamics. Within the near-surface atmosphere,
atmospheric observational constraints remain sparse. This reflects both
the limitations of orbital remote sensing and the geological focus of
lander/rover operations to date. Viking lander in situ observations of
surface pressure and winds reflect active planetary wave systems and
storm fronts (e.g., Barnes \[1980\] and Murphy et al \[1990\]).
MER-based thermal and dust-aerosol profiling within the lower (\<5 km)
atmosphere also indicate strong PBL variability over local turbulent to
diurnal to seasonal timescales (Smith et al. \[2006\]). MSL and Phoenix
will conduct limited meteorological measurements as constrained by the
primary surface science objectives of these missions. ***Dedicated
observations of surface pressure and temperature-wind-dust profiles of
the PBL from distributed surface stations constitutes a key priority for
HEM investigations of Mars atmospheric dynamics.***

### Atmospheric Dust

Radiative forcing of the Mars atmosphere may be represented roughly as
an energy balance between cooling through CO~2~ thermal infrared
emission and heating through absorption of solar flux by suspended dust
particles. Atmospheric heating associated with atmospheric dust
intensifies global atmospheric circulation and near surface winds, which
in turn increases lifting of surface dust into the atmosphere. A
dramatic result of this dust radiative-dynamic feedback is ubiquitous
aeolian activity on Mars, with significant dust lofting and transport
occurring over a wide range of spatial and temporal scales. These range
from nearly continuous dust devil activity, to regional dust storms in
every Mars year, to global dust storms that may occur once every three
or four Mars years (Martin and Zurek \[1993\], Cantor et al \[2001\]).
As a consequence, atmospheric dust plays a major role in the spatial,
seasonal, and interannual variability of Mars atmospheric thermal
structure and circulation. Global imaging and thermal IR dust abundance
observations of Mars atmospheric dust extend from the Mariner 9 mission
to Viking, MGS, and current MER, Mars Express, and MCO missions,
providing an accumulating timeline of Mars dust storm activity. Current
mission observations have also substantially advanced vertical profile
and dust radiative property definitions (McCleese et al \[2007\], Wolff
and Clancy \[2003\]), with further progress in these areas would be
contributed by MSO. Both of these factors are critical to understanding
the radiative-dynamical relationships associated with Mars dust storm
activity. A key element yet to be addressed regards the particle size
dependent flux of dust at the surface-atmosphere boundary as a function
of atmospheric and surface conditions. Hence, our understanding of dust
lifting rates from the Mars surface is characterized by relatively
simple surface wind parameterizations, and it remains uncertain as to
whether global surface dust distributions limit or are influenced by
atmospheric dust transport. ***In-situ observations of dust surface flux
(lifting and deposition), particle sizes, radiative properties, and
vertical profiles within the PBL constitute primary objectives for HEM
atmospheric dust studies.***

### Atmospheric Water

Atmospheric water, in the form of vapor and ice clouds, plays
significant roles in atmospheric chemistry, dust radiative forcing, and
climate balance. The photolysis products of atmospheric water vapor
determine Mars trace specie abundances (e.g., Nair et al \[1994\]) and
regulate current escape rates for the atmosphere (Liu and Donahue
\[1976\]). Water ice clouds have long been associated with major
topographic features, autumnal polar hoods, and a variety of cloud wave
structures (Kahn \[1984\]). The existence of an aphelion, low latitude
cloud belt is identified as a significant influence on the vertical
distribution of atmospheric dust and water vapor, as well as meridional
transport of atmospheric water (Clancy et al \[1996\]). Atmospheric
exchange with polar cap water ice deposits dominates the seasonal
variation of atmospheric water vapor (Jakosky and Farmer \[1983\]),
whereas atmospheric exchange with subsurface ice and adsorbed water at
lower latitudes remains uncertain (e.g., Montmessin et al \[2004\]).
Recent spacecraft observations of atmospheric water vapor (Smith
\[2002\]), subsurface water ice (Feldman et al \[2004\]), and polar cap
water ice (Langevin et al \[2005\]) from MGS, Odyssesy and Mars Express
have begun to illuminate surface-atmospheric exchanges of Mars water
over seasonal, interannual, and possibly longer timescales. MCO supports
dedicated vertical profiling of atmospheric water vapor and ice clouds
(McCleese et al \[2007\]), which are likely to be augmented by high
sensitivity MSO limb profiling observations. The Phoenix lander (Smith
\[2006\]) will excavate and analyze subsurface water ice on Mars for the
first time, and MSL will provide measurements of surface humidity and
the water content of surface materials over the course of a Martian
year. ***HEM studies of atmospheric water are likely to focus on
vertical profile measurements within the PBL, which are not easily
addressed from orbital remote sensing. Subsurface core sampling of
adsorbed water and water ice water deposits (site-dependent in this
case) also constitutes a key Mars water objective that is uniquely
facilitated by HEM operations.***

### Atmospheric Chemistry 

The trace chemical composition of the current Mars atmosphere reflects
photochemical cycles associated with the major atmospheric constituents
CO~2~, H~2~O, and N~2~; and perhaps non-equilibrium chemistry associated
with potential subsurface sources-sinks of methane (), SO~2~ (), and
peroxide (H~2~O~2~). Some of these compounds can be essential to sustain
a Mars cryptic biosphere through direct or indirect (bio)chemical
pathways (e.g., atmospheric oxidants can be used as electron acceptors
for microbial metabolism, whereas reducing gases --CH~4~- can be
electron donors). Existing measurements of the Mars trace species CO,
O~2~, O~3~, and H~2~O~2~ appear to confirm the dominant HO~x~ catalytic
cycle proposed to prevent buildup of large CO and O~2~ concentrations
from photolysis of the primary CO~2~ constituent (Parkinson and Hunten
\[1972\], McElroy and Donahue \[1972\]). Hence, atmospheric water vapor,
as the primary photolytic source of atmospheric HOx species, plays a
dominant role in Mars atmospheric chemistry. Definitions of spatial and
seasonal variations in atmospheric trace composition remain tentative,
with the exception of Mars ozone which exhibits large increases towards
winter high latitudes (Barth, ). The detailed seasonal variation of Mars
ozone also suggests that heterogeneous HO~x~ chemistry may occur on the
surface of Mars water ice clouds (Lefevre et al \[2004\]). Vertical
gradients in trace specie abundances, associated with a
saturation-dependent water mixing profile (Clancy and Nair \[1996\]) or
vertical variations in photolysis rates (Nair et al \[1994\]), are
inferred but not definitively measured. The most problematic trace
specie measurements, on both observational and modeling grounds, are the
recent reported detections of significant atmospheric methane abundances
(Formasano et al \[2004\], Krasnopolsky et al \[2004\]). Methane is not
photochemically produced and is not stable in the current Mars
atmosphere such that detectable amounts (parts per billion) require a
source from the subsurface (Krasnopolsky et al \[2004\]). Reported
variations in methane abundance versus time and space (Mumma et al
\[2007\]) place further requirements on atmospheric loss rates for
methane, which remain extremely challenging. Subsurface sources for
sulfur bearing gases such as SO~2~ (Krasnopolsky \[2005\]), and
triboelectric sources for enhanced production of peroxide (Atreya et al
\[2007\])) remain unsubstantiated by observations and so unconstrained.
MSL, the Mars Aeronomy Scout mission, and MSO should address many of the
above questions regarding Mars atmospheric chemistry, including the
degree to which subsurface sources of non-equilibrium gases are
significant globally**. *HEM observations of atmospheric chemistry are
likely to focus on detections of locally enhanced methane, SO~2~, H~2~S,
HCN, or peroxide concentrations associated with confined source regions
specific to the geophysics (or biology) of the HEM site.***

Existing measurements of the Mars trace species CO, O~2~, O~3~, and
H~2~O~2~ appear to confirm the dominant HO~x~ catalytic cycle proposed
to prevent buildup of large CO and O~2~ concentrations from photolysis
of the primary CO~2~ constituent (Parkinson and Hunten \[1972\], McElroy
and Donahue \[1972\]). Hence, atmospheric water vapor, as the primary
photolytic source of atmospheric HOx species, plays a dominant role in
Mars atmospheric chemistry. Definitions of spatial and seasonal
variations in atmospheric trace composition remain tentative, with the
exception of Mars ozone which exhibits large increases towards winter
high latitudes (Barth, ). The detailed seasonal variation of Mars ozone
also suggests that heterogeneous HO~x~ chemistry may occur on the
surface of Mars water ice clouds (Lefevre et al \[2004\]). Vertical
gradients in trace specie abundances, associated with a
saturation-dependent water mixing profile (Clancy and Nair \[1996\]) or
vertical variations in photolysis rates (Nair et al \[1994\]), are
inferred but not definitively measured. The most problematic trace
specie measurements, on both observational and modeling grounds, are the
recent reported detections of significant atmospheric methane abundances
(Formasano et al \[2004\], Krasnopolsky et al \[2004\]). Methane is not
photochemically produced and is not stable in the current Mars
atmosphere such that detectable amounts (parts per billion) require a
source from the subsurface (Krasnopolsky et al \[2004\]). Reported
variations in methane abundance versus time and space (Mumma et al
\[2007\]) place further requirements on atmospheric loss rates for
methane, which remain extremely challenging. Subsurface sources for
sulfur bearing gases such as SO~2~ (Krasnopolsky \[2005\]), and
triboelectric sources for enhanced production of peroxide (Atreya et al
\[2007\])) remain unsubstantiated by observations and so unconstrained.
MSL, the Mars Aeronomy Scout mission, and MSO should address many of the
above questions regarding Mars atmospheric chemistry, including the
degree to which subsurface sources of non-equilibrium gases are
significant globally**. *HEM observations of atmospheric chemistry are
likely to focus on detections of locally enhanced methane, SO~2~, H~2~S,
HCN, or peroxide concentrations associated with confined source regions
specific to the geophysics (or biology) of the HEM site.***

### Electrical Effects

Experimental and theoretical investigations of frictional charging
mechanisms in both small- and large-scale meteorological phenomena
suggest that Mars very likely possesses an electrically active
atmosphere as a result of dust-lifting processes of all scales,
including dust devils and dust storms. Naturally occurring dust activity
is nearly always associated with significant electrification via the
process of triboelectricity --- the frictional charging of dust grains
in contact with one another or the surface as they are transported by
wind or convective circulations. Based on the results of terrestrial
experiments and their implications for the presence of electrification
processes on Mars, Melnick and Parrot (1998) used a particle-in-cell
numerical model to show that electric fields up to the breakdown
potential of 25 kV/m can easily occur near the martian surface. A
large-scale electric dipole moment can be generated by nearly any
process with a vertical lifting component, as the smaller, negatively
charged grains are transported to higher altitudes than the heavier,
positively charged grains. In dust devils and dust storms, the vertical
stratification of grains based on size and mass will create a
stratification of charge, which creates an electric dipole moment with a
spatial scale on the order of the storm size (Figure 1).

Electrical effects have impact on human exploration and on the
environment of Mars as a source of both continual and episodic energy.
Differential charging between separate objects in the presence of
electrified dust that then come into contact and cause a discharge,
directly damaging electronics or interfering with radio communications.
Suspended electrified dust presents a hazard for launch operations (an
example is the Apollo 12 launch, struck by lightning due to the
short-to-ground caused by the vehicle exhaust trail). Dust adhesion may
also be dominated by electrical effects --- with implications in terms
of its transport into the hab/human environment where other effects may
take over (toxicity, friction in seals/machinery, etc.)

Currently, measurements of electric charging within the Mars atmosphere
do not exist and experiments necessary for such measurements are not
incorporated in the Phoenix lander or MSL missions. For operational
safety concerns alone, basic measurements of martian surface charging
conditions should be obtained prior to HEM activities. ***HEM
measurements of atmospheric charging within active dust devils are
especially relevant to the dynamic response times associated with dust
devil occurrences and motions.***

![](media/image26.wmf){width="5.208333333333333in"
height="3.2083333333333335in"}

Delory et al, 2006

Figure 1. Caption.

### Desired Precursor Measurements

Dynamics --- global direct wind measurements, network measurements of
near-surface pressure, temperature and winds, improved definitions of
upper atmospheric thermal tides, circulation, and aerosol loading

Dust Storms --- The vertical distributions of dust radiative properties,
particle sizes, and number densities versus time and space; improved
characterizations of dust lifting rates and localities, and dust
deposition localities, dust charging levels

Water Vapor and Ice Clouds --- Improved water vapor, cloud opacity and
particle size vertical profiling (in vertical and global coverage),
lander/rover based measurements of surface ice fogs and frosts, diurnal
coverages for water vapour and cloud vertical profiles

Atmospheric Chemistry --- Further definition of Mars atmospheric
methane, in abundance and spatial/temporal variability. Global,
temporal, and vertical variations in CO~2~ ozone, and H~2~O~2~
abundances. Dependence of trace gas species with seasonal ice cap growth
and recession.

Electrical Effects --- Identification of dust charging in dust devils
and storms.

### Investigations for the Human Era of Exploration

Surface-atmosphere interactions: dynamics, heat and mass balance.

-   Dynamics --- near surface wind vectors and temperatures with high
    temp resolution (minutes) and extent (diurnal, daily, seasonal) at
    multiple sites separated by at least 10 km. (ground weather
    stations)

-   Lower (0-10 km altitude) atmospheric temperature, wind, dust
    profiling (tethered balloon --- borne thermocouples, nephelometers,
    thermal IR spectrometers, surface-based DIAL lidar)

Ground heat and moisture flux (heat and conductivity probes)

-   Dust storms --- measurement of vertically integrated dust column
    optical depths, dust particle composition, size distribution,
    radiative properties. Same for surface dust (solar extinction
    spectroscopy, dust collection for microscopic imaging and
    compositional analysis). Measurements of surface dust lifting, lower
    atmospheric profiling of dust opacity and particle sizes,
    (backscatter lidar, visible-to-thermal IR spectroscopy, tethered
    balloon borne nephelometer, thermal IR spectrometer), coincident
    temperature measurements

-   Water vapor and Ice Clouds --- Monitoring column optical depths,
    whole sky imaging for cloud forms and drift velocities. (solar
    extinction spectroscopy, backscatter lidar, visible wide-angle
    imaging, visible-to-thermal IR spectroscopy, tethered balloon borne
    nephelometer, thermal IR spectrometer). Surface temperatures,
    thermal gradients and humidity versus time (diurnal, dailiy, and
    seasonal). Subsurface water adsorption and ice contents
    (thermocouples, drilling/trenching with laboratory evolved gas
    chromatography and nms).

-   Electrical Effects --- Dust particle charges, Dc electric field
    monitoring, warning of both distant and local dust electrification.
    Portable electrometers, on site hazard assessment

Search for sources of volatiles and trace gases

-   Atmospheric Chemistry- surface trace gas compositions versus space
    and time (gas chromatography and nms), water vapor and ozone
    vertical profiling (surface and balloon borne UV to IR
    spectroscopy),

### Microclimates

Microclimates are defined in 2006 MEPAG Goal II as "exceptionally or
recently wet or warm locales, exceptionally cold localities, and areas
of significant change in surface accumulations of volatiles or dust"
"identified through local surface properties (e.g., geomorphic evidence,
topography, local thermal properties, albedo) or changes in volatile
(especially H~2~O) distributions." Definitions for Earth typically also
include a spatial scale varying from centimeters to hundreds of metres
(eg. Geiger et al, 2003). Microclimates, by definition regions of
extremes and exceptions, are fascinating and important targets for
study. An exceptionally warm and wet locale could correspond to the
proposed new definition for a Mars Special Region (Beaty et al, 2006)
and hence be of great interest for extant biology. A region of change in
surface accumulation of volatiles or dust identifies a source or sink
region for global atmospheric volatile and dust transport. The climate
objective relevant to these sites is to understand local heat, mass and
momentum balance and transport of dust and volatiles. **Whereas the 2006
MEPAG Goal II investigation focused on detecting these locales, a 2030
objective will be to carry out in situ studies to understand the
processes responsible for generation of the microclimate**. Several
locales that would qualify as interesting microclimates have already
been detected and some examples are given here.

Topographically controlled microclimates (small scale to large scale)

-   Gully systems (Malin and Edgett, 2000; Dickson et al, 2007)

-   Deep pits or caves (Cushing et al, 2007)

-   Polar cap edge (eg Siili et al, 1999)

-   Tharsis volcanoes (Noe Dobrea and Bell (2005), Benson et al (2003),
    Rafkin et al, (2002))

Locales where changes in volatile distributions are observed (both
spatial and temporal change; small scale to large scale)

-   Bright deposits in gully systems (McEwen et al, 2007)

-   Possible sources of methane and other volatiles (local sources have
    not yet been identified)

-   Polygons (e.g., van Gasselt et al, 2005)

-   Remnant ice e.g., Louth crater (Roush et al, 2007)

-   Possible glacial deposits (Shean et al, 2007)

-   Polar dune fields (eg. Kossacki and Leliwa-Kopystynski (2004))

-   Seasonal polar caps

-   Equatorial region --- Aphelion cloud belt (Clancy et al, 1996)

Locales where significant changes in dust distribution are observed
(e.g., Szwast et al, 2006)

-   Solis

-   Daedalia Planum

-   Northern Syrtis

-   Hellas

Exceptionally cold locales

-   Cold spots on polar caps (e.g., Pocock and Calvin, 2007)

### Desired Precursor Measurements

Ideally, meteorological stations would be emplaced at each of the HEM
sites by precursor missions for long term (multi-annual) monitoring to
record in situ climate variables over diurnal and seasonal cycles.

-   Temperature, wind speed and direction

-   Optical depth (water vapor and dust)

-   Water vapor

-   Long wave and short wave radiation

Continual monitoring from orbit for mulitannual variability and seasonal
change

-   Global daily maps of surface temperature, pressure, dust, ice, water
    vapor optical depth

-   Atmospheric profiles of temperature, pressure, dust, water vapor

### Investigations for the human era of exploration

Surface-atmosphere interactions: dynamics, heat and mass balance.

In situ investigations to meet microclimate objectives require
micrometeorology measurements at the microclimate site, preferably in
conjunction with upwind reference stations outside its boundary to give
regional context. Emphasis on instrumentation may vary depending on
characteristics and focus of site.

### Search for sources of volatiles and trace gases

A search would involve characterizing the chemical environment (surface
and atmospheric) and using portable instrumentation to follow local
gradients in trace and volatile gases.

## Polar Processes and Formation of the Polar Cap

MEPAG 2006 Goal II-Objective B Investigation 5 lists four objectives for
polar cap measurements: (i) the relative and absolute ages of the
layers, (ii) their thickness, extent and continuity, (iii) their
petrologic/geochemical characteristics (including both isotopic and
chemical composition), and (iv) the environmental conditions and
processes that were necessary to produce them. Progress on (iv) is very
much tied to progress on global atmospheric dynamics (section 1.1) as
the poles comprise a key element in the global annual cycle of volatiles
and dust. Orbital geophysical sounding is currently proving information
at \~100 m resolution (Figure 2) in the vertical to address (ii), and
early results indicate the existence of non-continuous layers in the
Polar Layered Deposits (PLD) suggesting periods of retreat and advance
of the residualcaps over climate time scales (Figure 3). The Phoenix
mission will provide the first information on Mars ice grain and dust
characteristics using microscopy, wet chemistry and thermal evolved gas
analysis (Smith, 2006), and will provide meteorological information from
its landing site on Vastitas Borealis, the vast plains which surround
the north pole. The return of a sample from within the PLD could provide
an important snapshot of absolute age, isotopic and chemical composition
for that segment of the PLD record, but unraveling the complex climate
history evidenced in the PLD would require access to the full
stratigraphic record through deep drilling or sustained sampling through
exposed scarps. Understanding the asymmetries between north and south
polar caps would require access to the stratigraphic record at both
poles.

In 2030, it is anticipated that access to the climate record held in the
PLD would remain one of the most exciting and important challenges in
the scientific exploration of Mars.

![](media/image27.png){width="6.5in" height="1.351388888888889in"}

Figure 2. Cross section of the north polar cap showing extent of cap and
layering. Vertical depth is \~2km (Putzig et al, 2007, 7th Int
Conference, Abstract #3295) Red box indicates a target region for a
drill site where SHARAD shows homogenous layering on a macro scale.

![](media/image28.wmf){width="2.676388888888889in"
height="1.992361111111111in"}

Figure 3. Detail of complex cross-bedding. Horizontal scale of image is
\~210 m (Tanaka, 2007, LPSC).

### Planum Boreum baseline recent climate record and constraint on maximum obliquity

Estimates of the age of the North Polar Layered Deposits based on crater
counts vary significantly from 3 x 10^5^ -- 10 x 10^6^ years, with the
South Polar Layered Deposits appearing significantly older, 7-15 x 10^6^
years (Fishbaugh and Head, 2001 and references therein). The North Polar
Layered deposits show evidence of at least one retreat due to
topographical features in the Vastitas Borealis (Fishbaugh and Head,
2001) and complex cross-bedding (Tanaka, 2007) --- see Figure 3. Chaotic
solutions for Mars climate history, based on uncertainities in orbital
parameters, can show obliquity constrained between 15 and 35 degrees for
the past 100M years (Folkner *et al.*, 1997) or a significant change of
state 5M years ago towards a high obliquity state of \~60 degrees
(Laskar et al, 2002; Laskar et al, 2004). Models have shown that a
change to a high obliquity state of \>40 degrees can cause the loss of
North Polar Dome ice at a rate of 10cm/year with preferential deposition
in the equatorial region (Haberle et al, 2003; Mischna et al, 2003).

Another approach to understanding the age and formation processes of the
North Polar Layered Deposits has been to associate the layered structure
with precession-related (51,000 years) or obliquity-related (120,000
years) polar insolation cycles with varying amounts of ice and dust
deposited in each cycle. The dustier layers are hypothesized as lag
deposits associated with higher insolation phase (e.g., Levrard et al,
2007). From Fourier transform analysis of imaged stratigraphy in north
polar dome troughs in the upper 800 m, a dominant wavelength is found
for the layered structure of \~30 m (Laskar et al, 2004; Milkovitch and
Head, 2005).

A paradox arises with the combination of insolation information,
observed layer thickness and the North Polar Dome depth of \~2 km
observed by MARSIS and SHARAD (Picardi et al, 2005 (check), Putzig et
la, 2007). Modelled polar insolation is clearly driven by obliquity
rather than precession (eg. Levrard et al, 2007) with insolation values
first reaching the modeled threshold value (300 Wm^-2^) that would
produce net loss of water vapour and formation of lag deposits around
0.5M years ago, and with around 34 insolation cycles crossing the
threshold value in the last 5M years. As has been pointed out by both
Levrard et al (2007) and Milkovich and Head (2005), there are many more
layers observed in PLD troughs, with various interpretations: more than
one layer is laid down each obliquity cycle with unknown process, the
polar layered deposits survived the large obliquity change at \~5M
years, or the obliquity range has not exceeded 40 degrees over a period
significantly longer than 5M years. **A key scientific goal to address
this paradox is to access the stratigraphic record from the current
residual cap through to the base of the PLD.**

Dome sites are chosen on Earth to give baseline climate records via an
extracted ice core. Figure 4 shows that most deep drill sites in
Antarctica (Vostok aside) are associated with dome features. Typically
dome sites are selected as they represent regions of net accumulation,
close to a flow divide, and where flow distortion of the ice sheet is
minimal and well understood (Morse et al, 2002). An alternative approach
to accessing the ancient ice at the base of the PLD is to sample from
the scarp face, using mobility to access scarps of different ages, with
shallow core segments pieced together using stratigraphic markers and
flow modeling to provide the ancient climate history. As the north polar
dome has been hypothesized to have undergone at least one retreat (eg.
Fishbaugh and Head, 2001), and major dust lag unconformities can be
predicted from climate modeling (Levrard et al, 2007), sampling from the
base may be difficult to interpret in terms of chronology and local
versus regional effects.

![](media/image29.png){width="4.7555555555555555in"
height="4.110416666666667in"}

Figure 4. Deep drill sites in Antarctica mainly associated with dome
features. (ICWG, 2003).

### Horizontal Sampling of the NPD

Horizontal sampling (shallow drilling at several sites along a transect)
of the NPD could be complementary to deep drilling as a way of
investigating heterogeneity across a polar dome (Mayewski et al, 2005),
or trying to understand specific local episodes of cap retreat evidenced
by e.g., cross-bedding. Sampling overlapping stratigraphies along a
descending transect may be an alternative means of reconstructing the
long-term climate record.

### Stratigraphic Markers and Dating

Due to the expectation of uncomformities described above, a visual
dating of stratigraphy would best be supported by an absolute dating
method. The nuclear-decay modulated Ar^40^/Ar^39^, or atmospheric loss
modulated N^15^/N^14^ have been suggested as Martian chronometers (Doran
et al, 2005) with values sampled from atmospheric inclusions and
calibration of δ^15^N from absolute dating of rocks which contain
inclusions by other methods.

Cosmogenic nuclides in trapped dust may also be used for dating (eg.
^53^Mn (half life 3.7My), ^10^Be (1.5 My), ^26^Al (0.705 My) and ^14^C
(5730 years) (Doran et al, 2005)) but due to high background cosmogenic
radiation it may be necessary to return selected samples of dust to
Earth for sensitive analysis. ^26^Al is deposited on a planet directly
from supernovae ejecta and can be used also to identify pre-solar
condensates (Cole et al, 2006). On the basis of a model of Mars ice
reservoirs and isotope fractionisation, Fisher (2006) has suggested that
the D/H ratio may provide a very effective chronometer for the polar
cap, with obliquity cycle variations (120,000 years) appearing as a
variation of 1000 to 2000 per mil, and an additional small component of
variability at 2500 years detectable with precision of 1 per mil.
Exchange with subpolar reservoirs is suggested to appear as a trend in
D/H superimposed on the above mentioned avrialbility. Lacelle et al (in
preparation) have proposed that a measure of molar ratios of the set of
occluded gases CO~2~, O~2~/Ar, N~2~/Ar and N~2~/O~2~ could additionally
discriminate between vapour and water deposited ice and perhaps indicate
the presence of microbes.

Composition (atmospheric gases and dust) and dating of lag deposits
found would be especially interesting, to understand extremes of global
dust and volatile cycles. Measurements of ice composition, mass
concentrations of ionic species and electrical conductivity, associated
with stratigraphy could help with the detection and interpretation of
recent impacts or volcanic events.

Visual stratigraphic markers could include gas bubbles as well as dust.
On Mars, dust is expected to dominate. Expected grain and crystal sizes
would determine imaging needs.

### Desired precursor measurements

-   Long term global network of meteorological stations --- with good
    representation across and around the poles --- coordinated with
    orbital monitoring of weather. (called out in 3^rd^ mars polar
    conf).

-   Orbital imaging and geophysical survey applied to site selection:
    Monitoring of accumulation over dome area over several seasons from
    high resolution orbital measurements (e.g., lidar).

-   Return of a sample from a future deep drilling site to establish net
    rate of surface accumulation (confirm zero level).

-   Return of a sample from the PLD base to provide information about
    the absolute age and for sensitive cosmochemistry.

### Investigations for the human era of exploration

Deep core and baseline chronology

-   Relative and absolute age of layers as a function of stratigraphic
    position, D/H, Ar^40^/Ar^39^ cosmogenic isotopes.

-   Composition: occluded gases (CO~2~, Ar, N~2~, O~2~), ions, dust
    grain composition, mass, particle size distribution

-   Visual survey: crystal size, detection of lag deposits

-   Geophysical survey

Polar cap mass and energy balance for current climate state and seasonal
cap formation processes

-   Present surface displacement rate

-   Local accumulation (temporal and spatial variability)

-   Incident, reflected, emitted, transmitted radiation

-   Local wind, temperature, dust, water vapor profiles

-   Near surface temperature profile for correlation with observed grain
    sizes

-   Surface-atmosphere heat flux

Geophysical investigation

-   Embed heat probes and seismometers in bore hole for long term
    monitoring of cap

## Early Atmospheric Evolution

The early evolution of the Mars atmosphere, as discussed here, refers to
the first 1-2 billion years of coupled exchanges among Mars interior,
surface, and atmospheric volatile inventories and subsequent loss of
these volatiles to space. Key measurement objectives, as developed in
MEPAG 2006 Goals IIB, are gas and ice isotopic ratios, current
atmospheric escape processes and rates, and surface morphological and
chemical records of early Mars climate. A number of these objectives
will have been substantially addressed prior to HEM activities. However,
HEM in situ measurements should play an especially important role in the
study of the early Mars atmospheric environment, given the
Archean-Hesperian ages presented over much of the current Mars surface.

### Impact Breccias 

Sample return might target impact breccias of different ages, which are
good sources of fluid inclusions.

### Inferring the Paleoclimatic Conditions of Mars: the Geological Record of the Ancient Atmospheric State

The paleoclimatic --- paleoatmospheric (this would be quite much
complicated) --- conditions that reigned during earlier atmospheric
episodes of Mars can be inferred through several types of geological
evidence ranging from planetary/regional to molecular scale. As on
Earth, wet climate episodes, under interplay with geological processes,
produced different geomorphic and sedimentological imprints that are
related to the occurrence of quiet or running water bodies. Fan-shaped
structures or meandering to braiding channels, but also fluvial-like
terrace deposits or fine-grained continuous deposits are evidence for an
active and stable hydrosphere. Some other sedimentary record as
evaporites (i.e. Mars sulfates are a good example) can be used to
determine the thermal regime of the paleoclimate, whereas some
fine-grained deposits--mainly composed by phyllosilicates- can denote
wet and temperate ancient climates. Stratigraphy and geochemical
analysis of very peculiar materials formed in-situ or deposited as
paleosoils, gossans/laterites, sulfide orebodies --sedimentary or
hydrothermal- and red beds are geological markers of the chemical state
of Mars ancient atmosphere.

Oxygen and silicon stable isotopes of chemical sediments --- e.g.
silica-rich, sulfates, carbonates --- can be used to estimate the
temperature of waters that generated them. Moreover, other chemical
tracers of sediments have a great importance to the evaluation of the
redox state of the waters interplaying the ancient Mars atmosphere --
bearing in mind that an oxidizing atmosphere does not mean in this case
an O~2~ -enriched atmosphere. On Earth several trace elements (U, Ce,
Mo), but also isotopes of Fe and S (mass independent fractionation) are
been used to determine the oxidizing potential of solutions in contact
with the atmosphere, as well as of the atmosphere directly.

### Desired precursor measurements

-   Orbital imaging, remote sensing and surface robotic exploration of
    early Mars geomorphic structures and deposits focusing in
    recognizing the major composition, stratigraphic framework
    (relationships between different kind of structures/deposits) and
    chronostratigraphy, in order to determine the ancient surface
    environments and its temporal succession at least in a relative
    aging succession.

-   Sample return would be required to make some mineral and geochemical
    analyses that shed light in characterizing paleoclimatic parameters,
    chemical state of ancient paleoatmospheres and aging of deposits.

### Investigations for the Human Era of Exploration

-   Field work for searching weathering profiles (gossan, laterites,
    etc), paleosoils, layered materials and sedimentary deposits
    sensible to paleoclimate record

-   Surface sampling/soft drilling to deep drilling (to 200-500 m?)

-   Characterization of paleoenvironments and/or paleoclimates

-   Composition: petrological, mineralogical and geochemical
    determination of sediments.

-   Building the stratigraphical framework, chonostratigraphy and
    geochronology. This would result in obtaining the succession of
    climatic stages along the time through the sedimentary/deposit
    bodies.

### Appendix C. The Human Exploration of Mars: Lessons Learned from Apollo (Written by James W. Head) 

Born from international competition with the Soviet Union at the height
of the Cold War, the Apollo Lunar Exploration Program accomplished the
first significant and sustained scientific exploration of another
planetary body by human explorers. Following the precursor missions
Apollo 7-10, Apollo 11 touched down at Tranquility Base on July 20th,
1969, accomplishing for all humankind U.S. President John F. Kennedy\'s
goal of sending humans to the Moon and returning them safely by the end
of the decade. Why did human exploration of the Moon continue past this
major milestone? U.S. national political, scientific and engineering
leadership understood that this huge investment in exploration
infrastructure could pay fundamental dividends in terms of inspiration,
scientific results, technological and economic competitiveness, and
international leadership.

Having understood this from the outset, participants ensured that the
capabilities built into the exploration architecture and engineering
infrastructure were much more than what was simply required to place
humans on the Moon and return them safely. Thus, with each successive
Apollo mission, expanding confidence in rendezvous and docking, landing
site accuracy, astronaut mobility, human capability, and systems
engineering of a hugely complex task, led to increased capabilities and
ever more profound scientific results. Apollo 12 was targeted to the
western lunar nearside to make a pinpoint landing near the Surveyor III
spacecraft and performed an additional EVA. Apollo 13/14 were targeted
to rough terrain of the Fra Mauro Formation in order to sample the
ejecta of the Imbrium Basin. Astronauts carried a wheelbarrow-like
Mobile Equipment Transporter (MET) to the top of the ridges. Apollo 15
was targeted to high latitudes at the edge of Hadley Rille nestled in
the Apennine Mountains, undertook three EVAs and a SEVA (Standup EVA;
involved suiting up, depressurization of the LM, opening of top hatch,
and regional description of the landing site), and deployed a satellite
in lunar orbit. A Lunar Roving Vehicle (LRV) provided access to
important scientific sites separated by almost 15 kilometers. Apollo 16
was targeted to the rough and varied lunar highlands and revealed the
mysteries and complexities of the lunar crust and the processes that
shaped it. Apollo 17 carried the first geologist to another planetary
body and landed in a narrow box canyon at the edge of the Serenitatis
Basin, unlocking many of the secrets of impact basin formation and
subsequent lava filling. Apollo 18-22 were to involve ever more complex
and capable exploration capabilities, and development of the
human-robotic partnership. Such efforts included DM-LRVs (Dual-Mode
Lunar Roving Vehicles) that the astronauts, at the end of their mission,
would set to automated mode. Controllers and scientists in Houston would
then undertake scientific exploration traverses hundreds of kilometers
in length, ending at the next human landing site, to provide scientific
interpolation between different key regions explored in detail by human.
Loss of national will and the financial burdens of the Viet Nam war
resulted in the termination of the Apollo Lunar Exploration Program
following Apollo 17.

There are several important lessons to be learned from these events
relevant to the human exploration of Mars. First, landing humans on the
Moon was a fundamental accomplishment that brought tremendous pride and
prestige to the United States. The lasting legacy, however, was not just
this historical event, but what humans actually
[accomplished]{.underline} during this period of exploration. Wise
leaders ensured that the capability was built into the system so that
what was learned along each step of the way could be folded back into
the system to improve its capability. Apollo was an Exploration Program,
not just a single landing. And exploration was not just \"flags and
footprints\", but indeed was fundamental scientific exploration. The
true and lasting legacy of the Apollo Exploration Program is the wealth
of scientific observations made by the astronaut explorers, the
materials that they collected and the instruments that they deployed.
The results of this exploration fundamentally changed, and continues to
change to this day, the way in which we view Earth, our own Home Planet,
and its place in the Solar System.

Therefore, when humans explore Mars, it would be prudent to follow our
experience in the first great wave of the human exploration of other
planetary bodies, the Apollo Lunar Exploration Program. We should plan
for a program, not a single landing. We should build in broad
capabilities from the start, to take advantage of what we learn at each
step along the way. We should understand that the true lasting legacy is
not just going to Mars, but what can actually be accomplished by humans
when they are there, and the scientific results that they can obtain.
Using these simple guidelines as a broad compass will lead us to a
successful human exploration of Mars, and a legacy that will outlast us
all.

In addition to these broad guidelines, a host of individual lessons were
learned from the Apollo Lunar Exploration Program that provide guidance
for the task of visualizing and planning for the human exploration of
Mars. These lessons are documented in numerous publications, some of
which are referenced below. For landing site selection, it would be
important to develop science and engineering synergism, so that
scientific goals and crew safety can be optimized. Single landing sites
should provide the capability to access multiple broad scientific
objectives, in order to optimize the scientific return. System
engineering concepts should be applied to the planning of surface
exploration activities, in order to optimize the wide range of human
surface exploration capabilities. Astronauts should be trained in
fundamental scientific exploration capabilities (e.g., geological
observations), so that they are prepared for both the expected, and can
deal intelligently with the unexpected. Astronauts should be involved in
planning at all steps in the process. Infrastructure should be developed
to take advantage of the human capability for in situ analysis and
on-site decision making and scientific traverse planning adjustments.
The human-robotic partnership should be explored to its fullest, with
robotic capabilities providing for scouting and scientific
interpolation, as well as performance of analysis tasks in order to
optimize the utility of human insight, analysis and decision-making.
There should be sufficient payload capability to return abundant samples
and related materials from Mars to undertake measurements that would
always be more capable on Earth than in situ analyses. Returning
astronauts should be involved in the post-mission analysis of the data
at all stages. These guidelines, together with more detailed operational
experience, provide a basis for successful planning for the human
exploration of Mars.

### Sample Reference: 

Heiken, G. et al., eds., *Lunar Sourcebook*, Cambridge University Press,
736 p. (1991).

Heiken, G. and Jones, E., *On the Moon, The Apollo Journals*, Springer,
492 p. (2007).

Jolliff, B. et al., eds., *New Views of the Moon*, Min. Soc. Am., 60,
721 p. (2006).

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Angelats i Coll, M., F. Forget, M. A. Lopez- Valverde, and F.
Gonzalez-Galindo (2005), The first Mars thermospheric general
circulation model: The Martian atmosphere from the ground to 240 km,
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Antol, J., Woodard, S., Hajos, G., Heldmann, J., Taylor, B. Using Wind
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