**Report on the 4th 2003 Mars Exploration Rover Landing Site Selection
Workshop**

Held at the Embassy Suites, 201 Huntington Drive, Arcadia/Pasadena,
California

January 8^th^-10^th^, 2003

January 8^th^, Wednesday

**[Introduction]{.underline}**

**9:00 a.m.** Welcome, Overview of the Landing Site Selection Process
and Workshop Goals

John Grant (Co-Chair, Landing Site Steering Committee)

**9:15 a.m.** Mars Exploration Program

Jim Garvin, Mars Program Scientist

**9:30 a.m.** Landing Site Selection and the Athena Science Payload

Steve Squyres

**9:45 a.m.** History of Ellipse Changes since 3^rd^ Workshop

Matt Golombek (Co-Chair, Landing Site Steering Committee)

10:15-10:30 a.m. Coffee Break

**10:30 a.m.** Engineering Constraints, Factors, Process in Selecting
the MER Landing Sites

Mark Adler, Project Landing Site Engineer

**11:30 a.m.** EDL System Updates

Rob Manning , JPL

**[Summary of Introductory Presentations (provided by J.
Grant):]{.underline}**

**[John Grant:]{.underline}**

Presented overview of landing site process

Community input critical to success

Described expected outcomes

Tables of Testable Hypotheses to be filled out at workshop

Quad Charts for NASA Headquarters (presented by J. Garvin)

**[Jim Garvin:]{.underline}**

Repeated that science community input is critical to the success of the
process

Requested identification of representative images for each of the
remaining sites

Request assistance in developing Quad Charts for each of the sites that
will be shown to E. Weiler

Includes site name, expected science impact if we go there, advantages
and disadvantages of the site, and what could be accomplished at the
site.

Cathy Weitz ended by showing an example of a Quad Chart template with
sample entries

**[Steve Squyres:]{.underline}**

Presented examples of data collected using flight hardware

Emphasized the comprehensive calibration that will ensure high quality
data

Spoke to comprehensive nature of Athena instrument suite and expected
data

Specific to landing site selection activities:

All activities must be documented completely

All of the details must be known to team, project, and Headquarters

Need a set of testable hypotheses to help define initial operations

Community can provide hypotheses used to plan initial science operations

**[Matt Golombek:]{.underline}**

Gave update on the process of defining ellipses

Began with where we left off at third workshop

Used science to select 6 sites assessed at 3^rd^ workshop

Winds and other concerns eliminated Melas, Eos, Athabasca

Changes since third workshop

Athabasca demoted to back-up, then deleted due to radar signature and
trafficability concerns

Isidis promoted to prime site

Revisited process to identify "wind safe" sites

Identified multiple potential sites

Chose EP78B2

Due to low rock abundance

Acceptable winds, smoothest at all scales

Farther south sites have more power

Remaining sites now Meridiani, Gusev, Isidis, Elysium

Name change of Hematite now referred to as Meridiani Planum

Elysium name provisionally maintained

**[Mark Adler:]{.underline}**

Started by reminding that we are one year from landing!

Provided summary of the process to date with interplay of science and
engineering

Described current phase as the endgame leading to landing site selection
in April

Moved on to summarize EDL events

Described mission success drivers that include how fast landers impact
surface, what it impacts on the surface, how many bounces the landers
make, and how long the rovers will survive after landing.

Summarized how various parameters could impact the mission success and
how each has been mitigated

Reviewed the DIMES instrument and ongoing testing (which has not been
approved for use)

Showed numerous examples of "bounce-down" for a 2 X 4 km area in Gusev

Discussed very preliminary mission success rankings based on work to
date:

Landing Site: Rock Abundance (%) Shear (MPF ratio) Horiz wind (m/s)
Turb/vert (m/s)

Meridiani 5 0.4 4 1-2

Elysium 5 0.3 4 Higher

Gusev 8 0.9 7 Higher

Isidis 14 0.7 9 Higher

Which of the sites may be best suited to meeting mission success?

No definitive answer yet, but depends on assumptions regarding relative
science value of sites (e.g., if Meridiani is greater value than
Elysium, Gusev greater than Elysium, and Gusev greater than Isidis)

Bottom line: not yet sure if Meridiani and Gusev are safe enough, but
feel that Meridiani, Gusev, and Elysium are likely safe enough. Not
clear if Isidis is safe enough, but Gusev would be higher science value
than Isidis based on community input to date.

Described that a lot of contingencies are built into the process (e.g.,
defer TCM-1 for MER-A until after MER-B launch). May also be significant
fuel left for retargeting of landing site after TCM-1 and well into
cruise.

Question was also posed: if there is only one rover, due to failure,
where would we go? Meridiani versus Gusev? Adler would like the landing
site community to provide input and decide.

Squyres pointed out that this was done at the third workshop and that
changes are unlikely at this point unless there is significant new data
showing new interpretations are likely and/or that previous
interpretations were flawed.

**[Rob Manning:]{.underline}**

Provided a review of EDL accomplishments to date: 40 --50 drop tests
made, new bladder layer in air bags greatly helps mitigate problems
encountered earlier.

Data shows that the landing system can handle 20 m/sec tangential and
12-15 m/sec normal velocity at impact.

Parachutes have been redesigned and improved based on earlier test
results.

DIMES tests are ongoing, but instrument is not yet approved for flight
and operation

EDL flight software is being tested.

EDL work remaining includes:

Final parachute lot acceptance

EDL system tests

Completion of descent-rate limiter qualification

One additional radar flight speed drop test

Summary: EDL is robust and is not a threat to MER Development

12:00-1:00 p.m. Lunch

**1:00 p.m.** Analysis of Nighttime Temperatures at the Landing Sites

N. Bridges and T. Martin, JPL

1:30 p.m. Discussion

Science of the Landing Sites

**2:00 p.m.** Analysis of THEMIS Data for Meridiani, Isidis, and Elysium
Sites

Phil Christensen and THEMIS Science Team

**[Summary of Introductory Talks (cont'd) (provided by K.
Tanaka):]{.underline}**

**[Nathan Bridges and Terry Martin:]{.underline}**

Near-surface temperatures at the MER landing sites affect mission
lifetime. Lowest temperatures at 1 m above the surface occur during
pre-dawn hours. Worst-case temperatures have been estimated for Sol 1 at
each site using a 1-D model by J. Murphy (NMSU). This model is based on
Viking and Mars Pathfinder lander measurements and has input parameters
including thermal inertia, albedo, elevation, dust abundance, season,
and time of day. The MER mission is concerned with temperatures falling
below -97°C (176 K). The analysis included TES-derived albedo and
thermal inertia provided by the TES team. Thermal inertia has the
greatest influence on results.

Results indicate the following probabilities for landing at sites
\<-97°C for each ellipse in increasing order: Isidis, 0%; Gusev, 3%;
Elysium, 7%; Meridiani, 8%. Squyres emphasized need to analyze data for
Sol 90 at each site. Christensen suggested that temperatures likely
would not decrease by more than a few degrees, but that could be
important; also, temperatures could be 10-15° warmer near rocks and 3-5°
variations may occur within TES pixels. Kass indicated that advection
(wind chill) has been factored into the -97° temperature limit.
Correction made after the meeting: Nathan Bridges checked, and found out
that the modeling was done for Sol 90, not Sol 1.

Other effects on temperature could include ponding of cold air in
topographic lows such as craters and warmer air descending from higher,
nearby topography. THEMIS nighttime IR data and mesoscale atmospheric
models may help improve future analysis.

**[Phil Christensen and THEMIS Science Team:]{.underline}**

Christensen reviewed the THEMIS day (DIR) and night (NIR) infrared (100
m resolution) and VIS (18 m resolution) multispectral data for the MER
sites. Dust cover generally obscures determination of mineralogy, but
thermophysical properties are nicely portrayed in the IR data. Bedrock
is \~20 K warmer than dust at night. Squyres questioned whether the
bedrock could be duricrust; Christensen indicated that the thermal
inertias indicate very dense rock. NIR data show warm, rocky slopes are
common. Also, warm, blocky slide material in Melas Chasma contrasts with
the cool plateau surface in NIR. Athabasca region also shows lots of
rocky material in IR data.

The Gusev ellipse shows thermophysical and albedo variations, with a 15
K temperature range. In detail, some morphologic units have distinct
thermophysical properties. The Isidis ellipse shows uniform
thermophysical properties, with slight variations in plains north of the
ellipse. The THEMIS Team suggests a geologic history involving fluvial
dissection of ancient highlands, infilling of intermontane basins, wind
erosion to form etched, high thermal-inertia units, infilling of Isidis
basin with smooth and ridged volcanic plains, and finally, deposition of
sand and dust deposits. The Team has produced a map of the units
associated with this history. The DIR, which now has been collected for
40% of the planet, does a better job at resolving morphology than
comparable the Viking MDIM. Other non-volcanic interpretations for the
origin of the Isidis ellipse material were noted by Crumpler.
Christensen cited as possible evidence of volcanism collapse pits and
ridges along the margins of the lowland materials that may represent
high lava stands. North of the ellipse, rows of knobs that in some cases
have summit pits may be pseudocraters, volcanic cones, or glacial
moraines, among other possible explanations. The margin of the units
forms a subtle ridge in MOLA data. The Elysium ellipse shows 15-20 K of
variability in NIR data.

The Meridiani site has extensive THEMIS and MOC coverage. TES mapping of
hematite abundance has been registered to the image data. High DIR
thermal contrasts of \>25 K occur among the units. Crater rays can be
traced for hundreds of kilometers. Hematite abundance mapping correlates
extremely well with morphologic mapping using THEMIS VIS and IR data.
Thickness of hematite unit not yet studied but may be meters to tens of
meters. Crater ejecta generally appears to superpose the hematite layer.

THEMIS multispectral data in some cases can show compositional
variations, including an olivine-rich basalt layer within Valles
Marineris. However, THEMIS was designed to detect silicate, carbonate,
sulfate, and other mineralogies but not hematite. MiniTES will be
capable of detecting hematite. Meridiani ellipse displays 8-10 K of
temperature variation. Squyres: What does the hematite have to do with
water? Christensen: Aram Chaos may be an important clue because it
contains a layer of hematite in a closed basin and thus could have a
lacustrine origin or may be goethite that was baked into hematite. It
could also be a cement, but clearly not wind deposited. Parker: Appears
in MOC that hematite might embay crater rays. Christensen: The rays
detected in THEMIS are subtle and may be without secondaries. Gentry:
What is probability of finding hematite with rover considering TES pixel
size? Christensen and others: The sharp correlation of TES hematite
signature and smooth unit morphology suggests that hematite likely
distributed throughout. Carr: MOC images show two units throughout, with
bright unit locally. Squyres: The rover might spend a week or so
investigating the hematite unit, then go to nearby outcrop of bright
unit.

3:00-3:15 p.m. Coffee

**3:15 p.m**. Crater Counts at the Landing Sites: Implications for
Surface Materials

Martha Gilmore and Ken Tanaka

**3:45 p.m**. Characterization of Hematite Deposits and Associated Units

Frank Seelos, Washington University

**4:15 p.m.** Possible Relationships Between Hematite and Large Impact
Basin

Horton Newsom

**4:45 p.m.** Discussion

**[Summary of Gusev Crater talks (compiled by Jack
Farmer):]{.underline}**

**[Marty Gilmore and Ken Tanaka:]{.underline}**

The USGS PIGWAD crater data base was used to estimate the age of units
at the Meridiani site. These results suggest that the hematite-bearing
unit is Noachian in age and has been exposed during the Amazonian. The
hematite-bearing unit is a medium-low albedo unit which overlies a
light-colored (higher albedo) unit. This light unit is presently being
exhumed and is visible as crater rims, ridges and other higher relief
features that stick up through the hematite unit.

**[Phil Christensen:]{.underline}**

THEMIS is a 9-band, multispectral infrared spectrometer with uncooled
bolometer presently mapping from orbit on the Odyssey spacecraft. The
spectrometer maps 32 km swaths. Comparison of THEMIS day-night images
have revealed in amazing detail the thermal properties of surface
materials at the Meridiani site. TES images overlain on THEMIS provides
a basis for understand the distribution of the hematite-bearing unit
(mapped spectrally by TES at 3 km/pixel) in relationship to
thermophysical and albedo units mapped at much higher spatial resolution
by THEMIS (\~100 m/pixel).

Rocks retain heat at night and are cooler during the daytime, relative
to fines, which are cooler at nighttime and warmer during the daytime.
The observed thermal contrast is large (25 degC difference between rock
units). The marked differences in thermal inertia reveal many important
details about the state of surface materials not apparent in visible
images. For example, crater ejecta rays not apparent in daytime images
show up in vivid detail in nighttime mosaics. The range of rock
abundances for the area is estimated between 2 and 15%. In contrast to
previous ideas, there appear to be large areas of exposed rock (i.e.,
outcrops do not appear to be dust covered).

Hematite at the site is concentrated on mesa-like features. As noted
above, it maps as a darker unit, overlying a light-colored unit. There
is an excellent correlation of hematite occurrence mapped by TES and
this mappable darker unit. MOLA shows that the hematite surfaces are
essentially flat. However, the 18-meter visible image shows clear
evidence for a stratigraphy at the site. THEMIS data suggest that the
hematite deposit is not a loose windblown deposit that mantles the
surface (i.e. as a surface lag), but is instead an indurated unit that
is being actively eroded and reworked locally from a thin,
hematite-bearing horizon that is on the order of tens of meters thick.
The hematite present could be a cement, but is not a loose material. The
likelihood of encountering the hematite bearing material within the
landing ellipse appears to be excellent, although the major scientific
goal is to discover associated materials that may provide definitive
evidence for the activity of water.

Within the landing ellipse, THEMIS data do not show much spectral
contrast, suggesting that the area is relatively uniform
compositionally. However, the spectral regions covered by THEMIS (and
similarly, the mini-TES) do not include the active intervals for oxides.
In addition, the low spectral resolution of THEMIS may be contributing
to this apparent compositional uniformity for other mineral groups.
THEMIS data do show the ellipse to be more or less uniform in terms of
thermophysical properties. However, even though it appears to be
thermophysically uniform, it is not a parking lot, with temperatures
ranging from 8-10 degK over the ellipse. Superimposed younger craters
are revealed in THEMIS nighttime images as cool (dark) ejecta rays
sitting on the hematite unit. While the Meridiani landing ellipse
appears safe, ejecta rays from adjacent impact craters indicate that
material has been deposited within the ellipse. The good news is that
ejecta from the underlying units has been redistributed into the ellipse
over a distance of \~three times the crater diameter and should be
accessible by the rover.

**[Frank Seelos presentation (incomplete):]{.underline}**

A rover access model (RandoMER) was used to better understand the
mobility capabilities of MER at the landing site. The modified random
diffusion model estimated a mean step size of 11.5 m after 52
iterations.

**[Horton Newsom:]{.underline}**

Several alternative hypotheses have been proposed for the origin of the
specular hematite deposit. These include deposition from an oxygenated,
standing body of water (i.e., lake), hydrothermal alteration of
pre-existing volcanic units (e.g. air fall tuffs), low temperature
aqueous weathering of mafic volcanics, and high temperature, non-aqueous
oxidation of basalt. The majority of these hypotheses require the active
involvement of water, although the latter does not.

Regional context mapping of the Meridiani site has revealed that the
site falls on the margin of a large arcuate features interpreted to be a
very old, large (800 km diameter) multi-ring impact crater. MOLA data
were used to confirm the existence of a central high separated with an
annular ring crest and basin. Channel networks within this terrane are
controlled by the topography of the ring structure. The proposed landing
site at Merdiani is positioned along the outer annulus, in one of three
basins that were connected to a large channel network that dissected a
southern watershed the size of the state of Texas. THEMIS and MOC data
suggest that Iani chaos to the north also received surface and
groundwater flow from these basins. Epithermal neutron data is
consistent with a concentration of hydrated minerals in all of these
basins.

5:30 p.m. Adjourn

**[January 9th, Thursday]{.underline}**

Science of the Landing Sites (cont.)

**8:30 a.m.** Eolian History at Meridiani and Gusev

Ron Greeley, ASU

**9:00 a.m.** Synthesis of the Testable Hypotheses for Gusev

Nathalie Cabrol, NASA Ames

**9:30 a.m.** Testing Hypotheses in Gusev Crater using the Athena
Payload

B. Sutter, J. Moore, N. Cabrol, and A. Zent

**9:45 a.m.** THEMIS Thermophysical and Spectrascopic Properties of
Gusev

J. Moersch, H. McSeeen, University of Tennessee

10:15-10:30 a.m. Coffee

**[Summary of early Gusev Crater talks (compiled by George
McGill):]{.underline}**

**[Greeley:]{.underline}**

Surface albedo landform features at these sites were used to test GCM's
and mesoscale wind models. For Gusev, there is a large-scale correlation
between dark albedo patterns and the GCM, but local features relate to
mesoscale models predicating inward-oriented night winds and
outward-oriented day winds. For Meridiani Planum, there is no
correlation between albedo features and the GCM, but dunes do correlate
with summer winds. The mesoscale model predicts vertical cells of winds
at Meridiani in the afternoon.

**[Cabrol:]{.underline}**

It was pointed out that, because of the diversity of materials and their
properties at Gusev, the site provides an opportunity to calibrate
orbital TES data. Six hypotheses were discussed, and for each the
relative instruments and measurements were listed:

GRS Hydrogen abundance is due to near-surface ice or to hydrated
minerals

Sediments in Gusev are of global provenance

A lake or lakes once existed in Gusev, either long-lived or ephemeral

Ma'adim is a fluvial channel

Deposits in Gusev are volcanic, being derived from Apollinaris Patera

Deposits in Gusev are related to glaciation.

**[Sutter:]{.underline}**

Five different types of hypotheses were presented (lacustrine, eolian,
fluvial, volcanic, and glacial), but only the first two of these were
discussed. The specific properties diagnostic of eolian and lacustrine
processes were listed and discussed. These included definition of
characteristic grain-sizes, round, sorting, and bedding (or absence of
bedding).

**[Milan and Moersch:]{.underline}**

Independent unit maps were prepared using thermophysical properties and
morphologic data in images. The two maps defined 8 units, most of which
were correlatable between the two maps (some of which did not). All
units are probably Hesperian based on crater counts. Results of the
mapping are consistent with a fluvial/lacustrine model, but do not prove
it. A principal component analysis of multispectral THEMIS data
demonstrates that two components dominate the site: basalt and dust. Low
albedo areas are dominantly basalt, whereas high albedo areas are
dominantly dust.

**10:30 a.m.** Fluvial/Lacustrine Analysis of the Gusev Site Based on
THEMIS, MOC, and MOLA

Jim Rice, ASU

**10:45 a.m.** Geologic Units in Gusev Crater

Ross Irwin, NASM CEPS

**11:00 a.m.** MER Science Goals and Testable Hypotheses at the Isidis
Site

Larry Crumpler, NMMNH, and Jeff Moore, NASA Ames

**11:30 a.m**. Geologic Setting of the Isidis Site

George McGill, UMASS

**11:45 a.m.** Scientific Hypotheses Addressable at the Elysium Site

Jim Rice, ASU, Mike Carr, USGS

12:15-1:15 p.m. Lunch

**1:15 p.m.** Geology of the "Elysium" Site

K. Tanaka, J. Skinner, M. Carr, M. Gilmore, and T. Hare

**1:45 p.m.** Beyond the Hematite: Additional Motivation to Land in
Meridiani

Wendy Calvin, University of Nevada

**[Summary of later Gusev, Isidis, Elysium, and Calvin Meridiani talks
(compiled by Ginny Gulick):]{.underline}**

**[Jim Rice:]{.underline}**

Jim Rice summarized his observations using THEMIS and MOC images and
MOLA topographic data. He noted that there are several units in the
Gusev area. Smooth material is retreating, layering is everywhere. Not
sure whether the dark streaks are erosional or depositional. Jim thinks
the dark streaks are actually deposits, because they embay obstacles.
Crater floors have dark mantles while crater ridges are always bright.
Older knobby material is embayed and knob morphology is scattered
throughout Gusev. Jim doesn't think the knobs and mesas are delta
deposits. Instead, he interprets the knobby landform to be exhumed and
similar to knobs in the fretted terrain. He interprets "Rumpled"
material as lava or debris flows.

**[Summary of extended discussion by Steve Ruff (not a listed
presentation):]{.underline}**

Steve has identified two distinct materials: lobate and etched material.
These two units are spectrally distinct from each other. The floor of
Thyra crater located on the eastern side of the landing ellipse within
Gusev crater has spectral properties suggestive of "dust". There is high
temperature, low albedo material located on the southern rim of Thyra.

Lobate material is located in four different regions south of Thyra.
This material may be slightly different material than dust.

Etched material contains two components: 100m and 1-2cm dusty material
over both. Steve thinks that the sandy material is being deposited onto
the higher albedo material.

**[Ross Irwin:]{.underline}**

The stratigraphy with Gusev Crater consists of four distinct units:

1\) Duricrust or cap layer in low-inertia material that probably
consists of fine sediments. Ross interprets this unit as possible
duricrust or dust devil deposits.

2\) Low thermal inertia layer that fills the interior of craters has
been impact gardened and etched. Ross interprets these materials as
possible varves, pyroclastic or other airfall deposits.

3\) High thermal inertia layers are located within ejecta and etched
terrain; high TI is caused by material differences not by illumination.

4\) 1km deep Ma'adim deposit located beneath these surface units

# [Jeff Moersch:]{.underline}

Jeff summarized his viewpoint on Gusev:

> -high thermal inertia material on top
>
> -top 100 microns is dust
>
> -high thermal inertia strips is basaltic in composition

# [Larry Crumpler and Ken Tanaka:]{.underline}

The regional geology of the Isidis site was reviewed. Libya Montes,
Isidis rim contains the oldest stratigraphic unit on Mars and
potentially provides a long-term record of fluvial activity and about
the earliest and wettest periods. The ellipse region contains high
valley network density that provides information on the regional
sedimentation. Highland material is being deposited into the landing
ellipse area by the valley networks. Therefore, the sedimentation record
within the ellipse reflects ancient water flow processes with a low
energy fluvial environment, not catastrophic processes. These sediments
contain rocks and fines and detritus from fluvial and mass wasting
processes. Using the MOC image data, four distinct units/features were
within the ellipse: 1) craters and tables, 2) streak, 3) channels, and
4) contact ridges. A number of hypotheses that could potentially be
tested were summarized including the composition of the highland rocks,
erosion by fluvial activity, presence of spring deposits, and the
character of the HL-pediments.

# 

# [Jeff Moore:]{.underline}

The southern rim of Isidis basin has been extensively modified by
fluvial and mass wasting processes during the Noachian to early
Hesperian.

2 terrain units dominate in the ellipse region:

1)  putative Libya Montes-derived alluvium

2)  younger thumbprint terrain

MOLA topography indicates several indistinct ramps sloping down into the
southern edge of the ellipse. Jeff interprets these ramps as possible
alluvial fan material. If ramps are alluvium then might be able to
sample them. Most of the ellipse is located in this material. North of
the ellipse is a unit associated with "thumbprint" terrain that
superposes and forms a sharp contact with the "fan" material. This
material appears similar to material located in the Beagle landing
ellipse.

# [Mike Carr:]{.underline}

Mike summarized key science issues surrounding the Elysium site.

What is bench material?

What underlies it?

Ancient cratered terrain underlies the bench, but do northern plains
materials also underlie the bench material at a depth of a few hundred
meters or less?

What is the bench material?

Hypothesis 1: Interbedded volcanic plains and interbedded units

> Pro: looks like parts of ridged plains, pancake structures like
> structures
>
> Con: no visible flows, no major volcanic sources

Hypothesis #2: Sediments deposited in northern ocean

> Pro: bench materials are layered and appear to lap onto adjacent
> uplands.
>
> Con: evidence for ocean is not compelling

Hypothesis #3: Alluvium/colluvium derived from adjacent highlands

> Pro: located close to steep highland front
>
> Con: no evidence for fluvial activity very low slope would be
> difficult to transport material across bench (\~500m) by mass wasting
> processes(e.g., solifluction)

Hypothesis#4:Wind deposits analogous to Medusae Fossae formation

Little to support this hypothesis as there is little evidence for wind
erosion here.

Mike thinks that unit is reworked highland material transported probably
across bench by fluvial processes.

Questions:

Ross Irwin asked: Can it fit in with materials of resistant horizons?

Mike Carr.: It is not consistent with deflation processes.

Tim Parker: What would produce the scarp at the end of the bench?

Mike Carr.: The scarp is inconsistent with shoreline hypothesis because
the hollows are local.

Jim Rice: The hollows don't glow at night...

Jeff Moersch: That's unusual to have a steep slope hollow that doesn't
have higher temperatures at night.

**[Ken Tanaka:]{.underline}**

The MER Elysium site regional geology consists of a degraded highland
boundary, with a series of eroded units and plains materials that is
underlain by the Vastitas Borealis formation. Landforms seen within the
landing ellipse consist of wrinkle ridges, craters, knobs, and irregular
depressions. There are two large wrinkle ridges and numerous subtle
ridge forms. Four craters are larger than 1 km in diameter. Knobs likely
have multiple origins forming wrinkle ridge arches, crater rims,
outliers of older materials and possible mud and/or silicate volcanoes.
Irregular depressions are located in the center and east end of the
ellipse and are possibly related to collapse.

Pancake domes with small knobs are interpreted by Ken as mud volcanoes

Large knobs and depressions are pronounced in MOLA data but not in
images.

Classic flow features are not seen in the ellipse just flow margins.
With MOLA topographic data, one can see depressions going into the
ellipse area.

Question: Mike Carr: Why do you think collapse occurs only at margins?
M.C. thinks it's caused by deflation.

K.T.: Why are the collapse regions seen to be structurally controlled?
We can ask the same question for deflation.

Is there evidence for fluvial processes in the ellipse?

K.T.: There are degraded series and eroded units and plains materials.

Summary of geologic history:

> *LN/EH:* Highland boundary zone degradation:
>
> Collapse may have been due to mass wasting processes, volcanic
> intrusion, volcanic resurfacing.

*EH/LH:* Tectonic compaction indicative of mechanical discontinuities at
2 km depth.

> Marine sediments?

*LH/EA* Local collapse? Mud/silicates, volcanic activity.

*LA:*Local dune formation in craters and along scarps.

The Elysium site offers several advantages: 1) The potential to sample
both Noachian highland dissected rocks and Hesperian lowland sediments.
2) The opportunity to assess highland/lowland boundary geology. 3) The
potential to sample possible mud volcanism and spring discharge
deposits. 4) The opportunity to study a relatively simple geologic
setting at least as it appears from the regional scale. 5) The site
offers well-defined, testable hypothesis. The problem with the Elysium
site is that it may be primarily volcanic in origin.

# [Wendy Calvin:]{.underline}

Spectral data from the Meridiani site was further evaluated to determine
whether this region ever contained appreciable amounts of water. Early
Mariner 6 data show some low albedo regions being more hydrated and
there is a correlation between classic low albedo regions and drainage
density. Mariner 6 spectral data indicate that there is a strong
correlation of hydration and hematite in Aram Chaos and in Meridiani.
Results using apparent absorbance Mariner data suggest 2% additional
water by weight at hematite sites. Because the average is inferred to be
only 1-2%, this is a significant local increase in water bound in
minerals.

2:15 p.m. Science Discussion

3:15 -- 3:30 p.m. Coffee

Site Safety Presentations

**3:30 p.m.** Plans for EDL Simulations and Sensitivities

Wayne Lee, JPL

**4:45 p.m.** Meter-Scale Slopes from MOC Photoclinometry

R. Beyer and A. McEwen, University of Arizona

**5:15 p.m.** Topographic Mapping and Slope Analyses

R. Kirk, USGS Flagstaff

**[Site Safety Presentations (provided by A. Haldemann):]{.underline}**

**[Wayne Lee:]{.underline}**

(These notes complement the presentation materials)

Will construct a sensitivity analysis to generate a range of "pass"
(successful landing) percentages.

Will report on types of failure.

Simulation has 4 stages: (i) cruise jettison, (ii) hypersonic flight,
(iii) terminal descent, and (iv) terrain interaction.

Each run includes 500 to 2000 trials.

Terrain \"pass\" criteria:0.5 to 0.7 m rocks generate failure; this is a
conservative assumption, and no difference is assumed between good and
bad rocks.

Will check if failures are due to conservative assumptions.

Atmosphere inputs:

The Kass-Schofield model range includes the MarsGRAM mean, which is
lower than that of K-S. We believe K-S more because is based on
measurements from TES.

The mesoscale wind model is included via a dispersed set of wind vector
columns for each site.

Terrain inputs:

\"Statistically representative\" digital terrain maps are chosen based
on hazard zone maps, and we run separate statistics for each zone in the
ellipse.

Rock interactions are NOT correlated with terrain features and/or
slopes. We use \"bad\" rock estimates. Bad rock effects depend on lander
orientation which is accounted for/simulated.

Will examine variations on the sensitivity matrix.

Will be ready to run at the end of January. Results are due mid-March
for the landing site peer review.

**[Ross Beyer:]{.underline}**

Does point photoclinometry.

The slopes generated are upper bounds.

Does 100 m averaging and reports/maps the rms deviations.

At each landing ellipse:

1\. the slope upper limits are good.

2\. slope information highlights morphology changes.

3\. slope images may be useful for traverse planning.

**[Randy Kirk:]{.underline}**

Description of technique and a list of error assessments are presented.

The Elysium stereo DEM is rugged, but is still low compared to all the
ellipses.

5:45 p.m. End of Day Two

**[January 10th, Friday]{.underline}**

Site Safety (cont'd)

**8:30 a.m.** Hazard Maps of the Landing Sites

Tim Parker, JPL

**9:00 p.m.** Terrestrial Interferometric Radar Observations of Terra
Meridiani and Isidis

K. Larson, A. Haldemann, R. Jurgens, R. Arvidson, M. Slade

**9:30 a.m.** Boulder Counts in the Gusev Ellipse

R. Schroeder and M. Golombek

**9:45 a.m.** Probability of Impacting and Accessing Rocks at the MER
Landing Sites

M. Golombek, A. Haldemann, E. DiMaggio, R. Schroeder, and J. Matijevic,
JPL

**10:15 a.m.** Athena Science Team Perspective on MER Landing Sites

Steve Squyres

**[Summary of Safety Talks (cont'd) (compiled by M.
Shepard):]{.underline}**

**[Tim Parker:]{.underline}**

Overview of geomorphic/hazard maps of the Meridiani Planum, Gusev,
Isidis, and Elysium landing sites. Discussion for all sites centered on
various interpretations of units. Gusev coverage is extensive, with
60-70% MOC coverage and most of the remainder filled in by Themis. It
also appears to have approximately 5 different hazard units -- the
largest variety of all sites. Meridiani Planum has \~50% MOC coverage
and \~80% MOC plus Themis. Isidis has approximately 90% Themis/MOC
coverage. Elysium is the least covered landing site with \~20% MOC and
\~50% Themis/MOC total coverage. All hazard units identified will be
used to select representative digital elevation models (DEMs) from R.
Kirk's work as inputs into the Entry/Descent/Landing (EDL) simulations.

**[Larson et al. (presented by A. Haldemann):]{.underline}**

Presentation of latest radar imaging of Mars (2001 opposition) which
utilized four different receiver stations and MOLA topography to remove
the N-S ambiguity inherent in radar imaging of Mars. Only data from two
stations have been linked to date. The Meridiani track went through the
landing ellipse and shows a correlation of radar albedo with known
locations of hematite. The Isidis tracks went south of the landing
ellipse and into the highlands.

**[Schroeder and Golombek:]{.underline}**

Authors conducted a search for boulder fields in and around the landing
ellipses. Seven boulder fields were found in the landing ellipse within
Gusev crater, six within the Isidis ellipse, one within the Elysium
ellipse, and none within the Meridiani Planum ellipse. All boulder
fields appear to be associated with old degraded craters. Boulder sizes
ranged from \~2m to 10m. Areal coverage of boulder fields in Gusev is
\~1.4%; convolving in the targeting probability, the probability of the
MER lander encountering a boulder field in Gusev (during landing) is
very small (\<1%).

**[Golombek et al.:]{.underline}**

The authors used IRTM estimates of rock abundance at each landing site
and model size-frequency distribution curves (based on observations at
terrestrial and Martian sites) to estimate the probability of
encountering rocks of various sizes during landing and roving.

For landing, airbag tests suggest no failures for encounters with rocks
\<0.5m in size, but failure rates increase for rock sizes \>0.7m. At all
landing sites, the probability of encountering a rock of this size
within the first few bounces is at the 1% level or smaller. Rocks \>5m
in size are not considered a hazard since they effectively present a
planar surface to the airbags. Boulder fields have a cumulative
probability of impact at the 1% level (or less) for all landing sites.
Smaller triangular rocks are believed to be a hazard by causing a
failure of the inner bladder on impact. They are estimated to be
encountered \<2% of the time within the first two bounces (the most
critical) at all landing sites. In sum, improvements to the airbag
system coupled with estimates of rock abundance suggest rocks will not
prove to be a significant hazard for landing at any of the sites.

For roving, the authors estimated probabilities for encountering rocks
\>0.1m to analyze with instruments on the IDD, and rocks \>0.3m on which
to use the RAT. Two ranges were estimated; within reach of the IDD and
within three rover lengths drive away. For rocks of within reach of the
IDD, they estimate \>60% probability of encountering a rock \>0.1m in
size at all sites. For rocks within three rover lengths, they estimate a
35-99% probability of encountering a rock \>0.3m at all sites (lowest at
Meridiani, highest at Isidis). In sum, even at the sites with low rock
abundance (e.g. Meridiani), there is a significant probability of
encountering rocks within a short distance suitable for analysis

**[S. Squyres:]{.underline}**

Outline of the procedure for landing site selection. A science
recommendation is made by the MER team to the MER project based on the
scientific community input. These recommendations are based solely on
the science. The recommendations must include a single best science site
in the event of a failure of one rover. The MER project folds in the
engineering constraints and EDL analysis and makes a recommendation to
NASA HQ where the final decision is made. The PI requests continued
input from the science community for the next year, especially in
formulating new site-specific hypotheses that can be tested by the rover
immediately after landing.

**10:45 a.m**. Discussion

**[Summary of Discussion (compiled by J. Crisp):]{.underline}**

**[J. Grant: Introduction to Discussion:]{.underline}**

We would like to get these write-ups (lists of hypotheses to be tested)
in a more polished form. Let's discuss what we have right now.

# [Ron Greeley: Gusev:]{.underline}

Imagine doing remote sensing of the Earth based on just three landing
sites. MER ground truth information will be very helpful for improving
our interpretations of the orbital data sets.

In the application of Athena science, we'll have to consider the
different scales of observation (context, outcrop, hand specimen, and
"laboratory") and the likely materials we'll find (fines, rocks,
bedrock). What we get will be a function of where we land and rove. See
Nathalie Cabrol's tables (Main hypotheses on the origin of the materials
in the Gusev landing ellipse and possible results from Athena
Instruments on different materials) for a higher level of detail.

What process is responsible for the material in the floor of the crater?
First of all, there's the primary geology, which is greater than "skin
deep." What was the primary process that formed this material? This same
question would apply to a lot of areas on Mars. If we're wrong about the
water hypothesis, it would reset our thinking about other areas on Mars,
too. Hypotheses that should be considered for the primary geology
process are:

-   Aeolian, saltation (look for well-sorted, rounded grains \< 4 mm,
    cross bedding)

-   Aeolian, suspension (look for fine-grained dust)

-   Volcanic, explosive (fine-grained, angular, glassy)

Note that ambiguities will arise among these 1^st^ three hypotheses,
above

-   Paleolake, distal (fine-grained, thin beds, mud cracks, oscillation
    ripple marks)

-   Fluvial (clastic, wider range of sizes, rounded grains, graded
    bedding, current ripples, imbrication)

-   Volcanic, effusive (crystalline with vesicles, flow texture "cords")

-   Impact ejecta (clastic, poorly sorted, angular, brecciated, shatter
    cones)

What processes were responsible for the surficial geology (the upper
meter or so)? The dark streaks -- are they exposed bedrock, lag "desert
pavement" deposits (we'd expect granule to cobble size grains in a thin
layer that you could dig through using the rover wheels) or a dark
deposit of grains \< 4 mm in size? The drift deposits -- are they active
dunes or remnants of a formerly more extensive fluvial or aeolian
deposit?

There is the calibration of remote sensing, and ground truth, which
includes removal of atmospheric effects, determination of compositions
(checkerboard distribution versus intimate mixing), and estimation of
thermophysical properties (dust, rock abundance, induration).

There's also the secondary or alteration processes, such as
hydrothermal, aeolian, and chemical/physical weathering processes
(details are TBD.)

Ron showed an example of an Analysis Tree, which is essentially "Geology
101." All of the branches were not filled out; it was meant just as an
example of how specific Athena-determined indicators could be used to
infer processes.

Textures and structures are really important for determining the primary
processes (igneous, sedimentary, impact, etc.). Mineralogy and chemistry
narrow down the specific characteristics of those primary processes.
Mineralogy and chemistry are more important for the identification of
secondary processes.

What are the science pros and cons of Gusev? Ron said that it can be
done, but the list isn't ready yet.

The "attractiveness" of Gusev is its geomorphologic evidence at the
Viking scale.

Dave Des Marais noted the difference in the kind of water evidence for
the various landing site candidate. At Meridiani, it's mineral evidence.
At Gusev, it's physical evidence. At Isidis, it's the timing...that the
rocks may be from the early part of Mars' history.

Steve Ruff: What's the likelihood that the surface we'll land on
represents the lakebed?

We know enough to suggest a stratigraphy in Gusev.

Dave Des Marais: Impact gardening process will help churn up lakebed
sediments if they're buried. The craters should excavate to at least
1/10 their diameter. It's likely you'll have access to rocks from lake
sediments if they're there, but you can't guarantee it. That particular
"con" needs to include science judgment and include the extent to which
it may be mitigated by impact gardening and expected rover traverse
capability.

We may find impact blocks at Gusev. Just to the SW of Gusev, Kane Crater
impacted into Noachian rocks. The rover might encounter rocks from that
impact.

The MOC images of Gusev don't look like the Gale images. That's a "con."
Steve Ruff: An observable that's disconcerting is that there's a
suggestion that one of the last depositional events is this lobate
material viscous flow material that doesn't look like a lake deposit.
What if we land on that material?

Ross Irwin: The scale of many of the impact craters is 200 m and larger,
which should garden up the deposits in Gusev. There's a fairly good
chance to see rocks brought up from depth with the rover. To
discriminate between aeolian and lacustrine deposition, we could look at
the blocks, and identify the composition of the cementing material.

Send your comments on Gusev to Ron Greeley by email so that he can
generate a more comprehensive list.

**[George McGill: Isidis:]{.underline}**

George presented three main testable hypotheses and their key
observation and measurement requirements: (1) Wet early Mars (rocks
derived from Isidis rim), (2) Isidis basin was once the site of a body
of standing water, and (3) Isidis is floored by basalt that embays the
highlands.

If the Isidis site is lava flows (hypothesis #3), then there could be a
lot of dangerous rocks at this site.

Evidence for #1 included rounded rocks, but someone noted that alluvial
fans on Earth often contain angular rocks, and also secondary processes
like frost shattering could produce some very angular rocks.\
It was recommended that for each of the sites, we should start with the
higher order hypotheses, and work down to more details. The more you can
add to this 1 page sheet for Isidis, the better (on separate pages).\
One particular con that should be noted: If it's basalt, then it doesn't
have aqueous processes.

Pros: This site directly addresses the principle goals of the Mars
Program, there are lots of rocks for the rover to study, it may allow us
to obtain compositional information about highlands rocks, and it should
provide a good view.

Alluvial processes have less to do with habitability than lacustrine or
sites with longer-term water activity.

We need to add testable hypothesis for the more recent alluvial
environment as well as the ancient environment that formed the highlands
rocks.

The "Cons" for each site should include the scientific risk of being
able to address the top 3 science objectives of the mission (aqueous
processes, habitability, and the likelihood of preservation of evidence
for aqueous processes and habitability).

A "pro": Even if it's basalt lava, impacts may give you access to things
underneath that does involve water.

Make sure Larry Crumpler and Phil Christensen are involved in the
updates to this list of hypotheses.

The atmospheric hypotheses are less important.

It would be much more useful to look directly at the sun with solar
filters.

David Kass did produce a set of atmospheric hypotheses for all 4 sites.

These should be cycled through the atmospheric science Athena team
members for their comments and additions.

Gentry Lee: The process for evaluating the sites with respect to
atmospheric science has not been well addressed.

Let's not introduce that now. Let's only include it as a "Pro," if
something significantly extra as a science bonus comes out of it for a
particular landing site.

Could you aim Mini-TES at a nearby mountain and compare it to the
rover's surface? No, it would be worse than orbital remote sensing.

A "smoking gun" observation that would nail this: If there's an
abundance of rounded rocks, they've been shed from highlands. An absence
of rounded rocks would dispute this.

If they're Noachian rocks with "goldfish" in them, how would you know
they're Noachian?

**[Mike Carr: Elysium:]{.underline}**

Mike thought the pros and cons referred to the hypotheses, not the site.
He presented a 1-sheet write-up on each of 5 hypotheses for the origin
of the materials in the Elysium site:

1)  Volcanic

2)  Marine sediments

3)  Layered alluvium

4)  Aeolian (Mike Carr thinks this is very unlikely)

5)  Alluvium modified by mud volcanoes and springs \[but identification
    of mud volcanoes is ambiguous, seepage at ridges is ambiguous\]

The biggest problem is that the geologic model of the site is so
uncertain, that it's difficult to strongly advocate this site with
respect to the broad goals of MER. The models are too uncertain. It's
hard to get enthusiastically behind this site. It's probably a mixture
of stuff.

The nearest highland source is where? The nearby knobs could be the
source.

At EVERY SITE we should consider hypotheses for all these processes:
aeolian, volcanic, mass wasting, aqueous, and impact. Then we should
look at which predominate.

Someone mentioned that it's not so much processes that deposited
materials here, but the processes that stripped it, that may be of
interest. Determining the stripping process can only be addressed with
the rover cameras

**[Frank Seelos/Ray Arvidson: Meridiani:]{.underline}**

Frank showed a spreadsheet listing testable hypotheses, key
observations, and measurement requirements.

Hypotheses for the hematite deposit:

Formed in a subaqueous environment, hydrothermal system, surface
coating, or nonaqueous oxidation

Should these be added to the list: Impact metamorphism, and contact
metamorphism? If it was metamorphism, did it involve water so it was
really more of a hydrothermal (metasomatic) process? Clastic or
precipitate sedimentation?

Hypotheses for the light-toned material:

Is it a volcaniclastic formation, is it stratigraphically below the
hematite-bearing layer, are the light-toned aeolian bedforms derived
from the light-toned material. The light-toned aeolian bedforms...are
they granule ripples?

Add to the list of hypotheses to test: Is the light-toned material
sedimentary? Is it the light-toned material that contains the
coarse-grained hematite?

Do you want 1^st^ order and 2^nd^ order hypotheses?

John Grant: We want as complete a story as possible, but a distinction
between what's 1^st^ and 2^nd^ order.

The rings of bright material at Meridiani: are those tops of crater
rims? If so, they're Noachian, which would give us a chance to sample
possible wet early Mars, and this is a strong "pro" for this site
(unless they're only subdued by burial, and still buried).

Dave Des Marais: The other speakers organized their lists according
relate to processes. This list is based on two features (the hematite
and light-toned material).

This is a mineralogical vs. morphological site, so it's not surprising
that they organized them differently. The Gusev charts also apply to
this site too, the same process hypotheses should be considered.

Dave Des Marais: Aqueous processes are in the science goals. Here,
you're talking about features, so processes become 2^nd^ order. These
hypotheses should be re-organized in terms of processes.

How do we factor in the role of volcanic processes, etc.? Is that
considered primary or secondary?

Ross Irwin: The same sorts of characteristics for the surface of Gusev
apply here too. How did that material get there, and what is it? We
should focus on the origin of the layer, that'll be more like the way
the other sites were described.

Pros: Unique mineral signature, likelihood of sampling multiple units,
first investigation of a low albedo surface, provides ground truth for
orbital spectroscopy.

Cons: Low rock abundance (although that enhances trafficability); and
possibly of landing on top of a horizontal layer-cake stratigraphy so
you might not see much except the very top, although gardening will
help; possibility that this site has nothing to do with aqueous
processes.

**[General Discussion:]{.underline}**

A question was raised about the effect of dust coatings on our ability
to do spectroscopy with the rovers. We can't do ground truth if there's
nothing we can truth. The scale of data from THEMIS is 100 m. The only
site that's relatively dust-free is Meridiani. The other 3 candidate
landing sites have a higher dust cover than Viking Landers 1 and 2.

If dust cover obscures what we see, it will hinder our ability to figure
out the best places to send the rover. (1) Will we be able to do
spectroscopy for in-situ investigation? Steve Squyres thinks this will
not be a problem. Looking obliquely, you'll see the sides of rocks, and
Mini-TES is pretty good at penetrating through 10 microns of dust. Matt
Golombek noted that a lot of rock sides were heavily dust covered at
Pathfinder, and it may be that the real "gems" in the field may not be
apparent because they're dust covered. The Pathfinder site was the least
dusty of the 3 we've been to so far. The sites under consideration here
(Elysium, Isidis, and Gusev) are even dustier -- they're more like
Viking. (2) Will we be able to do good ground truth? The 3 dustier sites
will be a problem. It will harder to do.

Wendy Calvin: We should estimate the thickness of aeolian coatings at
the Viking Lander 1, 2, and Pathfinder landing sites. When you'll start
obscuring rocks at x thickness, observed from a distance y, how do the
landing sites compare? Trevor Graf at ASU is wrapping up his Master's
thesis on this.

Is it harder to correlate orbital with ground truth at some of the
sites? Is there an operational advantage of low-dustiness at some of the
landing sites?

From orbit, the spatial resolution is 3 to 5 orders of magnitude larger
than what we'll have on the ground. We may see more dust-free surfaces
with the rover.

The tables that were presented today are not finished works. Please
contribute to making them more complete over the coming week, by sending
comments to the leads (Ron Greeley for Gusev, George McGill for Isidis,
Mike Carr for Elysium, and Frank Seelos/Ray Arvidson for Meridiani).

Let's use a common format and try to fit in the template we've provided
(testable hypotheses, key observations, and measurement requirements).
An Excel spreadsheet would be fine.

List the 1^st^ order, then the 2^nd^ order hypotheses.

Describe the pros and cons for the site as a whole (pros and cons with
respect to the science mission objectives, not with respect to each
hypothesis).

The Analysis Tree that Ron showed was good. Could that be elaborated on?

For all the sites, there should be a set of hypotheses that address the
origin of the unit you're sitting on.

12:30 p.m. End of Workshop -- Adjourn

**[Tables of Testable Hypotheses Generated for each of the Landing
Sites:]{.underline}**

**The Meridiani Site (Compiled by Ray Arvidson and Frank Seelos):**

+-------+-------------+---------------+-------------+----------------+
| **To  | *           | **Key         | **Key       | **             |
| pic** | *Hypotheses | O             | Measurement | Implications** |
|       | to be       | bservations** | Req         |                |
|       | Evaluated** |               | uirements** |                |
+-------+-------------+---------------+-------------+----------------+
| Hem   | \*Is        | \*Unequivocal | \*Pancam    | \*Validation   |
| atite | hematite    | evidence for  | mul         | of inferences  |
| Occur | present?    | the presence  | ti-spectral | from TES       |
| rence |             | of hematite   | and         |                |
|       |             | inferred from | Mini-TES    | \*Key ground   |
|       |             | Athena        | mosaics,    | truth for      |
|       |             | observations  | combined    | orbital        |
|       |             |               | with        | observations   |
|       |             |               | detailed    | in general     |
|       |             |               | o           | since the site |
|       |             |               | bservations | is thought to  |
|       |             |               | of key      | be unusual in  |
|       |             |               | deposits to | mineralogical  |
|       |             |               | derive and  | properties     |
|       |             |               | analyze     |                |
|       |             |               | reflectance | \*Starting     |
|       |             |               | and         | point for      |
|       |             |               | emission    | further data   |
|       |             |               | spectra     | acquisition    |
|       |             |               |             | and hypothesis |
|       |             |               | \*Mössbauer | testing        |
|       |             |               | Spectra     |                |
+-------+-------------+---------------+-------------+----------------+
| Hem   | \*Did       | \*Hematite    | \*Ensemble  | \*The extent   |
| atite | hematite    | occurrence    | of Athena   | to which the   |
| Form  | form via    | detailed and  | O           | deposits       |
| ation | aqueous     | determined to | bservations | formed or      |
| Mecha | processes   | be due to     |             | where modified |
| nisms | and under   | platy         |             | by aqueous     |
|       | what        | outcrops,     |             | processes      |
|       | en          | discrete      |             |                |
|       | vironmental | specular      |             | \              |
|       | conditions? | grains, or as |             | *Environmental |
|       |             | hematite      |             | conditions     |
|       |             | particles     |             | associated     |
|       |             | embedded in   |             | with aqueous   |
|       |             | volcanic      |             | processes      |
|       |             | glass or as   |             | (lacustrine,   |
|       |             | coatings on   |             | hydrothermal)  |
|       |             | lithic        |             | or perhaps     |
|       |             | fragments of  |             | anhydrous      |
|       |             | basaltic or   |             | oxidation and  |
|       |             | other         |             | associated     |
|       |             | composition   |             | environmental  |
|       |             |               |             | conditions     |
|       |             | \*Minerals    |             |                |
|       |             | formed with   |             | \*Implications |
|       |             | hematite      |             | for            |
|       |             | defined and   |             | preservation   |
|       |             | inferences    |             | of             |
|       |             | derived as to |             | biosignatures  |
|       |             | whether the   |             | through the    |
|       |             | ensemble      |             | development of |
|       |             | formed via    |             | coatings and   |
|       |             | low           |             | other minerals |
|       |             | (lacustrine)  |             | that formed    |
|       |             | or high       |             | when hematite  |
|       |             | temperature   |             | formed (e.g.,  |
|       |             | (             |             | silica         |
|       |             | hydrothermal) |             | deposits)      |
|       |             | aqueous       |             |                |
|       |             | processes or  |             | \*Implications |
|       |             | via anhydrous |             | for            |
|       |             | oxidation     |             | geochemical    |
|       |             | (magmatic or  |             | cycles of      |
|       |             | ambient)      |             | biological     |
|       |             |               |             | relevance      |
|       |             | \*Local       |             |                |
|       |             | geologic      |             |                |
|       |             | setting       |             |                |
|       |             | defined,      |             |                |
|       |             | including     |             |                |
|       |             | grain size    |             |                |
|       |             | distributions |             |                |
|       |             | and other     |             |                |
|       |             | textural      |             |                |
|       |             | parameters,   |             |                |
|       |             | presence of   |             |                |
|       |             | layering and  |             |                |
|       |             | primary       |             |                |
|       |             | sedimentary   |             |                |
|       |             | features,     |             |                |
|       |             | including how |             |                |
|       |             | hem           |             |                |
|       |             | atite-bearing |             |                |
|       |             | deposits fit  |             |                |
|       |             | in            |             |                |
+-------+-------------+---------------+-------------+----------------+
| Geo   | \*Are       | \*Exploration | \*Mobility  | \*Fundamental  |
| logic | hemat       | and           | to get to   | to             |
| Se    | ite-bearing | cha           | various     | understanding  |
| tting | materials   | racterization | locations   | if the landing |
| Assoc | the top     | of the dark   | and the     | site is        |
| iated | stratum of  | materials     | ensemble of | located on the |
| with  | an          | evident at    | Athena      | upper strata   |
| H     | extensive   | the site as   | o           | of a vast      |
| emati | layered     | plains and    | bservations | lacustrine (or |
| te-Be | deposit     | dark dunes    | to          | marine)        |
| aring | draped over |               | c           | deposit or if  |
| Mate  | the ancient | \*Exploration | haracterize | the site on    |
| rials | cratered    | and           | the sites   | the top of a   |
|       | terrain?    | cha           | and         | thick          |
|       |             | racterization | materials   | (hundreds of   |
|       | \*Did the   | of the bright |             | meters)        |
|       | layered     | substrate     | \*OMEGA     | volcaniclastic |
|       | deposits    | evident at    | hy          | pile, with or  |
|       | form via    | the site as   | perspectral | without        |
|       | lacustrine, | subdued       | o           | evidence for   |
|       | volc        | crater rims,  | bservations | aqueous        |
|       | aniclastic, | bright        | (0.36 to    | alteration     |
|       | or other    | plains, and   | 5.2         | processes      |
|       | means?      | bright dunes  | m           |                |
|       |             |               | icrometers) | \*Implications |
|       |             | \*Search for  | to provide  | for defining   |
|       |             | and           | mi          | planetary      |
|       |             | characterize  | neralogical | habitability   |
|       |             | crater ejecta | inferences  | and the extent |
|       |             | from          | at few      | to which       |
|       |             | underlying    | hundred     | subsurface or  |
|       |             | cratered      | meter scale | surface        |
|       |             | terrain crust | (           | habitats may   |
|       |             |               | Acquisition | have existed   |
|       |             | \*Use all     | will MER is |                |
|       |             | data to       | o           |                |
|       |             | develop       | perational) |                |
|       |             | stratigraphic |             |                |
|       |             | column and    |             |                |
|       |             | test the      |             |                |
|       |             | model with    |             |                |
|       |             | continued     |             |                |
|       |             | observations  |             |                |
+-------+-------------+---------------+-------------+----------------+

REA 1/17/03

Pros: We have specific, well-defined hypotheses to test that relate to
the geologic history and set of processes that have operated, with a
focus on the extent to which aqueous processes have been involved.
Athena Payload and MER mobility system very well matched to testing the
hypotheses. Spectral signatures relative to rest of the planet and the
low-albedo, dust free nature of the site make it a good site for ground
truth calibration of orbital data.

Cons: may not be evidence for aqueous processes and the site does not
have a lot of topography for exciting vistas.

The Gusev Crater Site (Compiled by Ron Greeley):

+-------+-------------+---------------+-------------+----------------+
| **To  | *           | **Key         | **Key       | **             |
| pic** | *Hypotheses | O             | Measurement | Implications** |
|       | to be       | bservations** | Req         |                |
|       | Evaluated** |               | uirements** |                |
+-------+-------------+---------------+-------------+----------------+
| Dete  | W           | Very fine     | Imaging, ,  | May constrain  |
| rmine | ind-related | grains,       | RAT,        | evolution of   |
| the   | deposits    | massive       | s           | hydrologic     |
| o     | (global     | homogenous    | pectroscopy | cycle,         |
| rigin | dust mantle | beds vs. well | (grain      | implications   |
| of    | vs. local   | sorted,       | sizes below | for water      |
| the   | saltation   | rounded       | resolution; | inventory      |
| pr    | vs.         | grains \< 4   | c           |                |
| imary | volcanic,   | mm, cross     | ompositions | Any outcome    |
| mate  | air-fall)   | bedding       | not unique) | can help       |
| rials |             | locally       | Imaging     | evalauate      |
| fi    | Lacustrine  | derived       | s           | changing role  |
| lling | (distal vs. | compositions  | pectroscopy | of processes   |
| Gusev | proximal    | vs. angular,  | (ambiguous; | through time   |
|       | materials)  | massive, fine | could be    |                |
| C     |             | grained,      | well-sorted | Access to      |
| rater | Fluvial     | glass shards, | sands of    | materials with |
| (req  |             | silicate      | fluvial     | good to fair   |
| uires | Volcanic,   | compositions  | origin, but | preservation   |
| r     | effusive    | (e.g., from   | frosted     | potential if   |
| ocks, | (i.e., lava | Ap. Patera)   | likely      | lacustrine or  |
| bed   | flows)      |               | aeolian     | fluvial        |
| rock) |             | Thin, fine    |             |                |
| and   | Impact      | grained beds  | Imaging,    |                |
| eva   | (i.e.,      | (rythmites),  | RAT,        |                |
| luate | ejecta      | mud-cracks,   | s           |                |
| role  | deposits)   | ripples;      | pectroscopy |                |
| of    |             | authigenic    |             |                |
| water | Mass        | aqueous       | Imaging,    |                |
| in    | wasting     | minerals      | RAT,        |                |
| sh    | (e.g.,      | (e.g.,        | s           |                |
| aping | debris      | carbonates,   | pectroscopy |                |
| c     | flows,      | evaporite     |             |                |
| rater | so          | salts)        | Imaging,    |                |
| fi    | lifluction) |               | RAT,        |                |
| lling |             | Clastic       | s           |                |
| dep   |             | materials,    | pectroscopy |                |
| osits |             | rounded       | (flow       |                |
|       |             | variably      | features    |                |
|       |             | sized; graded | unlikely to |                |
|       |             | or cross      | be          |                |
|       |             | bedding,      | preserve    |                |
|       |             | imbrication,  | d/observed, |                |
|       |             | variety of    | and         |                |
|       |             | compositions  | v           |                |
|       |             | (carbonates?) | esicle-like |                |
|       |             |               | features    |                |
|       |             | Fine-grained  | can be      |                |
|       |             | crystalline   | no          |                |
|       |             | rocks         | n-volcanic) |                |
|       |             | (phenocrysts, |             |                |
|       |             | vesicles,     | Imaging,    |                |
|       |             | corded        | RAT,        |                |
|       |             | textures      | s           |                |
|       |             |               | pectroscopy |                |
|       |             | or vesicle    |             |                |
|       |             | \"trains\")   | Imaging,    |                |
|       |             |               | s           |                |
|       |             | Clastics,     | pectroscopy |                |
|       |             | brecciatted,  |             |                |
|       |             | poorly sorted |             |                |
|       |             | variable      |             |                |
|       |             | sized,        |             |                |
|       |             | Noachian      |             |                |
|       |             | impact melt   |             |                |
|       |             | matrix        |             |                |
|       |             | compositions, |             |                |
|       |             | schlieren,    |             |                |
|       |             | shatter       |             |                |
|       |             | cones;        |             |                |
|       |             | hydrothermal  |             |                |
|       |             | alteration)   |             |                |
|       |             |               |             |                |
|       |             | Clastics,     |             |                |
|       |             | poorly        |             |                |
|       |             | sorted, sizes |             |                |
|       |             | and shapes    |             |                |
|       |             | dependent     |             |                |
|       |             | upon source   |             |                |
|       |             | material;     |             |                |
|       |             | little if any |             |                |
|       |             | internal      |             |                |
|       |             | bedding       |             |                |
|       |             | structure;    |             |                |
|       |             | compositions  |             |                |
|       |             | correlative   |             |                |
|       |             | with likely   |             |                |
|       |             | source area   |             |                |
+-------+-------------+---------------+-------------+----------------+
| Dete  | Exposed     | Bedrock       | Imaging,    | Verification   |
| rmine | bedrock     | surface is    | s           | of first two   |
| the   | (i.e.,      | observed and  | pectroscopy | hypotheses     |
| o     | removal of  | it is darker  |             | indicative of  |
| rigin | bright dust | than the      | Wheel       | high-energy    |
| dark  | from the    | surrounding   | trenching;  | wind regime,   |
| st    | surface;)   | area          | imaging of  | whereas third  |
| reaks |             |               | surface and | indicates low  |
| (can  | Lag deposit | Clastic       | sub-surface | energy regime) |
| have  | (e.g.,      | materials     | materials   |                |
| more  | stone       | darker or     |             | May identify   |
| than  | pavement)   | larger than   | Imaging,    | access to      |
| one   |             | dust          | s           | bedrock or in  |
| or    | Deposit of  |               | pectroscopy | situ indurated |
| igin) | dark        | And may form  |             | sediments      |
|       | material    | pavement)     |             |                |
|       |             |               |             |                |
|       |             | Deposit of    |             |                |
|       |             | dark          |             |                |
|       |             | particles \<  |             |                |
|       |             | 4 mm;         |             |                |
|       |             | composition   |             |                |
|       |             | correlates    |             |                |
|       |             | with source   |             |                |
+-------+-------------+---------------+-------------+----------------+
| Dete  | Active      | Grains \> 60  | Imaging     | Determine      |
| rmine | wind-       | microns and   |             | whether drift  |
| the   | transported | coarsening-up | Imaging     | represents     |
| o     | material    | indicate as   |             | wi             |
| rigin | (e.g.,      | ripples;      |             | nd-transported |
| of    | dunes or    | grains        |             | materials      |
| drift | ripples)    | fining-up     |             | versus remnant |
| dep   |             | indicate dune |             | of mantle      |
| osits | Remnant of  | transport     |             | (eolian,       |
|       | former      |               |             | volcanic,      |
|       | mantle      | Internal      |             | fluvial,       |
|       | (sand,      | structure     |             | colluvial,     |
|       | dust,       | (e.g.,        |             | other)         |
|       | fluvial, or | cross-beds of |             |                |
|       | ma          | former dunes  |             |                |
|       | ss-wasting) | vs. larger    |             |                |
|       |             | fluvial or    |             |                |
|       |             | mass-wasting  |             |                |
|       |             | clastics)     |             |                |
+-------+-------------+---------------+-------------+----------------+
| Dete  | Weathering  | Clay minerals | S           | Determine      |
| rmine | in a wet    | (pedogenic or | pectroscopy | weathering     |
| pos   | environment | as sulfates   |             | environment of |
| sible |             | and salts if  | Imaging,    | Mars           |
| secon | Alteration  | h             | s           | near-surface   |
| dary/ | in a        | ydrothermal). | pectroscopy | over time      |
| alter | relative    |               |             |                |
| ation | water-free  | Crystalline   | Imaging,    | Constrain role |
| proc  | environment | minerals or   | s           | of water in    |
| esses |             | mineroids     | pectroscopy | weathering     |
|       | H           | associated    |             |                |
|       | ydrothermal | with primary  |             | Constrain      |
|       | alteration  | minerals      |             | modern         |
|       |             |               |             | hydrologic     |
|       |             | Porous        |             | cycle          |
|       |             | carbonate     |             |                |
|       |             | deposits,     |             |                |
|       |             | siliceous     |             |                |
|       |             | sinter        |             |                |
+-------+-------------+---------------+-------------+----------------+

Pros:

1\. Relatively clear geological models can be posed and tested,
including that involving long-duration aqueous environments.

2\. Depending on the outcome of \"hypothesis testing,\" the results are
directly relevant to the primary MER project goals

3\. Results (e.g., a channel intersecting a flat-floored, large crater)
can be applied to other areas of Mars and carry significant implications
for the general geological evolution of the planet

4\. Secondary objectives (origin of dark streaks, drifts) can also give
insight to these features seen elsewhere on Mars

Cons:

1\. Many of the hypotheses do not have definitive tests using the Athena
payload

2\. Most of the \"primary geology\" (modes of origin for the floor
materials) are dependent on having access to the relevant materials;
processes, such as solifluction, might have emplaced thick(m??)
materials not related to the primary floor-filling; we will be dependent
on small impact craters to have excavated the relevant materials and in
our being able to differentiate among the potential sources of the
ejecta materials.

3\. Gusev is a geologically complex area with an interesting history
that can be difficult to deconvolve; this would make for lively
discussions!

**The Isidis Basin Site (Compiled by George McGill):**

<table>
<colgroup>
<col style="width: 5%" />
<col style="width: 9%" />
<col style="width: 11%" />
<col style="width: 1%" />
<col style="width: 3%" />
<col style="width: 3%" />
<col style="width: 1%" />
<col style="width: 11%" />
<col style="width: 1%" />
<col style="width: 9%" />
<col style="width: 17%" />
<col style="width: 21%" />
</colgroup>
<tbody>
<tr class="odd">
<td><strong>Topic</strong></td>
<td><strong>Evaluated Hypotheses</strong></td>
<td><strong>Key Observations</strong></td>
<td colspan="3"><strong>Instruments</strong></td>
<td colspan="2"><strong>Implications</strong></td>
<td colspan="4"></td>
</tr>
<tr class="even">
<td></td>
<td rowspan="7"><p>1) Ellipse in Isidis Basin lies</p>
<p>within an ancient alluvial</p>
<p>fan depositional</p>
<p>environment</p></td>
<td rowspan="7">Detailed evaluations of rock shapes and surface
morphology, e.g., rock shapes (roundness), juxtaposition of landforms
(bar and swale), presence of weathering/alteration products (hydration
minerals), fragment composition/petrology, textures (crystalline or
clastic, veins)</td>
<td colspan="3" rowspan="7"><p>PANCAM</p>
<p>PANCAM, THEMIS, MOC</p>
<p>MS, Mini-TES &amp; RAT</p>
<p>APXS, mTES &amp; RAT</p>
<p>MI &amp; RAT (MI before</p>
<p>and after RAT)</p></td>
<td colspan="2" rowspan="7"><p>Noachian Rocks from Isidis rim present
within landing ellipses.</p>
<p>Transport from Isidis rim into</p>
<p>basin involved streams and</p>
<p>alluvial fans</p>
<p>Mars had an active hydrologic system involving overland flow and
active drainage networks.</p>
<p>Place limits on climate evolution.</p></td>
<td colspan="4"></td>
</tr>
<tr class="odd">
<td rowspan="17"><p>Early Mars was</p>
<p>wetter than today</p></td>
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td rowspan="6"><p>2) Isidis Basin was once the</p>
<p>site of a standing body of</p>
<p>water ("lake")</p></td>
<td rowspan="6"><p>Landforms (Benches or berms, cuspate forms</p>
<p>Rock shape and structure (sorted, rounded, sediments)</p>
<p>Rock type/Petrology (mature versus immature, major versus minor
component composition, crystalline versus clastic)</p>
<p>Statigraphy (any low angle truncations, accretion or forset beds,
orientation relative to basin margin, continuity)</p></td>
<td colspan="3" rowspan="6"><p>PANCAM, THEMIS, MOC</p>
<p>PANCAM</p>
<p>MI &amp; RAT (MI before</p>
<p>and after RAT)</p>
<p>Mini-TES, MI, APXS</p></td>
<td colspan="2" rowspan="6"><p>Shoreline features are present and
indicate that either nearshore or pelagic deposits</p>
<p>comprise near-surface materials and embay the highlands</p>
<p>If near-shore, high energy environment, lower preservation
potential</p>
<p>If pelagic, low energy environment, higher preservation potential</p>
<p>Mars had an active hydrologic system involving overland flow and
active drainage networks.</p>
<p>Place limits on water budget, cycling and climate</p></td>
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td rowspan="5"><p>3) Isidis Basin is floored by</p>
<p>basalt that embays the</p>
<p>highlands</p></td>
<td rowspan="5"><p>Rock textures (grainsizes, glasses, phenocrysts)</p>
<p>Rock structures (vesicles, jointing, banding)</p>
<p>Morphology (typical of flows, aa, pahoehoe, tumuli)</p>
<p>Stratigraphy</p>
<p>Composition (major and minor minerals and elements</p></td>
<td colspan="3" rowspan="5"><p>PANCAM, MI, RAT (MI</p>
<p>before and after RAT)</p>
<p>PANCAM, MI</p>
<p>PANCAM, THEMIS, MOC</p>
<p>RAT, MS, APXS, Mini-TES</p></td>
<td colspan="2" rowspan="5"><p>Materials erupted in Isidis Basin and
flowed to edge of basin</p>
<p>Constrain timing and inventory of volcanics</p>
<p>Does not resolve role played by water in evolution of site or early
Mars conditions</p></td>
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="4"></td>
</tr>
<tr class="even">
<td colspan="4"></td>
</tr>
<tr class="odd">
<td colspan="4"></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td colspan="2"></td>
<td colspan="3"></td>
<td colspan="4"></td>
<td></td>
</tr>
<tr class="odd">
<td></td>
<td>Scientific Pros:</td>
<td colspan="3">Water and habitability involved with hypotheses 1 and
2</td>
<td colspan="2"></td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td colspan="7">Water, habitability, and preservation in Noachian tested
by hypothesis 1</td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td></td>
<td></td>
<td colspan="8">Abundant rocks, which may be rounded and thus less
dangerous to landing for hypotheses 1</td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td></td>
<td></td>
<td colspan="5">Obtain compositions of highland rocks for hypothesis
1</td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td></td>
<td></td>
<td colspan="3">Good view!</td>
<td colspan="2"></td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="even">
<td></td>
<td>Scientific Cons:</td>
<td colspan="3">For hypothesis 3 the site does not address mission
goals</td>
<td colspan="2"></td>
<td colspan="2"></td>
<td></td>
<td colspan="2"></td>
</tr>
<tr class="odd">
<td></td>
<td></td>
<td colspan="7">Habitability and preservation difficult in an alluvial
fan environment (but water alteration in veins good for habit/pres)</td>
<td></td>
<td colspan="2"></td>
</tr>
</tbody>
</table>

The three hypotheses predict different assemblages of observables.
Differences between these are discussed below.

> 1\. Overview: For hypotheses 2 and 3, THEMIS images and possibly
> PANCAM images should suggest embayment of the Isidis rim massifs by
> the adjacent plains material. The only adequate data available as of
> mid-January, 2003 bearing on this issue are day and night THEMIS
> thermal images at 100m/pxl. One THEMIS VIS image at 18m/pxl includes a
> small area of Isidis massifs, but the embayment relationships on this
> image are ambiguous. Embayment relationships also are possible for
> hypothesis 1 if deposits due to a process younger than the formation
> of alluvial fans are present. Large rocks present within the landing
> ellipses most likely would be blocks excavated by small, young impact
> craters for hypotheses 2 and 3. For hypothesis 1, some large rocks
> would be emplaced by fluvial +/- mass wasting transport from the
> Isidis rim, and could be more rounded as a result. PANCAM could image
> fan morphologic characteristics such as shallow leveed channels and
> imbricated boulders if these have been preserved.
>
> 2\. Rock Structures: Hypothesis 1 predicts that many (perhaps most)
> larger rocks within the landing ellipses were derived from the Isidis
> rim, and thus should be very ancient. With the exception of one
> meteorite sample, we do not know what the structures of Noachian
> highland rocks are. Considering the probable source, impact breccias
> and fractured rocks are likely. Hypothesis 2 predicts that the Isidis
> site is underlain by deposits of a \"lake\". Because the site is close
> to the shoreline, the lake deposits likely would include layers with
> differing grain size and sorting, with graded bedding also possible.
> Hypothesis 3 predicts basalt, and primary basaltic rocks could contain
> vesicles and flow banding. These various structures should be visible
> in PANCAM or MI images, depending on scale.
>
> 3\. Rock textures: Basalt (hypothesis 3) has a crystalline texture
> with interlocking grains of feldspar and mafic minerals. Phenocrysts
> also might be present. Lake deposits (hypothesis 2) most likely would
> be clasitic sedimentary rocks without interlocking grain boundaries
> (an exception might be chemically precipitated evaporite minerals, but
> these should be identified by MINI-TES if they are present). Impact
> breccias (hypothesis 1) would be chaotic mixtures of angular fragments
> of different rocks at both PANCAM and MI scales.
>
> It is clear in the MOC and THEMIS VIS images that some dune and sand
> sheet material is present at the site. If this is sampled, it should
> be possible to identify it from its expected very well sorted,
> sand-sized texture.
>
> 4\. Mineralogy and petrology: Bulk mineralogy from MINI-TES, iron
> mineralogy from MS, and elemental make-up from APXS should permit
> inference of basaltic composition. If textures are interlocking
> (primary igneous), a basaltic lava would be indicated (hypothesis 3);
> if textures are clastic, a sedimentary origin with basaltic provenance
> would be indicated. Alteration minerals (including hydrous ones if
> detectable) would be possible with all three hypotheses, but would
> seem more likely for hypothesis 1, by analogy with meteorite ALH84001.
> MIN-TES could identify evaporite minerals formed as a result of
> hypothesis 2, or occurring in veins likely to be present in Isidis rim
> rocks (hypothesis 1).

**The Elysium "Wind Safe" Site (Compiled by Mike Carr):**

+----------+--------------+-------------+--------------+-----------+---+
| *        | # Testabl    | **Key       | *            | **Impli   |   |
| *Topic** | e hypothesis | ob          | *Measurement | cations** |   |
|          |              | servation** | r            |           |   |
|          |              |             | equirement** |           |   |
+----------+--------------+-------------+--------------+-----------+---+
| Can      | 1\. Bench is | a\) surface | \(a\)        | Not able  |   |
| geologic | a sequence   | m           | PANCAM, (b)  | to sample |   |
| setting  | of           | orphology - | PANCAM, MI,  | Noahcian  |   |
| be       | interbedded  | flows,      | RAT, c)      | highlands |   |
| dec      | volcanic     | outcrop     | MINITESS,    | materials |   |
| onvolved | flows and    | textures,   | MOS          | or        |   |
| so as to | pyroclastics | etc, (b)    |              | address   |   |
| identify | overlying a  | rock        |              | most      |   |
| where    | Noachian     | textures    |              | mission   |   |
| h        | basement     | (massive,   |              | science   |   |
| ighlands |              | vesicular,  |              | o         |   |
| material |              | friable,    |              | bjectives |   |
| might be |              | etc), (c)   |              |           |   |
| sampled  |              | rock        |              |           |   |
| (either  |              | mineralogy  |              |           |   |
| in situ  |              |             |              |           |   |
| or       |              |             |              |           |   |
| su       |              |             |              |           |   |
| bsequent |              |             |              |           |   |
| to       |              |             |              |           |   |
| tra      |              |             |              |           |   |
| nsport)? |              |             |              |           |   |
+----------+--------------+-------------+--------------+-----------+---+
|          | 2\. Bench is | a\)         | a\) PANCAM,  | Mars had  |   |
|          | a marine     | presence of | b) PANCAM,   | a robust  |   |
|          | terrace,     | terraces,   | C) PANCAM,   | h         |   |
|          | comprised of | layered     | MI, RAT, d)  | ydrologic |   |
|          | layered      | sediments,  | APXS, MOS    | system    |   |
|          | marine       | b)          |              | involving |   |
|          | sediments    | sedimentary |              | overland  |   |
|          | derived from | fabrics-    |              | flow and  |   |
|          | highland     | sorting,    |              | oceans.   |   |
|          | front and    | cement,     |              |           |   |
|          | overlying    | ripples,    |              | Place     |   |
|          | Noachian     | rounding,   |              | limits on |   |
|          | basement     | etc. c)     |              | water     |   |
|          |              | rock        |              | budget,   |   |
|          |              | m           |              | cycling   |   |
|          |              | ineralogy - |              | and       |   |
|          |              | evaporites, |              | climate   |   |
|          |              | cement, d)  |              |           |   |
|          |              | rock        |              | Possible  |   |
|          |              | m           |              | access to |   |
|          |              | ineralogy - |              | materials |   |
|          |              | fra         |              | with good |   |
|          |              | ctionation, |              | pre       |   |
|          |              | sorting.    |              | servation |   |
|          |              |             |              | potential |   |
+----------+--------------+-------------+--------------+-----------+---+
|          | 3\. Bench    | a\) surface | a\) PANCAM,  | Might be  |   |
|          | consists of  | m           | b) PANCAM,   | able to   |   |
|          | layered      | orphology - | MI, RAT,     | sample    |   |
|          | alluv        | channels,   | MINITESS,    | reworked  |   |
|          | ium/coluvium | debris      | APXS, MOS    | and       |   |
|          | derived from | flows,      |              | tr        |   |
|          | highland     | layering,   |              | ansported |   |
|          | front and    | b)          |              | Noachian  |   |
|          | overlying    | sedimentary |              | highlands |   |
|          | Noachian     | fabrics and |              | material  |   |
|          | basement.    | rock        |              | (might be |   |
|          |              | mineralogy  |              | very      |   |
|          |              | as in 2     |              | difficult |   |
|          |              | above.      |              | to        |   |
|          |              |             |              | i         |   |
|          |              |             |              | dentify), |   |
|          |              |             |              | but       |   |
|          |              |             |              | little    |   |
|          |              |             |              | context.  |   |
|          |              |             |              | Difficult |   |
|          |              |             |              | to        |   |
|          |              |             |              | address   |   |
|          |              |             |              | many      |   |
|          |              |             |              | mission   |   |
|          |              |             |              | ob        |   |
|          |              |             |              | jectives. |   |
+----------+--------------+-------------+--------------+-----------+---+
|          | 4\. Bench    | Same as 3   | Same as      | Might be  |   |
|          | consists of  | above       | above        | able to   |   |
|          | layered      | except make |              | sample    |   |
|          | alluvi       | o           |              | reworked  |   |
|          | um/colluvium | bservations |              | and       |   |
|          | derived from | on pancake  |              | tr        |   |
|          | highlands,   | like        |              | ansported |   |
|          | overlying    | structures  |              | Noachian  |   |
|          | Noachian     | and         |              | highlands |   |
|          | basement,    | indistinct  |              | material  |   |
|          | and modified | flows       |              | (might be |   |
|          | by mud       | observed in |              | very      |   |
|          | volcanism    | orbiter     |              | difficult |   |
|          | and/or local | images.     |              | to        |   |
|          | groundwater  |             |              | i         |   |
|          | seepages.    |             |              | dentify), |   |
|          |              |             |              | but       |   |
|          |              |             |              | little    |   |
|          |              |             |              | context.  |   |
|          |              |             |              |           |   |
|          |              |             |              | Access to |   |
|          |              |             |              | widely    |   |
|          |              |             |              | scattered |   |
|          |              |             |              | forms     |   |
|          |              |             |              | that may  |   |
|          |              |             |              | be mud    |   |
|          |              |             |              | volcanoes |   |
|          |              |             |              | or        |   |
|          |              |             |              | springs   |   |
|          |              |             |              | might     |   |
|          |              |             |              | permit    |   |
|          |              |             |              | a         |   |
|          |              |             |              | ssessment |   |
|          |              |             |              | of        |   |
|          |              |             |              | aspects   |   |
|          |              |             |              | of more   |   |
|          |              |             |              | modern    |   |
|          |              |             |              | h         |   |
|          |              |             |              | ydrologic |   |
|          |              |             |              | cycle,    |   |
|          |              |             |              | possible  |   |
|          |              |             |              | life.     |   |
+----------+--------------+-------------+--------------+-----------+---+
|          | **Scientific |             |              |           |   |
|          | pros**: A)   |             |              |           |   |
|          | may provide  |             |              |           |   |
|          | opportunity  |             |              |           |   |
|          | to examine a |             |              |           |   |
|          | former       |             |              |           |   |
|          | marine       |             |              |           |   |
|          | environment, |             |              |           |   |
|          | B) Local     |             |              |           |   |
|          | knobs appear |             |              |           |   |
|          | to be        |             |              |           |   |
|          | highland     |             |              |           |   |
|          | basement and |             |              |           |   |
|          | bench most   |             |              |           |   |
|          | likely a     |             |              |           |   |
|          | degradation  |             |              |           |   |
|          | product of   |             |              |           |   |
|          | the          |             |              |           |   |
|          | highlands so |             |              |           |   |
|          | highland     |             |              |           |   |
|          | rocks may be |             |              |           |   |
|          | abundant. C) |             |              |           |   |
|          | Bench        |             |              |           |   |
|          | material may |             |              |           |   |
|          | have been    |             |              |           |   |
|          | emplaced by  |             |              |           |   |
|          | aqueous      |             |              |           |   |
|          | processes    |             |              |           |   |
|          | (fluvial,    |             |              |           |   |
|          | s            |             |              |           |   |
|          | olifluciton, |             |              |           |   |
|          | etc) so may  |             |              |           |   |
|          | provide an   |             |              |           |   |
|          | opportunity  |             |              |           |   |
|          | to study     |             |              |           |   |
|          | such         |             |              |           |   |
|          | processes.   |             |              |           |   |
+----------+--------------+-------------+--------------+-----------+---+
|          | **Scientific |             |              |           |   |
|          | cons**: No   |             |              |           |   |
|          | satisfactory |             |              |           |   |
|          | geologic     |             |              |           |   |
|          | model for    |             |              |           |   |
|          | the origin   |             |              |           |   |
|          | of the bench |             |              |           |   |
|          | on which the |             |              |           |   |
|          | landing site |             |              |           |   |
|          | is located.  |             |              |           |   |
|          | Great        |             |              |           |   |
|          | uncertainty  |             |              |           |   |
|          | about what   |             |              |           |   |
|          | will be      |             |              |           |   |
|          | found and    |             |              |           |   |
|          | whether the  |             |              |           |   |
|          | findings     |             |              |           |   |
|          | will relate  |             |              |           |   |
|          | to the main  |             |              |           |   |
|          | goals of the |             |              |           |   |
|          | Mars         |             |              |           |   |
|          | exploration  |             |              |           |   |
|          | program, the |             |              |           |   |
|          | role of      |             |              |           |   |
|          | water and    |             |              |           |   |
|          | the          |             |              |           |   |
|          | prospects    |             |              |           |   |
|          | for life.    |             |              |           |   |
+----------+--------------+-------------+--------------+-----------+---+