**Science Analysis of the November 3, 2005 Version of the Draft Mars
Exploration Program Plan**

January 6, 2006

Prepared by the MEPAG '2005 Mars Program Plan Science Analysis Group'

Ray Arvidson, Washington University in St. Louis, Chair

Carlton Allen, NASA Johnson Space Center

David DesMarais, NASA Ames Research Center

John Grotzinger, California Institute of Technology

Noel Hinners, Former NASA and aerospace industry executive

Bruce Jakosky, University of Colorado

John F. Mustard, Brown University

Roger Phillips, Washington University in St. Louis

Christopher Webster, Jet Propulsion Laboratory

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# Correspondence contacts: Dr. Ray Arvidson (senior author), arvidson@rsmail.wustl.edu, 314-935-5609, or Dr. David Beaty (MEPAG contact), <David.Beaty@jpl.nasa.gov>, 818-354-7968. 

# This report has been approved for public release by JPL Document Review Services (CL#06-0090), and may be freely circulated. Suggested bibliographic citation:

Arvidson, R.E.,  Allen, C.C., DesMarais, D.J., Grotzinger, J., Hinners,
N., Jakosky, B., Mustard, J.F., Phillips, R., and Webster, C.R.,
(2006).  Science Analysis of the November 3, 2005 Version of the Draft
Mars Exploration Program Plan.  Unpublished report dated Jan. 6, 2006,
13 p, posted January, 2006 by the Mars Exploration Program Analysis
Group (MEPAG) at <http://mepag.jpl.nasa.gov/reports/index.html>.

**1. Purpose and Scope:**

The purpose of this report is to provide comments on the draft Mars
Program Plan for the next decade. Specifically, comments are provided on
the version of the plan presented during the MEPAG Meeting on November
3, 2005. These comments are authored by the Draft Program Plan Science
Analysis Group (SAG). The SAG was chartered by MEPAG to consider the
extensive discussion and input about the draft plan from the MEPAG
attendees, together with analyses conducted by the SAG, and to provide a
report that delineates the strengths and weaknesses of the draft plan,
together with possible alternative approaches. Further, the SAG
considered the overarching scientific themes for the next decade of Mars
exploration and the technological infrastructure needed to implement the
plan and viable alternatives.

This report first considers the overarching goal and objectives that the
SAG believes are crucial for a sustained program that will engage the
public and address important scientific questions. A summary of the
draft program plan is then presented in light of the goal and
objectives, followed by detailed analyses of the plan. The SAG notes
that its main role was to define issues with and alternatives to the
plan, without recommending a specific implementation approach. The SAG
does make specific comments about its preferences as appropriate in this
report.

**2. SAG Membership**

Membership for the SAG is listed below and was chosen to ensure both
breadth of understanding of Mars and important science questions,
together with depth in particular aspects of Mars missions and
scientific disciplines:

Ray Arvidson, Washington University in St. Louis, Chair

Carlton Allen, NASA Johnson Space Center

David DesMarais, NASA Ames Research Center

John Grotzinger, California Institute of Technology

Noel Hinners, Former NASA and aerospace industry executive

Bruce Jakosky, University of Colordao

John Mustard, Brown University

Roger Phillips, Washington University in St. Louis

Christopher Webster, Jet Propulsion Laboratory

In addition, Dave Beatty, Jet Propulsion Laboratory, organized telecons
and participated in discussions.

**3. Program Scientific Goal and Objectives:**

After extensive discussion within the SAG, and consideration of comments
made during the November 2005 MEPAG Meeting, the following broad
scientific goal and associated objectives emerged as ones that are
judged to be scientifically of highest importance and that will provide
a high level of interest to the various stake-holders involved in Mars
exploration (scientific community, Congress and Executive Branches of
government, public):

-   Program Goal: *"Understand the evolution of Mars, the presence or
    absence of habitable zones, and if life formed or existed."* This
    approach will allow us to understand how tectonic (internal and via
    impact) and climatic processes led to past and current conditions on
    Mars and how these processes may have generated habitable zones and
    life. Following this goal will also maximize our understanding of
    how planets evolve over time and how the evolution of Mars compares
    to the evolution of the other terrestrial planets, including Earth.

-   Objectives for the Next Decade: *"Follow the Water and Search for
    Habitable Zones."* These objectives will focus a search for
    habitable zones as part of the overall goal of understanding Mars as
    a system and how that system led may have led to formation of
    habitable zones for supporting life.

The SAG believes that each mission that is part of the program plan
should be judged against how the investigations would help meet the goal
and objectives listed above.

**4. Overview of Draft Program Plan**

The draft plan presented during the MEPAG Meeting included the following
set of missions and associated investigations, with a timeline that
extended over \~15 years. The extended timeline is a consequence of
budgetary limitations.

-   2011/2013 Scout and core science orbiter with telecommunications
    capability

-   2016 Mid-rovers or Astrobiology Field Laboratory

-   2018 Scout

-   2020 Planetary Evolution and Meteorology Network

-   2022 Mars Sample Return Orbiter with Telecom

-   2024 Mobile Mars Sample Return

There are four core science investigations expressed in the plan, in
addition to the use of Scouts to enhance the core program. The four core
investigations are listed below, together with the SAG's view of the
most important measurements and/or approaches that should be associated
with each of the core investigations. The core investigations map
directly into the missions listed above.

-   2011/2013: Determine: (a) atmospheric escape rates for key species,
    and (b) the detailed composition, abundance, and distribution of
    atmospheric trace gases (e.g., for methane).

-   2016: Determine if there were or are habitable zones and life, and
    how their development was related to the overall evolution of the
    planet, through surface observations using rover-based systems that
    acquire and analyze samples.

-   2020: Determine the structure and dynamics of the interior using
    seismic and heat flow measurements since these measurements are
    fundamental to understanding Mars as a system.

-   2022/2024: Return samples using rover-based collection systems in
    locations for which Earth-based sample analyses would maximize
    understanding of the evolution of the planet, habitable zones, and
    whether or not life developed or existed on Mars.

**5. Analyses of the Draft Program Plan**

Based on comments on the draft plan made by community members during the
MEPAG Meeting, and its own analyses, the SAG determined that the draft
program plan overall approach, with its four core science
investigations, augmented by Scouts, is a scientifically robust plan
that will meet the program goal and objectives. Key issues are the
relative timing of the missions (i.e., how to decide on a particular
temporal implementation of the plan), the role of Scouts, and
consideration of the infrastructure (particularly technology readiness
for specific missions, together with telecommunication systems) needed
to implement the draft plan.

**5.1 Comments on the Draft Program Plan Through 2013**

The SAG felt that the combination of a Scout and a core orbiter mission
for the 2011/2013 opportunities represented a reasonable approach
consistent with expected budget profiles and technological readiness
issues. A core orbiter mission during the 2011/2013 opportunity would
add a great deal of information about the loss of atmospheric species to
space and/or determination of the nature, abundance, fluxes, and source
locations for trace species. These atmospheric measurements are
fundamental for understanding the evolution of the atmosphere, climate,
and the presence of habitable zones.

A concern associated with the 2011/2013 opportunity is the manner by
which potential conflicts between core orbiter and Scout missions will
be managed. Definition of both programs is ongoing at present and, in
fact, the order of the two missions for 2011 or 2013 has not yet been
decided. The core orbiter "strawman" investigations are in the process
of being defined by a core orbiter science SAG, which has been assembled
and is expected to complete its report within several months. The Scout
Announcement of Opportunity for the 2011/2013 mission will also be
released within the next several months, although numerous Scout teams
are already deeply involved in the proposal generation process. The best
strategy, both from programmatic and scientific perspectives, is for
planning for the two missions to proceed in parallel, with the selection
of the science thrust for the earlier mission clearly impacting the
science thrust that will be selected for the later one. This approach
provides maximum scientific and programmatic flexibility, without unduly
hindering likely proposers for either mission.

**5.2** **Comments on the 2016 Opportunity**

The SAG spent most of its deliberations focused on the 2016 mission
opportunity and debating whether the appropriate mission should be
continued *in-situ* exploration of the surface and/or subsurface, a
sample return mission, or implementation of a network of surface
stations to conduct seismic, heat flow, and atmospheric observations.
All three missions would meet the program goal and objectives. In the
paragraphs below we present arguments associated with keeping *in-situ*
observations in the 2016 time slot, as opposed to swapping in the: (a)
Mars sample return mission (2016/2018) and (b) network science mission.
The report also lists implications for technology development and other
infrastructure issues associated with various alternatives for the 2016
opportunity. We note that during the November 2005 MEPAG Meeting and
during the SAG telecons the issue of which mission to fly in 2016 caused
the most heated discussions.

1.  **Surface-Based *In-situ* Investigations**

The draft plan includes a rover-based mission with *in-situ*
investigations for the 2016 opportunity. Given the likely budget
profile, this may be one large rover, such as the Astrobiology Field
Laboratory (AFL), or two mid-range rovers with the capability to make
both remote sensing and *in-situ* observations, but without the
extensive analytical laboratories aboard the planned for AFL. AFL would
be a natural follow-on to MSL, providing a long-lived rover with remote
sensing and *in-situ* laboratory capabilities to explore regions and
materials thought to have supported habitable zones. The mid-range
rovers would investigate the geologic evolution and biological potential
of multiple locations on Mars where orbital data show the presence of
aqueous minerals and thus a history involving water. In particular,
mobile rovers provide by far the most effective means to distinguish
between the rock types that are most likely to preserve evidence of
life, for example chemically precipitated sedimentary rocks. Mid-range
rovers might have a Mars Exploration Rover (MER) Athena-like payload
\[1\] with remote sensing and contact *in-situ* measurements, with some
capability to detect reduced carbon compounds**,** (e.g. Raman
Spectroscopy). The two MER rovers have traversed over a dozen kilometers
and have clearly demonstrated the need for lateral mobility to find key
rocks and soils for analyses and to place results in geologic context.
Thus the SAG strongly endorses the need for rover capabilities for the
*in-situ* mission for the next decade and would reject any suggestion
that the 2016 *in-situ* opportunity focus instead on measurements from a
static lander only.

There are compelling science and exploration rationales for implementing
a rover mission or missions and associated *in-situ* observations during
the 2016 opportunity.

-   MER \[2,3\] and recent orbital \[4,5\] observations show that the
    Martian crust is surprisingly diverse in composition, structure and
    in the variety of aqueous processes that have modified it over time.
    These discoveries greatly expand the number of compelling sites
    relevant to the search for evidence of habitability and life and to
    understand climate and geological history.

-   A rover-based *in-situ* mission would extend to new sites the
    detailed characterization of surfaces and materials for ground-truth
    calibration of orbital data. Prior surface missions have
    demonstrated that ground truth data are critical to calibrate
    orbital observations. Therefore the accuracy of orbital observations
    of the diverse martian crust depends critically upon surface
    observations conducted at diverse sites.

-   Results of the 2007 Phoenix Lander (e.g., TEGA-based evolved gas
    analysis) and Mars Reconnaissance Orbiter (MRO) observations (e.g.,
    targeted HiRISE, CRISM, and CTX for \~1000 sites) would be available
    to guide site and instrument selection. Initial results would also
    be available from the 2009 MSL mission to help guide selections,
    although the SAG expresses concern that MSL results may not be
    available in time to guide instrument selection for a 2016
    opportunity.

-   Evidence of life and ancient climates would reside in certain rock
    types and mineral phases (e.g., silica, phosphates, carbonates) that
    can most effectively preserve such evidence. In many cases these
    materials can only be located during a surface mission with
    significant mobility and on-site measurement capability. The 2016
    rover mission is perhaps the most effective means for discovering
    samples that preserve records of life and climate and thereby would
    optimize the probability of sending a later MSR mission to a
    location that maximizes the probability of collecting samples of
    direct relevance to habitability and life.

-   It can be argued that the cycle of orbital and landed observations
    of the martian crust is the "engine" that drives discovery in
    multiple disciplines in Mars science and that addresses the search
    for direct evidence of life, ancient climates, and the compositional
    and structural evolution of the martian crust. The 2016 Mars rover
    mission is in many ways the keystone that can sustain these multiple
    lines of inquiry during the next decade.

One issue raised during the MEPAG Meeting was that cosmic rays and their
spallation products over the aeons may have caused organic compounds to
convert to graphite for deposits that have remained within the top meter
from the surface. Therefore drilling to depths beyond a meter was
suggested to ensure access to any organic materials. The contention that
organic material within a meter of the surface would be destroyed needs
quantification, both the process and the timescale. Further study is
also needed to understand the extent to which surfaces have remained
static for aeons. Certainly MER and orbital observations show extensive
burial and erosion by wind, water, and volcanism at many locations and
scales. Lateral mobility conceivably could access materials that have
been exhumed relatively recently from depths \>1m. The SAG also notes
that the requirement for vertical mobility to access unprocessed carbon
compounds will be better understood following the results from the
evolved gas analyzer (TEGA) that is part of the payload on the 2007
Phoenix Lander mission. MSL results will also provide direct information
on the depth distribution of reduced carbon compounds. The SAG's opinion
is that lateral mobility, with AFL or mid-range rovers, is more
important for the 2016 opportunity than extensive vertical mobility
(i.e., \> 1 m).

The SAG considered scientific results that would lead to a selection of
an AFL or a pair of mid-range rovers for the 2016 opportunity. It is the
opinion of the SAG that either mission approach would be scientifically
compelling and consistent with the program goal and objectives. The AFL
selection was judged to more directly address habitability and life and
would be preferred if the combination of existing data (e.g., MGS,
Odyssey, MEx, MER), coupled with data expected from MRO and Phoenix,
lead us to suspect that there are key areas where evidence for habitable
zones and perhaps life are best preserved. MSL results may be available
too late in the rover development cycle to impact whether an AFL or
mid-range rover is the appropriate choice. It is noted that technology
development for AFL will benefit greatly from MSL development efforts.
Development of mid-range rovers represents a new line, based only partly
on MER. Careful consideration must be given to the timing of a decision
for an AFL or mid-range rover mission in 2016 to ensure enough
development and testing time for the selected vehicle.

The SAG notes that technology investment in *in-situ* instruments is
critical and may not be happening at the rate it should to support a
2016 rover-based mission. It is noted that MEPAG, during its April 2006
Meeting, plans on addressing from an end to end perspective the
development of instrumentation needed to implement the draft program
plan and viable alternatives.

Finally, the SAG notes that the European Space Agency (ESA) has
initiated detailed planning for its ExoMars rover mission, with
measurement capabilities similar to what one might envision would be
included on an AFL. The SAG's opinion is that collaboration with ESA
might make an AFL-like mission happen during the 2016 opportunity (or
earlier) and perhaps allow earlier implementation of sample return or
network science elements of the draft program plan.

1.  **Swapping in Sample Return**

The value of a Mars Sample Return (MSR) Mission and Earth-based analyses
of samples is summarized below as part of an alternative plan that
includes MSR in 2016/2018. The SAG notes that The National Research
Council Decadal Survey for Solar System Exploration considered MSR to be
so important that it was ranked as the highest priority for a large
(\>\$650 million) Mars mission in the next decade \[6\].

-   The resolution and range of analyses available in terrestrial labs
    will be much better than anything we will be able to fly in the
    foreseeable future.  Further, as instruments improve
    and understanding evolves, the samples are in hand to support new
    discoveries.  For example, a major conclusion about early lunar
    evolution was announced in November, 2005 based on new techniques of
    Hf-W (Hafnium-Tungsten) chronology - some 30 years after Apollo
    returned the samples. In a real sense, each new analysis performed
    on returned samples may be viewed as an equivalent to a new
    *in-situ* measurement performed on Mars, but at much less cost and
    much greater frequency.

 

-   The samples will serve as ground truth for the huge volumes of
    remote sensing and *in-situ* data that have been and will
    be obtained.  For example, Mars Exploration Rover (via Moessbauer
    Spectrometry) and Mars Express OMEGA (via reflectance spectrometry)
    data \[3,4\] indicate the presence of hydrated iron and magnesium
    sulfates in layered sedimentary deposits. These results have had a
    significant impact on our understanding of the aqueous history of
    Mars. These crucial mineral identifications can be confirmed or
    refuted unequivocally within days based on analyses of
    carefully-selected returned samples.

-   Unequivocal identification of evidence for life and habitability may
    require returned samples and exhaustive terrestrial analysis. For
    example, isotopic analysis of nanoparticles of carbon, indicative of
    origin, can be done only in terrestrial labs.

-   Potential international partners, including ESA, are now considering
    incorporating sample return into their mission plans. Buoyed by the
    recent success of Mars Express, they realize the great scientific
    potential and that they have the technical ability to do the
    mission. MSR is an important, yet costly and technically challenging
    mission. This mission is perhaps best implemented as a joint
    NASA/ESA activity, thereby sharing the cost and technology
    development.

-   An MSR mission directly supports the eventual human exploration of
    Mars. Results from sample return will provide science and
    engineering data not readily obtainable by remote sensing or
    *in-situ* analysis (see MEPAG Goals document). It further
    demonstrates \"proof-of-concept\" and learning relevant to the
    round-trip essential for human exploration of Mars. Similarly, it
    can provide the model for how to conduct in international human Mars
    exploration program. An MSR mission in the 2016/2018 opportunity
    will provide the public with a tangible demonstration that the
    United States is taking steps towards human exploration beyond the
    moon.

-   Results from the first sample return mission will affect the course
    of the subsequent flight program.  The detailed analyses will, as
    did Apollo sample analyses, provide guidance to instrument
    development and future surface *in-situ* investigations.

A sample return site could be selected using existing data (i.e., from
MGS, Odyssey, MEx, MER data), although observations from MRO and MSL
will provide valuable information needed to maximize the probability of
choosing a site that will provide information about habitability and
perhaps life. Results from Phoenix, MRO (and initial results from MSL)
will be available in time to provide additional data for landing site
selection.

A simple grab sample obtained from a stationary lander is judged by the
SAG to be inadequate. The MER mission demonstrated the value of
acquiring a range of samples from various localities within a given
landing site. Thus a rover-based mobility system must be a fundamental
aspect of MSR, either to collect samples and return them for ascent, or
to return to a site where samples have been cached during a previous
mission.

Cost and the reliability of cost estimates for MSR were two issues
discussed at great length during the MEPAG Meeting and by the SAG. The
history of recent MSR cost-estimation is as follows: NASA contracted
with four industry groups (Ball Aerospace, Boeing, Lockheed-Martin, and
TRW) in 2000 to independently design and estimate the costs for an MSR,
with a nominal launch date of 2011. The reports were completed in 2001
and delivered to NASA. Although differing in details, all of the
original mission designs include a rover with extensive on-board science
instrument packages. Most of the designs mitigate mission risk by some
level of redundancy of landers, launches, or both. As proposed, cost
estimates for the original industry designs approach \$3 billion in real
year dollars. When normalized to single-launch/single-lander
configurations, the industry designs have estimated costs in the range
\$1.3 B to \$2.0 billion (FY02 dollars) \[7,8\]. SAIC and Aerospace
Corporation both performed independent cost estimates on a non-mobility
version of each of the team's designs, as well as JPL's internal design,
and confirmed the validity of their costs. Additional work has been
ongoing at JPL to determine the full costs of MSR. The current mission
design included separate launches of an orbiter and a lander, a
sample-collecting rover with a range of 1 km, and no in-situ science.
The study also estimated the costs of a technology program (defined by a
2004 multi-center MSR Technology Board), operations, and post-return
sample handling. Three industry groups independently provided NASA with
design concepts and costs for a Sample Receiving Facility. The mission,
featuring an initial launch in 2016 and sample return in 2018, was
estimated to cost \$3.3 billion real-year dollars \[9\]. The SAG
concludes that costs are fairly well understood and that cost
uncertainty should not be an impediment for a 2016/2018 MSR mission. .

A key issue associated with implementing an MSR Mission in 2016/2018 is
technological readiness. A recent JPL study \[9\] defined the mission
elements which require technology development, commencing in FY08, at
the latest, to support a launch in 2016/2018:

-   Parachute Development

-   Pinpoint Landing

-   Forward Planetary Protection

-   Sample Containment

-   Sample Acquisition

-   Mars Ascent Vehicle

-   Orbital Detection, Rendezvous and Capture

-   Earth Entry Vehicle

-   Sample Receiving

Technology development programs in direct support of an MSR mission have
been ongoing for several years. The Mars Program Office Base Technology
and Focused Technology Programs directed to the MSR flight segment has
resulted in design concepts and prototype hardware for key mission
components. This program was terminated in FY05. Three industry groups
independently provided to NASA design concepts for a Sample Receiving
Facility and identified key technology developments needed to be ready
to receive and analyze samples. A companion program to develop key
technologies for the Sample Receiving Facility has been designed,
although not implemented. A separate program to develop technologies
specific to Planetary Protection is ongoing. Technology development
efforts must be reestablished as soon as possible and no later than FY08
to be able to meet a 2016/2018 MSR opportunity.

1.  **Swapping in Network Science**

Network science focuses on study of the interior structure (seismology
and heat flow), atmosphere and climate, made from multiple, simultaneous
measurements on the Martian surface. The capabilities needed to deploy
and operate multiple surface stations are substantial and require core
mission funding to implement, i.e., they are beyond the capabilities
that could be implemented with a Scout mission.

Seismic and heat flow measurements from carefully selected sites would
provide fundamental information on the origin and subsequent evolution
of Mars, its bulk composition, volcanic and tectonic history that drive
the evolution of the atmosphere and water budget, the thermal state and
history of the crust and mantle, the timing and character of the early
dynamo and its possible role in pre-biotic chemistry. In particular, the
existence of ancient (or contemporary) habitable zones depended (or
depends), *inter alia*, on the thermal and crustal evolution of the
planet. In analogy to the key measurements from an aeronomy mission
(e.g. species escape rates), a geophysical network provides the boundary
conditions on the role that the interior has played in enabling
habitable environments. Additionally, regional variations in the thermal
environment may modulate the locations and timing of habitable zone
development and evolution.

An atmospheric network would provide diurnal and seasonal measurements
of gases, water, dust, and fluxes, and thereby characterize the general
circulation and climate for input to global models of Mars chemistry and
dynamics, including horizontal and vertical transport. Ultimately, these
parameters are critical for habitability and future human exploration.
The SAG notes that for atmospheric science, more mission options exist
as compared to implementing the seismic and heat flow investigations. As
evidenced in earlier proposals, Mars Scout missions can accommodate
multiple probes, penetrators, or ground stations devoted to atmospheric
and climate studies. Also, Entry, Descent, and Landing phases of surface
missions include acquisition of descent atmospheric profiles (e.g.
Pathfinder and the Mars Exploration Rover Missions) that contribute to
network atmospheric science. The SAG endorses the concept that each
surface mission be considered part of an atmospheric network science
"virtual" mission and include, to the extent possible, relevant
atmospheric measurements.

There are two principal advantages of bringing the planned network
science mission in 2016:

-   We would in a more timely and direct way address one of the four
    core investigations, namely: "Determine the structure and dynamics
    of the interior using seismic and heat flow measurements." Thus a
    geophysical evolutionary context for planetary habitability would be
    provided.

-   Our European partners continue to express strong interest in network
    science, both geophysical and atmospheric, and it may prove an
    effective and cost-sharing partnership that would retain Scout
    funding for the following 2018 opportunity. ESA has formally
    endorsed geophysical and meteorological investigations as a high
    priority for Mars. They have included a GEP
    (Geophysical/Environmental Package) in the design of their ExoMars
    mission for 2011. In terms of the technological readiness, virtually
    all the European instruments are basically ready to fly now, and
    this could possibly form the basis for a NASA-ESA collaboration for
    a network mission.

Failing the inclusion of a network mission in the 2016 opportunity, the
SAG believes that every effort should be made to include a seismometer
on other landed missions in order to characterize the seismicity of
Mars. The level of seismicity can be related to the present thermal
state of the planet and would help refine the strategy for a future
network mission. Inclusion of capabilities to measure heat flow should
also be considered for landed missions.

2.  **Comments on the Role of Scout Missions**

Scout Missions were discussed during the November 2005 MEPAG meeting and
during SAG telecons and key results are summarized in this subsection.
Through an open competition, Scout missions create opportunities for
diverse, innovative, P.I.-led missions to be included in the Mars
program. Such opportunities assist in building the community of future
aerospace engineers and scientists. Scouts provide operational
alternatives to core missions while still striving to achieve the key
goals and objectives of the Mars program. This alternative mechanism
potentially allows greater flexibility to respond relatively rapidly to
discoveries and/or technological advances. And the lower cost of Scout
missions, relative to core missions, helps to keep the Mars program
within its budget while still utilizing each launch opportunity to
achieve important science.  Scout missions indeed offer operational and
budgetary flexibility to the Mars Program, however they still should
contribute directly to the key goals and objectives of the program.

The current cost cap imposed on Scout missions curtails many of the key
advantages potentially offered by Scout missions. For example, many
potentially valuable landed missions might no longer be financially
viable. The current cost cap should be re-examined in light of
anticipated costs of certain types of high-priority Scout mission
concepts.

3.  **Comments on Program Telecommunications Infrastructure**

The Mars Exploration Rover mission has clearly demonstrated the benefits
of relay communications for support of Mars *in situ* exploration,
including increased data return, reduced lander energy and mass
requirements, provision of contact opportunities at a wide range of
local times (thus increasing data return from the surface missions), and
capture of high rate engineering telemetry during critical mission
events such as Entry, Descent, and Landing.  While current program
budget constraints do not allow for inclusion of a dedicated Mars
Telecommunications Orbiter, as had been originally planned in 2009, a
strategy of periodic launch of long-lived science orbiters with
telecommunications capability can sustain and grow the Mars relay
infrastructure capabilities.  To this end, the inclusion of an orbiter
mission with telecommunications capability in either the 2011 or 2013
opportunity represents an appropriate implementation of that
strategy. In addition, to ensure a robust infrastructure plan, the
program should strive to maintain redundant on-orbit relay assets by
managing the Odyssey and Mars Reconnaissance Orbiter spacecraft with the
goal of significant extended lifetime. An alternative to the
science/telecommunications orbiter implementation is inclusion in the
Program Plan of one or more dedicated telecommunications orbiters. This
may be necessary if orbits and mission concepts for the science portion
of an orbiter mission compromise telecommunications capabilities during
important surface operation periods.

**6. Concluding Remarks**

The program goal and objectives outlined above focus on understanding
the evolution of Mars and whether or not habitable zones and life
existed. This overarching approach will sustain an exciting and
scientifically rich program of Mars exploration for the next decade and
beyond. The draft program plan, with its four core science investigation
themes, augmented by Scouts, is a scientifically sound and
technologically viable approach for meeting the program goal and
objectives. Scouts should remain an important component of the program
to engage directly the community and implement missions that directly
address the program goal and objectives in ways that complement the core
investigations.

Technology development for instrumentation and missions is a key element
of a successful program. Much needs to be done to ensure that these
efforts are started early enough and funded well enough to enable the
plan to be implemented on schedule.

Telecommunications capabilities are an integral part of what is needed
to implement the plan and must be in place in time to support surface
missions. These capabilities might be best implemented by including them
on the core science orbiters planned for the next decade. If not, then
alternatives need to be in the plan, including dedicated
telecommunications capabilities.

Strong arguments can be made to have an AFL or mid-range rover mission
in 2016, to swap in a rover-based sample return mission, and to swap in
a network science mission. All of these choices address the program goal
and objectives. We note that the selection of a particular mission will
be based on science, cost, and political agendas. We also note that ESA
is implementing its ExoMars rover in the next decade, with significant
capabilities planned for determining aqueous history and habitability.
ESA has, in the past, also considered network science missions to Mars.
Both NASA and ESA have sample return as mission objectives in their
plans. We strongly encourage NASA to consider international cooperation
as a way of implementing the draft program plan in less than \~15 years
that is currently envisioned. In fact we challenge the agency to
implement the plan in a \~10 year time frame, including returning
samples by 2020. Sharing mission costs via international participation
will maximize our scientific return relative to investments in the
program.

**6. Acknowledgement**

Chris Webster acknowledges support from the Jet Propulsion Laboratory,
California Institute of Technology, under a contract with the National
Aeronautics and Space Administration.

**7. References**

\[1\] Squyres, S. W., R. Arvidson, E. Baumgartner, J. Bell,
P.Christensen, S. Gorevan, K. Herkenhoff, G. Klingelhofer, M. Madsen, R.
Morris, R. Rieder, R. Romero, 2003, The Athena Mars Rover Science
Investigation, *J.* *Geophys. Res., 108(E12),* doi:10.1029/2003JE002121.

\[2\] Squyres, S. W., R. E. Arvidson, J. F. Bell, III, J. Brückner, N.
A. Cabrol, W. Calvin, M. H. Carr, P. R. Christensen, B. C. Clark, L.
Crumpler, D. J. Des Marais, C. d\'Uston, T. Economou, J. Farmer, W.
Farrand, W. Folkner, M. Golombek, S. Gorevan, J. A. Grant, R. Greeley,
J. Grotzinger, L. Haskin, K. E. Herkenhoff, S. Hviid, J. Johnson, G.
Klingelhöfer, A. Knoll, G. Landis, M. Lemmon, R. Li, M. B. Madsen, M. C.
Malin, S. M. McLennan, H. Y. McSween, D. W. Ming, J. Moersch, R. V.
Morris, T. Parker, J. W. Rice, Jr., L. Richter, R. Rieder, M. Sims, M.
Smith, P. Smith, L. A. Soderblom, R. Sullivan, H. Wänke, T. Wdowiak, M.
Wolff, and A. Yen, 2004, The Spirit Rover\'s Athena Science
Investigation at Gusev Crater, Mars, *Science, 305(5685),* 794-799,
doi:10.1126/science.1100194.

\[3\] Squyres, S. W., R. E. Arvidson, J. F. Bell III, J. Bruckner,N. A.
Cabrol, W. Calvin, M. H. Carr, P.R. Christensen, B.C. Clark, L.
Crumpler, D. J. DesMarais, C. d'Uston, T. Economou, J. Farmer, W.
Farrand, W. Folkner, M. Golombek, S. Corevan, J. A. Grant, R. Greeley,
J. P. Grotzinger, L. Haskin, K. E. Herkenhoff, S. Hviid, J. Johnson, G.
Klingelhofer, A. H. Knoll, G. Landis, M. Lemmon, R. Li, M. V. Madsen, M.
C. Malin, S. M. McLennan, H. Y. McSween Jr., D. W. Ming, J. Moersch, R.
V. Morris, T. Parker, J. W. Rice, Jr., L. Richter, R. Rieder, M. Sims,
M. Smith, P. Smith, L. A. Soderblom, R. Sullivan, H. Wanke, T. Wdowiak,
M. Wolff, A. Yen, 2004,The Opportunity Rover's Athena Science
Investigation at Meridiani Planum, Mars, 2004, *Science 306(5702)*
1698-1703 doi: 10.1126/science.1106171\]

\[4\] Bibring, J.-P., Y. Langevin, A. Gendrin, B. Gondet, F. Poulet, M.
Berthe, A. Soufflot, R. Arvidson, M. Mangold, J. Mustard, P. Drossart,
2005, Mars Surface Diversity as Revealed by the OMEGA/Mars Express
Observations, *Science, 307(5715),* 1576-1581,
doi:10.1126/science.1109509.

\[5\] Poulet, F., J.-P. Bibring, J. F. Mustard, A. Gendrin, N. Mangold,
Y. Langevin, R. E. Arvidson, B. Gondet, C. Gomez, 2005, Phyllosilicates
on Mars and Implications for the Early Mars History, *Nature*, 348,
623-627.

\[6\] National Research Council, 2003, New Frontiers in the Solar
System: An Integrated Exploration Strategy, National Academy Press,
Washington, DC.

\[7\] MacPherson, Glenn J. (Chair), and the MSR Science Steering Group,
2002, Groundbreaking MSR: Science requirements and cost estimates for a
first Mars surface sample return mission,
<http://mepag.jpl.nasa.gov/reports/index.html>, Unpublished white paper.

\[8\] Mattingly, R., Matousek, S., Jordan, F., 2003, Mars Sample Return,
Updated to a Groundbreaking Approach, 2003 IEEE Aerospace Conference,
Paper #1392.

\[9\] Mattingly, R., 2005, Mars Sample Return w/sampling-rover, 2016/18
split-mission version, Internal JPL presentation, 9/23/05.