**The Astrobiology Field Laboratory**

September 26, 2006

Final report of the MEPAG Astrobiology Field Laboratory Science Steering
Group (AFL-SSG)

[SSG Members]{.underline}: Andrew Steele and David Beaty (co-chairs), ,
Jan Amend, Bob Anderson, Luther Beegle, Liane Benning, Janok
Bhattacharya, David Blake, Will Brinckerhoff, Jennifer Biddle, Sherry
Cady, Pan Conrad, John Lindsay, Rocco Mancinelli, Greg Mungas, Jack
Mustard, Knut Oxnevad Jan Toporski, Hunter Waite

# (For correspondence, please contact [**a.steele@gl.ciw.edu**](mailto:paul.r.mahaffy@nasa.gov) 202-478-8974, or [**David.Beaty@jpl.nasa.gov**](mailto:David.Beaty@jpl.nasa.gov), 818-354-7968) 

This report has been approved for public release by JPL Document Review
Services (Reference Ref. \# CL#06-3307), and may be freely circulated.

Suggested bibliographic citation:

Steele, A., Beaty, D.W., Amend, J., Anderson, R., Beegle, L, Benning, L,
Bhattacharya, J., Blake, D., Brinckerhoff, W., Biddle, J., Cady, S.,
Conrad, P., Lindsay, J., Mancinelli, R., Mungas, G., Mustard, J.,
Oxnevad, K., Toporski, J., and Waite, H. (2005). The Astrobiology Field
Laboratory. Unpublished white paper, 72 p, posted Dec., 2005 by the Mars
Exploration Program Analysis Group (MEPAG) at
http://mepag.jpl.nasa.gov/reports/index.html.

#   {#section .unnumbered}

# Table of Contents

Table of Contents [2](#table-of-contents)

Membership [4](#membership)

1.0 EXECUTIVE SUMMARY [5](#executive-summary)

2.0 AFL CHARTER [8](#afl-charter)

2.0 DEFINTIONS [10](#defintions)

4.0 INTRODUCTION [12](#introduction)

5.0 SCIENCE GOALS [13](#science-goals)

5.1 Assumptions [13](#assumptions)

5.2 Objectives [16](#objectives)

5.2.1 Habitability [16](#habitability-1)

5.2.2 Extinct or Extant Life. Abiotic or Prebiotic Material
[17](#extinct-or-extant-life.-abiotic-or-prebiotic-material)

5.2.2.1 What techniques have been used to detect and characterize
terrestrial and meteoritic biosignatures?
[22](#what-techniques-have-been-used-to-detect-and-characterize-terrestrial-and-meteoritic-biosignatures)

5.2.2.2 What are the challenges for AFL in the search for biosignatures
on Mars?
[23](#what-are-the-challenges-for-afl-in-the-search-for-biosignatures-on-mars)

5.3 Preservation Potential [25](#preservation-potential-1)

6.0 Precursor Discoveries [25](#precursor-discoveries)

7.0 Mission Site Selection [26](#mission-site-selection)

7.1 Sediments [27](#sediments)

7.2 Hydrothermal [29](#hydrothermal)

7.3 Ice [33](#ice)

7.4 Water [38](#water)

8.0 Core Mission Components [39](#core-mission-components)

8.1 Payload strategy [40](#payload-strategy)

8.2 Core Measurements and Instrumentation
[41](#core-measurements-and-instrumentation)

8.3 Sampling and Precision Sub sampling
[46](#sampling-and-precision-sub-sampling)

8.3.1 Obtaining a sample [47](#obtaining-a-sample)

8.3.2 Sedimentary deposits: [48](#sedimentary-deposits)

8.3.3 Precision sampling of a core [48](#precision-sampling-of-a-core)

8.3.4 Ice Samples [49](#ice-samples)

8.3.5 Liquid and Heat extraction of organics
[49](#liquid-and-heat-extraction-of-organics)

8.3.6 Contamination concerns [52](#contamination-concerns)

8.4. Time resolved Measurements [52](#time-resolved-measurements)

9.0 Engineering analysis of AFL core
[53](#engineering-analysis-of-afl-core)

10.0 Planetary Protection [56](#planetary-protection)

11.0 Relationship between AFL and MSL
[57](#relationship-between-afl-and-msl)

12.0 The Future of AFL [57](#the-future-of-afl)

13.0 References [59](#references)

14.0 Appendix 1. Discoveries AFL must respond to.
[66](#appendix-1.-discoveries-afl-must-respond-to.)

15.0 Appendix 2 - Instrument descriptions and capabilities
[67](#appendix-2---instrument-descriptions-and-capabilities)

# Membership

  ----------------------------- ------------------------------------------
  ***[Science                   
  Members]{.underline}***       

  Andrew Steele                 Carnegie Institution of Washington

  Bob Anderson                  University of Colorado

  David Blake                   Ames Research Center

  Hunter Waite                  University of Michigan

  Jack Mustard                  Brown University

  Jan Amend                     Washington University

  Jan Toporski                  Carnegie Institution of Washington

  Janok Bhattacharya            Univ. of Texas, Dallas

  Jennifer Biddle               Penn State

  John Lindsay                  JSC/LPI

  Liane Benning                 Leeds University

  Luther Beegle                 JPL

  Pan Conrad                    JPL

  Rocco Mancinelli              SETI/ARC

  Sherry Cady                   Portland State

  Will Brinckerhoff             APL

  ***[Engineering               
  Members]{.underline}***       

  Greg Mungas                   JPL

  Knut Oxnevad                  JPL

  Roger Diehl                   JPL

  ***[Program]{.underline}***   

  David Beaty                   Program Office\--JPL

  Jim Garvin                    Program Office\--HQ

  Marguerite Syvertson          Program Office\--JPL
  ----------------------------- ------------------------------------------

During the course of the SSG several breakout groups were formed to
answer specific issues related to our discussions. These are as follows;

[AFL subcommittees]{.underline}

-   **Sedimentary sub-team**. Pan Conrad, leader.

-   **Hydrothermal sub-team**. David Blake, leader

-   **Ice sub-team**. Luther Beegle, leader

-   **Sample preparation sub-team**. Jan Toporski, leader

-   **Definitions sub-team**. Pan Conrad, leader

-   **Instruments sub team.** Will Brinkerhoff leader

-   **Water sub-team**. Jan Amend, leader

# EXECUTIVE SUMMARY

The AFL SSG was asked to develop an analysis of a possible future
mission called the **Astrobiology Field Lab**. This mission is a generic
concept, consisting of a lander equipped with a major in-situ laboratory
capable of making significant advancements towards MEPAG's Goal I
("Determine if life ever arose on Mars"). In essence, the purpose of
this analysis was to evaluate the question, "what is the most that can
be accomplished in this area by in situ means?" In order to give the
analysis team room to work, financial and timing constraints were very
loose. Although at the time of convening this exercise 2013 was the
closest discussed deadline and so considerations were given to what
technically could be accomplished for this deadline.

The AFL SSG considered the problem at several levels:

-   What overall programmatic exploration strategies are needed to
    achieve Goal I? Results from many missions will contribute to these
    strategies, and a mixture of ambiguous and definitive outcomes will
    need to be accommodated.

-   What result would AFL need to deliver to make a meaningful
    contribution to this strategy?

-   What are the engineering options for configuring a landed mission
    that would make such a contribution?

######### Programmatic exploration strategies

In order to plan missions during the period 2013-1018, it is necessary
to predict the state of human knowledge at that time. Although this is
hard to do in detail, it is possible to reach some important
generalities. First of all, habitability is the [potential]{.underline}
of an environment (and applied to either the past or the present) to
sustain life. By this definition, habitability will be the integrated
and accumulated knowledge of many missions and many different kinds of
scientific investigations. However, as with any other potential, it will
not be possible to achieve certainty unless life itself is discovered.
Habitation, on the other hand, is a simple yes-no question. A key
planning question, therefore, is when has the habitability potential
risen high enough that a habitation test can be justified?

Although it has been generally assumed in the past that these two
objectives need to be pursued sequentially, the AFL SSG has concluded
that organisms and their environment together constitute a system, and
each produces an effect on the other. Many kinds of investigations of
this system can simultaneously provide information about both. This
implies that habitability and habitation can be investigated together.
This expands significantly on the current mission concept for MSL, with
AFL having an expanded instrument suite dedicated more towards life
detection and precision sample handling than MSL. Moreover, the process
of life detection on Mars involves two sequential steps: 1). Proposing
that a set of phenomenon are, or could be, biosignatures. This will
constitute a working hypothesis that life is or was present. 2).
Establishing that at least one of these biosignatures is
[definitive]{.underline}. This requires extensive effort and careful
planning and a number measurements mutually confirming each other.
Finally, we know that some kinds of scientific investigations will
measure signs of both extinct and extant life without needing to
distinguish between these two possibilities before launch.

Given the expected state of our knowledge about Mars during the period
2013-2018, the AFL SSG has reached three conclusions:

1.  It is both possible and reasonable to do life detection first, then
    determine whether it is extinct or extant on the basis of a positive
    result.

2.  Missions during this period can reasonably begin the process of life
    detection by characterizing potential biosignatures.

3.  It is reasonable to set mission objectives that relate to both
    habitability AND habitation. It is not necessary to choose one at
    the expense of the other.

Finally if a definitive biosignature is located by AFL instrumentation
and missions must be configured to definitively characterize that life
signature. It is only by thorough study of a positive signal will
skepticism be kept to a minimum and the maximum understanding of how
this relates to the formation of life on earth be understood.

######### Engineering options

The AFL SSG has concluded that the following overall scientific
objective is both achievable by AFL as early as 2013 (although 2018 was
also postulated as a target from the pathways document, Figure 1), and
is a significant extension of currently planned missions:

**For at least one Martian environment of high habitability potential,
quantitatively investigate the geological and geochemical context, the
presence of the chemical precursors of life, and the preservation
potential for biosignatures, and begin/continue the process of life
detection.**

By targeting an environment of high habitability potential, a response
to prior discoveries is implied. Investigating the context is a
reflection of the reality that our understanding of habitability will
not be complete by 2013 we need to plan for more work. Understanding
prebiotic chemistry is necessary to allow planetary-scale life-related
predictions, especially in the contingency that life is not found in a
specific experiment. Understanding preservation is key to interpreting
the results of biosignature investigations, and is also critical
feed-forward to future missions. Finally, life detection, as AFL SSG
defines it, is a process that will take time. It is reasonable to expect
that missions like AFL will play a significant role in this process, but
unreasonable to expect that they will bring it to a conclusion.

######### Engineering options for an AFL mission

The AFL SSG has defined a landed mission that can achieve the above
objective. There are multiple possible variations of what could be
called "AFL", and different scientists see these variations in different
context, and with different systems of priority. However, it is possible
to define an invariant base that is common to most versions, along with
a discovery-responsive and competition-responsive cap. The basic landed
system needs to be able to accomplish four things:

-   Acquire the right samples (access a place with high general
    habitability potential, understand preservation potential, have a
    high ability for scientific sample selection, capable sample
    acquisition system)

-   Know the context (Setting, mineralogy, chemistry, relationships)

-   ID best place on the sample (Mid-scale observations.

-   Precision sub-sampling (down to mm scale) for investigation by
    analytical suite)

-   At least 3 mutually confirming A/B measurements (Suites of
    observations by different means of the same or related phenomena
    will be necessary to reach definitive conclusions).

Initial engineering concepts for this mission place AFL as a COSPAR
level 4B mission.

# 2.0 AFL CHARTER

The AFL SSG was given the following charter.

[Introduction]{.underline}

The Mars Program Office at NASA HQ (Code S) requests a study of the
preliminary scientific options and engineering characteristics of the
AFL mission. This mission was identified in the final report of the
MSPSG (Mars Science Program Synthesis Group).

[Starting assumptions (to be refined)]{.underline}

1.  Assumptions for each mission need to be compiled separately.

2.  Assume TBD mission must be ready to launch as early as TBD.

3.  Science priorities will be derived from the MEPAG Goals document.

[Requested Tasks:]{.underline}

1.  Develop a set of candidate whole mission concepts. For each:

-   Define preliminary general science objectives, and science floor
    (the level below which the mission is not worth flying).

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-   Identify and evaluate the primary science trades

-   Determine whether instruments capable of addressing the science
    objectives are likely to be available in time.

-   Landing site accessibility: Propose the size of the latitude band
    which needs to be held open for this mission, the landing precision,
    and required ability to land in rough terrain

-   Identify possible facility subsystems related to sample acquisition
    and sample preparation.

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-   Describe the essential engineering constraints on the mission

-   Determine if positioning in the pathways makes a difference to the
    science/engineering of the mission.

-   Describe how the mission fits into NASA's long-range strategic
    framework for the exploration of Mars

2.  Based on the above analysis, present a prioritized set of
    preliminary options for consideration by NASA HQ.

[Methods]{.underline}

-   The SSG is asked to conduct its business primarily by telecons,
    e-mail, and or web-based processes. There is enough budget to
    convene 1 or 2 face-to-face meetings.

-   Logistical support will be provided by the Mars Program Science
    Office.

[Timing]{.underline}

-   It is expected that the team will be ready to start its
    deliberations in mid-November.

-   A mid-term telecon status check by Jim Garvin, Dan McCleese, and
    Bruce Jakosky is requested after the new year.

-   The near-final report of the AFL SSG is requested by Feb. 28, 2004.

-   It is expected that the results of this study will be presented to
    MEPAG at its June, 2004 meeting. Feedback from this discussion will
    be incorporated in the final report, which will be due July 31,
    2004.

[Report Format]{.underline}

-   It is requested that the results be presented in the form of both a
    PowerPoint presentation and a white paper. Additional supporting
    documents can be prepared as needed. After the white paper has been
    accepted by program management (including the MEPAG executive
    committee), it will be posted on a publicly accessible web site.

-   The report should not include any material that is a concern for
    ITAR (as is true of everything done by MEPAG).

Note, the bulk of this work and the draft white paper was completed by
September 2004. There have been unavoidable delays to its publication.
In the meantime thinking about AFL has progressed. This document
reflects the thinking in September 2004. Whilst engineering and
programmatic changes have occurred since then, the strength of this
document lies in the science definition for the mission.

# 

# DEFINTIONS

During the course of the AFL-SSG discussions several questions related
to the MSPSG statement arose. Specifically these questions relate to the
definitions of, for example, the terms habitability (or what constitutes
a habitat) and biosignature. Critical questioning by the group resulted
in the formation of a definitions subgroup

The following definitions were decided upon by that group. These
definitions are consistent through this document and although we cannot
suggest the wider community adopt these definitions it is suggested that
some consensus within the MEPAG members is reached to prevent numerous
iterations of this process in other reports.

####### Abiotic Chemistry 

Mainly carbon based chemistry the speciation and composition of which
has remained simple with the production of all different isomeric
possibilities and show no chiral or species preferences. In this
scenario complex molecules may only be kerrogenous in nature (type iv)
and similar to that found in meteorites.

####### Biosignature 

Any phenomenon produced by life (either modern or ancient). Two
sub-definitions: Definitive Biosignature: A phenomenon produced
exclusively by life.  Due to its unique biogenic characteristics, a
definitive biosignature can be interpreted without question as having
been produced by life. Potential Biosignature: A phenomenon that may
have been produced by life, but for which alternate abiotic origins may
also be possible.

####### Extant life

General reference to living or recently dead organisms which may also
possess a fossil record.

####### Extinct life 

General reference to past life (and no longer present on the planet). If
evidence remains, it is ONLY fossil.

######## Habitability 

A general term referring to the potential of an environment (past or
present) to support life of any kind. In the context of planetary
exploration, two further concepts are important: Indigenous habitability
is the potential of a planetary environment to support life that
originated on that planet, and exogenous habitability is the potential
of a planetary environment to support life that originated on another
planet.

######## Habitat

An environment (defined in time and space) that is or was occupied by
life.

####### Life detection

The process of investigating the presence of biosignatures (including
potential biosignatures). Life detection can apply to either past or
present life.

**Micro BioSensors (not to exclude organic chemical detection)**

Miniaturized instruments or instrument suites that are developed from
technology such as Micro Electronic Machine Systems (MEMS), Micro
electronic optic systems (MEOS), Microfluidics, Micro Total Analytical
Systems (uTAS) or Lab-on-a-Chip (LOC).

####### Prebiotic Chemistry 

Mainly carbon based chemistry the speciation and composition of which
has a complexity and has produced a number of polymeric systems that
could be used for structural, metabolic processes and information
storage and retrieval.

####### Present life investigation 

One that specifically targets living or recently dead organisms. Time
resolved studies on seasonal and daily (with perhaps higher frequency)
time scales may be required to confirm observations that a biosignature
of present life has been detected.

####### Preservation Potential

The potential for a particular biosignature to survive and therefore be
detected in a particular habitat.

####### Primary Sample 

Geological material (e.g. rock, regolith, dust, atmosphere, ice)
acquired from its natural setting on Mars.  Note: specific locations
where data are collected by contact instruments are referred to as
\"targets\", not samples.

####### Secondary Sample 

Any sample derived from the primary, including splits, extracts,
sub-samples, etc.

# 4.0 INTRODUCTION 

The primary science driver for the mission concept was to define the
first Mars mission to concentrate fully on Astrobiology science goals
(as defined within the recently updated Astrobiology roadmap).
Therefore, to define the preliminary general science objectives, and the
science floor, the level below which the mission is not worth flying.
The Astrobiology Field Lab was created as a concept by the Mars Science
Program Synthesis Group (MSPSG) during their Pathways planning
discussions in 2002-03 and can be paraphrased as;

**[Astrobiology Field Laboratory.]{.underline}** "This mission would
land on and explore a site thought to be a habitat. Examples of such
sites are an [active or extinct hydrothermal deposit]{.underline} or a
site confirmed by MSL to be of high astrobiological interest, such as a
[lake or marine deposits]{.underline} or a specific [polar
site]{.underline}. The investigations would be designed to [explore the
site]{.underline} and to search for evidence of [past or present
life]{.underline}. The mission will require a rover with "go to"
capability to gather "fresh" samples for a variety of detailed *in situ*
analyses appropriate to the site. *In situ* life detection would be
required in many cases." (*[From MSPSG (2003)]{.underline}*

However, MSPSG deferred to a successor team (AFL-SSG) the definition of
AFL's specific scientific and engineering constraints, possibilities,
and priorities. The AFLSSG team was initially convened in October 2003
and operated through a number of telecons and one face to face meeting.
Therefore this team was asked to plan during a constantly shifting
science focus and have constantly endeavored to keep abreast of the Mars
Exploration Rover findings and review the goals and outcomes of the SSG
accordingly. Undertaking this activity at a time when 3 new space craft
have started to explore Mars has been exciting, inspiring and already
produced new evidence to which we have responded. Many notions of how to
perform this mission have therefore been updated from preconceived
notions held before specifically, the MER data was returned. We hope
that these changes reflect a renewed sense of optimism and realization
of the location of interesting samples to interrogate with
instrumentation currently under development.

# 5.0 SCIENCE GOALS

## 5.1 Assumptions 

To undertake this task the AFL-SSG was asked to consider the following
assumptions;

-   Assume AFL will need to be ready to launch as early as the 2013
    opportunity

-   Assume all missions scheduled before 2013 are successful.

-   The MSL entry-descent-landing (EDL) system has successfully been
    demonstrated, and the engineering heritage can be used on AFL.

-   Assume the primary goal of AFL is to make a major advance in
    astrobiology.

-   Assume a cost cap approximately equal to that of Ground Breaking
    Mars Sample Return.

These assumptions are based on the timeline suggested by the Pathways
SSG, summarized in Figure 1.

![](media/image1.wmf){width="5.999305555555556in"
height="3.575in"}Figure 1. A summary diagram of the pathways proposed by
MSPSG.

From Figure 1 it can be seen that the pathways leading to AFL are
propelled by the discoveries of hydrothermal habitats and the search for
evidence of past life. During the course of the AFL-SSG discussions
several questions related to the MSPSG statement arose. Specifically
these questions relate to the definitions of, for example, the terms
habitability (or what constitutes a habitat) and biosignature. Critical
questioning by he group resulted in the formation of a definitions
subgroup the results of which are shown in Section 2.

Responses to discoveries other than pathway to discover hydrothermal
habitats as shown in Figure 1 were deemed necessary and led to the
formation of the hydrothermal, ice, sedimentary and water subgroups.
Through these discussions the parallel nature of exploration and
engineering goals in different environments was explored and a "core" of
similar themes and objectives arrived at that included life detection
philosophy, measurements, rover capabilities and sample preparation.
This notion is explored further in section 8.1.2.

Other questions arising from the MSPSG guidelines and our discussions
related to "the capability to gather fresh samples" which led to the
formation of the sample preparation subgroup. The mention of *in-situ*
life detection led to the Instrument subgroup surveying and documenting
the current instruments in development.

Several assertions for the completion of these science goals were
formulated and are as follows:

1\. By 2013 a full model of the potential habitability of Mars,
organized by environment, and applicable to both the present and
geological past will be partially understood. Therefore the Mars program
will have to choose to either; select one environment with a high
habitability potential and test for habitation *or* continue to refine
the habitability models to allow better targeting of a subsequent
habitation mission.

Therefore we forecast one of two conditions will be true in 2013:

> •[More likely]{.underline}: Models of habitability require either
> further definition or further confirmation before a specific test for
> habitation should be attempted.
>
> •[Less likely]{.underline}: At least one environment (past or present)
> with high habitability and preservation potential has been identified,
> and a habitation test is justified.

We therefore questioned whether AFL would be effective in both
scenarios. Which further reinforced the concept of defining a core set
of mission parameters (Section 8).

2\. Organisms and their environment together constitute a system. Each
produces an effect on the other. Some kinds of investigations can
simultaneously provide information about both the environment (e.g.
habitability potential) and associated life forms (habitation).

3\. Traditional Mars mission planning has involved choosing scientific
objectives and investigations for EITHER prebiotic chemistry, extinct OR
extant life. (PP policy is structured the same way.) However, some kinds
of scientific investigations will detect all of the above categories and
potentially measure the signs of life without prior need to assume
search parameters that will pre-categorize whether it is extant or
extinct.

4\. As our exploration of Mars (through robotic and sample return
missions and terrestrial studies on Martian meteorites) proceeds,
anomalous features will be discovered that are [POSSIBLE
biosignatures]{.underline} for Martian life forms. It is important that
this

-   Observation of [POSSIBLE biosignatures]{.underline} can be made by
    relatively simple observations (e.g. geological, textural,
    geochemical). Such features would constitute a [working
    hypothesis]{.underline}, **NOT** confirmation that life exists and
    has been detected.

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-   Concluding that evidence of a Martian life form (past or present)
    has been discovered requires proving that a POSSIBLE biosignature
    was produced by the activities or remains of Martian life. Unless a
    POSSIBLE biosignature is proven to be a DEFINITIVE biosignature --
    an object or phenomenon that could only have been produced by life
    -- it may not possible to prove the presence or former presence of
    life on Mars using AFL alone. However, the AFL mission has been
    configured so that it will not miss POSSIBLE biosignatures if they
    occur in a similar habitat and with similar character to those found
    on Earth and may indeed detect those non-earth centric signatures
    that would, without prior knowledge of the state of an unknown
    biochemistry, appear to be reasonably measurable.

-   Once several POSSIBLE biosignatures are identified, additional
    efforts will need to be made to prove that they definitively
    represent extant life or former life, or determine whether the group
    of POSSIBLE biosignatures is CONSISTENT with the hypothesis that
    life exists or once existed on Mars.

The current MEPAG goals document highlights the following strategy for
Goal 1 "The search for Life" Determining if life ever arose on Mars is a
challenging goal. *The essence of this goal is to establish that life is
or was present on Mars, **or** if life never was present to understand
the reasons why Mars did not ever support its own biology. A
comprehensive conclusion will necessitate understanding the planetary
evolution of Mars and whether Mars is or could have been habitable and
will need to be based in multi-disciplinary scientific exploration at
scales ranging from planetary to microscopic. The strategy we have
adopted to pursue this goal has two sequential aspects: Assess the
habitability of Mars (which needs to be undertaken environment by
environment), and in environments which can be shown to have high
habitability potential, to test for prebiotic processes, past or present
life. These constitute two high-level scientific objectives. A critical
means to achieve both of these objectives is to characterize Martian
carbon chemistry and carbon cycling. The science associated with carbon
chemistry is so fundamental to the overall life goal that we have
established it as a third primary science objective. To some degree,
these overarching scientific objectives can be addressed simultaneously,
as each requires basic knowledge of the distributions of water and
carbon on Mars and an understanding of the processes that govern their
interactions.*

Importantly this statement points out that the seemingly differing
goals, habitability, Carbon chemistry and the search for biosignatures,
overlap and can therefore be addressed to a significant degree by the
interpretation of measurements undertaken by certain instruments.
Examples, habitability demands the presence of Carbon, biosignatures are
often Carbon based etc. Amino acid analysis, n alkane distributions,
selection of informational and catalytic polymers based on a narrow
range of particular molecules and isomers of a particular molecular
group. For example nucleic acids contain ACTGU on earth, but may contain
LMNOP on Mars, it is the presence of a narrow range of the possible
purines and pyrimidines available through abiotic processes that would
constitute a biosignature. This could be true of any potential novel
biomolecule and it *may be* that upon detecting a small range of the
possible isomers of a particular compound speculation as to their
informational or catalytic roles can begin.

Therefore AFL can reasonably begin the process of life detection by
characterizing potential biosignatures.

## 5.2 Objectives

Proposed overall scientific objective of AFL:

For at least one Martian environment of high habitability potential,
further investigate the potential for habitability, the potential
presence of the chemical precursors of life, the potential for
preservation of biosignatures, and possible signs of life.

This objective must balance the need to be a significant extension
beyond currently planned missions, yet not an unrealistic extension of
current technology. The detailed objectives proposed include (in no
order of importance);

> 1\. Within the region of Martian surface operations, identify and
> classify Martian environments (past or present) with different
> habitability potential, and characterize their geologic context.
>
> 2\. Quantitatively assess habitability potential.

-   Measure isotopic, chemical, mineralogical, and structural
    characteristics of samples, including the distribution and molecular
    complexity of carbon compounds.

-   Assess biologically available sources of energy, including chemical
    and thermal equilibria/disequilibria.

-   Determine the role of water (past or present) in the geological
    processes at the landing site

> 3\. Investigate the factors that will affect the preservation of
> potential signs of life (past or present) on Mars
>
> 4\. Investigate the possibility of prebiotic chemistry on Mars
> (including non-carbon chemistry)
>
> 5\. Document any anomalous features that can be hypothesized as
> POSSIBLE Martian biosignatures. This will constitute a set of working
> hypotheses, which will need refinement and further testing on Mars or
> in return samples.

### 5.2.1 Habitability 

A definition for habitability is contained in section 2. From the first
assumption above the following recommendation was made: Habitability
models have the potential to integrate many different classes of
information that have been made recently and will be acquired over the
next decade. However, they will be most effective if placed on a
semi-quantitative footing (see Appendix II for an example). This
question was then followed up in discussions within the definitions
subgroup and illustrated by Figure 2.

Habitability should be described by measurable parameters that index the
potential of an environment to support life. Only in this way can the
scientific community achieve consensus regarding whether or not a given
environment is habitable, either for Martian or Earthly life. For any
living system, certainly there will be a range of environmental
requirements, outside of which life will be unsupportable. Even though
we have no information on potential Martian biological requirements, we
can learn from universal Earthly life requirements. The AFL study group
has agreed that Earth life requires water and certain chemical raw
materials such as carbon, hydrogen, nitrogen, phosphorus and a few
others in trace amounts (Williams and Fraústo da Silva, 1996). We also
know that life makes products from these raw materials with the
additional requirement for an energy source, so sufficient habitat space
must be available for the products to be mobilized or diffuse away,
otherwise metabolic reactions would run to equilibrium, or possibly
reverse. On Earth, the chemistry of life involves oxidation-reduction
reactions, and metabolism from the archaea to some highly-evolved
eukarya requires electron donor/receptor pairs. The spatial distribution
of both oxidized and reduced forms of ions involved in respiration may
be as important as their concentration in the context of biological
requirements.

We assume that the astrobiology community will have made progress toward
consensus regarding the indexing of habitability before the launch of an
AFL mission, as the concept of habitability will have an impact on
missions with the scope of Terrestrial Planet Finder to SSE missions in
search of present or past Martian habitable environments. One approach
toward such progress may lie in development of terms that lead to a
probabilistic evaluation---a scale of habitability based upon
measurements of agreed-upon parameters such as threshold concentrations
of water and other raw materials, energy, etc.

### 5.2.2 Extinct or Extant Life. Abiotic or Prebiotic Material 

It is important to recall that life on Mars may be composed of many
molecules that differ from those of Earth life. However, most current
hypotheses on extraterrestrial life maintain that Martian life, if it
exists or once existed, will resemble life on Earth in that it will
be: 1) composed of carbon, 2) based on a 'nucleic acid like' replication
mechanism and 3) packaged in cellular compartments. Measuring the
distribution, isomerization and quantities of carbon species limits the
search to life based on carbon chemistry, an appropriate goal that
reflects the strategies used to locate the biosignatures of ancient
carbon-based life forms on Earth. Potential organic carbon species that
would need to be distinguished by AFL are given in Table 2.

In the search for biosignatures on Mars the interpretation of
measurements will determine whether a particular results indicates the
category to which a particular a/biosignature should be placed i.e.
pre/abiotic extinct or extant. The important issue is to make the
correct measurements to ensure the sensitive detection of molecules of
interest can be undertaken.

Figure 2 Illustrated the cross cutting relationships between the
searches for habitability in comparison with the search for evidence of
past or present habitation.

![](media/image2.wmf){width="6.004724409448819in"
height="2.2283464566929134in"}![](media/image3.wmf){width="5.802755905511811in"
height="1.958267716535433in"}

From assertions 2 and 3 and illustrated by Figure 2 the implications are
that***[:]{.underline}*** The distinctions between investigations of
[habitability potential, habitation, extinct life, and extant
life]{.underline} are blurred. It is possible to configure a mission
that has relevance to ALL of these subjects.

Without evidence of liquid water on Mars, the potential to locate extant
Martian life is less, as all conceivable life forms require liquid
water. Hence the focus of upcoming missions on determining whether
liquid water is available. Until this information is known, an AFL
mission will need to be prepared to detect both extinct and extant life,
as well as be able to distinguish abiotic and prebiotic material. We
assume that the investigation of abiotic and prebiotic chemistry will be
useful in evaluating the postulated meteoritic and cometary delivery of
exogenous organics to the lithosphere and the formation of organic
material by indigenous hydrothermal processes. The current MER
information that Mars harbors environments that contained liquid water
in the past indicates that the possibility of discovering extinct life
has increased.

All information gained from AFL will be useful with regard to either
describing what kind of life exists/existed on Mars or describing
conditions found on Mars and determine why life evolved on Earth and not
Mars (assuming the conditions on Mars are similar to those on Earth).
The search for the signatures of prebiotic chemicals or components of
life--past or present will provide important information that will
advance the field of astrobiology and the understanding of our own
planet. In addition, there is now considerable evidence pointing to the
presence of methane in the atmosphere on Mars (Kerr 2004a.b commentary).
This implies that geological processes on Mars could provide a chemical
potential and carbon source that could be used by microorganisms and may
indicate the presence of hydrothermal sites and liquid water. The
generation and fate of atmospheric methane on Mars would be a
significant goal for missions that fly prior to AFL. Such measurements
would significantly improve our understanding of habitability.

Investigating early planetary surface chemical processes on Mars is
important to understanding two possible program-level exploration
outcomes:

-   If life is not present at a specific test site, can we predict that
    it might exist elsewhere?

-   If life never formed on Mars, WHY?

Studying such issues will also address specific goals, issues:

-   Understand planetary evolution through elucidating organic chemical
    input i.e. meteoritic versus abiogenic synthesis reactions.

-   Mars may give clues to the prebiotic evolution of the Earth. On
    Earth an unaltered geologic record of early planetary evolution
    (4.5-3.8 Ga) does not exist.

-   Allow conjecture as to why life did not start on Mars (should that
    be the outcome). Were the chemical processes and building blocks
    present there as on Earth?

By definition, a biosignature is an indicator of life or biological
activity. Therefore, by definition, the discovery of even one
biosignature on Mars would indicate that life once existed on the red
planet. However, discoveries of ancient POSSIBLE biosignatures on Earth
and Mars have shown that it can be extremely difficult, if not
impossible, to prove their biogenic origin. Our inability to prove an
object or phenomenon's biogenic origin (i.e., biogenicity) is hampered
by the fact that inorganic processes can produce abiotic mimics of
biosignatures. Hence the need to make a distinction between a POSSIBLE
biosignature and a DEFINITIVE biosignature.

A DEFINITIVE biosignature is one that has attributes that can ONLY be
produced by life or biological activity. Until such time that a POSSIBLE
biosignature is proven to be a DEFINITIVE biosignature, the former
constitutes a working hypothesis that requires additional
characterization. AFL will contain the necessary equipment to detect
POSSIBLE biosignatures (e.g., microfossils, biofabrics, biominerals,
biomarkers, biomolecules isotopes, etc.). However, short of locating a
living or perfectly preserved cell that displays the structural
complexity indicative of biosynthesis, establishing that a POSSIBLE
biosignature is DEFINITIVE evidence for life will require further
testing. It will also be necessary to prove that a biosignature is
indigenous to Mars and not a contaminant, regardless of whether we
discover it on Mars or in rocks or sediment returned to Earth from a
future sample return mission from Mars. These considerations underscore
the need to distinguish a DEFINITIVE biosignature from a POSSIBLE
biosignature. This underscored the goal of the definitions sub group
that postulated that only by producing several mutually supporting lines
of evidence (i.e. possible biosignatures) could a definitive
biosignatures be postulated.

The lack of a conclusive set of criteria for life detection and
preservation has been illustrated recently by two debates; the search
for the oldest evidence of life on Earth and the raging debate on the
claims for life in ALH84001 (McKay, 1996). The scientific controversies
over the former debate, that of the earliest evidence of life on Earth,
have recently intensified but are still unresolved (Schidlowski, 1988;
Schopf, 1993; Mojzsis et al., 1996; Rosing, 1999; Mojzsis and Harrison,
2000; Brasier et al., 2002; Fedo and Whitehouse, 2002, Pasteris and
Wopenka, 2003, Furness 2004). The common denominator in both of these
debates is the underlying difficulty, or inability to demonstrate
conclusively the biological origin of the respective evidence, which in
either of the above cases would have to be seen as conclusively proving
the presences of fossil microbial life. However, a consensus that has
emerged from these discussions, and is now seen as a critical
requirement, is the demand for further lines of evidence in addition to
any morphological data that supports such extraordinary claims. Since
the inception of the second debate, that of life in Martian meteorite
ALH84001, it has become evident that there is no consensus on the nature
of life in extraterrestrial materials. Indeed techniques supposed to
detect life failed, for whatever reason, to conclusively detect the
presence of terrestrial organisms within this meteorite (Steele et al.,
1999, 2000, Toporski, 2000). Recent studies suggest that the mass
spectrometry experiments on the Viking lander would have missed 3x10^7^
bacteria per gram of Martian regolith (Glavin et al., 2001). These
examples are beginning to show that only by means of a
multi-disciplinary, multi-instrument scientific approach, will the above
questions be answered. It is clear that a great deal of additional
systematic experimentation and testing must be undertaken in terrestrial
environments to better determine the criteria by which biogenicity and
therefore preserved biosignatures can be quantified.

Though there are a number of ways of categorizing biosignatures,
microbial biosignatures found in ancient Earth rocks can be organized
into three categories: *bona fide* microfossils, microbially influenced
structures, and chemical fossils, also known as chemofossils (Cady et
al., 2003). Bona fide microfossils, which may include cellular and/or
extracellular remains (e.g., carbonaceous microfossils), display
structural and chemical characteristics that confirm their biological
origin. Microbially influenced sedimentary structures (e.g., biogenic
stromatolites and microbialites), display biofabrics and morphologies
known to have been produced by the presence and/or activity of biofilms
or microbial mats. Chemofossils (e.g., biomarkers and biominerals),
display chemical, isotopic, and structural characteristics indicative of
biological activity.

[]{.mark}

Among the chemical biosignatures that have been identified as applicable
to past and present biological activity on Earth are the biominerals,
that is, minerals formed by biotic processes, either directly, or
indirectly. Biominerals have been found in the fossil record that date
back to the Precambrian. It has been suggested that biominerals could be
important indicators of life and thus could play an important role in
the search for past or present life on Mars (Schwartz et al., 1992, Cady
et al 2003). Furthermore, organic components (biomarkers) that are often
associated with biominerals are believed to play crucial roles in both
pre-biotic and biotic reactions. For measurements carried out on Mars, a
crucial step will be the in situ quantification of the nature, structure
and concentration of biosignatures as a function of depth and time.

The search for biosignatures requires an extensive knowledge of the
context in which they are found. The types of rocks and
paleoenvironments that have the highest potential to trap and preserve
biosignatures on Earth and Mars include: mineralized sinters, evaporite
basins, mineralized soils, subsurface sedimentary systems, permafrost
and ground-ice (Farmer and Des Marais, 1999). Recent data from the Mars
orbiter, which suggests the presence of reduced gases of biological or
volcanic origin, indicate that gas seeps in any type of terrain should
also be targeted for possible biosignatures. On Earth, additional
criteria such as tectonic setting and alteration history are taken in
consideration when looking for biosignatures. The amount of alteration a
deposit has experienced since its time of formation is particularly
important for assessing the preservation potential of a deposit (see
next section).

Typical lithologies for searching for biosignatures of past life in
ancient terrestrial settings are similar to the ones we hope to find on
Mars. Interestingly the haematite rich sites like those found by the MER
rovers at Meridiani and Gusev may not be the ideal sites to search for
Carbon signatures due to the poor preservation of organic material in
haematite (Sumner 2004). Settings with a higher preservation potential
include aqueously deposited chemical sediments, such as cherts,
carbonates, or phosphates, which are known to be effective at preserving
biosignatures on Earth. Because the spatial scale or distribution of
such deposits on Mars is presently unknown, and because of the
difficulty of resolving mineral mixtures using available or recently
acquired remote spectral data (i.e., TES, THEMIS or CRISM), the
acquisition of data at high spatial resolution (30-100m/pixel) from
selected locations is considered a crucial precursor to defining an
adequate landing site for the AFL mission.

A critical component for identifying biosignatures on any planetary body
is the ability to assess in-situ the potential for an aqueous
geochemical environment to create and support life. As an example for
Mars, in-situ characterization could provide evidence as to whether the
chemical composition of the evaporites located in suspected ancient
water bodies were biologically influenced or possessed the chemical
parameters within which life may have existed, or may still exist.

It is almost certain to be the case that any life signature found on
Mars will become the basis for intense debate and necessary follow up
investigations. These investigations must be targeted at
characterization of any positive signal.

If investigations prove negative for all forms of carbon / biosignatures
then spatially resolved measurements must be undertaken to different
sites to ensure all reasonable target areas have been explored.

**Table 2**. Possible sources of organic carbon that need to be
distinguished in Martian samples.

  ---------------------- ---------------------------------------------------
  **Source of Carbon**   **Carbon compounds. examples/comments**

  Abiotic molecules from Amino acids, purines and pyrimidines, polycyclic
  meteoritic / cometary  aromatic hydrocarbons, chain hydrocarbons, fatty
  influx                 acids, sugars and sugar derivatives.

  Prebiotic/abiotic      Amino acids, purines and pyrimidines, polycyclic
  molecules from         aromatic hydrocarbons, chain hydrocarbons, fatty
  synthesis reaction     acids, sugars and sugar derivatives.
  process on Mars        

  Terrestrial            Condensation products derived from rocket exhaust,
  contaminating organics lubricants, plasticizers, atmospheric contaminants

  Terrestrial            Whole cells, cell components (LPS, DNA, proteins,
  contaminating          cytochromes) found on AFL itself.
  organisms              

  Terrestrial like       Organisms not present on the craft measuring them,
  organisms -- from      but had been previously transferred from Earth by
  Earth                  either meteorite impact or contamination of
                         previous spacecraft. Target molecules could include
                         individual genes, membrane constituents, specific
                         enzymes, and co-enzymes that would be expected to
                         be over expressed or adapted in Martian conditions

  Terrestrial-like       Organisms that utilize terrestrial like
  organisms -- evolved   biochemistries and have evolved on Mars Target
  on Mars                molecules could include individual genes, membrane
                         constituents, specific enzymes, and co-enzymes that
                         would be expected to be over expressed or adapted
                         in Martian conditions or organisms using
                         metabolisms that would not be present on a space
                         craft contaminant such as methanogens,
                         psychrophiles endolithic survival mechanisms.

  Non-terrestrial-like   Utilizes an array of molecules for information
  organisms              storage, information transfer, compartmentalization
                         and enzymatic activity that differ from those used
                         by extant terrestrial life. Examples would be the
                         use of novel amino acids and nucleotides or the use
                         of novel nitrogen utilization strategies.

  Fossil biomarkers      Detection of established terrestrial fossil
                         biomarkers such as hopanes, archaeal lipids and
                         steranes, for the detection of the diagenetic
                         remains of terrestrial based life. Characterization
                         of potential breakdown products that can be
                         reasonably extrapolated from the detection of
                         molecules comprising an extant Martian life form.
                         Detection of the diagenesis products of extinct
                         Martian organism based on carbon compositions
                         consistent with biological fractionation of a
                         narrow range of abiotic precursors.
  ---------------------- ---------------------------------------------------

#### 5.2.2.1 What techniques have been used to detect and characterize terrestrial and meteoritic biosignatures?

1\. Morphological observation using microscopic tools (Light, SEM, TEM,
AFM, Fluorescence). The controversy mentioned earlier regarding the
oldest fossils on Earth illustrate that it is difficult using all
available analytical tools in a laboratory to unambiguously determine if
something is truly of biological origin. Recognizing a fossil using the
criterion of shape alone poses some challenges, particularly without
actually being on the surface of Mars and knowing *a priori* whether it
has a fossil record. In contrast, observing movement in extant life is
easy. However, not all extant life moves, especially microbes, therefore
making it difficult to determine if it is alive by shape alone.
Interdisciplinary multi-instrument approaches have been shown to be
effective for studies on deep subsurface ecosystems on Earth (e.g., Fisk
et al., 2003; Steele et al., 2002; Toporski et al., 2002; Steele).

2\. Biochemical analyses. A range of analyses based on either pure
chemical or biochemical methods have proven to be useful on Earth in
determining if a sample is of biological origin. However, in difficult
cases it has usually taken several different methods of analyses to
determine if a sample is unequivocally of biological origin. Carbon
isotopes have successfully been correlated with individual Proterozoic
microfossils (House et al., 2000) and FT-RAMAN spectra were obtained on
presumed Proterozoic microfossils (Schopf et al., 2002). Furthermore,
fossil and modern bacterial biofilms have been classified using a
combination of bulk and spatially resolved measurements including XPS,
EDX, XRD, Time of Flight -- Secondary Ion Mass Spectroscopy (ToF-SIMS),
pyrolysis GCMS, GCMS, GC-IRMS confocal laser microscopy and Raman and
infrared microspectroscopy (Steele et al., 2001; Toporski, 2001;
Toporski 2002; Toporski 2004, Hall-Stoodley et al, 2004; Benning et al
2004). Only the combination of a multiple-set of instruments lead to a
unequivocal determination of the specific characteristics of biofilms.

#### 5.2.2.2 What are the challenges for AFL in the search for biosignatures on Mars?

1\. Tested Technologies. Of the techniques listed in table 1 those that
have been shown to be successful during space missions include: gas
chromatography, mass spectrometry, simple thermal analysis, Mossbauer
and some types of interactive chemical techniques (e.g., the Viking
biology experiments (see Mancinelli 1998 for review).

For Mars applications, it is necessary for the detector to be sensitive
to the picogram level and capable of responding to a broad variety of
compounds, i.e., have universal response. A flight proven detector that
is both universal and sufficiently sensitive is the metastable
ionization detector. The primary disadvantage of gas chromatography is
the small margin of error associated with the column retention times for
definitive identification of compounds, which can lead to
mis-identification of compounds with similar retention times. This
disadvantage should be minimized by use of multiple columns with
different separation capabilities (i.e., different column coatings or
packings) and calibration standards. A GC/MS has been used successfully
on space missions, including the Viking mission The disadvantages are
that the MS cannot be simultaneously tuned to be sensitive for the
analysis of low and high molecular weight substances at the same time,
and it is a bulky and heavy instrument*.* Various types of analytical
instruments equipped with different pyrolytic devices have been used
during space missions. These ranged from simple pyrolysis (combustion)
to step-wise heating of samples and measuring the power input and
temperature. Step-wise heating is usually followed by collecting any
volatiles evolved from the sample during heating, and identifying and
quantifying them by GC, or GC/MS. For example, heating samples of soil
from earth in a step-wise fashion would first volatilize adsorbed water
and gases (e.g., CO2, and lower molecular weight organic compounds) at
the lower temperatures. At higher temperatures, water from mineral
hydration, CO2 from carbonate decomposition, and volatiles from
pyrolysis of higher molecular weight organics would be released.
Although this technique allows one to analyze the evolved gases, it does
not yield any direct information regarding the nature of the sample
(e.g. clays vs. hydrated silicates). Mossbauer spectroscopy provides
information on the valence state of specific elements (i.e., Fe, Sn, Sb,
Ru, and Au), how these elements are combined in the structure of a
compound, and the magnetic properties of the sample. Mossbauer
spectroscopy can provide information about H~2~O only if it is
associated with the elements Fe, Sn, Sb, Ru, or Au. This again is an
area where micro total analytical systems and micromachining may allow
significant weight and energy savings.

2\. Non-tested technologies. Scanning electron microscopy-energy
dispersive X-ray spectrometry (SEM-EDS), which maps electron intensities
for identification of elements with atomic numbers greater than sodium,
although windowless detection allows all elements heavier than boron to
be detected. Electron spectroscopy for chemical analyses (ESCA)
quantitatively determines the valence states and bonding energies of
most naturally occurring elements (excluding hydrogen and helium). This
technique is limited to analysis of the top 1-10 monolayers of the
sample. X-ray diffraction (XRD) analysis directly and nondestructively
probes atomic scale structural correlations of mineral samples yielding
sample mineralogy along with information about the presence of H~2~O.
X-ray fluorescence (XRF) analysis non-destructively provides information
on the elemental composition of a sample for elements having atomic
numbers greater than that of boron. However, no information is given
about how those elements are combined in the sample. Rutherford
backscattering spectrometry (RBS) maps the elemental composition and
distribution measured on sample surfaces (the top 0.5 -- 3 microns).
Elements that can be analyzed by this non-destructive technique range
from Li to U. Secondary ion mass spectrometry (SIMS) analysis has a very
high sensitivity and can identify all elements including hydrogen and
deuterium. A mass spectrometer (MS) provides information on elemental
and molecular composition, including that of H~2~O, and the isotopic
abundances found in a sample. Differential scanning calorimetry (DSC),
in which the amount of heat required to maintain isothermal conditions
between the sample and an inert reference placed in a continuously
heating oven, is recorded, and the enthalpy provided directly. Sample
identification is made by examination of the patterns of exotherms and
endotherms along a temperature scale. The DSC provides quantitative data
to \~700°C. For temperatures \>700°C the signal-to-noise ratio becomes
too great. Differential thermal analysis (DTA) is similar to DSC in that
the sample and an inert reference are heated at the same rate, but to
\~1200°C. The temperature of the sample and reference are monitored
simultaneously. It differs from DSC in that when endothermic and
exothermic events occur in the sample, no attempt is made to keep the
sample and reference isothermal to each other. In DTA, the temperature
difference between the sample and the reference is recorded as a
function of oven temperature and provide the information for sample
identification. The thermogram obtained from a DTA or DSC analysis
provides information on the mineralogy and chemical composition of the
sample. Where the DTA or DSC is coupled to a gas chromatograph (GC), the
GC collects and analyzes the volatiles (including H~2~O) evolved from
the sample as it is heated.

Specifically for extant life detection interactive chemical methods were
performed as part of the Viking mission. This approach is fraught with
problems. It assumes prior knowledge of Martian organism metabolism.
Using these culturing methods only detect 1-2% of the microbes in earth
soil can be detected. A distribution mass peaks obtained by a mass
spectrometer of alkanes showing a decrease in concentration with
increasing carbon number would indicate abiotic processes. Similarly a
predominance of biogenic amino acids with an excess of the L isomer
would indicate extant or recently extinct life. Whereas, a suite of
racemized biogenic amino acids may indicate fossil life. Detection of
hopanes by Time of Flight Mass Spectrometry may also be indicative of
life. Field ATP luminometry measurements of the cryptoendolithic
communities may provides a rapid method of detecting relative amounts of
metabolic turnover in microbial communities. None of these techniques
would provide definitive evidence of life during the MSL mission.
Clearly, multiple approaches need to be done on samples to determine if
they contain viable extant organisms. For example, if organic mass gas
chromatography spectrometry analyses combined with deep UV florescence,
SEM and RAMAN all point toward life, then there is a high probability
that the sample may contain life.

## 5.3 Preservation Potential

A biosignature preservation model, guided by data from AFL, will be
critical to long term Martian life detection strategy. That is to say
that AFL in detecting carbon chemistry in various sites of possible
habitability (see definition) can indicate whether such niche areas
could preserve clues of Martian life. This must be modeled by suitable
experimentation in laboratories before suitable interpretation of any
data can be undertaken. We still do not know the exact composition of
the mysterious Martian oxidant postulated in the Viking experiments.

Long-range Astrobiological exploration of Mars will require an
understanding of the preservation potential of biosignatures. This is an
important part of the scientific logic of going from possible
biosignature to confirmed biosignature.

[Lessons from Earth]{.underline}

•[Life processes]{.underline} produce a range of biosignatures, and
[geological processes]{.underline} progressively alter and ultimately
destroy them.

•Understanding the potential for preservation has been a key part of
biosignature interpretation.

[Application to Mars]{.underline}

•We don't know the biosignatures of Martian life forms (if they exist).

•However, with appropriate data, it should be possible to postulate a
preservation model relating biosignatures as we understand them on Earth
to various Martian geologic environments. This model will likely have
important predictive value in guiding future search strategy. Models
predict that biomolecules and organisms can survive in simulated
conditions such models need refinement and to address diagenetic
processes in predicted conditions (Scheurger et al., 2003).

# 6.0 Precursor Discoveries

Relevant data may already be available but two major classes of
discovery would be of essential relevance to AFL mission planning:

######## MRO

•Sending AFL to a hydrothermal site is impossible with present
knowledge, because none are known. However, the CRISM spectrometer on
MRO is very powerful, and it has potential to discover the mineralogic
expression of hydrothermal zones.

######## Phoenix

•Phoenix will be the first lander designed to acquire and analyze
ice-bearing samples.

•It will collect data of relevance to each of the three primary
components of habitability (water, carbon, energy), and thus is capable
of returning a result which significantly improves or reduces our
interest in sending AFL to an ice-related site.

Table 3 A summary of types and amounts of biomolecules present in a
single bacterial cell and compared to known preservation potential for
such molecules.

+--------------+------------+------------+---------------------------+
| *            | **% Total  | **Number   | **Preservation**          |
| *Component** | Weight (or | of Types** |                           |
|              | mass C     |            |                           |
|              | x10^-13^   |            |                           |
|              | g)**       |            |                           |
+--------------+------------+------------+---------------------------+
| **Water**    | 70 (NA)    | 1          | Unknown in Organic and    |
|              |            |            | mineral phases            |
+--------------+------------+------------+---------------------------+
| **Proteins** | 15         | \~2000     | 1000's without protection |
|              |            |            | by a mineral matrix.      |
|              |            |            | \~45Ma with protection?.  |
+--------------+------------+------------+---------------------------+
| **Nucleic    |            |            |                           |
| Acids**      |            |            |                           |
+--------------+------------+------------+---------------------------+
| DNA          | 1          | 2+         | Oldest ? \~350,000        |
+--------------+------------+------------+---------------------------+
| RNA          | 6          | (see       | Days -- Months (studies   |
|              |            | below)     | on longevity of RNA other |
|              |            |            | than in clinical settings |
|              |            |            | have not been performed.  |
+--------------+------------+------------+---------------------------+
| *rRNA*       | 5.5        | 3          | Days -- Months            |
+--------------+------------+------------+---------------------------+
| *tRNA*       | 0.1        | \~32       | Days -- Months            |
+--------------+------------+------------+---------------------------+
| *mRNA*       | 0.3        | 1000's     | Days -- Months            |
+--------------+------------+------------+---------------------------+
| *Non coding  | 0.1        | 1000's     | Days -- Months            |
| RNA*         |            |            |                           |
+--------------+------------+------------+---------------------------+
| **Polys      | \~1        | Uncounted  | Chitin - 25Ma. Exopolymer |
| accharides** |            |            | sheaths \~2Ga             |
+--------------+------------+------------+---------------------------+
| **Lipids**   | 2          | \~50       | Cell wall components -    |
|              |            |            | Hopanes 2.7Ga             |
+--------------+------------+------------+---------------------------+
| **Amino      | 0.4        | \~100 (20  | As protein diagenesis --  |
| acids**      |            | main ones) | Ma.                       |
|              |            |            |                           |
|              |            |            | Chiral signal in fossils  |
|              |            |            | lost after \~ 1 Ma.       |
+--------------+------------+------------+---------------------------+
| **Sugars**   | \~3        | \~200      | Days to weeks (see        |
|              |            |            | polysaccharides)          |
+--------------+------------+------------+---------------------------+
| **Other      | 0.2        | \~200      | Porphyrins \~ 2 Ga        |
| small        |            |            |                           |
| organics**   |            |            |                           |
+--------------+------------+------------+---------------------------+
| **Inorganic  | 1 (\~100%  | \~20 -- 30 | Isotopes may preserved    |
| species (C,  | dry        | (including | for ? 3.5 Ga for C.       |
| H, N, O, Fe, | weight)    | inorganic  |                           |
| P, S etc).** |            | complexes) | Research is continuing to |
|              |            |            | define other isotope      |
|              |            |            | systematics for           |
|              |            |            | preservation of a         |
|              |            |            | biogenic signature.       |
+--------------+------------+------------+---------------------------+
| **Diagenetic | Total cell | Kerrogens  | Kerrogens -- ? 3.5Ga for  |
| Ma           | breakdown  | (4 types)  | biogenic (Type 1-3). Type |
| cromolecular | products   |            | 4 indicative of           |
| material**   | (100% dry  | M          | meteoritic input.         |
|              | weight of  | elanoidins |                           |
|              | cells)     | (100's)    | Melanoidins conbination   |
|              |            |            | of sugar and proteins,    |
|              |            |            | \~50 Ma.                  |
+--------------+------------+------------+---------------------------+

? -- debate over the data. Total mass of the organic inventory is based
on the assumption that most terrestrial prokaryotes contain
approximately 10^-13^ g of carbon per cell.

# 7.0 Mission Site Selection

Four subgroups were founded to begin to address the need for AFL to
respond to the discoveries and requirements for as yet to be determined
site. Through this process a core mission concept was arrived at and
presented to the engineers for costing.

There are four obvious general types of site in which the overall
scientific goal of AFL (major advance in A/B) can be pursued:

•The sedimentary record.

•Fossil (inactive) hydrothermal systems

•Sites with ice

•Sites where it may be possible to sample liquid water

We do not have enough information as of this writing to know how these
four options would be prioritized by a future SDT. Future discoveries
could have a major effect on planning. At the time of writing this
document all of the above sites may be postulated to currently exist on
Mars. The sedimentary record has been explored by at Gusev and Meridiani
by Spirit and Opportunity respectively (Squyres et al., 2004; Grant et
al., 2004; Morris et al., 2004; Kerr 2004c (commentary); Arvidson et
al., 2004; Bertelsen et al., 2004; Herkenhoff et al., 2004; Gellert et
al., 2004). Fossil (slightly active) hydrothermal systems may be
concluded from initial papers outlining the concurrence of water vapour,
shallow ground ice and methane at Arabia Terra, Elysium Planum and
Arcadia Memnoma, (See Kerr 2004a,b and c for commentary). Sites with ice
and the obvious poles or shallow "dirty" ice sites such as Phoenix
proposes to explore. Sites with possible hydrothermal activity represent
a chance to sample liquid water, although this may be at some distance
below the surface. To remain flexible to current and future discoveries
we

![](media/image4.wmf){width="5.993055555555555in"
height="3.3805555555555555in"}Figure 3 Shows the antecedent discoveries
that will impact and guide the choice of sites and final payload of the
AFL mission

## 7.1 Sediments

Here we present a mission concept with the overall goal of finding
evidence for past or present life in the Martian stratigraphic record in
an environment that is highly likely to have formed from the subaqueous
deposition of sediment in a shallow marine or lacustrine environment
such as exposed in craters at both the Spirit and Opportunity sites
(Squyres et al., 2004; commentary by Kerr 2004c).

######## Objectives

Specific supporting objectives that support this goal are to:

-   Assess spatially resolved changes in mineralogy with depth on a
    scale consistent with the depth of individual strata.

-   Determine the abundance and nature of organic chemicals at the same
    scales as above.

-   Seek information regarding water cycling from the strata, eg. is
    there free or bound water in any of the layers? Ice? Hydrous mineral
    phases?

-   Confirm the depositional environment.

-   Determine provenance of the sediment

-   Assess the fossil preservation potential of the environment. Factors
    which might be considered are temperature, rock type, local weather,
    UV flux, depositional regime as suggested by sedimentary structures

######## Approach

Central to this mission is the selection of a landing site that
possesses multiple outcrops of layered sedimentary rock. We would use
remote sensing methods that possess sufficient spatial resolution to
resolve individual layers to acquire information from several outcrops.
Subsequently, a rover would visit at least one 3D outcrop of layered
sedimentary rock, measuring variation in chemistry, mineralogy and
texture of the strata for at least 100 meters along the strike and ten
meters in the dip of the outcrop. Subsurface penetration would be an
important feature of this mission for the acquisition of subsurface
samples that are from depths great enough to extend beyond the level of
surface oxidation. This may mean accessing a depth of one meter in a
horizontal area, though it would be desirable to penetrate the exposed
bedding along the slope of an outcrop in a larger feature such as the
wall of a crater. Examining the subsurface of such beds would only
require a relatively shallow penetration (perhaps a few centimeters),
and we would then have access to the primary sediment without having to
go through the more recent Aeolian deposits.

Required measurements for meeting the scientific objectives must be
conducted at multiple spatial scales, and we recommend three suites of
instruments that can provide integrated measurements *a la* the remote
sensing, non-contact/contact and analytical suite designations
originally suggested by the MEPAG PSIG for the MSL mission. Both
spectroscopy and imaging will be key to an integrated science package,
and we assume technical progress in science autonomy before the launch
of AFL that optimizes science operations on the Martian surface.

There are several engineering /science trade issues associated with
taking a large number of measurements from a large outcrop in three
dimensions. Some of them are:

-   "Go to" mobility is required. The degree of mobility will be
    complementary to the degree of precision of the landing.

-   The ability to land in a terrain which is rougher than previous
    targets would be valuable. A priority should be given to precision
    targeting and hazard tolerance.

-   Fresh material should be exposed with a RAT or its descendent.

-   Surface penetration is also required to a level below any weathering
    layers, a few cm to perhaps a meter.

-   Sample acquisition and some processing, at least to the level of
    crushing will be required.

-   There will be a requirement for positioning---perhaps a laser range
    finder.

-   Autonomy should be plentiful---not just for the rover, but for some
    of the scientific operations in order to maximize efficient use of
    resources.

######## Landing Site Selection

One of the primary assumptions of this mission concept is that we will
have advanced in our ability to assess habitability for a range of
potential landing sites by the missions that are to precede AFL. For
example, recent inferences made regarding the environment of deposition
for the MER B landing site, Meridiani Planum would suggest that it is an
excellent candidate site for an astrobiology follow-up mission. However,
as of the time of this writing, there are few exposed examples of the
cross-bedded rock from which the shallow marine inferences were drawn at
that site. Much of the Martian surface will be mapped in exquisite
detail by the time the AFL mission site selection is made, and there are
likely to be other candidate target areas that demonstrate appropriate
geomorphological and mineralogical character to suggest deposition in a
standing body of water. For example Northeast Holden crater, may be a
good candidate; geomorphological evidence strongly suggests classical
deltaic deposition (Bhattacharya, in prep):

Figure 4 Holden crater

![](media/image5.png){width="4.192361111111111in"
height="2.1680555555555556in"}

## 7.2 Hydrothermal

Science theme: Assess past Martian Astrobiology in an inactive
hydrothermal system.

The apparent harsh climate at the surface of Mars suggests that, should
life exist on Mars, the most likely energy source would be subsurface /
chemosynthetic rather than surface / photosynthetic. Hydrothermal
systems are attractive sites for Astrobiological exploration because
they contain all of the requisites for the origin and maintenance of a
biosphere and the subsequent preservation of its biosignatures. In such
systems, water is typically present in the liquid state in a
near-surface environment. Both thermal and chemical energy are made
available for use by chemosynthetic organisms as a result of water-rock
interactions. Common reactions between mafic/ultramafic minerals, water
and volcanic gases such as CO~2~ lead to the formation of reduced carbon
compounds that could have been the building blocks of early life.
Secondary mineralization of hydrothermal deposits by carbonate, silica,
and other hydrothermal precipitates can preserve evidence of prebiotic
carbon chemistry as well as evidence of life. Finally, while the bulk of
a hydrothermal system is quite likely to be beyond detection in the
subsurface, surface expressions of such systems should be
morphologically and mineralogically identifiable from space. However,
even when surface expressions of hydrothermal systems are missing or
cryptic, impact gardening, mass wasting and simple erosion by wind or
water will dissect and expose such systems over geologic time. The
detection of the correlation between the concurrence of water vapour,
shallow ground ice and methane at Arabia Terra, Elysium Planum and
Arcadia Memnoma, may indicate such a system exists in these areas (See
Kerr 2004a,b and c for commentary).

**Finding hydrothermal areas:**

At present, we know of no *bona fide* hydrothermal zones or regions on
Mars. However, the apparent association of fluvial features with
volcanic terrains in many places on Mars suggests that such areas must
be common. One can deduce from the young crystallization age of most
Martian meteorites (which appear to post-date major fluvial/lacustrine
features on the planet) that volcanism and (presumed) associated
hydrothermal activity persisted throughout Mars history. Indeed, a
number of Mars meteorites (including the famous meteorite ALH84001)
contain carbonates or minor hydrous phases suggestive of a hydrothermal
setting (Treiman et al 2002).

Clues to the presence of fossil (inactive) hydrothermal zones include
morphological, mineralogical and chemical features. A morphological
feature could consist, for example, of a spring mound (positive
topographic feature) associated with evidence of water flow. A
mineralogical feature could consist of surface deposits of carbonates,
silica, etc. Global surveys of hydrogen in the near-subsurface,
discussed largely in the context of near-surface water, could in some
cases represent hydrated mineral phases associated with hydrothermal
features.

Future missions will provide clues, perhaps even compelling evidence of
past hydrothermal activity. The Mars Reconnaissance Orbiter will have a
high-resolution camera from which morphological data will be obtained.
CRISM will provide high resolution chemical or mineralogical maps of
surface features. Orbital or landed neutron detectors and radar sounding
devices could provide maps of near-surface water over large areas of the
Mars surface. The '07 Phoenix Scout mission, as well as Mars '09 MSL
will provide *in-situ* information on both morphology and mineralogy at
the sub-meter to sub-millimeter scale.

Five possible landing site hydrothermal geologic settings are
envisioned:

1.  [Point source hydrothermal zones (igneous-driven convection
    systems]{.underline}).

Point source hydrothermal zones are well known on the Earth -- as for
example those present in Yellowstone National Park (a continental-type
environment) (e.g., Walter and Des Marais, 1993) or at the mid-ocean
ridges (oceanic-type "black smokers") (e.g., Kelly et al., 2001). These
features should be identifiable by their morphology and their
mineralogy/chemistry (Farmer, 1998). High-resolution mineralogical data
should allow the identification of systems such as these, which may vary
in size from kilometers (Grand Prismatic hot spring, the largest hot
spring on Earth, is \~1 km in size) to meters in size. Mineralogical
signatures of these systems range from monomineralic deposits (silica,
carbonate, sulfide, oxide) to polymineralic assemblages. In general, the
areal extent of hot springs, which are the surficial expression of
point-source hydrothermal zones, are dwarfed when compared to the volume
of hydrothermally altered rock in which chemosynthetic life could live
in the subsurface (Cady et al., 1997). As a result, even without a large
surface expression of hydrothermal activity, one could search for
hydrothermal alteration minerals similar to those found around ore
deposits on Earth (Horn, 1996). Surface and near-surface deposits of
hydrothermal systems will contain a variety of alteration minerals that
vary as a function of the underlying mineralogy of the system (e.g.,
oxides, carbonates, sulfates, hydrated minerals, etc).

2.  [Impact-generated hydrothermal systems (craters).]{.underline}

Newsom et al. (2001) reviewed many of the key concepts that support a
search strategy for life on Mars in aqueous and hydrothermal deposits
associated with Martian impact craters. For example, impact craters on
Earth (e.g., the Sudbury impact crater, 1.85 Ga ; \~250 km diameter in
Sudbury, Ontario) contain extensive evidence of post-impact hydrothermal
activity. Impact melt and uplifted basement heat sources could sustain
hydrothermal activity and keep crater lakes from freezing for thousands
of years, even under cold climatic conditions (Newsom et al., 1996).
Post-impact fluids could result from dewatering of deeply buried
hydrated materials, and the breach of local aquifers or regional
cryospheres. The lifetimes of impact-generated hydrothermal systems
depend on the size and cooling rate of the heat source, the permeability
and depth of the disturbed zone, the presence of deeply buried water or
hydrated materials, and the rate of burial of the impact melt (e.g.,
Newsom et al., 2001). The lifetime of hydrothermal systems, which is
perhaps long enough to create or sustain a biota, has been estimated as
10^4^ -- 10^5^ years for terrestrial craters 100 km in diameter, and up
to 10^6^ years for 180-km diameter craters. Impact-generated
hydrothermal zones may be quite common in areas of subsurface water or
permafrost, such as those areas present in the high latitudes. The
surface manifestation of such a system could be mineralogical or
morphological, but would be co-located with an identifiable impact
structure from which it was generated.

3.  [Serpentinizing terranes]{.underline}.

The single most widespread environment of *chemical* disequilibrium on
present-day Earth is the oceanic crust (Deming and Baross, 1995;
McCollom and Shock, 1997). The composition of the modern lower crust and
upper mantle of the Earth is essentially the same as that of the early
Earth and Mars (Nisbet, 1987; Longhi et al., 1992), and the early
histories of these two planets are similar. It follows that an
understanding of these zones of chemical disequilibria on Earth would be
of great value in devising a search strategy for similar regions on
Mars.

In addition to being potential sites for the genesis of life,
hydrothermal systems associated with serpentinization are also excellent
candidate sites for the study of prebiotic biogeochemistry. On Earth
there is abundant evidence for the formation of abiotic organic
compounds along the modern mid-ocean ridge system where it has been
linked to serpentinization (H~2~ source) and hydrothermal activity (Rona
et al., 1992; Bougault et al., 1993; Charlou and Donval, 1993; Holm and
Charlou, 2001; Schroeder et al., 2002; Kelley and Fruh-Green, 1991;
2001). Serpentinization has also been linked to hydrogen and methane
generation onshore in association with ophiolites (Neal and Stanger,
1983; Abrajano et al., 1988). This may also be an explanation of the
observations of methane in the Martian atmosphere (Kerr 2004a,b)

An excellent example of subsurface life on Earth is associated with the
"Lost City hydrothermal complex" located in an off-axis area of the
mid-Atlantic ridge hydrothermal system (Kelley, et al. 2001). Similar
sites have been described elsewhere (Chapelle et al, 2002; Stevens and
McKinley, 1995; Mottl et al., 2003). In locations such as this,
ultramafic rocks from the oceanic crust react with water to form
secondary minerals such as serpentine. The process is exothermic, and
yields a volume increase of nearly 60%. This type of hydrothermal
activity is distinct from all others in that no external source of heat
is required (the heat generated by the reaction is sufficient to
initiate or perpetuate the system), and the volume increase produced by
the reaction results in a self-perpetuating system in which cracks
formed in freshly altered material create pathways for water to react
with fresh ultramafic rock. The process of serpentinization, through
which olivine and pyroxene are altered into serpentine minerals, can be
generally described as:

olivine + H~2~O = serpentine + brucite + magnetite + H~2~ (1)

and

olivine + pyroxene + H~2~O = serpentine. (2)

Reaction (1) could provide a biological energy source through the
production of H~2~, the basis for many chemoautotrophic biochemical
processes, including methanogenesis (CO~2~ + 4H~2~ = CH~4~ + 2H~2~O).

The serpentinization process should be relevant to present-day Mars,
which lacks plate tectonic processes, and even to an ancient Mars that
never developed standing oceans or large-scale plate tectonics. The
apparent widespread distribution of olivine-rich basalts at the surface
of Mars as well as reported outcrops of olivine on the Mars surface
(Hoefen et al., 2003) suggest that interactions of ultramafic rocks with
water might have been commonplace in the past.

4\. [Meridiani type areas -- hematite or water-associated
mineralogy]{.underline}.

Prior to the MER missions, remote and spectroscopic images of Sinus
Meridiani suggested an ancient (\~4 Ga,) wind-eroded subarial or
subaqueous sedimentary comprised of 10-15% hematite. As reviewed by
Christensen et al. (2000), five possible mechanisms that involve water
could explain the formation of the hematite deposit at Sinus Meridiani:
(1) direct precipitation from standing, oxygenated Fe-rich water; (2)
precipitation from Fe-rich hydrothermal fluids; (3) low-temperature
dissolution and precipitation through mobile ground-water leaching; (4)
surface weathering and coatings; and (5) thermal oxidation of
magnetite-rich lavas. Allen et al., (2001) discussed, on the basis of
terrestrial examples, the possibility that a Martian hematite deposit
could be associated with microbial mediation and discussed: (1) four
possible mechanisms for producing banded iron formations; (2) the
accumulation of iron oxides in hydrothermal deposits; (3) formation
mechanisms for iron-rich laterite and ferricrete soils; and (4) the
association of bacteria that can oxidize ferrous to ferric iron at
neutral pH in rock varnish. It is clear from the recent discovery of
buried and exhumed hematite concretions and impact ejected hematite-rich
rock near the MER landing site that the area exposed to iron-rich fluid
is quite extensive, and much remains to be learned about its origin
(Squyres et al., 2004, Kerr 2004c commentary). Such sites are important
not only for elucidating the history of water on Mars but also because
aqueous mineral precipitates could preserve evidence of an early biota,
prebiotic chemistry, or exogenous delivery of organics to the planetary
surface during the heavy bombardment period.

5.  [Sub-ice Volcanos]{.underline}

A distinctive source of hydrothermal fluids and water-rock interaction
is volcanic eruptions into ice or icy regolith. These eruptions
necessarily involve heat, liquid water, and reactive rock (fresh lava),
on which a biota could thrive. Evidence of "catastrophic outflows" of
water from beneath polar caps is reminiscent of similar environments in
Iceland and elsewhere, where sub-ice volcanism might create habitats for
life. Evidence of habitable under-ice environments might reside within
frozen outflows that extend outward from the margins of the polar caps.

The advantages of seeking sub-ice volcanos on Mars are: \[1\] Volcanos,
ground ice, and surface ice are known to be present, and \[2\] Sub-ice
volcanos produce distinctive landforms, easily recognized from orbital
imagery. Point eruptions beneath ice produce a characteristic landform,
a tuya -- a sharply bounded mesa, capped by lava flows, and commonly
with volcanic cones and flows visible on its top (Allen, 1979; Hodges
and Moore, 1979). Fissure eruptions beneath ice produce distinctive,
parallel Moberg ridges (Allen, 1979). Many hills in Mars' northern
plains resemble tuyas, at least in Viking imagery (Allen, 1979; Hodges
and Moore, 1979), and the Valles Marineris interior deposits have been
similarly interpreted as tuyas (Chapman et al., 2003).

## 7.3 Ice 

Science Theme: Assess the potential for Habitation in Icey samples

All life on the Earth is constructed from 2 major ingredients: Water and
organic carbon. One of the basic investigation AFL will perform is the
identification and inventory of organic carbon species on the Martian
surface. The understanding of the nature and chemistry of carbon on Mars
can help elucidate astrobiology principals and help us understand the
potential of Mars as an enclave of life. The other key ingredient of
life, water, has been shown to be present in the polar caps as well as
mixed in the regolith at higher latitudes. Therefore a search strategy
including exploring a sites that contains a significant amount of H~2~O
(i.e. follow the water) is a possible mission scenario for AFL.

Orbital data has indicated that there exists sub surface water ice in
large quantities, as well as making up the majority of the northern
polar caps. Mars Odyssey has detected large amounts of subsurface
Hydrogen, especially accessible in the northern plans indicating that
there exists a reservoir of subsurface H~2~O (Feldman et al. 2002,
Anfimov et al. 2002). This water has been systematically moved from the
low latitudes where geologic features indicate there was water present
at one time and redistributed in the higher latitudes region (Mellon and
Jakosky 1995, Crisp et al. 2000).These permafrost like regions
constitute a mixture of regolith and H~2~O that is accessible in the
upper few meters and is accessible by a rover. The current orbit Mars
Express orbiter will be deploying the MARSIS orbital radar to better map
the subsurface water distribution, and the up coming SHARAD instrument
on the Mars Resonance Orbiter, will be able to produce maps of
subsurface water to a better resolution and sensitivity then is possible
from the Odyssey data. This mapping of the subsurface H~2~O will enable
a determination of the accessibility from a rover type platform, and
hence its likelihood of exploration by AFL.

[]{.mark}

While the current temperature and pressure conditions on Mars does not
allow for stable liquid water on the surface, it potentially can exist
in a meta stable state in some specific environments (Hecht 2002).
Additionally, it has exited in the geologic past when Mars possessed
different orbital and atmospheric conditions which allowed liquid water
in at least transient states (Malin and Edgett 2003). This can be
demonstrated by numerous geomorphoicial features, photographed from
orbit, which were created by large amounts of liquid water as well
recent evidence found by the MER rovers of evaporative deposits from
standing water (Squyres et al. 2004). If life formed on Mars it may
still exist in an environment where it has access to H~2~O and energy to
sustain itself. If life never started, discovering the differences
between Mars and Earth is vital for the determination of how prevalent
life is in the universe. Visiting a site with ice can help us understand
both possibilities.

Life also has the ability to exist in terrestrial environments where the
temperature is below 0°C for a vast majority of the time. These
organisms can exists in environments where only occasionally does the
temperature rise above freezing, (Nienow, et al. 1988; Friedmann, et al.
1993), in regions where it reduces the freezing point of water by
existing in either brine solutions or excreting chemicals to lower the
freezing points of the water (Junge, et al. 2004) and by potentially
becoming dormant only to repaired itself in intervening thaw periods
(Thomas, et al. 2000; Bakermans, et al. 2003; Gilichinsky, et al. 2003).
These vastly different terrestrial settings all have analogies on
present day Mars which makes them interesting targets for Astrobiology
in situ science.

Finally, there is the exciting possibility that a preceding Mars lander
mission making a compelling discovery and having AFL return to that same
location. By visiting the same site that a previous mission has
explored, at least some of the preliminary reconnaissance of that
region, can be accomplished. For example, the Phoenix 2007 scout lander
will be performing investigations of the chemical compositions of the
soil including bulk constituents and mineralogy (TEGA with MS) and
astrobiologically important characteristics (MECA) such as Redox
potential, pH, and trace metal content, among others, in a region of the
Northern permafrost regions. If compelling science discovery is made at
this landing site, a follow up mission will be able to expand upon the
discoveries. This can be thought of as being analogous to the early
practice of planetary flybys followed by orbiters, and then eventually a
lander or two. There are also possible discovery driven missions in
response to MSL in 2009, and a scout mission in 2011 which an 2018 AFL
can capitalize on.

*[Proposed Landing Site Geologic Setting]{.underline}*

Recent orbital data from Mars Odyssey has located potential water ice
that can be accessible to a rover with access to the near subsurface (up
to 2 meters) (Boynton, et al. 2002; Mitrofanov, et al. 2002) in vastly
different geological settings of high latitudes. We have identified
several of those sites as potential sites for exploration by the AFL to
include but not be limited to:

-   Northern Polar Caps

-   Northern Polar Layered Deposits

-   Northern Permafrost regions

-   Site with recent evidence of ground melt

The northern and southern polar caps are different both in composition
and geologic setting (Thomas, et al. 2000). This includes the age of the
deposits in which the southern cap can be 2 orders of magnitude older
then the northern one (Herkenhoff 2000; Thomas, et al. 2000) The
northern polar caps offer a better target for AFL exploration then the
southern cap due to H~2~O (Vs CO~2~) and geological formations including
layered deposits which can have a record of part geologic and
climatologic activity (Thomas, et al. 2000). These polar layered
deposits can be created by Aeolian processes which can strip material
from the base of the scarp. A mission to the polar caps would obtain and
analyze ice cores for remnants of biological activity. Orbital data
indicates that recent activity Martian gullies has taken place, and that
this can be a result accompanied by submission and ablation (Howard
2000; Edgett, et al. 2003) of ground melt (Malin and Edgett 2000). This
indicates that there is some cycling of material in the near surface
ground which has potentially huge astrobiology relevance.

*[Proposed science objectives and requirements]{.underline}*

The science objectives for the mission to an ice rich environment
include the search for both extinct and extant traces of life. Due to
the different types of sites that can be visited, these science
investigations require different payload accommodations which would need
to be made when the instruments are selected to fully maximize the
science return for the AFL. The universal science objectives for any
exploration of ice rich environments include:

-   Detect the geo-chemical remains of extinct life.

-   Determine the potential for extant life in an environment where
    H~2~O is present.

-   Detect of dormant organisms in an environment which can periodically
    contain liquid water.

-   Determine if extant life is in contact with the Martian atmosphere
    elsewhere on the Martian surface.

-   Understanding the long term climate and geological evolution to
    determine if Mars could have been habitable in the past.

One underling theme of astrobiology is the differences in planetary
evolution and how that relates to habitability of planets. If Venus,
Earth and Mars all formed in the "Habitable zone" of the sun why is
Earth the only one to be teaming with life? An AFL mission to high
northern latitudes can help elucidate this concept, by helping to
understand both geologic and climate changes on Mars over it's history.

Ice exists on Mars in vastly different geologic settings and therefore
there are several major differences in the science requirements both
with respect to ice bearing regions as well as other Martian regions
(i.e. sedimentary and hydrothermal environments). Here we will discuss
science requirements that span the different geologic settings, above
and beyond what the core AFL science requirements. As mentioned
previously life can exist in these locations by either becoming dormant
until conditions exist where the temperature is above freezing point of
water, or by creating pockets of liquid water by lowering the freezing
point of water. Determining if an acquired sample contains liquid water
requires the collection of sample without raising the temperature above
the local melting point of water (keeping in mind that the concentration
of brines in the sample can dramatically lower the melting point below
0°C). The determination of liquid water in a sample is not necessarily a
measurement of life, because liquid water can exist in meta stable state
in some Martian environments without being associated with life (Hecht
2002). However, samples containing liquid water would be a priority
target to be analyzed by the analytical laboratory instruments. In the
Northern polar layered deposits the measurement of strata of layered
terrain to see potential differences in layering and effects due to
Aeolian processes. This would require imaging at several spatial scales.

A determination of the yearly cycling of CO~2~ and H~2~O will not only
lead to a better understanding both current and past atmospheric
dynamics (Clifford, Crisp et al. 2000) it can potentially identify if a
biosphere is in contact with the surface elsewhere on the surface.
Recent discovery of methane in the atmosphere from both ground based
observations and from the Planetary Fourier Spectrometer (PFS) onboard
the ESA's Mars Express, although most likely not from biologic process,
demonstrates that a better understanding of atmospheric process are
needed (Kerr 2004a,b). If biology is in contact with the atmosphere,
this maybe detectable from orbit (i.e the recent measurements of
methane) but whether life produced these gases can only be ascertained
by painstaking surface measurements.

*[Science Trades]{.underline}*

Because potential ice missions have different geologic regions there are
several science trades that can be made so as to maximize the science
return of the mission. The first science trade that can be made is the
level of mobility requirement. For missions to the permafrost regions
and on the polar caps potentially require very little mobility (only
10's to 100's of meters) depending on high resolution orbital mapping by
Mars express and Mars Reconnaissance Orbiter. Current orbital data on
those scales indicate not much difference in geologic setting over km
distances. Therefore large surface mobility could be not as
scientifically important as it is for other regions. There would be,
however, a need for greater subsurface access including drilling well
below 1 meter to increased ice concentrations. Therefore a potential
trade of horizontal distances vs. depth, would need to be made

On the other end of mobility spectra is the recent ground water site
which can require large "goto" capability of at least the level of the
landing precessions if of a landing ellipse can be placed near that
site. This may require mobility in the 10's of km, similar to what would
be required in the sedimentary region.

The nature of high latitude northern sites indicate that for extended
missions nuclear power is most likely the only feasible alternative for
mission power generation as Mars progresses through its year. However,
for more equatorial missions solar power can be a feasible alternative
especially given the projected longer lifetimes that the on going MER
missions are demonstrating. This trade will depend on the expected
duration of the mission and ground operations and ability to land at
high latitudes as set forth in the science requirements.

*[Site Specific Measurements and sample handing and preparation
requirements]{.underline}*

Measurement requirements are dependent on location. The measurements
that are required for ice missions resemble the instrument complement
for the other missions scenarios postulated (hydrothermal, and
sedimentary deposits) and the measurements requirements can be found in
section 8.2. Here we discuss measurement requirements specific to ice
regions.

[Remote instruments]{.underline}

Mast based instruments must be able to do visual site reconnaissance at
a level at least as well as PanCam on MER. Identifying potential targets
from the distance of a daily traverse should be a requirement so that
interesting samples can be targeted. Remote mineralogy of potential
samples from a distance of 10 meters so that samples can be identified.
The remote mineralogy instruments may have to account for ground frost
when choosing a spectral range for a mast-based instrument. These
requirements are virtually the same regardless of the environment AFL
explores. In addition, if AFL is going to perform subsurface sample
acquisitions in a high H~2~O environment, some subsurface reconnaissance
must be done, especially if H~2~O varies dramatically in depth over 1
meter scales. A body-mounted detector capable of reconnaissance styled
elemental abundances would also be desirable measurement if feasible and
kept within the cost cap of the mission. This measurement could detect
high potential astrobiological sites, as well as ground truthing orbital
data. Finally, for polar cap missions, the cycling of H~2~O and CO~2~
and the interaction of those molecules from the surface to the
atmosphere needs to be determined. The Martian atmospheric dynamics is
not currently in equilibrium (Clifford, Crisp et al. 2000) (i.e. Aeolian
processes, ablation and sublimation) Determining the atmospheric polar
properties can help put a constraints on atmosphere compositions and
help determine if a biosphere presently exists, as well as long term
possibilities that a more favorable climate once existed. This is
especially true given the recent detection of methane in the atmosphere
at trace levels by both ground and orbital observations.

[Contact Instrumentation:]{.underline}

The instrument delta between AFL ice and other AFL missions is that
direct detection of liquid water present in a sample needs to be made.
The Phoenix lander is attempting to make this measurement as well, and
lesions learn in that mission will affect the design of this
measurement. For mission to the polar cap, any contact instrument will
also have to account for the ice core that is being obtained.

[Sample Acquisition and Processing:]{.underline}

All of the hardware infrastructure referred to in this environment must
be able to handle relatively large amounts of water. This includes the
drills, corers, and precession sample processing and distributions
stations. Water can interfere with the drilling process either by making
material harder to drill into or by melting and creating a mud like
material that can interfere with machinery. Drilling into this material
without melting the water or using drilling fluids will need to be
developed and demonstrated in both a relevant terrestrial environment
and under simulated Martian conditions. Finally, for missions to the
polar cap, a different sample acquisition system will need to be
developed. This instrument will have to be able to melt and sublimate
any CO~2~ or H~2~O while collecting impurities in the ice material.

## 7.4 Water

*[Science Theme]{.underline}*

Assess present (*and past?*) Martian astrobiology by studying liquid
water in the shallow subsurface.

*[Proposed science strategies]{.underline}*

-   Drill, core, or otherwise obtain liquid water sample.

-   Determine concentrations of redox sensitive aqueous compounds,
    including O~2~, H~2~, HCO~3~^-^, NO~3~^-^, Fe^2+^, SO~4~^2-^, H~2~S,
    NH~4~^+^.

-   Determine presence (if possible, concentrations) of DOC and aqueous
    organic monomers, including carboxylic acids, amino acids, sugars,
    hydrocarbons (or should be target functional groups instead?).

-   Determine presence (if possible, sequence or composition) of organic
    polymers, including proteins, lipids, nucleic acids.

-   Visualize microbial cells (if present) with light microscopy on
    stained and/or unstained cells.

-   Carry out microculturing on 1-3 samples using tens to hundreds of
    pre-designed growth media at several different temperatures.

# 8.0 Core Mission Components 

As discussed in sections 6 and 7, there currently are multiple possible
variations on the AFL mission theme. Opinions differ as to the specifics
of these variations in terms of context and priority, which may lead to
revisiting the chosen site if selected. However, the AFL-SSG feels that
it is possible to define an invariant core, which is common to most
versions, along with a discovery-responsive and competition-responsive
cap.

The proposed mission requirements to ensure the greatest scientific
return for the AFL mission include:

-   "Go-to" mobility (ability to access a specific target).

When sites are identified from orbit that possess high astrobiological
interest (see Section 6.0) the rover has to be able to access them, even
if the nearest safe landing site is 10's of km away. The rover also has
to explore several different regions within a high interest site. An
example of this is Holden Crater (see Section 7.1) in which what
resembles an ancient river delta is clearly visible in orbital images.
Exploring the specific features found there would require not only a
landing ellipse directly outside the feature but the ability explore
several different locations several km's apart within the potential
delta system.

-   +60 to --60 (seasonal polar cap) for sedimentary/hydrothermal. +45
    to +85 for ice mission (See section 7.3).

-   Precision landing (1 km) and the ability to land in terrain that is
    rougher than we have targeted in the past (hazard tolerance, hazard
    avoidance).

In order to access more of the planet for exploration by AFL, as well as
limiting costly "Go-To" traverse, having a suitable landing ellipse
smaller then 10km is required. This enables access to regions like Melas
Chasma, where suitable landing ellipses greater then \~5 km prove
difficult to identify.

-   Subsurface access of 1-3 m, and multiple holes. Probably also have a
    need to expose / drill into material in outcrops .

Organic material on the Martian surface may be extremely scarce,
primarily due to an oxidizing layer thought to exist because of UV
fluxes at the surface. How far down this oxidant penetrates is not
presently known or constrained, therefore shallow (\<3 meters)
subsurface material may be void of organic material. Accessing and
analyzing this material may indicate if extant life is possible in a
protected subsurface environment. However, if the surface regolith is
largely made-up of unconsolidated material, organic free material may be
thoroughly mixed by several billion years of global dust storms. In this
scenario all organic material may have destroyed down to \>3 meters,
making analysis of this material a lower propriety (hence not a
requirement). Subsurface access of potential bedrock and out-crops is
highly desirable in any scenario where it is present.

-   Organic contamination: be able to collect and deliver Earth-clean
    samples to on-board laboratory

It is a requirement to have samples that are not contaminated by
terrestrial organics to a level greater then the minimum level of
detection of the astrobiology specific instruments. See report of the
Organic contamination Science Steering group (Mahaffy et al., 2004).

[]{.mark}

-   Sample preparation including spatially controlled precision
    sub-sampling and liquid extractions for selected high-potential
    samples.

The AFL-SSG has determined that identifying the best possible sample for
analysis is a primary requirement for a future AFL mission. See section
8.3 for a discussion of these requirements in more detail.

## 

## 8.1 Payload strategy

It was determined that payload characteristics could be defined as core
to any potential AFL mission concept as described in Section 7. These
include:

-   Acquiring the right sample.

In order to maximize the probability of detecting biosignatures in a
***location with the high general habitability potential*** has to be
identified. Several of the reconnaissance missions (see section 6), will
be used to identify this location. In identifying the location, the
***understanding of the preservation potential*** of this location must
be better understood. The Earth is inundated with biological material,
where most (if not all) sites on the surface (and possibly the
subsurface) should have a continual influx of biologic material. On Mars
this is not the case. A location on Mars which once supported life, may
not have any record of that life, due to chemical interactions, or by
meteoritic impacts. Understanding how a site on Mars preserves a record
of past life is essential toward acquiring the right sample. In this
regard there is the need to be able to access samples with the highest
probably of being astrobiologically important. This includes both
***identification of specific samples*** as well as the ***ability to
acquire that sample***.

-   Understanding the geological, mineralogical, and chemical context of
    that sample

The labeled release experiment aboard Viking, released nutrients into a
Martian regolith sample to determine if metabolism took place. The
results of this experiment on their own can indicate that metabolism was
taking place. However when taken with the GC/MS data it was generally
understood that a chemical reaction was taking place within that sample
due to the oxidants present in the surface material (Mancinelli 1998). A
complete understanding of the relationships between geological,
mineralogical and chemical characteristics of the sample is needed to
determine Astrobiologically implications of analytical measurements.

-   Identifying the best place on the sample

Instead of introducing a core into a bulk rock crusher, in which most of
the material will not be analyzed, it was determined that sampling of
small features of a sample would be required. Section 8.3 describes this
precision sub-sampling in more detail.

-   Performing at least 3 different Astrobiologically related
    measurements.

The detection of biosignatures on Mars would, to put it mildly,
fundamentally change our perception of life else where in the universe.
In order to avoid ***potential false positives***, three separate
measurements would need to be preformed on a sample to confirm any one
measurement. Furthermore, repeat measurements will also help to avoid
***false negatives***. Since Martian life may be very different from
terrestrial life, different measurement techniques may return a
positive, while others measurements may miss more subtle signs that life
is present in the samples. If one or two instruments detect interesting
signatures, future missions can be designed to further explore the same
site for these signatures.

## 8.2 Core Measurements and Instrumentation

As stated in Section 5.2, the proposed overall scientific objective of
AFL is, for at least one Martian environment of high habitability
potential, to further investigate the potential for habitability, the
potential presence of the chemical precursors of life, the potential for
preservation of biosignatures, and possible signs of life. This is to be
accomplished through measurements supporting the following
(un-prioritized) detailed ***Mission Objectives***:

1.  Within the region of Martian surface operations, identify and
    classify environments (past or present) with different habitability
    potential, and characterize their geologic context.

2.  Quantitatively assess habitability potential:

    1.  Measure isotopic, chemical, mineralogical, and structural
        characteristics of samples, including the distribution and
        molecular complexity of carbon compounds.

    2.  Assess biologically available sources of energy, including
        chemical and thermal equilibria/disequilibria.

    3.  Determine the role of water (past or present) in the geological
        processes at the landing site.

3.  Investigate the factors that will affect the preservation of
    potential signs of life (past or present) on Mars.

4.  Investigate the possibility of prebiotic chemistry on Mars
    (including non-carbon chemistry).

5.  Document any anomalous features that can be hypothesized as possible
    uniquely Martian biosignatures. This will constitute a set of
    working hypotheses, which will need refinement and further testing
    on Mars.

The following ***Measurement Requirements*** for the AFL Core, derived
from these objectives, were specified in order to support the instrument
development and selection process for AFL:

A.  **Comprehensive Imaging** - Fully image the overall landscape and
    each investigation scene to assess the variety of local environments
    (past or present) that can be discerned from expressed surface
    features such as outcrops. Include both color optical stereo imaging
    and higher-resolution long-focal-length telescopic imaging of key
    areas of high interest for further investigation of habitability
    potential. Target range is 1 m to infinity/horizon. High
    magnification or high resolution imaging should be able to discern
    layering at the 10 cm scale from a distance of 1 km. These
    measurements support the decision to focus more closely on specific
    sites, targets, and samples. *Supports Objectives: 1*

B.  **Definitive Mineralogy and Chemistry** - Determine mineralogical
    and chemical (elemental) composition at all scales of investigation:
    *site/scene surface reconnaissance scale* (range: infinity/horizon
    to meter; resolution: km to cm), *hand-sample scale* (range: meter
    to cm; resolution: cm to mm), and *acquired subsample scale* (bulk
    measurement of a few-mm subsample with high accuracy), with
    respectively increasing degrees of definitiveness and sensitivity.
    *Supports Objectives: 1, 2, 3.*

C.  **Redox Potential** - Assess the redox potential and oxidation
    chemistry of the near-surface environment. This measurement details
    how much energy is available for an organism to use in growth and
    reproduction and would be required to be measured to a precession of
    10 mV. *Supports Objectives: 2, 3*

D.  **Fine-Scale Surface Analyses** - Investigate the surfaces of
    exposed or acquired samples at fine scales for morphological,
    chemical, and molecular signatures suggesting preservation of
    pre-biotic or biotic organic compounds. This may include
    directly-detected compositional markers, evidence of minerals formed
    in or altered by liquid water, or particular sample textures (i.e.
    concretions). Color optical imaging with resolution below 30 μm
    (although for bacterial analysis in anything other than a
    macroscopic biofilm structure this would be inadequate) within a
    larger field of view should provide the context for co-focused
    spectroscopic tools such as UV-excitation fluorescence, laser Raman,
    or other fine-scale techniques to perform chemical signature
    detection. Spectroscopic tools must be able to analyze mm-scale
    regions on surface or drill core samples (e.g., through a focused
    excitation source or through high imaging/detector resolution).
    These surface measurements provide first-order astrobiological
    analyses and support the intelligent selection of subsamples to be
    processed in the analytical laboratory. *Supports Objectives: 2, 4,
    5*

E.  **Subsample Biosignature Analyses** - On selected subsamples,
    perform an array of high-sensitivity, mutually-confirming laboratory
    investigations related to astrobiology goals. *Supports Objectives:
    4, 5*

    1.  The identity, abundance, and isomeric distribution of carbon
        compounds should be thoroughly analyzed to low detection levels
        (ppb or below by weight within bulk \~10^2^ mg subsamples) and
        to high molecular weights (hundreds to thousands of Da) at high
        peak resolutions (\~2000 FWHM). Measurements utilizing broadband
        techniques such as pyrolysis GC-MS should be configured to
        enable the detection of less volatile species that are
        particularly relevant to determining preservation of
        biosignatures.

    2.  The isotopic ratios of H, C, N, O, and S should be characterized
        with sufficient precision to enable biogenic, environmental, or
        meteoritic fractionation trends to be identified based on
        requirements determined from MSL and other measurements
        (sub-per-mil to % levels). Compound-specific ^13^C/^12^C ratios
        coupled to the analyses in (1) are highly desired. Additional
        isotope ratios that further characterize atmospheric loss and
        other environmental fractionation processes relevant to
        astrobiology are also desired. Analyses may also be conducted on
        atmospheric samples to provide a more complete understanding.

    3.  Highly sensitive tests for the presence and characteristics of
        specific biosignatures should be conducted on bulk subsamples or
        isolated downstream extraction products (e.g., phases or
        concentrates). Biosignatures of particular interest include
        molecular compounds (or abundance patterns thereof) of
        distinctly biological origin as known on Earth, indicators of
        extant metabolic processes such as disequilibrium chemistry
        (molecular, biogeochemical, agent response, etc.), as well as
        chemical and morphological traces of such compounds and
        processes as preserved in the mineralogical microenvironment
        sampled. While the specific tests to be conducted will depend on
        the chosen AFL landing site and previous mission results,
        *examples* include detection of amino and nucleic acids, lipids,
        and proteins (with ppt detection limits if possible); chirality
        of amino acids and sugars (with %-level enantiomeric excess
        detection sensitivity); detection of concentrations of distinct
        molecules or isomers of the potential abiotic inventory that may
        represent the use and or concentration of a fraction of the
        molecules available through non biological interactions and
        finally direct detection of microbes, cells, or their fossils.

It must be mentioned that the advent of micromachining and the concept
of micrototal analysis systems (uTAS) mean that through miniaturization
the payload described may be integrated into a very small space whilst
retaining accuracy and possible increasing analysis times.

The above information is summarized graphically in Figure 5.

Within the proposed AFL strategy, techniques to address the above
requirements are structured in "tiers" following the expected level of
physical sample contact: remote/standoff; contact; and laboratory. In
the remote/standoff tier, the target "sample" is a wider area and not
acquired by definition. In the laboratory tier, a small sample of
interest has been acquired and possibly subjected to a preliminary
analysis that supported the decision to subsample and deliver it to the
laboratory for further analysis. However, in the contact tier, the
sample may be analyzed before or after it is acquired (or both). This is
designed to allow multiple levels of "triage" for determining the
appropriate course of action with a given sample. An example of a
post-acquisition contact measurement is a point-by-point imaging and
chemical analysis along the surface of a several-cm long core. Based on
this analysis, it may be decided to grind and/or otherwise process some
or all of this core for analysis in the laboratory. For a description of
the suggested mapping of measurements onto instruments placed in each of
these tiers, refer to Section 8.1.4.

For completeness, the connection between the *AFL measurement strategy*
and the *mission objectives* may also be characterized by indicating
those objectives addressed while conducting the following activities:

-   Acquire the right samples (primarily 1; also 3)

-   Understand the context (primarily 1, 2; also 3, 4)

-   Identify the best place on the sample (primarily 5; also 2-4)

-   Perform mutually confirming astrobiology measurements (primarily 5;
    also 2-4)

This is summarized in Figure 5.

As mentioned above the instrumentation recommended for the Astrobiology
Field Laboratory is divided into three categories or tiers: 1) remote
sensing instrumentation located on a deployed mast, 2) a contact
instrument suite located on a robotic arm, and 3) the laboratory suite
located inside the rover and/or platform and fed with a sample
acquisition and distribution system. The remote sensing suite is used to
provide site characterization and rover navigation targeting. The
contact suite performs "triage" analyses, mimicking a field
biologist/geologist. The laboratory suite performs the detailed biology,
chemistry, and mineralogy experiments required to quantitatively assess
samples for past or present biological potential. Sample analysis
instruments are supported by sample acquisition and processing
infrastructure such as an articulated corer, (cm to 1 m) a rock
abrasion/polishing tool, a precision subsampling tool, and possibly a
2.5 m drill.

The remote sensing suite includes at a minimum a panoramic multi-filter
camera system that is used for site characterization, rover navigation,
and first-order target selection. Additional instrumentation that may
also be desirable may include reconnaissance-scale chemical and
mineralogical experiments, such as hyperspectral imaging, stand-off
(multi-meter) laser induced breakdown spectroscopy with fluorescence and
Raman detection, and thermal infrared mapping for identifying geothermal
sources of heat within the near-horizon of the Martian environment.

The contact suite must provide the second order triage for sample
selection. The analogy is the selection and preliminary analysis of a
surface material or hand sample by a field biologist or geologist. A
sample arm equipped with an articulated coring drill and a rotating
abrasive tool for clearing and polishing rock surfaces is envisioned for
contact arm infrastructure. The contact suite includes at a minimum a
course resolution (\~20 μm) microscope to examine the texture and other
features of rocks and fines. Sample triage on AFL will however require
additional contact instrumentation that further identifies materials of
high interest for subsequent precision subsampling and laboratory
measurements. The complement of contact instruments will be determined
by the objectives at the type of site chosen for AFL: sedimentary,
hydrothermal, ice, or liquid water. Possible arm-mounted spectrometers
include: near infrared reflectance, Raman, Mössbauer, APX,
deep-ultraviolet fluorescence, and/or various types of laser ablation
sampling spectrophotometers and direct-inlet mass spectrometers. These
tools are used to probe for and characterize samples of potential
biological interest that may be delivered to the laboratory analysis
portion of the payload.

![](media/image6.wmf){width="5.866666666666666in"
height="3.7875in"}Figure 5. AFL Measurement Requirements

The presence and design of the laboratory portion of the AFL payload is
predicated upon a high degree of flexibility with respect to
sub-sampling of the acquired rock core or soil sample. Therefore, there
should be a strong emphasis on an *integrated* analytical laboratory
approach to fully characterize common or related sub-samples: using
microscopy as the "eyes"; definitive mineralogical and chemical
identification from techniques such as x-ray diffraction, x-ray
fluorescence, and laser ablation; and organic chemical and stable
isotopic analyses that include at a minimum instrumentation capable of
similar measurements to a pyrolysis-gas chromatography-mass
spectrometer. Enhanced capabilities for identification of trace
pre-biotic or biochemical compounds may be provided by staining followed
by fluorescence detection techniques, solvent extraction/derivatization
followed by a suitable ion mobility or mass spectrometry system, and
other more specific techniques that target the detection of biomarkers
such as amino acids, proteins, and/or DNA such as capillary
electrophoresis, use of specific probes i.e. polymer or antibody systems
and chemical assays. The particular implementation of more-specific
biological/chemical analyses will depend both on the results of prior
missions, such that their design and interpretation is advised by a
solid first-order organic chemical characterization of Martian surface
samples, as well as through analog field experiments targeted at
terrestrial extremophiles. Additional capabilities such as detection of
enantiomeric excess (chirality), rock dating, and fine-scale chemical
imaging would be strongly complementary to the laboratory suite and
highly desired for AFL. Such experiments might be provided by
enhancements of previously mentioned instruments or by additional
instruments.

The final selection of instrumentation on AFL will be based on a careful
cross-matching of measurement requirements to instrument capabilities.
It is recommended that the payload resources (mass, power, cost), and
thereby the mission scope, for AFL be fundamentally and primarily driven
by the sample preparation and instrument needs that are required to
fulfill the measurement goals, rather than vise-versa. New
instrumentation techniques as well as methods to optimally integrate
techniques are desired and encouraged, but these must be maintained
within a reasonable cost-risk profile. This necessitates a well-funded,
well-advanced instrument development and integration program with
strategic oversight form cognizant AFL program members.

The core measurements of AFL has been decided upon to answer the
specific questions posed in the science rationale. The high number of
instruments on this mission definition is a direct response to the
findings of both sedimentary and hydrothermal deposits by the Mars
Exploration Rovers and the subsequent realization that samples of
Astrobiological interest may be much more accessible than originally
thought. This allows deep drilling to be traded off against increased
number of instruments.

## 8.3 Sampling and Precision Sub sampling

According to the various mission scenarios, different types of samples
will need to be obtained, i.e. from rock, ice, regolith and sedimentary
samples. The design of the SHAP facility and the exact number of samples
to be handled and processed will depend on which mission scenario is
decided on. This number will help define the sample collection system
that will have to be developed. The basic concepts and design of the
facility, however, will in principle remain the same for each type of
sample and each type of measurement to be performed. Four different
facets of the overall process are identified:

1.  Obtaining a sample

2.  Precision sampling of that core

3.  Liquid and Heat extraction of organics

4.  Contamination concerns

Issues were discussed with respect to each of these types of
environments and are discussed in more detail in the following.

[]{.mark}

### 8.3.1 Obtaining a sample

Several sample acquisition tools are suggested for integration into SHAP
facility. In order to be more precise the following defining terms have
been made:

[Corer]{.underline}: A device that can obtain a core which is \~ 5 cm in
length with \~ 1 cm in diameter from an outer region of a rock on the
surface of Mars.

[Drill]{.underline}: A device, which can obtain sample from inside of a
rock permafrost or sediment (cm -- 1m) or from a distance underneath
regolith (1-3 m).

[Precision sub-sampling mechanism]{.underline}*:* A device, which can
obtain a representative sample form a larger core. This would replace
the rock crusher, which crushes the entire core, and produces fines,
which might not be representative of the entire core.

[Scoop]{.underline}: A device which can collect either fragments from a
RAT, or unconsolidated regolith or permafrost material from the surface.

An aspect to consider is that idly sitting and drilling for significant
time spans on Mars, drilling does not seem to be an efficient use of a
limit mission lifetime. However, a system that could drill while not
shaking the rover or consuming major power would need to be developed.
For example, if an instrument such as XRD or deep UV fluorescence can
analyze rock fines and fragments during drilling, we can identify
samples that might be interesting, either because they are a
fundamentally different type of mineralogy, or because of interesting
organic components detected in them. This will not only help in sample
identification, but also in the operations profile so that overall more
samples can be analyzed.

[Ice:]{.underline}

A drill would be required capable of gathering an ice rich sample while
avoiding sublimating the ice, melting it, or volatilizing any
constituent molecules. The sample must be as chemically similar to the
material it is collected from in order to do a proper analysis. This
most likely requires nighttime drilling operations in ice rich
environments with a drill cooled to a temperature lower than that of the
ice to mitigate cutting, melting and drill trapping problems .

[Permafrost regions:]{.underline}

Samples that contain a mixture of ice and other material will have to be
specially treated. Terrestrial permafrost can create problems when
attempting to obtain a core from it in terms of both hardness and
ability to keep the sample pristine. Samples will need to be obtained
from a device that can be used multiple times while not heating the
sample above freezing.

[Surface Rock:]{.underline}

The depth MSL is coring to, 5 cm, seems to be a good number for the
depth inside a surface rock that should be sampled. Terrestrial
organisms practicing photosynthesis inside rocks inhabit approximately
the outer 2 cm of sample a rock. Sedimentary material can be identified
by obtaining several cm in length cores. It would be desirable to
analyze the fines from the core if coring is progressing by a pneumatic
device for introducing fines into the analytical suite. In this
scenario, the XRD can analyze material as it is chilled in order to
identify regions of interest, since the XRD can do infinite number of
samples. When an interesting sample is identified it can be further
processed via the other analytical instrumentation.

[Regolith:]{.underline}

Regolith material would be obtained by a scoop attached to the rover arm
and be delivered to sample processing facility. It is worth considering
that if the regolith material is unconsolidated, we may assume that it
was never in contact with the atmosphere. If it was at some point in the
recent past, it could mean that it would be chemically the same as the
surface material, and hence not worthy of a drilling effort. Unless the
rover is going to head to a site where larger amounts of near surface
(to the depth of the drill) water drilling into regolith would be
desirable, otherwise it most likely is not.

### 8.3.2 Sedimentary deposits:

If a landing site were selected where drilling into for sedimentary
deposits is required, it would be preferable to look at the entire core
length. If a complete core could not be obtained because of engineering
constraints, having a borehole instruments that can be lowered into the
borehole, and examining the entire length of it would be very desirable.
Instruments that could be utilized to answer astrobiologically relevant
questions (rather then pure geologic questions) would need to be
identified. In this scenario it might be worthwhile considering a
drill/corer combination, where a drill takes 5 cm cores at a time,
delivers to the sample processing facility and be lowered back into the
borehole and continue drilling to the desired depth. The ocean drilling
industry has begun to develop instrumentation for borehole
instrumentation where a geophysics package of instrumentation examines
the bore hole. Further development along these lines would be invaluable
to any drilling that would take place on Mars.

### 8.3.3 Precision sampling of a core

Once a core has been obtained, it would be injected it into a sample
triage station. On this station we would like to look down the axis of
the core with the contact suite of instruments, especially if the core
was delivered intact. This way layering structures can be identified
that might be indicative for a sedimentary material or any other area of
interest in any type of sample. After the initial analysis, it is not
necessarily desirable to process the entire core in an instrument like
the rock crusher. If any regions/layers of interest have been identified
in the core, these layers would be diluted/mixed with the other
less-interesting layers, and thus make the analysis of the core material
give results that are not necessarily indicative of a specific region.
Furthermore, the rock crushing mechanisms could produce material that is
not necessarily representative of the entire core, due to the crushing
mechanism. Simply put, a precision sample handling system needs to be
developed that is much more advanced then the rock crushers on MSL. This
precision sample handling system would most likely replace the rock
crushers on MSL as they are currently designed, because there most
likely is not enough mass to have both type of instruments aboard.

The precision sample handling system would need to produce fines from a
core that are on the order of 100 μm, although finer material is always
preferable. These fines would need to be produced from regions of the
core that are less then 1 cm in length. Although an exact amount of
samples that would be useful for each analytical instrument cannot be
accurately defined without knowing what instruments have been chosen, a
good working number is 100 mg.

A further developed system for AFL would allow for fines to be obtained
from various parts of the core, where astrobiologically interesting
signatures were observed. These fines then could be identified by the
contact suite or by analysis of the fines that were collected during the
coring. A possible method this material can be obtained is via a
pneumatic drill, analogous to a dentist drill. This type of sample
processing of a core needs to be further addressed, as it may require
holding the core so that further processing can occur. If the core would
be held in a fixed position, a grinder could grind parts of the core
while those fines are collected. Any other material that is produced
from this step could be looked at with a microscopic imager, if one is
chosen as apart of the science payload, but no further analytical
analysis of it would need to be made.

### 8.3.4 Ice Samples

Terrestrial organisms can maintain a layer of liquid water around them
in an environment where the temperature is below the freezing value for
that corresponding pressure. Therefore, one of the main science
investigations with ice is to determine if there is any liquid water in
a sample. In addition, volatile material present in the sample might
undergo reaction and hence change its form, which might lead to
incomplete analysis of the obtained sample. Because of these reasons, it
seems desirable to obtain a sample without allowing the temperature to
pass above conditions in which phase transition that any water (and
potential brine solution) present would undergo for the ambient pressure
and temperatures present. From permafrost, it is expected that a core
approximately 5 cm long and 1 cm diameter would be sufficient for
further studies, however, a larger core would likely allow more
comprehensive analysis to be performed. With permafrost samples, the
possibility should be considered to include a sample concentration
device in the sample possessing suite. This concentration process would
only take place after any measurement on liquid H~2~O on the pristine
sample has been performed.

The overall strategy for a "polar" mission largely depends on the choice
of landing site, i.e. whether it is permafrost or on the polar cap. If a
polar region is decided upon, it is suggested that the obtained ice core
is analyzed as a whole, especially if only 5 x 1 cm core are obtained.
This based on the assumption that the recent ice deposits will not show
much evidence of layering or zoning. However, should new data become
available through *Phoenix* investigations, this approach may have to be
restructured and a more capable precision sub-sampling system be
integrated into this mission concept.

### 8.3.5 Liquid and Heat extraction of organics

Organic analysis has been one of the important measurements the
Astrobiology Science Steering Group has identified that AFL should be
able to perform. In order to identify organic material, they need to be
released from the matrix material they are a part of, especially since
surface organics on Mars might be very rare. Several ways to extract
organics form rock samples were discussed, including using heat and
solvent extractions. Each extraction technique has its advantages and
disadvantages. However, it is currently not clear whether there would be
enough mass to be able to perform both techniques on the same mission.
Also, in an extended surface mission (\~900 days), which is powered by a
nuclear power source, either extraction technique would need to
demonstrate that it can perform analysis on a large number of samples
(exact number TBD) that such a mission would be able to collect.
Different materials require different extraction strategies. For
example, some liquid extractions will miss kerogen type material because
of its high molecular weight and low solubility, while heat will destroy
most of the more fragile biomarkers such as amino acids or hopanes,
resulting in the loss of important molecular information. MSL will, most
likely, have some form of heat extraction, although what this will look
like will be dependent on the instrumentation that is chose for that
mission.

Generally, more refractory, fossil, nonpolar compounds require organic
solvent extraction. The choice of solvent depends largely on the
polarity of the target compounds. Solvents commonly used are for example
hexane, dichloromethane, toluoene, methanol, ethylacetate, propanol, or
mixtures thereof. It is necessary to identify mixtures that have highest
extraction efficiencies and at the same time covering the broadest
possible polar-nonpolar stretch. Organic solvents would be needed for
GC/MS sample preparation (and to some degree HPLC but this varies
depending on column design and target compounds; H2O and methanol are
commonly used as eluents, but could also be acetonitrile, dioxane,
ethanol, isopropanol, etc.), in order to obtain molecular information
from refractory compounds.

Aqueous solvents (such as super critical water) would be used for amino
acid, DNA/protein extraction e.g. for microarray analyses, capillary
electrophoresis, culturing experiments, flow cytometry or perhaps even
PCR. Numerous proprietary and commercially available extraction kits
exist using a variety of different solvent compositions, all being
aqueous solutions. It would be required to identify optimized procedures
and optimized solvents and/or solvent combinations in future laboratory
experiments, e.g. using Mars analogue materials spiked with microbial
cells and/or organic target compounds.

Other extraction technologies are currently available and need to be
examined more in the context of Mars missions these techniques are not
limited to but include; microwave, super critical gas (i.e CO~2~)
ultrasonic and sublimation.

It is important to point out here that no judgment is made on which
extraction technique is preferable. This is simply an attempt to
identify which technique (if either) can be made a facility instrument
aboard AFL, and hence have several instruments analyze the extract from
the surface samples. Currently, different instrument developers focus on
developing extraction techniques for their individual instruments. These
techniques do not necessarily have much overlap from instruments to
instrument. If consensus could be formed that a particular set of
extraction mechanism is desirable (i.e. utilizing H~2~O at 100^o^C) it
could necessitate a facility instrument to perform that extraction and
pass the extract to different instrumentation. This would accomplish
reduced mass and power requirements, as well as allow for several
instruments to analyze the exact same sample.

Extraction conditions are currently being investigated utilizing
different techniques solvents and temperatures. However, the extraction
mechanisms need to demonstrate that they are small and repeatable.
Null-results from AFL can have great meaning, but they need to be
absolute and definable. The Viking GC/MS results showed no organics, but
those results don't necessarily mean there were no organics in the soil
that was analyzed. The GC/MS has limits of detection that can be easily
determined for single species. However recent work has demonstrated that
the Viking ovens were set to a temperature that would have not released
certain organics that could have been present in the soil (Glavin et
al., 2001). In addition other types of organics could have been
destroyed by the heat, and thus not detected. In order to determine what
a possible null-result means, an end-to-end analysis would need to be
carried out.

[Pyrolysis heating:]{.underline}

The Viking landers each had ovens as part of the GC/MS system, although
the ovens themselves were not able to reach the temperature necessary to
detect some of the organics that could exist there. The Rosetta mission
has a small oven, Phoenix has the TEGA, which has eight one-time-only
use ovens attached to an EGA and a MS. MSL is intended to investigate
multiple samples (24 floor, 78 goal) and has baselined a GC/MS as an
instrument. If the development of a multi-use oven is not made, then it
would require a ground decision as to whether or not to analyze a
sample, if only a limited number of samples that can be analyzed. This
would necessitate a science decision, which could delay other analysis
on the surface, and limit the number of overall sites that can be
visited.

Another prospect of the pyrolysis method is whether it could be designed
in such a way that it is capable of concentrating signatures on a
sorption trap. If so, any use of those traps will also have to be shown
for the same number of samples that the rover will analyze. Also, as
mentioned previously, all limits of detection should be for the entire
end-to-end system, for a variety of different mineralogical samples.

[Liquid extraction:]{.underline}

Liquid extraction is a more gentle way to extract organic molecules from
rock and soil samples. One analogy to Martian surface investigations is
the analysis of organics from meteoritic material. In those
investigations, the organic molecules were released by either hot water
extraction or by HCl extraction. Current development of novel techniques
for the extraction of exophase biomarkers needs to continue, as does the
determining the most efficient solvent extraction parameters. Should a
sample be analyzed for its indigenous water content, it might require
using another, yet to be determined, technique. In addition, different
solvents can extract different types of molecules, water, as it
approaches the critical point, becomes a good organic solvent. Clearly,
more science groundwork has to be carried out to obtain comprehensive
information to allow the best possible choice of solvents to be used.
Other solvents that are used in the laboratory include HCl and other
acids. These acids perform a more complete digestion of the matrix
material, and increase efficiency of extraction, but are harder to
handle because of their corrosive nature. With any solvent that is
chosen for this step it should be noted that it would be able to
concentrate the material to ensure a better signal to noise level.

It is currently unclear whether the liquid sample handling system needs
to be completely reusable or whether one-time only use should be the
preferred option. This information will become available as
experimentation and technology development continues. The only
stipulation that needs to be made is that the extraction technique
minimizes mass and power resources.

Finally, there are other measurements that can be made during the
extraction phase, which would not be possible during pyrolysis heating.
These include pH, Redox potential of the material, etc. All of these
measurements can help elucidate habitability issues and are an extra
measurement that can be made, and if the liquid extraction step is a
facility instrument should be made.

### 8.3.6 Contamination concerns

There are two issues that need to be addressed from for contamination
concerns:

-   Contamination issues from organisms brought from Earth

-   Cross sample contamination

The issue of terrestrial contamination being detected and identified, as
material present on a Martian sample is, by far, the main concern.
Several different mechanisms can help reduce the possibility of this.

A sterile sample can be brought from Earth and run through the system
for the first analysis to show that the end-to-end system is clean and
contamination free. If this step produced positive results, it will show
that the sample system was not clean and would have to be cleaned e.g.
by flushing with a sterile material blank. After the initial sterile
material is analyzed, surface dust could be analyzed next. This material
is most likely sterile due to UV irradiation and is most likely
homogenous across the planet. After the analysis of such sample through
the entire system, this material can be used as a negative check for the
entire system. If a sample is later found to have the signatures of
life, analyzing another soil sample can perform a negative response
check of those results, which will further validate the biosignatures
that might have been identified.

The other form of contamination is sample to sample. While it should be
noted that a general cleaning between samples should be performed,
reducing the cross sample contamination should not be a major power and
mass drain, which could be better used in other systems.

## 8.4. Time resolved Measurements

For some versions of AFL, time-separated repeat measurements (to observe
changes) will be valuable, and these were strongly advocated by some
members of the SSG. Given current understanding of Mars, we do not know
enough to design the time gap that would be needed in such an experiment
(minutes?, hours?, days?, months?), or the fidelity to which the
subsequent experiment(s) needs to duplicate the conditions of the first
in order to provide a meaningful hypothesis test. The AFL SSG takes the
position that time-separated repeat measurements are not essential to
all versions of AFL.  Thus, this should not be a part of the common
overall mission scientific objectives. The AFL SSG recommends that the
capability to do at least some time-separated repeat measurements be a
general functionality of the surface science system, and that the
decision on how and when to use it be deferred to the competitive
process***.***

# 9.0 Engineering analysis of AFL core

Based on input from the AFL SSG, a preliminary engineering design
concept was defined so that basic mission parameters (such as mass, cost
and power generation systems) could be developed. This was done so that
technology developments that will be required to undertake the mission
could be identified and pursued. This design concept was based upon the
AFL SSG core mission requirement and included possible investigation of
sedimentary, hydrothermal and liquid water regions. Other investigation
(namely to ice covered and sub-surface ice regions) may require a
different architecture and hence have a different mass, cost, and power
generation systems. The mission architecture was defined by taking into
account the measurement objectives, payload infrastructure rover
mobility requirements and lander capabilities (Section 8). Given all
these requirements and capabilities, a core AFL mission was developed.

[]{.mark}

The mission studied included 2 instruments for remote sensing placed on
the main mast, 2 contact instruments located on an instrument deployment
device (IDD), and 6 analytical laboratory instruments capable of
analyzing samples obtained from the Martian surface for a total of 10
instruments. The analytical instruments, as well as the sample
acquisition and processing infrastructure, will be able to process 25-75
physical samples (rock, regolith, and ice) for detailed analyses by both
pyrloysis and wet chemistry instrumentation. Landers, Entry Descent
Landing (EDL), cruise launcher, were defined in such a way to meet the
mission requirements and so that costing the rover and mission could be
done. In order to accomplish this, a list of generic instruments were
identified so that parameters such as cost, mass, volume, and power
requirements could be included in the engineering design concept. No
attempt was made to identify and place individual instruments on the
strawman payload (used to assess cost only) and where several instrument
from different developers were identified, average mass power and
volumes were used.

[]{.mark}

The engineering design concept assumed a launch in either 2013 or 2018
with a Technology Readiness Level (TRL) of 6 for instruments and
subsystem technologies that would have to be reached by 2009 and 2014
respectively. Functional redundancy was required on all subsystems
except for the science payload, and this included the sample acquisition
and processing infrastructure. Landing site availability for the AFL SSG
included access to the Martian surface between: +85 to --60 so that
access to both ice regions as well as a wide variety of potential
Sedimentary and hydrothermal regions can also be investigated. Landing
altitudes of 2.5 km or less relative to the MOLA geoid should be reached
within a 10x10 km (3-sigma) landing dispersion ellipse assumed for
landing. Because AFL will be assumed to be a mission to a specific site
of high scientific interest, rover was designed with "Go-to" mobility
capabilities of 10-15 km (linear traverse range) so most astrobiology
interesting sites could be reached and explored. For data transmission
between Earth and Mars, either MTO or the second generation Mars Telecom
Orbiter (MTO) was assumed to be available for Mars to Earth telecom
greatly increasing the amount of data that could be acquired on the
mission. The collected data would be passed to Earth via 0.3 m HGA for
1024 kbps link via MTO. This design allowed for a data intensive 1-3
GBits of daily science data generation. X-Band from rover direct to
Earth (DTE) would be used for back-up purposes only. Finally the main
power system of the mission was assumed to be a Radioisotopic Thermal
Generator (RTG) system, although solar power could also be utilized for
missions that are more equatorial, and potentially shorter in duration
(depending on final MER mission power results). The power systems was
sized to be able to provide sufficient power with reserves for "worst
case" extreme drive Sols (large rocks and slopes) and for analytical
laboratory days. Based on this analysis a 4 Brick Small RPS system
capable of producing 50We, or 1200WeHRS per sol in combination with a 2
x 8 Ahr-Li-Ion battery system was chosen. Because of the inefficiencies
in power generation from an RPS system waste heat has to be dissipated.
Therefore, A passive thermal loop system driven by the 1000Wt energy
from the RTG system, in combination with electrical heaters, thermal
switches, and radiators was designed for the rover for keeping the Warm
Electronic Box (WEB), external actuators, and instruments at acceptable
temperatures ranges. The passive thermal system on the rover would in
combination also be used for dissipating energy from the RTG system the
during EDL and cruise stages.

[]{.mark}

To generate the required science and analyze 25-75 samples, accommodate
the selected science payload strawman and provide sufficient power, data
storage, data rate, and telecom to an MTO type orbiter, the rover itself
would have a mass of \~550 kg (30% reserve included). Of this \~110 kg
(\~20% of rover mass) would constitute the science payload (once again,
depending on the exact parameters of the instruments selected through
AO). Bringing such a rover to the Martian surface would require a
launched mass of 2456 kg, which would demand an Atlas V521 or a Delta IV
4040 launcher. Assuming, a MER cruise stage, Viking style EDL system
with a live lander, this would give an injected mass at Mars of 2174 kg,
and require a 4.57 m aeroshell and two chutes during descent.

[]{.mark}

The rover assumed in this study shares heritage with MER however, final
design characteristics for the 2009 MSL mission will influence this
decision. The rover includes a mast for the remote sensing instrument,
an IDD for the contact instruments and sample acquisition, a detailed
sample handling system and an analytical laboratory suite of
instruments. The six rover wheels were increased in size to 35 cm
(diameter) to negotiate larger rocks and extensive Go-To requirements
(as discussed below). Each wheel includes a brushless actuator, which
would draw 16-25 W per wheel, and a total of 100-150W for all wheels
during traverse depending on surface characteristic of the site (i.e.
slop, rock distribution, surface material etc.).

The result of the costing exercise resulted in a 2013 mission cost of \$
1.55 Billion (in RY dollars) and 2018 mission cost of \$ 1.78 Billion
(in RY dollars). This includes \~ 200 million for instruments and
infrastructure and \~ 500 million for all the rover subsystems. These
numbers should be adjusted as the design for MSL becomes more set.
Savings for things like built-to-print hardware and heritage in the EDL
and avionics systems may result in mission savings.

In order to meet the mobility requirements for AFL, the mass of the
rover and the potential investigation site are taken into account. One
requirement for AFL is to investigate a site(s) that are most likely to
have high astrobiology interest. This requirement can mean traverses of
up to 10's of km depending on landing ellipse constraints such that the
rover design for longer traverses in Mars terrains must be taken into
consideration. In addition, the AFL payload will be much bigger than MER
with a scaled rover and hence the wheel contact area has to grow from
the 25 cm wheel diameter on MER to accommodate low surface pressure for
minimizing wheel sinkage. There are some basic assumptions we can make
based upon Mars geology and the proposed investigation sites, such that
the mission requirements (see section 8.0) can be accomplished and \\ a
reasonable preliminary design can be created from which approximate
mission costs can be estimated. It needs to be pointed out here that
this preliminary analysis is by no means a complete engineering
analysis, but it is designed to show approximate system requirements for
planning of total mission costs as well as mobility potential for site
selection. Finally, with this analysis a decision on the level of
required precision (or pinpoint) landing can be made so that investment
in technology development for AFL can be carefully planned.

Figure 6. A schematic diagram of how AFL may look

![](media/image7.png){width="2.5833333333333335in"
height="2.2270833333333333in"}

Technology development to fulfill science and engineering goals is
summarized in Table 6.

can be seen from Table 6 significant development of critical enabling
technology should begin as soon as possible, especially for 2013 launch.

As with all other JPL Rovers, AFL's drive train subsystem was assumed to
be a 6-wheel design. Each wheel has two motors: one turning the wheel,
the other steering the wheel. All motors are brushless and 2, 4 or 6
wheels can be driven at a time depending on the terrain. Each wheel
consumes approximately 8 W in stand-by mode and about 18 W when driving,
making the drive train subsystem the largest power consumer (when
operating) on AFL. Additionally, a maximum slope tolerance 30^o^ is
assumed due to both current design configurations and projected
technology advancement. We have assumed that the technology for
continuous drive and autonomous hazard avoidance will be developed and
eventually will undergo flight qualification so it can be utilized on
AFL. The wheel diameter to be chosen will be large enough to avoid
typical Martian hazards (i.e. surface rocks) so that linear odometer
distance can be maximized while being small enough to minimize mass and
power (which is related to wheel size).

![](media/image8.wmf)

Table 6. Summary of necessary technology for AFL, in particular
highlighting instrument development in critical areas as defined by the
AFL team. This is not to exclude established technologies from
development but merely highlights other critical technologies that
should be further developed.

# 10.0 Planetary Protection

The different variants of AFL may end up in any of three Planetary
Protection classifications.

[Category IVb]{.underline} is applied to missions that investigate
extant Martian life forms. This may include AFL-Liquid Water and AFL-Ice
(depending on the instruments).

[Category IVc]{.underline} is applied to missions that access Mars
"special regions". This would include AFL-Liquid Water, AFL-Ice, and
perhaps other AFL versions, depending on landing site.

[Category IVa]{.underline} is applied to landed missions other than the
above. This could apply to AFL-Sedimentary and AFL-Hydrothermal
(depending on landing site).

To achieve maximum flexibility, mission engineering should be planned
assuming IVb, and de-scoping, if appropriate, can take place from there.
The four variants of AFL will have very different implications for
Planetary Protection and therefore must be reviewed on a case by case
basis.

It is noted that many developing technologies are available for
contamination monitoring, decontamination and space craft cleanliness
issues. These technologies should be vigorously pursued. In particular
the following;

-   Low temperature sterilization techniques such as microwave plasma
    and other plasma ashing techniques,

-   Radiation sterilization technologies for whole space craft as well
    as 'hot-spot' removal.

-   Real time non culture based systems for monitoring amount and types
    of bioburden.

-   Providing of a suitable mineralogical bio and organic clean sample
    blank for proofing critical sample handling pathways and

It should be noted that several of the analytical techniques mentioned
in the AFL instrument section cannot undergo heat sterilization.
Protocols that either ensure that instruments are delivered cleaned to
the level of the space craft and integrated to the craft after heat
sterilization, for the use of cooling loops to keep critical instruments
cool during sterilization (obviously the previous point would apply
here) or alternatives to heat sterilization must be put in place for
these technologies to fly.

# 11.0 Relationship between AFL and MSL

AFL will depend on the following heritage from MSL.

-   Precision landing using a novel (non airbag) landing system

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-   The use of RTG technology

-   The use of remote, contact and analytical suites of instruments

-   Crude sample processing to be used but improved on AFL

2.AFL will differ from MSL in the following essential respects:

-   Advanced sample preparation system.

    -   Precision sub-sampling is an advanced sample management step
        that will allow a scientific focus on meso- to micro-scale
        discoveries of enhanced astrobiological interest. This will
        allow a much higher capacity to investigate specific anomalous
        features.

    -   Liquid extraction. For advanced studies of carbon chemistry,
        more efficient sample extraction (and instrument delivery)
        methods are needed.

-   Better and miniaturized organic molecule and life-detection related
    instruments.

-   Greater interplay between

-   Precision landing, hazard tolerance/avoidance, go-to mobility.

-   --Will give us the ability to follow-up on specific discoveries,
    including in "interesting" terrain.

# 12.0 The Future of AFL

It is suggested that the SSG reconvene at a later date to

-   Respond to discovery to hone mission concepts for site selection

-   Review sample handling and instrumentation choices and feed-forward
    to a possible sample return mission

-   Respond to shifting of the AFL timeline from 2013 to 2018, this
    would include revisiting the instrument choices based on comments
    from the SSG as to the use of instruments currently in development
    but of such a low TRL that it could not feature in the 2013
    timeframe example include high vacuum and high voltage
    instrumentation such as electron microscopy, or photoelectron
    spectroscopy.

In the past, there was competition between in-situ and sample return
mission concepts and there was a question as to whether the AFL was to
fly before MSR or after. The current schedule envisions an AFL flight as
early as 2016 and an MSR some time after 2020.

The advantages of flying in-situ missions first are that they are
relatively low cost compared to MSR (although the costly infrastructure
put in place for an initial MSR would not be needed for follow up
missions) and there are no issues of sample degradation, sample amount,
sterilization, quarantine or 'off nominal' delivery to earth.

In addition, the strength of in-situ missions is their ability to assess
multiple samples over a spatially diverse area without degradation of
the samples. AFL will aid in the identification of sample types for
future return missions. This may even include aiding sample caching for
a future MSR mission, although that would necessitate a further
assessment of precision landing of an MSR mission.

A point to remember is that if / once detected life on Mars should be
characterized in its entirety for similarity to earth life, evolution
and biochemistry (if viable). Therefore both AFL and MSR must be
considered necessary tools to be used at the right time to answer
science questions within the foreseeable realms of technology..

Several aspects of both the sample handling capabilities for AFL and the
choice of instrumentation will allow the further development of robotic
tools to explore elsewhere in the solar system e.g. Europa. This
instrumentation although initially geared for the detection of life
would upon the successful accomplishment of this task be needed to be
further developed to characterize that life in whatever form. It will
not be enough to ask was/is there life there, the next logical step is
how did it arise, how is it different from earth life and why? It is
only by taking this step will we able to understand truly the processes
of abiotic / prebiotic / biotic chemistry in the solar system.

Note, the bulk of this work and the draft white paper was completed by
September 2004. There have been unavoidable delays to its publication.
In the meantime thinking about AFL has progressed. This document
reflects the thinking in September 2004. Whilst engineering and
programmatic changes have occurred since then, the strength of this
document lies in the science definition for the mission.

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# 14.0 Appendix 1. Discoveries AFL must respond to.

Table 7 Summarizes crucial science discoveries that may also directly
affect AFL mission, potential follow up questions and measurements

![](media/image9.wmf){width="7.302777777777778in" height="6.65625in"}

# 15.0 Appendix 2 - Instrument descriptions and capabilities

In this table, a number of techniques were suggested by AFL SSG members
as potentially applicable to one or more identified measurement
objectives. This list is not meant to be comprehensive or definitive,
but rather to illustrate the kinds of information that would enable
instrument development efforts in general to connect to the specific
needs of AFL. As such the table does not identify all aspects of each
technique, but only those that were discussed in a preliminary analysis
of the desired measurements on AFL. The first and second columns
identify the technique and the type of measurement(s) with which it is
typically associated (Data/Signatures Sought). The third column
explicitly lists the most likely AFL measurement requirement that the
technique addresses (see Section 7.0). In this way, techniques
applicable to a given measurement of interest, or more generally to a
mission objective (see Figure 5), can be found by examining those rows
containing the category (1-5) desired. This column is meant to serve as
an example template, so all potential uses of each technique are not
identified. The next three columns indicate the most likely associated
tier(s) for the technique, corresponding to the recommended division as
discussed above.

The following thirteen columns provide data for *example*
implementations of the technique where useful specifications of the
sample analyzed and typical instrument parameters could be identified.
Given sample data include: 1. the physical form *as acquired or as
extracted/analyzed* -- solid (s), liquid (l), or gas (g); 2. the type of
material from which it is obtained and/or delivered to the instrument;
3. the type of sample preparation required and/or desired (see key); and
4. the typical size or mass of sample, additionally indicating where a
technique looks only at the surface of a solid sample rather than the
bulk. The first three columns of the Example Technique Characteristics
section provide some of the key distances involved: the standoff, the
field-of-view (FOV) or spot size, and the scale of the heterogeneity
probed, if appropriate. The heterogeneity is indicated by the structures
(e.g., layers or grains) that can be individually analyzed with the
method's FOV or spot size. For example, a Hand Lens instrument might
look at individual mineral grains and similar size structures within a
mm-cm FOV from a standoff focal length of a cm or so. In this example it
is the imaging resolution, not the FOV, that determines the smallest
structures observable, and that additional data is found in the
resolution column. On the other hand, for a laser mass spectrometer, the
spot size does roughly determine the spatial resolution of analysis -- a
spot size below 100 microns could enable analyses of mineral phases on
the mm scale; what is then found in the resolution column is in fact the
mass resolution, since that is how the term is used for that method.
Further, the Mass Range column gives the typical range of molecular
weights that are accessible with a given mass spectrometric method.

Finally, the remaining columns provide a correlation of where a
technique would be applied in support of various *discovery-responsive
measurements* by AFL that would be called for following the discoveries
listed in Appendix 2. This separate correlation, beyond the
technique-to-measurement requirement-to-mission objective logical chain,
permits a greater flexibility and responsiveness of the AFL concept to
specific scenarios that may develop from current Mars missions and over
the next several years.

  ------------------------ ------------------------- ---------- ------------------ --------- ------------ --------------- -------------- ------------ -------------- ----------------- ----------- ------------ ------------- ----------- ------------ ----------- ------------ ----------- --------------------- --------- ----------- ------------ ---------- ----------- ----------
  **Table 8- Techniques                                                                                                                                                                                                                                                                                                                                                     
  Suggested for AFL by SSG                                                                                                                                                                                                                                                                                                                                                  
  Members**                                                                                                                                                                                                                                                                                                                                                                 

                                                                Measurement Tier                          Example                                                    Example Technique                                                                                                      Discovery/Follow-up                                                             
                                                                                                          Target/Sample                                              Characteristics                                                                                                        per Table 7                                                                     
                                                                                                          Information                                                (instrument                                                                                                                                                                                            
                                                                                                                                                                     implementation)                                                                                                                                                                                        
                                                                                                                                                                     where appropriate                                                                                                                                                                                      

  Technique                Data/ Signatures Sought   Mmnt Reqts Remote             Contact   Analytical   Physical Form   Example        Processing   Sample Mass/   Distance to       Size of     Target       Selectivity   Detection   Resolution   Precision   Mass Range   Other       Recent Surface Water  Hydrous   Organic     Sedimen.     Sedimen.   Evidence    Microbes
                                                     Addessed   Sensing/Standoff   or Close  Lab          (Solid, Gas,    Origin/Host    Required/    Volume         Target            Area        Feature                    Limits                                                                              Mineral   Molecules   Structures   Rocks      for Fossil  
                                                     (Section                      Range                  Liquid)         Material       (Desired)                                     Probed/ FOV Scale                                                                                                          Phases                                        Life        
                                                     7)                                                                                                                                                                                                                                                                                                                     

                                                                                                                                                                                                                                                                                                                                                                            

  stereo optical imaging   identify targets,         A          x                                                         sedimentary    n                           1m - 10+km        10cm - 1+km                                                                                          1                     6                     1,2,3,4      4          1,2,3,6,8   3
                           evidence of weathering,                                                                        rocks/                                                                                                                                                                                                                                            
                           sedimentation,                                                                                 structures                                                                                                                                                                                                                                        
                           alteration, etc.                                                                                                                                                                                                                                                                                                                                 

                           identify surface samples  A                                                                                                               10-100 m          1-10 m      10cm-1m                                                                                                                                                                  

                           identify distant          A                                                                                                               1 km              10-100 m    1-10 cm                                10 cm @ 1 km                                                                                                                      
                           sedimentary outcrops                                                                                                                                                                                                                                                                                                                             

  VIS/NIR Spectroscopy     surface mineralogy,       B          x                  x                      s               rocks, fines   n (abr)                     cm - m                                                                                                                                                                                                 
                           texture                                                                                                                                                                                                                                                                                                                                          

  mini TES                 mineralogy                B          x                                         s                              n (abr)                     m - km                                                                                                                                                                          1                      

  long focal length        identify distant          A          x                                                                        n                           10m - km          cm-10m      cm                                                                                                                                                                       
  imaging                  sedimentary outcrops                                                                                                                                                                                                                                                                                                                             

  laser ranging            distance to target        A          x                                                         boulders,      n                           100m - km         cm spot                                            cm @ 100 m                                                                                                                        
                                                                                                                          vertical faces                                                                                                                                                                                                                                    

  LIBS                     elemental composition     B          x                                         s               boulders,      n                           1 - 25m           mm - cm                  low (l        ppmw                     \~ 10%      elements     laser                             2,4                                2,5        3           
                                                                                                                          slopes                                                       spot                     absorb.)                                                        ablation                                                                                    

  ground penetrating radar ice, H2O, other           B, C       x                                         s               subsurface     n                           m - 10s m                                                                                                              3                                                                               

  seismic sounding         ice, H2O, other           B, C       x                  x                      s               subsurface     n                           100\'s m - km                                                                                                          3                                                                               

  neutron spectroscopy     ice, hydrated minerals    B          x                  x                                      drill cores,   n (acq)                     10\'s cm - m\'s                            high          variable                                                                                                                                      
                                                                                                                          fines                                                                                               \<%-%                                                                                                                                         

  gamma ray spectroscopy   elemental composition     B          x                  x                                      any            n                           10\'s cm - m\'s                            med           variable                                                      5                                                                               
                                                                                                                                                                                                                              \<%-%                                                                                                                                         

  x-ray spectroscopy       elemental composition     B, E2                         x                                      any            n (acq)                     cm                cm+                      med           variable                                                                                                                                      
                                                                                                                                                                                                                              \<%-%                                                                                                                                         

  Raman spectroscopy       mineralogy, some          B, E       x                  x                                      rocks          n (abr)                     cm - m            cm+                      med                                                                                               1,5       1,4                      2          1           
                           geochemical/organic                                                                                                                                                                                                                                                                                                                              

  micro-Raman spectroscopy mineralogy, some          B,D,E                         x         x                            rock chips     n (acq, abr)                mm - cm           \< mm                    med                                                                                               1,5       1,4                      2          1           
                           geochemical/organic                                                                                                                                                                                                                                                                                                                              

  micro-LIBS               elemental composition     B,D                           x         x            s               rocks, chips   acq,pos                     mm - cm           \< mm                    low (l                                                                                            2,4                                2,5        3           
                                                                                                                                                                                                                absorb.)                                                                                                                                                    

  hand-lens-scale imaging  phase texture/identity    D                             x                      s                              n (abr)                     cm - m\'s         0.1-10 mm   grains                                                                                                                                                                   

  optical microscopy       fine morphology           D,E                           x         x            s                              n (abr)                     mm - cm           0.001-1 mm  subgrain                                                                                                                 2                                   1,2,3,6,8   

  confocal microscopy                                D,E                                     x            s                                                          mm                0.001-1 mm  subgrain                                                                                                                 2                                   1,2,3,6,8   

  near-field microscopy    very high res imaging     D,E                                     x            s               flat chip      acq, pos                                                  subgrain                                                                                                                                                                 

  Mossbauer                Fe-bearing mineralogy     B                             x         x            s                                                          mm - cm                       avg                                                                                                                                                                      

  Fe-NMR                                             B                             x                      s                                                          mm - cm                                    high                                                                                                                                                        

  XRD/XRF                  mineralogy                B,D                                     x            s               drill cores,   acq, pow     mg\'s          0                 whole       avg or                                                                                                         1                                  1,5                    
                                                                                                                          fines                                                        sample      grains                                                                                                                                                                   

  FTIR                     mineralogy, some          B                                       x            s                                                                                                                                                                                                       1,5       1,4,6                    2,5        3           4
                           geochemical/organic                                                                                                                                                                                                                                                                                                                              

  VCD                                                                                        x            s                                                                                                                                                                                                                                                                 

  deep UV fluorescence     organics: identity,       B,D,E                         x         x            s                              n (abr)      surface?       mm - m                        grain scale+                                                                                                             1                                   3           
                           oxidation state, ...                                                                                                                                                                                                                                                                                                                             

  pyrolysis/GCMS           organic and some          B,E                                     x            s,g,l                          acq, pos,    mg-10\'s mg    0                 whole       avg          low                                                                         4                               1,5                      5                      
                           mineralogical/inorganic                                                                                       vac                                           sample                                                                                                                                                                               
                           composition; isotopes                                                                                                                                                                                                                                                                                                                            

  chemical derivatization  less-tractable organics   E                                       x            s,l                            liq                         0                 whole       avg                                                                                      4                               1,4,7                    5                      
                                                                                                                                                                                       sample                                                                                                                                                                               

  isotope ratio MS (IRMS)  C and other isotopes for  E2                                      x            s,l                            acq, pos,                   0                 whole       avg                                                                                      2                                                                               
                           bio-fractionation, age                                                                                        vac                                           sample                                                                                                                                                                               
                           dating                                                                                                                                                                                                                                                                                                                                           

                           compound-specific IRMS    E2                                                                                                                                whole       avg          cmpd isolated                                                                                                                                               
                           using sampling                                                                                                                                              sample                   w/pyr, GC,or                                                                                                                                                
                           selectivity                                                                                                                                                                          other proc.                                                                                                                                                 

  chiral GC                enantiomeric excess (ee)  E3                                      x            s,g,l                          acq, pos,                   0                 whole       avg                                                                                                                      3                                               
                                                                                                                                         gas                                           sample                                                                                                                                                                               

  circular dichroism       enantiomeric excess (ee)  E3                                      x                                                                       0                             avg                                                                                                                      3                                               

  liquid chromatography    organics, ee              E                                       x            s,l                            liq                         0                 whole       avg                                                                                      4                               1,3,5                    5                      
  (LC)                                                                                                                                                                                 sample                                                                                                                                                                               

  2D GCMS/TOF-MS           organic and some          B,E                                     x            s,g,l           rocks/cores,   acq, pos,    10\'s mg       0                 whole       avg          low                                                \~1E3-1E5+               4                               1,5                      5                      
                           mineralogical/inorganic                                                                        fines          vac                                           sample                                                                                                                                                                               
                           composition; isotopes                                                                                                                                                                                                                                                                                                                            

  electrospray ionization                            E                                       x            s,g,l                          acq, pos,    g\'s           0                 whole       avg          low                       Dm/m                                  contact w/                                                                                  
  MS (ESI/IMS/CIT-MS)                                                                                                                    vac                                           sample                                             1E2-1E3+                              fluidized                                                                                   
                                                                                                                                                                                                                                                                                sample                                                                                      

  laser ablation TOF-MS    local elemental/isotopic  B,D                                     x            s               rock chips,    acq, pos,    surface        0                 10mm - 1 mm grain scale+ low (l        ppbw-ppmw   Dm/m 1E2-1E3 5-25%       \~ 300                   4                     2,4                                2,5        1,3         
                           composition                                                                                    fines          vac                                                                    absorb.)                                                                                                                                                    

  LD/MALDI-TOF MS          high-MW organics; some    D,E                                     x            s               rock chips,    acq, pos,    surface/prep   0                 100mm - 1   grain scale+ med (l        fmol-pmol   Dm/m 1E3-1E4             \~1E3-1E5+                                               1,2,4,7                             3           4
                           inorganic molecules                                                                            fines          vac (pow,    film                             mm                       absorb.)                                                                                                                                                    
                                                                                                                                         liq)                                                                                                                                                                                                                               

  REMPI-MS/RIMS            organics, elements        E                                       x            s                              acq, pos,                   0                 10mm - 1 mm              very high (l  s\. atom -  Dm/m 1E2-1E4             \~ 1E3                                                                                                   
                           (trace)                                                                                                       vac                                                                    absorb.)      pmol                                                                                                                                          

  AP-MALDI-MS (TOFMS or    organic, inorganic molec. D,E                           x         x            s               rocks, ices    vac          surface        mm                10mm - 1 mm grain scale+ med (l        fmol-nmol   Dm/m                     \~ 1E3-1E5                                                                                               
  ITMS)                                                                                                                                                                                                         absorb.)                  1E3-1E4+                                                                                                                          

  electrospray TOF-MS      high-MW organics          E                                       x            s,l             rocks/cores,   acq, liq,                   0                 whole       avg          med                       Dm/m 1E2-1E4             \~1E4-1E5+                                               1,2,7                               3           4
                                                                                                                          fines          pos, vac                                      sample                                                                                                                                                                               

  TOF-SIMS                 chemical imaging          B,E                                     x            s               rock chips     acq, pos,    surface        0                 50nm-50mm   sub-grain+   low                       Dm/m 1E3-1E4             \~1E3-1E4                                                                                                
                                                                                                                                         vac                                                                                                                                                                                                                                

  ICP-MS                   trace elements            B                                       x            s,g,l           rock chips,    acq, pos,                   0                 whole       avg or       low           pptw-ppbw   Dm/m 1E3+    0.1-10%     \~ 300                   2,4                             1,3,5                    5                      
                                                                                                                          fines          vac, gas                                      sample      grains                                                                                                                                                                   

  TIMS                     isotope ratios (\~IRMS)   B,E2                                    x            s                              acq, pos,                   0                 whole       avg          low           pptw-ppbw   Dm/m 1E3+    0.1-1%      \~ 300                   2                               5                                               
                                                                                                                                         vac                                           sample                                                                                                                                                                               

  AFM                      nanoscale imaging         D, E3                                   x            s               flat chip      acq, pos     chips                            1nm-1mm     sub-micron                                                                                                                                                               

  TEM/SEM                  nanoscale imaging         D                                       x            s               flat chip      acq, pos,    chips                            1nm-1mm     sub-micron                                                                                                                                                               
                                                                                                                                         vac                                                                                                                                                                                                                                

                           image microbes in ice     D,E3                                                                                                                                                                                                                                                                                                                   
                           cores                                                                                                                                                                                                                                                                                                                                            

  XPS                      chemical comp. and bond   B,C                                     x            s,l                            vac          100\'s mg                                                                                                                                                                                                             
                           state                                                                                                                                                                                                                                                                                                                                            

  Auger spectroscopy       bond state of elements    B,C                                                  s,l                            vac          100\'s mg                                                                                                                                                                                                             

  amino-acid sensors (eg   detection of amino acids  E                                       x            s,l                            acq          100\'s mg                        whole                    high                                                                                                        1,3                                             
  MOD)                                                                                                                                                                                 sample                                                                                                                                                                               

  oxidant sensors          detection of oxidants     C                                       x            s,l                            Acq, dry     100\'s mg                        whole                    high                      per sample                                                                        6                                               
                                                                                                                                                                                       sample                                             weight                                                                                                                            

  bio-assay chip lab                                 E                                       x            s,l                            liq          100\'s mg      0                 whole                    high          pptw        per sample               Kda                                                      7                                   1,5,6       1,5,6
                                                                                                                                                                                       sample                                             weight                                                                                                                            

  micro-array sensors                                E                                       x            s,l                            Liq          100\'s mg                        whole                    high          pptw        per sample               Kda                                                      7                                   1,5,6       1,5,6
                                                                                                                                                                                       sample                                             weight                                                                                                                            

  MORD                                                                                       x            s                                           100\'s mg      0                 whole                    high                      per sample                                                                                                                        
                                                                                                                                                                                       sample                                             weight                                                                                                                            

  fluorescence staining    organics                  E                             x         x            s,l                            Liq          100\'s mg                        whole       avg          high          single cell per sample                                                                        7                                               
                                                                                                                                                                                       sample                                             weight                                                                                                                            

                           SYBR gold, SYTO, DAPI     E                                       x            s,l                            Liq          100\'s mg                        whole                    Medium        single cell per sample                                                                                                                        1.5.6
                           nucleic acid stains for                                                                                                                                     sample                                             weight                                                                                                                            
                           counting microbes                                                                                                                                                                                                                                                                                                                                

                           CTC, tetrazolium salt     E                                       x            s,l                            Liq          100\'s mg                        whole                    Medium        Single cell per sample                                                                                                                        1,5,6
                           redox stains for                                                                                                                                            sample                                             weight                                                                                                                            
                           individual cells                                                                                                                                                                                                                                                                                                                                 

  isotopic labelling       ^14^CO~2~ or ^3^H for     E                                       x            s,g,l                          Lig          100\'s mg                        whole       avg          medium        single cell per sample                                                                                                                        1,5,6
                           total population activity                                                                                                                                   sample                                             weight                                                                                                                            

  flow-cytometry                                     E                                       x            s,l                            liq          100\'s mg                        whole       avg          medium        single cell per sample                            If have                                                                                     1,5,6
                                                                                                                                                                                       sample                                             weight                                required                                                                                    
                                                                                                                                                                                                                                                                                media                                                                                       

  culturing/cell-growth                              E                                       x            s,l                            liq          100\'s mg                        whole       avg          high          single cell per sample                            If have                                                                                     1,5,6
  assays                                                                                                                                                                               sample                                             weight                                required                                                                                    
                                                                                                                                                                                                                                                                                media                                                                                       

  ATP and LAL enzyme                                 E                                       x            s,l                            liq          100\'s mg                        whole       avg          high          pptw        per sample                                                                                                                        1,5,6
  assays                                                                                                                                                                               sample                                             weight                                                                                                                            

  DNA extraction/PCR                                 E                                       x            s,l                            liq          100\'s mg                        whole       avg          high          100 cells   per sample                            with                                                                                        5,6
                                                                                                                                                                                       sample                                             weight                                correct                                                                                     
                                                                                                                                                                                                                                                                                primers                                                                                     

  capillary                                          E                                       x            s,l                                         100\'s mg                        whole       avg          high          pptw        per sample                                                                        7                                               1,5,6
  electrophoresis (CE)                                                                                                                                                                 sample                                             weight                                                                                                                            

  microcalorimetry                                                                           x                                                        100\'s mg                        whole       avg          medium        pptw        per sample                                                                        7                                               
                                                                                                                                                                                       sample                                             weight                                                                                                                            

                                                                                                                                                                                                                                                                                                                                                                            

  **KEY:**                                                                                                                                                                                                                                                                                                                                                                  

  n - can be operated with                                                                                                                                                                                                                                                                                                                                                  
  no sample                                                                                                                                                                                                                                                                                                                                                                 
  acquisition/processing                                                                                                                                                                                                                                                                                                                                                    

  abr - abrasion to remove                                                                                                                                                                                                                                                                                                                                                  
  surface layers                                                                                                                                                                                                                                                                                                                                                            

  acq - sample acquisition                                                                                                                                                                                                                                                                                                                                                  
  from host matl (via                                                                                                                                                                                                                                                                                                                                                       
  whatever means)                                                                                                                                                                                                                                                                                                                                                           

  pow - powdering of solid                                                                                                                                                                                                                                                                                                                                                  
  sample                                                                                                                                                                                                                                                                                                                                                                    

  pos - sample positioning                                                                                                                                                                                                                                                                                                                                                  
  (e.g., manipulation to                                                                                                                                                                                                                                                                                                                                                    
  oven, point of focus or                                                                                                                                                                                                                                                                                                                                                   
  extraction)                                                                                                                                                                                                                                                                                                                                                               

  vac - vacuum processing                                                                                                                                                                                                                                                                                                                                                   

  liq - liquid processing                                                                                                                                                                                                                                                                                                                                                   

  gas - gas processing                                                                                                                                                                                                                                                                                                                                                      
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