**Summary of Discussion Sessions**

**at the**

**2007 Colloquium on Astrobiology and Mars Exploration**

Pasadena, CA

July 8, 2007

> Marc Allen (editor), Doug Archer, Bethany L. Ehlmann,
>
> Caleb Fasset, Abigail Fraeman, Nina Lanza, Kennda Lynch, Melissa Rice,
> Leah H. Roach, Victoria Swisher, Nicholas Tosca

**Introduction**

The Colloquium on Astrobiology and Mars Exploration was a one-day event,
organized by the Space Studies Board of the National Research Council
(NRC) for NASA's Mars Planetary Science Division and Mars Exploration
Program, on astrobiology and international planning for the robotic and
human exploration of Mars.  The Colloquium took place on July 8, 2007,
at the Hilton Hotel in Pasadena, California. The purpose of the
Colloquium was to bring together robotic and human exploration aspects
and U.S.-international aspects of Mars exploration planning in the broad
context of the findings of three recent NRC studies in astrobiology
science. An agenda is provided in Attachment A.\
 \
The Colloquium featured a morning session where NRC study leaders
briefed the findings of their reports: *An Astrobiology Strategy for the
Exploration of Mars, Exploring Organic Environments in the Solar
System,* and *The Limits of Organic Life in Planetary Systems*.  These
briefings were followed by a status report on NASA planning for
exploration of Mars, and time was allocated for questions and answers.\
 \
At noon, there was a lunch-time talk by ESA on future planning for ESA's
Aurora program. Subsequently, participants broke up into five splinter
sessions for further discussion. These splinter sessions focused on the
relationships among future Mars missions, including the Mars Science
Laboratory, ExoMars, and Astrobiology Field Lab missions; scientific
activities foreseen for the human exploration of Mars; exploration of
the Martian subsurface; planetary protection for both robotic and human
missions; and fundamental issues associated with Mars sample return.
 The day's activities closed with a short plenary session where splinter
groups had the opportunity to describe the principal conclusions of
their discussions.  

The current report was prepared by student rapporteurs in each session
and captures the main topics discussed and widely shared views of
participants, but does not necessarily represent the specific views of
any individual. An acronym list is attached as Appendix B.

[Please cite as]{.underline}:

M. S. Allen (editor), Douglas Archer, Bethany Ehlmann, Caleb Fasset,
Abigail Fraeman, Nina Lanza, Kennda Lynch, Melissa Rice, Leah Roach,
Victoria Swisher, Nicholas Tosca; (2007). Summary of Discussion Sessions
at the 2007 Colloquium on Astrobiology and Mars Exploration, Unpublished
white paper, 23 p, posted August 2007 by the Mars Exploration Program
Analysis Group (MEPAG) at
*<http://mepag.jpl.nasa.gov/workshop/index.html>.*

**[Session A -- Mars Landers (MSL, ExoMars, and AFL)]{.underline}**

Co-Chairs: Ed Stolper and Jorge Vago

Organizer: Michael Meyer

Rapporteurs: Nicholas Tosca and Caleb Fassett

The broad goal of the discussion in Group A as established was to lay
out the context for upcoming missions, including the Mars Science
Laboratory (MSL), ESA ExoMars mission, Astrobiological Field Laboratory
(AFL) or Mid-Rovers concept, as well as the connections between these
missions. The late-breaking development that a sample caching capability
was to be added to the analytical payload of the MSL mission became a
major topic of discussion. Preparation for future Mars Sample Return
(MSR), as well as characterization, analysis, and caching of samples, is
a potential connecting thread between the upcoming, pre-MSR missions.

**[Mars Caching]{.underline}**. There was general agreement that the
proposed sample caching effort on MSL faces severe challenges, including
the short tactical timeline and additional complexity it adds to the MSL
program, the threat to science operations of the MSL rover itself, and
major concerns over the sampling strategy and the science return from
MSL-cached samples. For example, the nature of geological samples
produced and cached by MSL will be composed primarily of fine powders
produced by the MSL grinding bits, stored as \"samples in a can.\" As a
result of the collection process, fine-scale textural features will not
be preserved; moreover, the integrity of volatiles, organic compounds
and other labile chemical species contained in the rock sample might be
compromised either by the sampling process or from exposure to the harsh
Mars surface environment in the ten years between MSL and a MSR mission.
Given that the MSL sample-caching effort will not likely represent the
most robust and valid step toward sample return, Group A agreed that
much more importance should be placed on maximizing the *in-situ*
analysis and exploration capabilities of the MSL vehicle per its
original design. For example, the presence of a sample cache should not
prevent the vehicle from entering craters or other areas that are
scientifically rich targets, but not amenable to sample pickup for
return to Earth. These complications may prevent the MSL sample caching
effort from becoming a robust precursor step toward Mars sample return.

**[Contribution of Future Missions to MSL]{.underline}**. The specific
drawbacks of the MSL sample caching led Group A to discuss how future
missions, such as AFL, could advance Mars sample return with additional
years of planning and technology development. One participant suggested
that it is important to conceive of how AFL could maximize both sample
return preparation as well as *in situ* analysis. *In situ* capabilities
are important to ensure that well-characterized and useful samples are
chosen for sample return. Many of the analytical techniques for this
purpose that could be deployed on AFL or another precursor-MSR mission
might be leveraged from instruments deployed on earlier missions such as
MSL and ExoMars. However, one key technology development necessary for
AFL or any robust MSR sampling is further improvement in sampling
technology, which was described to the Group as a significant challenge
for MSL. Other specific desired technologies for AFL or another MSR
precursor that builds on MSL and ExoMars include:

1\) Precision landing capability;

2\) Potential to go somewhere new (other than the site of MSL, ExoMars);

> 3\) Horizontal mobility;
>
> 4\) Adequate in-situ analysis and characterization, so it can *pick
> and choose* MSR samples;
>
> 5\) Full planetary protection certification.
>
> 6\) Sampling technology that allows key scientific questions to be
> addressed (volatile and organics preserved; larger samples and in
> better condition than what would result from drill filing)

It was noted that many requirements for MSR are also important for the
future human exploration program; potential synergies exist between the
technology and science of MSR and human exploration of Mars.

**[Defining MSL and "Scientific Success]{.underline}*."*** The
discussion of science return and expectations from MSL and its aftermath
evolved to define what scientific success would be for these upcoming
missions. The Group was concerned that a lack of organic carbon
detection by MSL would be viewed by the astrobiology community and by
the general public as a possible failure. However, as the expression of
life in ancient geologic environments may be textural rather than
chemical, more intermediate definitions of success must be presented.
Indeed, previous missions have significantly advanced the science
community's understanding of habitability of the Martian surface with
geochemical and mineralogical evidence, as well as the detailed
geological context of the explored landing sites. The Group thought that
\"Follow the Habitability\" was a better goal for mission success than
\"Follow the Carbon.\"

**[Technology Feedforward]{.underline}**. Group A believed that success
from MSL and ExoMars should be leveraged towards the scientific
questions and technology of AFL or other future missions. For example,
subsurface access technologies on AFL could build on those of ExoMars,
given that ExoMars will have already tested subsurface drilling
technology and helped establish the level of scientific return. The
Group felt that international cooperation between NASA and ESA on
technology is a priority for MSR, both to mitigate costs and to allow
international expertise to feed forward to future missions. Samples
cached by MSL may have trouble meeting a science floor for a sample
return mission, but samples gathered by AFL could handily surpass
requirements. There was a broad view that samples cached by AFL could by
analyzed, characterized, and preserved in a manner that would far
surpass the potential of samples that could be cached by MSL.

**[Session B -- Scientific Activities for the Human Exploration of
Mars]{.underline}**

Co-Chairs: Pascale Ehrenfreund and Jim Garvin

Organizer: David Smith

Rapporteurs: Doug Archer and Melissa Rice

**[Necessary Science]{.underline}***.* Group B assumed that human safety
factors, such as the physiological effect of microgravity and the
necessary radiation safety precautions, will have been addressed and do
not fall under the purview of Mars science.

Discussion suggested that there are no outstanding scientific questions
that must be answered prior to human exploration of Mars. The
possibility of Martian life, Mars' climate and water history, the fate
of Martian organics, and the sources and sinks of Martian methane are
all extremely important questions but need not be totally understood
before a human mission is launched. It was also felt that future
missions already planned as part of the Mars program will have answered,
to first order, most of these questions.

Again, though it is not necessary prior to a human mission, Mars Sample
Return (MSR) is the highest-priority investigation to be carried out.
Retrieving Martian samples and knowing the context from which the
samples come, coupled with powerful investigative techniques available
in terrestrial labs, will help inform the scientific goals to be
addressed as well as which analytical tools that will be needed *in
situ* by human explorers on Mars.

Other investigations such as mechanical properties of soil, the
near-surface electric and magnetic fields, would be interesting and
might inform engineering decisions but are not scientifically necessary
before human exploration.

**[Lessons Learned]{.underline}*.*** The operational experience of past
and ongoing robotic Mars missions coupled with the experience of the
Apollo program must be used to inform human exploration of Mars. First,
much of what you think you know scientifically about the area you have
chosen to explore will be wrong. Bringing new tools and new capabilities
to a new site or even a previously explored site will invariably lead to
new data that will cause you to reevaluate what you think you know.

Second, whatever you think you will accomplish in a given amount of time
will always take longer. Plan on the possibility that tasks might take 5
times as long as you expect them to take. On a long duration mission,
you will spend a large amount of time maintaining equipment that never
had problems on shorter missions. Long duration missions to the Moon and
Mars will differ significantly from Apollo experience in this regard.

Third, you will learn that risks that terrified you before you went are
not as big a deal as you thought. The best way to avoid too much risk
aversion is to critically examine everything you are afraid of and
honestly examine the risks. A good question to ask is: are there any
clues that you have missed or ignored from past missions or experience
that would mitigate some of the risk? Conversely, factors that were not
considered problematic could pose unforeseen risks or complications
during the mission. This is fundamentally connected with exploration and
a reasonable amount of risk must be accepted.

Fourth, the explorers on the ground must be given a lot of independence.
There must be margin built into the schedules to allow for
investigations that come up in the course of other activities.
Serendipity has proven to be the source of some of the biggest
discoveries on Mars and the Moon. The best way to support such
discoveries is to be willing to discard your plans in favor of something
new and better.

Finally, the 40-minute difference between the terrestrial and Martian
day creates operational issues. Experience with robotic missions on
Mars, as well as terrestrial analog experiments, show that the best way
to handle this problem for long duration operations is for people on
each planet to keep to their respective times. Explorers on Mars will
follow the Martian diurnal cycle, while the support staff on Earth
follows the terrestrial cycle. This will necessitate \~3 different Earth
shifts that rotate with the time offset. In situations where this is not
possible, artificial lighting is the best way to mitigate the negative
effects of living a day that your body does not experience. It was also
mentioned that the social adaptation is much more difficult than the
physiological expectation. It is not reasonable to expect that
terrestrial support staff will be able to cut off ties with friends and
family during the mission as they work a continually shifting schedule.

**[Exploration Science]{.underline}*.*** Human exploration will enable a
huge leap forward in the scientific exploration of Mars. Exploration is
an iterative process where you define your direction based on what you
discovered that day. The communication lag between Earth and Mars means
that robotic exploration from Earth is and always will be slow because
of the long timescale of each iteration. A human presence will cut down
the iterative timescale enormously and will allow for much more
efficient exploration. The resulting area explored will be much greater
and this should be factored into mission design. Conversely, humans are
much better at finding and exploring micro-environments which will be
incredibly important to the search for life on Mars.

Areas of scientific interest that will be greatly aided by human
presence are drilling, trenching, and network science. Investigating the
third dimension on Mars (depth) will be much easier for human than
robotic explorers and will result in many new discoveries and a better
understanding of Mars' history. Network science, such as meteorology and
seismology, that is realized by measuring parameters over a large area
will be greatly enabled by human explorers. Furthermore, such
investigations might be necessary from a safety perspective and thought
should be given as to the best ways to accomplish both goals.

**[Analytical Tools]{.underline}*.*** Like any sample return mission,
the mass of samples returned to Earth for analysis is limited. One of
the most important roles of humans on Mars will be triage. Therefore,
tools that help illuminate which samples have priority for return to
earth and which samples can be left on Mars are imperative. We
understand that there is a direct relationship between the mass and
complexity of an instrument and the accuracy and precision of a
measurement and that instruments on Mars will, therefore, not match
terrestrial counterparts. Advanced field tools are the first thing that
will allow human explorers to identify and gather appropriate samples.
In their Martian lab, more complex analytical tools will further
illuminate the relative importance of gathered samples.

Group B concluded that isotopic analysis allowing for rough age
estimates is the single most important investigation for sample triage.

**[Session C -- Exploration of the Subsurface of Mars]{.underline}**

Co-Chairs: Jeff Plaut and Steve Gorevan

Organizer: Bruce Banerdt

Rapporteurs: Kennda Lynch and Leah H. Roach

# The Exploration of the Subsurface of Mars splinter session (Group C) brainstormed several issues relating to the requirements for initiating subsurface drilling on Martian landed missions. To facilitate this, the organizer and co-chairs broke the discussion into discrete topics:

1.  What depths beneath the surface need to be accessed physically in
    order to address high priority geological and biological science
    questions?

2.  What is the role of remote sensing in addressing these subsurface
    science questions?

3.  What is importance of deep interior?

4.  Is scientific prudent to capture a sample without drilling? Would we
    recommend a sample return that is not a subsurface sample

## [What depths beneath the surface need to be accessed physically in order to address high priority geological and biological science questions?]{.underline} To answer this question, it was suggested that to address the science objectives as a function of depth. Table 1 shows the result of this discussion and what science objectives relate to particular depths. Below are the science questions deemed most important by the group

1.  What is the composition of the rock/ice/regolith?

2.  What are the operating pedogenic processes?

3.  Are there rock coatings and what is their composition?

4.  Are there organics present? What is the effect of the radiation
    environment at this depth on the organics? Does the host material
    affect organic preservation or formation?

5.  What is the effect of the radiation environment on the host rock,
    ice or regolith with depth?

6.  What is the thickness of the oxidizing layer? Vertical soil profile
    (oxidants, temperature, duracrust cohesion).

7.  Understanding of soil/lithographic profile

    a.  If in regolith, what is the stratigraphic story?

    b.  If in permafrost, what is the climate change history?

8.  What is the thickness and origin of the ground ice?

9.  At what depth is the process that brings the water from 100s of
    meters to the surface active?

10. What is the geothermal heat flux?

11. Is there an extant biosphere? Is liquid water possible?

12. Start looking for zones of liquid water

13. At this depth, would be probing paleo-biospheres. Could also reach
    base of Polar Layer Deposit (PLD)

14. Start looking for aquifers sourcing gullies and pockets of liquid
    water

15. If drilling beneath the permafrost cap, could make an inventory of
    gases, such as methane

Table 1. Science Objectives vs. Depth

  --------- ------------------- ------------------------------------------
  *Depth*   *Cumulative Science *Tools*
            Questions*          

  1-10cm    1-4                 RAT, wheels, scoops, scrapers, robotic
                                arm, ISAD

  10cm-1m   1-5                 RAT, wheels, scoops, scrapers,

  1+ m      1-7                 Drill

  10+ m     1-10                Drill

  1+ km     1-11                Drill (robotic if ice; human if
                                rock/regolith), could be dedicated
                                drilling mission from this depth on

  10+ km    1-12                Drill (robotic if ice; human if
                                rock/regolith)

  100+ km   1-15                Drill (robotic if ice; human if
                                rock/regolith)
  --------- ------------------- ------------------------------------------

It should be noted that though there was general agreement on the
science questions addressed in the above matrix, there was significant
discussion on several topics that warrant emphasis.

If life was present at 10cm depth, it would need to have an active
metabolism to repair itself from cosmic radiation and to maintain itself
in a dessicating environment. However, 10cm is interesting to consider
because there are more sources of energy, such as photosynthesis. At
what depth might be it useful to start looking for extant life?

By organics, we mean either fossil or current organic molecules --
either abiotic or biotic). Ice might be better than rock for preserving
organics because it keeps out the hydrogen peroxide.

There was no agreement about at what depth liquid water would first
exist. Hydrostatic pressure and geothermal flux might not be sufficient
to have liquid water. But the presence of gullies argues that other
processes must be occurring to create liquid water.

Are the gullies sourced in subsurface liquid aquifers whose outlet is
plugged, or in near surface ice layers that melt during an obliquity or
precession cycle? An important dichotomy is icy (poleward) versus dry
(equator-ward), not northern versus southern. Icy is modern, while dry
is integrated history. There is a potential for liquid water in northern
plains due to climate variation. How deep do you have to go to get at
sediments that were put down in the liquid water conditions of the
recent past? That determines how deep drilling would be required.

## [What is the role of remote sensing in addressing these subsurface science questions?]{.underline} The Group discussed the various methods of remote sensing that might be applied to address questions of subsurface science. The following table presents a matrix of techniques versus sensing platform location.

Table 2. Techniques versus Platform Location

+----------------------------------+-----------+----------+-----------+
| **Technique**                    | **        | **       | **        |
|                                  | Orbital** | Aerial** | Surface** |
+----------------------------------+-----------+----------+-----------+
| **Radar**                        | []{.mark} | [        | []{.mark} |
|                                  |           | ]{.mark} |           |
+----------------------------------+-----------+----------+-----------+
| HF Imaging SAR MHz-GHz           | X         | X        |           |
+----------------------------------+-----------+----------+-----------+
| Sounding 1 kHz-50MHz             | X         |          |           |
+----------------------------------+-----------+----------+-----------+
| GPR 1kHz-GHz                     | X         | X        |           |
+----------------------------------+-----------+----------+-----------+
| ### Electomagnetics mHz -- 10kHz | X         | X        |           |
+----------------------------------+-----------+----------+-----------+
| ### IP (Resistivity)             |           |          | X         |
+----------------------------------+-----------+----------+-----------+
| ### Magnetics and Gravity        | X         | X        | X         |
+----------------------------------+-----------+----------+-----------+
| ### Nuclear Physics              |           |          |           |
+----------------------------------+-----------+----------+-----------+
| ### Neutron                      | X         | X        | X         |
+----------------------------------+-----------+----------+-----------+
| ### Gamma                        | X         | X        | X         |
+----------------------------------+-----------+----------+-----------+
| ### Active                       |           |          | X         |
+----------------------------------+-----------+----------+-----------+
| ### Seismic                      |           |          |           |
+----------------------------------+-----------+----------+-----------+
| ### Acoustic                     |           |          | X         |
+----------------------------------+-----------+----------+-----------+
| ### Active                       |           |          | X         |
+----------------------------------+-----------+----------+-----------+
| ### Passive                      |           |          | X         |
+----------------------------------+-----------+----------+-----------+

Some orbital remote sensing instruments can be used to look for liquid
water reservoirs in the crust. The current lack of detection of areas
with shallow (\>2-3km) reflectors from MARSIS and SHARAD signal the
absence of large subsurface water bodies (10s of lateral km). The
minimum detection is 10% water in pore space, due to the great
difference in dielectric constants. Nondetection means that (1) liquid
water is deeper, (2) finely distributed, (3) frozen, or (4) not there at
all.

GPR can be used to look for evidence of past life and should be
considered a critical instrument to decide optimal drilling locations.
By probing the radar stratigraphy at short length scales, the data can
elucidate crater stratigraphy, probe depositional environments, and
identify potential habitable settings. It can map lateral continuity of
layers and reveal the depth of the regolith and the location of the
bedrock. Shallow seismic techniques can also look for subsurface water,
but can only indicate broad scale stratigraphy and density and are
limited to the size of the array.

Geoelectrical techniques can identify shallow subsurface water,
especially saline bodies, and minerals such as massive sulfides and
hematite.

Nuclear physics techniques, such as active gamma ray radiation, could
distinguish what molecule H is in (especially H in water or other
phases). Between 60N and 60S, the amount of hydrogen detected indicates
\>20% by weight mass fraction of water. An orbital collimated instrument
would improve current spatial resolution from 50km to 20-30km.

Few of these techniques address chemical information (i.e., they cannot
be used to find methane clathrates other than water ice). Most methods
look for geophysical properties that distinguish a liquid from a solid.

## [What is importance of the deep interior?]{.underline} There are two Mars: the early Mars (Noachian 2-400 million) and recent Mars (short periods of clement weather or periodic infusions of volatiles but otherwise dry). You can look at the deep interior to learn about the climate condition at 4 Gya, the most clement period for life on Mars. This is necessary to interpret a chemical record of biosignatures from earliest part of Martian history. Issues to probe include: (a) Interior structure and thermal history, (b) differentiation processes, how materials partitioned themselves in the core, what materials were on the surface, (c) how did the atmosphere get delivered, (d) volatiles and chemicals available, (e) what the magnetic field was like and how long it existed to shield life on the surface, (f) thermal structure and geothermal gradients, and (g) oxidation state of the interior. The recent Mars should also be considered. It can be probed by looking at the climate record in ice.

If we knew when the martian magnetic field (which shields from solar
radiation and solar wind sputtering of the atmosphere) collapsed, we
could know how long the thick atmosphere existed and how fast did it
decay to recent conditions. Paleomagnetic studies might not help much
because very little of the early surface record exists, having been
modified in the intervening 4 Gya. The size and structure of core and
its thermal history can help establish the physics of the dynamo and
when it shut down.

Seismic studies can inform us if Mars is tectonically or magmatically
active today, especially if the thermal history is known. Three or four
stations would be sufficient to triangulate location of seismicity and
the possible geothermal activity of recent volcanism.

## [Is it scientific prudent to capture a sample without drilling?]{.underline} Should return of a surface sample be recommended? If surface carbon that has a high potential to be organic carbon and a geologic context indicative of life is found, that is the preferred sample; otherwise a subsurface sample is warranted. 

**[Session D -- Planetary Protection for Both Robotic and Human
Exploration]{.underline}**

Co-Chairs: Cassie Conley and Gerhard Kminek

Organizer: John Rummel

Rapporteurs: Nina Lanza and Abigail Fraeman

Group D addressed a series of questions, aggregated into five general
topical clusters.

**[What are the planetary protection requirements that should be applied
to all Mars missions prior to launch? Are there planetary protection
requirements that should apply for all missions, both human and robotic?
Should human and robotic missions have different
standards?]{.underline}** The results of a planetary protection meeting
sponsored by ESA and NASA were reported; there it was decided that there
should be no distinction between human and robotic missions for
planetary protection on Mars, and that future provisions would likely
focus on special regions only. Additionally, it was determined that Mars
should be divided into zones of allowable contamination levels (forward
only).

A question was raised about the definition of "contamination." There are
different types of contaminants (human, soil, etc), and each will have a
different amount of impact in different martian environments.Trying to
separate different contaminants would be difficult, but while it is not
possible to eliminate all contaminants, we can control and monitor them.
Organics are as important as biotics as sources of contamination, but
only biotic contaminants can multiply their initial number. An extreme
example can be considered for illustration: what if martian life likes
the reduced carbon found in Teflon brought by astronauts? This would
cause the biochemistry of the system to change.

Monitoring biotic contaminants poses some unique challenges. The
majority of microscopic terrestrial life has likely not been cataloged
(the "unknown majority"), making it difficult to identify the source of
a biotic contaminant. Even if an unknown microbe were observed, there
would be a chance that it is an as-yet unidentified terrestrial rather
than a martian entity.

In order to mitigate the risks associated with biotic and organic
contamination, it was suggested that an inventory of both biodiversity
and organics should be taken for all Mars missions prior to launch.
Controls and blanks should also be generated prior to a mission to
ensure data quality.

Equal planetary protection requirements should be applied to both human
and robotic missions: human spacesuits should not contaminate an area
more than a robotic mission. A key difference between mission types was
suggested: for robotic missions, all protection mitigation occurs on the
front end and is complete by the time the craft reaches Mars, while
human missions require constant mitigation. This is not entirely true,
however, as rover operations will be influenced by the desire to avoid
areas that they are not clean enough to enter. But it does have some
merit in helping us think about the complications of human Mars
missions.

It was concluded that it is necessary to know the quantity and
biodiversity of the bioburden, and to take an organics inventory. The
following questions should be evaluated:

-   What is on the craft?

-   Where is it on the craft?

-   What does it do when it gets to Mars?

These requirements will be affected by technical capabilities such as
experimental sensitivity, and it is important to keep in mind that
terrestrial techniques are about 20 years ahead of techniques used in
space instruments.

**[What are the planetary protection requirements to enable access for
Earth vehicles/explorers to Mars special regions?]{.underline}** In
addition to the requirements set forth above for all missions, special
regions should also be identified by the limits on the ability of
terrestrial life forms to thrive in those environments. Certain microbes
may pose a greater threat to one region than to another, and care must
be taken that they do not encounter these places. Thus, depending on the
type of special region to be visited, it is conceptually possible (but
likely practically impossible) that the craft be sterilized for specific
contaminants.

In this discussion, it was emphasized again that it is not possible to
prevent contamination, only to mitigate its influence. In terrestrial
labs, 10-20% of organisms that are analyzed using current methodology
cannot be further identified. This is most often the case when there is
a low abundance of these organisms. If these organisms were encountered
on Mars, they might appear to be martian but in fact be terrestrial. A
single gene index could be developed to uniquely identify terrestrial
microbes, though this remains a difficult issue.

For human missions, it was generally agreed that human explorers must be
isolated from the martian environment as much as possible, using devices
such as positive pressure suits. In addition, the biodiversity inventory
for humans is of utmost importance; since there is no way to "sterilize"
a human, we must know exactly what has been brought to Mars in order to
correctly evaluate what is brought back.

**[What precursor planetary protection information is required prior to
sending humans to Mars, and how should that information be
obtained?]{.underline}** Environmental conditions on Mars should be well
understood before sending humans. This is not only to ensure the safety
of the astronauts, but also to ensure that we understand the spread of
potential contaminants. Weather and wind patterns should be well
understood in order to calculate when and how contaminates will spread.
The large global weather patterns on Mars create the possibility that
special regions may become contaminated even by missions to non-special
areas. Exactly where these contaminates will go and how fast they will
travel (1 month to contaminate special regions? 10 years? 100 years?)
should be taken in consideration when defining protection guidelines.

Laboratory simulations are an inexpensive way to model the effects of
contamination and should be run prior to sending humans to Mars. These
simulations can model how Earth organisms will react to the Martian
environment. Simulations can also be conducted to understand how
potential martian microbes would react to human material. As stated
before, these theoretical microorganisms could enjoy consuming the
Teflon and rubber in spacecraft and spacesuits, which could cause the
behavior of the microbes to change as well as present a risk to
missions. Further simulations could be run to predict the change in
behavior of the organisms, as well as to understand how to prevent this
outcome, e.g., addition of silver to some materials to make them less
edible.

There was also a discussion about whether or not a sample return mission
was a necessary precursor to a human mission. It was not agreed upon
whether or not it should be required; an additional question was whether
a single sample from an area would be sufficient to "clear" the area, or
if multiple samples are necessary to fully understand the environment.
This discussion continues. In any case, sample returns would provide
information about the toxicity and reactivity of the martian
environment, and could also determine whether harmful, non-terrestrial
microbes were present. The location of the human landing might need to
be known before samples were acquired.

Participants raised the question of whether it is worth the risk to send
humans to Mars at all was raised. Since they undoubtedly will
contaminate the planet, is it ethical to send them before knowing more
about the biological environment of Mars? This brings up an interesting
paradox: we could decide to send humans to Mars only if there is no
current martian life, but we may need humans to detect life in the first
place.

**[Should the "special regions" designation be
eliminated?]{.underline}** Special regions are defined differently today
than they were 10 years ago, and they are likely to be defined quite
differently 10 years into the future. As more information about Mars is
returned, it is inevitable that more regions will be defined as
"special." Special regions are likely to have the biggest science
return, as well as potential resources. If too many requirements are
placed on visiting a special region, we will never go there. Acceptable
risk levels were discussed; it was pointed out that on Earth, not all
consequences of certain actions are known, but prior to action the risk
levels are assessed and agreed upon. It was concluded that the special
region designation is here to stay.

**[How do we establish and track Mars special regions in a cogent and
internationally agreeable fashion?]{.underline}** An international
standard for a Mars GIS system for defining special regions should be
created. To do this, standards such as a single martian coordinate
system should be developed. All available data sets should be combined
in a single GIS, and then special regions could be mapped from these
data as they are defined. It was also suggested that algorithms could be
developed for defining special regions rather than adding them manually.
There was general agreement that an organization should be created as a
"keeper of the data" that would keep up to date with evolving
definitions of special regions as well as new data from Mars. The PDS is
good for archiving and validating data, while the USGS facility in
Flagstaff, AZ could assist with setting standards. A COSPAR panel should
be generated to ensure international consensus on these evolving
standards.

**[How can compliance with planetary protection protocols be
ensured?]{.underline}** There was general agreement that education of
project leaders and members about the importance and strategies of
planetary protection is essential. All members of a mission team must be
fully aware of and understand the motives behind planetary protection.
This knowledge will ensure that those working on the mission will take
the necessary steps to maintain the integrity of the protection process.
Lack of attention to required measures by only one or two people has the
potential to undermine the entire process. NASA Headquarters should
consider creating education requirements related to planetary protection
for all mission or project personnel.

**[Session E -- Issues in Mars Sample Return]{.underline}**

Co-Chairs: Michel Viso and Noel Hinners

Organizer: Dave Beaty

Rapporteurs: Bethany L. Ehlmann and Victoria Swisher

The group in this breakout session was tasked with examining issues
related to Mars Sample Return (MSR), including the nature of a MSR
program, the nature of a sample(s), and key technical challenges. Due to
the recent announcement of a study on the potential for caching on MSL,
substantial discussion also was made on methods, costs and benefits of
sample caching. The summary reflects key issues identified by the group.
Areas of general agreement are shown in italics.

**[Sample return: A key programmatic direction.]{.underline}** The group
was enthusiastic about the reinstitution of planning for Mars Sample
Return (MSR). The public support for MSR by the NASA Associate
Administrator of the Science Mission Directorate, definition of a time
scale, and declaration of sample return as an integral part of the Mars
program are particular reasons for optimism. Sample return also
contributes as an integral part of the vision to send humans to Mars. It
is an exciting and challenging mission that will garner substantial
public interest and excitement. (See below, however, for concerns
related to the specific nature of MSR and its impact on the rest of the
program).

Sample return has been a goal of the Mars science community since the
late 1960s. Previous missions, while announced, have not flown, however.
Thus, it is worthwhile to examine why these previous incarnations of an
MSR mission did not fly and derive lessons from them for preparing for
MSR at present. Previous missions

(1) Were not within the funding envelope

(2) Had substantial uncertainty as to the nature of the desired samples
    and the site(s) from which to obtain them

(3) Faced technical challenges in terms of infrastructure and planetary
    protection, particularly:

    a.  Sample return capsule design

    b.  Mars on-orbit rendezvous capability

    c.  Sample receiving facility on Earth (BSL-4 class)

    d.  Mars ascent vehicle

In recent years, we have largely satisfied (2) as discussed in the next
section. The focus of efforts of the community can now be how best to
make sample return happen: will we commit to the long-term investment
required for #3? Can this be done within acceptable budgetary
constraints?

*Group E generally felt that it was essential that MSR be part of a
larger program of Mars exploration.* The previous 10 years of Mars
exploration, with multiple discovery-driven pathways has been successful
in generating a robust, exciting scientific program. MSR should be a
flagship mission within a program of comparable or greater energy and
pace of discovery. The group recognized that substantial sustained
effort will be necessary to address technological challenges in the
years preceding the first MSR mission and this may reduce the number of
other near-term opportunities. However, after this investment is made,
it is anticipated the first MSR should not be the last MSR. After the
first returned samples are evaluated, a set of pathways driven by the
resulting science discoveries should dictate additional sample return
sites and future landers and orbiters.

Needed technology development and complex mission architecture make MSR
a substantial systems engineering challenge and require a long lead
time. Thus, appointing a person responsible for achieving the MSR goal
and coordinating subprojects to achieve them is a way to sustain the
long-term effort. An example of success in successfully surmounting the
technological and logistical challenge of sample facility construction
is that of the Japanese having nearly finished construction of a
receiving facility for potential samples from Hayabusa and subsequent
missions. Split mission architecture---a lander/rover to collect samples
followed by later landing of a vehicle to launch from Mars, might be
desirable. *The scientists and engineers in Group E generally agreed
that core MSR technology or telecom-geared missions can and should
include "opportunity science".* In addition to the scientific benefit,
such missions maintain the energy of the scientific community while
preparing for sample return. *The group felt that we need to establish a
milestone based technology plan for sample return*. Pre-phase A
technology development should be instituted immediately in order to make
a 2018 or 2020 launch opportunity. A commitment to and adequate funding
for technology milestones aimed at the earliest possible launch could
help anchor the mission in a concerted MSR program. Elements of an MSR
mission should incorporate collateral science along the way.

It is also realized that sample return would consume substantial
resources within the Science Mission Directorate. Several committee
members were interested in cooperation to open up other potential
funding sources from within NASA and internationally. There was a
suggestion to discuss with ESA within the next few months long-term
mission planning for MSR in order to establish collaborations and figure
into the European budgeting process. *There are also strong linkages
between human exploration and MSR in technology development and
understanding Mars material*. It was noted that MSR in ESA is part of
the Aurora Program. Though it is recognized that NASA's Exploration
Systems budget is constrained, given that sample return is a potentially
key precursor to human exploration, there was a question as to whether
funding from Exploration Systems could be applied to a sample return
mission. Samples are needed to understand planetary protection
requirements for preventing forward or backward contamination, for
understanding the oxidizing properties that are potential health
hazards, for developing dust mitigation techniques, and for implications
to in situ resource utilization (ISRU). A landing package and sample
return launch will feed forward (proof of concept) to landing large
human support systems and returning humans to Earth.

**[Where to go and what to get.]{.underline}** There is growing
consensus in the Mars community as to the nature of samples needed. The
past ten years of Mars exploration have been a great success, bringing
us where to we hoped to be: an understanding of the most interesting
sites on Mars based on composition as well as morphology. *Hence,
potential science from MSR has increased as result of the integrated
program of Mars exploration*, especially over the past few launch
opportunities (MER, Odyssey, MRO, and ESA's Mars Express). *In light of
new knowledge garnered from orbital and landed missions of the past
decade, there is a need to update and detail the science
requirements---astrobiological, geological, and atmospheric---for Mars
samples*. We know we can get good samples. We have realized *Mars is
diverse and thus sample variety is important -- grab samples should be a
last resort only*. Samples are needed to complement the information that
can be achieved from remote sensing alone (e.g. at the Meridiani
Opportunity landing site; hematite detected from orbit was only the cap
on a massive layer of sulfate-rich siliciclastic sedimentary deposits).

Three questions in particular were considered by Group E:

-   [Should returned samples be from the subsurface?]{.underline} There
    was no consensus for this as a demand on a first MSR. This could
    perhaps be an enhancement for later missions. The nature of the
    sample (rock type, ice) and astrobiological evidence (carbon,
    preserved organisms, extant organisms) would dictate the depth.
    Carbon could potentially be hosted within centimeters of the surface
    in phyllosilicates and sulfates.

-   [Does the sample have to be astrobiological?]{.underline} *Do we
    need to look for bizarre life?* The need for careful definition of
    science objectives was reiterated. Failure to find evidence for life
    would certainly not be a mission failure. *Identifying reduced
    carbon is important and there are substantial questions about
    climate and geologic history which may be addressed by samples and
    by dating them.* There are complex technical issues around both
    organic carbon and dating, and these need detailed study. Looking
    for "bizarre" life would be a bit ambitious for a first MSR. Once we
    have returned samples, we will be much better equipped to decide how
    to search for the unexpected.

-   [Does sample return require in-situ characterization? How extensive
    should this be?]{.underline} Two advantages of in-situ
    characterization were (a) provision of a quality control check of
    how well we do in-situ science and (b) understanding whether the
    sample had been altered between its collection on Mars and its
    analysis on Earth. While the committee recognized these as valuable,
    there was concern that adding too many complex in-situ analysis
    requirements would increase mission cost beyond an acceptable
    envelope. It was generally agreed that, unlike sample return
    missions such as Genesis or Stardust, we could not simply bring back
    just any sample. Ideally, *there should be enough on-board
    analytical equipment to collect a diverse suite of samples of
    interest, and reasonably preserve these*. However, *the first sample
    return mission should not be seen as a one-shot, perfection-required
    opportunity; rather the suite of techniques employed should be
    improved upon in future sample return opportunities.*

**[The potential of caching.]{.underline}** The group spent considerable
time discussing the concept of caching of samples for return by a future
MSR mission. As sites of key scientific interest will be visited by
upcoming landed missions, we have the opportunity to identify samples
for which laboratory analysis would be warranted. *Caching is a
promising concept but needs detailed assessment of costs and benefits
and further precise definition of science objectives.* The benefit of
science goals addressed from the types of samples that could be cached
by a particular mission must be balanced against the collection penalty
to upstream missions in cost, risk, or operational restrictions.
Additionally, *there was general agreement that the program architecture
around MSR should include the ability to decide to ignore a cache or
decide among caches.* The idea of an intermediate option of identifying,
but not collecting, samples for future return was also suggested.

A topic of some concern for all present was the potential add-on of
caching capability to MSL. Given the late incorporation of caching on
MSL, there are concerns about how well it can be done. Samples on MSL
would likely be powdered, and the increased reactivity of a powdered
sample would facilitate breakdown of organics and alteration of the
sample prior to its opening in a curatorial facility. The lack of a
capability to acquire rock pebbles or chips would be seen as a major
deficiency. There was concern about how addition of sample caching might
cause schedule slip and how an onboard sample might constrain MSL
traversing capabilities. In fact, MSL provides a first example of how
the tradeoffs between sample acquisition, sample quality and increases
in constraints/risks should be assessed in evaluating caching on landed
missions.

**APPENDIX A**

**Acronym List**

AFL Astrobiology Field Laboratory

BSL-4 Biosafety Level 4; required for work with dangerous and exotic
agents

> that pose a high individual risk of aerosol-transmitted laboratory
> infections and life-threatening disease.

COSPAR Committee on Space Research

ESA European Space Agency

GIS Geographic information system

GPR Ground penetrating radar

Gya Giga-years (billions of years)

H Hydrogen

HF High frequency

MARSIS Mars Advanced Radar for Subsurface and Ionospheric Sounding

(instrument flown on the ESA Mars Express mission)

MEPAG Mars Program Analysis Group

MER Mars Exploration Rover

MRO Mars Reconnaissance Orbiter

MSL Mars Science Laboratory

MSR Mars Sample Return

NRC National Research Council

PDS Planetary Data System

PLD Polar Layered Deposit

RAT Rock Abrasion Tool (carried on the Mars Exploration Rovers)

SAR Synthetic aperture radar

SHARAD Shallow Subsurface Radar (instrument flown on MRO)

USGS United States Geological Survey

# [APPENDIX B]{.smallcaps}

**Final Agenda**

# [Colloquium on]{.smallcaps}

# [Astrobiology and Mars Exploration]{.smallcaps}

Pasadena Hilton

168 South Los Robles Avenue

Pasadena, California

**Saturday, July 7, 2007**

6:00-7:00 pm. Registration (Entrance of the International Ballroom)

**Sunday, July 8, 2007**

7:30 a.m. Registration will be located at the entrance of the
International Ballroom

7:30 a.m. Breakfast for Invited Guests in the California Ballroom

[OPEN SESSION (International Ballroom)]{.underline}

8:30 a.m. Welcome and Goals of Colloquium

Michael Meyer, *NASA Science Mission Directorate*

8:35 a.m. Astrobiology and the Exploration of Mars

John D. Rummel, *NASA Science Mission Directorate*

8:50 a.m. Fifty Years of Strategic Planning for the Exploration of Mars

Lennard J. Fisk, *University of Michigan*

9:05 a.m. Exploring Organic Environments in the Solar System

James Ferris, *Rensselaer Polytechnic Institute*

9:40 a.m. The Limits of Organic Life in Planetary Systems

Steven Benner, *Foundation for Applied Molecular Evolution*

10:15 a.m. Break

10:45 a.m. An Astrobiology Strategy for the Exploration of Mars

Bruce Jakosky, *University of Colorado*

11:30 a.m. Planning for Future Mars Missions

Michael Meyer, *NASA Science Mission Directorate*

David Beaty, *Jet Propulsion Laboratory*

12:30 p.m. Lunch for Invited Guests in the California Ballroom

*Lunchtime Presentation*

ESA's Aurora Program: ExoMars, NEXT and Beyond

Jorge L. Vago, *European Space Agency*

[CLOSED SESSION]{.underline}

2:00 p.m. Discussion Groups

Group A: Relationship between MSL, ExoMars, and AFL (Santa Barbara Room)

Jorge Vago, *European Space Agency* (co-chair)

John Grotzinger, *California Institute of Technology* (co-chair)

Michael Meyer, NASA,*Science Mission Directorate* (organizer)

Group B: Scientific Activities for the Human Exploration of Mars (Santa
Rosa Room)

Pascale Ehrenfreund, *Leiden Institute of Chemistry* (co-chair)

James Garvin, *NASA, Goddard Space Flight Center* (co-chair)

David H. Smith, National Research Council (organizer)

Group C: Exploration of the Martian Subsurface (Santa Clara Room)

Jeffrey Plaut, *Jet Propulsion Laboratory* (co-chair)

Stephen Gorevan, *Honeybee Robotics* (co-chair, invited)

W. Bruce Banerdt, *Jet Propulsion Laboratory* (organizer)

Group D: Planetary Protection for Robotic and Human Missions (Pasadena
Room)

Gerhard Kminek, *European Space Agency* (co-chair)

John Rummel, *NASA Science Mission Directorate* (co-chair)

Katharine Conley, *NASA Science Mission Directorate* (organizer)

Group E: Mars Sample Return (San Marino Room)

Noel Hinners, *Lockheed Martin Astronautics* rtd. (co-chair)

Michel Viso, *CNES* (co-chair)

David Beaty, *Jet Propulsion Laboratory* (organizer)

[OPEN SESSION]{.underline}

4:45 p.m. Reconvene for Plenary Session in International Ballroom

5:00 p.m. Summary reports from Discussion Groups

6:00 p.m. Adjourn