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Elemental analysis as a first step towards "following the nitrogen" on Mars
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Elemental analysis as a first step towards "following the nitrogen" on Mars
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Content
ELEM ENTAL ANALYSIS AS A FIRST STEP TOWARDS
“FOLLOW ING THE NITROGEN” ON MARS
Copyright 2006
by
Derek Michael Shannon
A Thesis Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment o f the
Requirements for the Degree
MASTER OF SCIENCE
(GEOBIOLOGY)
August 2006
Derek Michael Shannon
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DEDICATION
F orO ctaviaE . Butler, 1947-2006:
“Only we are Earthseed.
And the destiny o f Earthseed is to take root among the stars.”
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ACKNOWLEDGEMENTS
I would like to extend my heartfelt thanks and acknowledgement to the
members o f m y thesis committee: Doug Capone for his framing o f the nitrogen
discussion, Frank Corsetti for his generosity in providing samples, and Ken Nealson
for his patience and insight dating from m y time as a freshman at Caltech all the way
through these years as my graduate advisor; instrument ace Will Beaumont; the USC
faculty including Will Berelson and Kathy Allen; the Jet Propulsion Laboratory
including Sasha Tsapin, Pan Conrad, Bob Carlson, and Rho Bhartia; office painter
extraordinaire M ichael Storie-Lombardi; Bob Zubrin, the M ars Society, and my
fellow members o f the Mars Desert Research Station Crew #7; the Agouron Institute
and its Summer Geobiology Program; the USC Provost’s Office; m y Caltech
mentors who continue to shine a guiding light including Bruce Murray, Diane
Newman, Joe Kirschvink, and Kerry Sieh; labmates including Orion Johnson,
Everett Salas, Rachel Schelble, and Beverly Flood; Ana and the Zumberge Hall
custodial staff; all my friends and firenemies including Sarina Mohanty, David
Rothley, Ted W yder, Kevin Parkin, and Tye Lautenshlager; m y loving and
supportive family; and the USC Earth Sciences staff including Barbara Grubb,
Vardui Ter-Simonian, John Yu, Stan Wright, and especially the glue that held it all
together, Cindy Waite.
iii
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TABLE OF CONTENTS
Dedication ii
Acknowledgements iii
List of Tables v
List o f Figures vi
Abstract vii
Introduction: Of leprechauns and little green men 1
Additional background: Differentiating Mars from Earth’s ancient record 6
Beyond Sediments to Hydrothermal Sites 7
Strong Potential for Clay Investigations Revealed by Mars Express 8
The Nitrate Question 9
Abiotic sources of ammonium, Experimental Approach 11
Chapter One: Elemental Analysis of Select Nitrogen Species 13
and Shewanella Oneidensis MR-1
Nitrogen species measurement discussion 15
Shewanella oneidensis M R-1 dilution series discussion 27
Limitations of elemental analysis 28
Chapter Two: Preparing for Mars by searching for nitrogen on Earth 30
Clay samples 30
Ancient sedimentary rock samples 32
Discussion 33
Arguing against contamination: C/N ratios 34
Implications for following the nitrogen 35
Chapter Three: Following the nitrogen through Mars on Earth 37
Elemental analysis of nitrogen for the discovery of life in a Mars analogue 38
Discussion 39
Chapter Four: Looking to the future 40
UV Fluorescence 40
Raman Spectroscopy 41
Establishing thresholds for abiotic nitrogen exchange and detection 41
Establishing thresholds for exchange and detection in biological systems 42
Distinguishing between cation exchange in abiotic vs. biological systems 44
Biochemical pathways associated with cation exchange within ecosystems 44
In situ nitrogen investigations in extreme environments 45
Analogues and integration of laboratory work with JPL instrument development 45
Conclusion: Looking to MER and Beyond 46
Bibliography 49
Appendix: The Mind of the Mars Analogue Explorer 61
iv
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LIST OF TABLES
Table 1: MR-1 concentration 15
Table 2: MR-1 dilution series sample preparation and results 15
Table 3: MR-1 Sample # lb dilution series discrepancy highlights 16
Table 4: Ammonium chloride series 16
Table 5: Sodium nitrate series 20
Table 6: Alanine series 20
Table 7: Adenine series 20
Table 8: Source clays elemental analysis 32
Table 9: Ancient samples elemental analysis 32
Table 10: Utah Mars analogue elemental analysis 38
v
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LIST OF FIGURES
Figure 1: Ammonium chloride sensitivity series 18
Figure 2: Ammonium chloride % N, normalized to 20 mg total sample size 19
Figure 3: Sodium nitrate sensitivity series 21
Figure 4: Sodium nitrate weight % N, normalized to 20 mg total sample size 22
Figure 5: Alanine sensitivity series 23
Figure 6: Alanine weight % N, normalized to 20 mg total sample size 24
Figure 7: Adenine sensitivity series 25
Figure 8: Adenine weight % N, normalized to 20 mg total sample size 26
Figure 9: First EVA at MDRS 37
Figure 10: Orange Lichen 38
Figure 11: White lichen 38
Figure 12: Sandstone with orange crust 38
Figure 13: Opal with hypolith 38
Figure 14: Overlooking Canyonlands National Park during simulation 62
vi
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ABSTRACT
Elemental analysis was shown to be a useful if rudimentary tool in taking the first
steps towards “Following the nitrogen” as an approach to astrobiology on Mars. By
determining sensitivity towards a variety of nitrogen species, key assumptions were
challenged regarding the role o f clays relative to other sediments in storing nitrogen
in the rock record. A high threshold was set for the number of microbes needed to
generate a nitrogen signature sufficient for elemental analysis. The presence o f
nitrogen was used to conclusively differentiate between biological and abiotic
samples in a Mars analogue environment.
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Introduction: Ofleprechauns and little green men
Mars is red. But the potential organisms past and present that so many are
seeking there are often referred to as “little green m en.” The paths taken in hot
pursuit after these little greenies— and their fossilized relics— have long followed the
tracks o f gullies, or outburst channels, or ancient alleged shorelines. In other words,
they have followed the paths prescribed by the NASA Mars Exploration Program’s
“Follow the water” mantra (Hubbard 2002, Irion 2002).
Following the water has been almost too successful, so much so that the
strategy today might bring to mind a cultural touchstone that predates the little green
men by a wide margin: The little green leprechaun. As Celtic lore describes, a naive
young astrobiologist once observed a storm burst over primeval forest give way to
sunlight, in the process unleashing a beautiful rainbow. The astrobiologist followed
this glimmering path straight and true to its end, where o f course a leprechaun
grudgingly acknowledged that— indeed!— this was the site o f a buried pot o f gold.
The astrobiologist very much needed this gold in order to fund a manned mission to
distant Blarney Castle, so he could sample the exotic biofilms that must be growing
on its Stone after so many strangers’ kisses.
The leprechaun became downright recalcitrant, however, when it came to
loaning the astrobiologist a shovel. The astrobiologist would have to leave the
treasure site to fetch one. But with GPS so many centuries in the future, how would
he find the site again upon his return? With the rainbow long gone, the
astrobiologist prominently tied a bit o f ribbon he had in his pocket to a bush adjacent
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to the treasure site. W ell aware o f leprechauns’ penchant for shadiness, he
admonished the tiny trickster to make a solemn vow not to move his marker, and to
his surprise the leprechaun agreed. As leprechauns cannot break a vow, the
astrobiologist took his leave with confidence.
On the return trip, however, shovel over shoulder, the astrobiologist noticed
something amiss. The return had seemed to pass much more quickly than the
departure, for here was the ribbon, on a bush much closer to the edge of the forest
than he recalled. But memory is fallible. A sweaty hour o f labor later, the
astrobiologist was interrupted in his digging by a giggle: The leprechaun had been
observing for some time, and could contain his impish glee no more. The most
severe threatening with the shovel’s broadside induced no change in the leprechaun’s
protestations: The trickster insisted that he had not broken his vow.
Finally stepping out o f his hole, the astrobiologist raised his eyes in dismay to
see that it was so, but he would be no richer for it. While his original ribbon could
certainly still be in its place, somewhere, the leprechaun during his brief absence had
made sure that every bush in the forest was now similarly festooned. Following the
ribbon could no longer narrow down the astrobiologist’s pursuit o f treasure.
In the same way, following the water on Mars no longer effectively narrows
the search for life and its remnants on the Red Planet, especially given the small
number o f shovels available. The white dots o f the M artian polar caps have
suggested the promise o f following the water since the time o f Giancomo Miraldi
(1704), fluvial channels since the time o f Mariner 9 (1971). These early signs shone
2
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just as the astrobiologist’s first ribbon as a certain beacon over the leprechaun’s pot
o f gold. But what was intended as a focused strategy in the search for life has now
been completely inundated. Success has come in waves: from laser altimetry hinting
at ancient oceans (Aharonson 2001, Head 1998) to gullies suggesting recent trickles
(Malin & Edgett 2000); from water-associated hematite (Christensen 2000) to
gamma ray-absorbing hydrogen (Boynton 2002); from the rippling sedimentary
textures o f Terra Meridiani (Squyres 2004a) to the sulfate salts o f Gusev Crater’s
“Peace Rock” (NASA 2005/Squyres, in press); all the w ay to the frozen sea of
Elysium Planitia (JB M urray 2005).
Each o f these discoveries is an invaluable contribution to the understanding
o f Mars and the potential for life there. For future planning purposes, however, each
new claim o f water is becoming more like another ribbon in the forest, each bit of
aqueous evidence the droplet for a new rainbow, until the sky is awash in a tangle of
color, and confusion reigns as to where the pot o f gold truly lies.
However, the dam has not completely given way: The areographic and
temporal extent o f liquid water on Mars remains constrained by the widespread
presence o f minerals vulnerable to chemical weathering (Hoefen 2003) and
consistently cold temperatures over the past 4 Ga (Weiss 2002). Hydrated minerals
remain limited in areographic extent, and the vast majority o f the rusty blanket
covering Mars is made up o f minerals that “are not hydrated nor do they require the
presence o f liquid water to form .. ..Liquid water is not responsible for Mars being
red (Bibring 2006).”
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Still, certain water discoveries could be sufficiently astounding to make
themselves heard above the flood, or stand out in any forest. These could very well
include subsurface liquid reservoirs revealed by the penetrating radar studies of
MARSIS (Nielsen 2004, ESA 2005), SHARAD (Seu 2004), and untold future
investigations.
Even if such discoveries had already been made, however, a direct
investigation in the near future would be unlikely due to planetary protection
protocols. For instance, even a rover investigation o f M artian gullies by the 2009
Mars Science Laboratory (MSL) has been largely ruled out because o f the danger of
contaminating a site where water might have flowed even a million years in the past.
According to John Rummel o f NASA Headquarters’ Planetary Protection Office,
because M SL’s radiothermal generators “will stay hot for a long time,” they could
create “a warm little pond” (David 2006) from which hitchhiking Earth organisms
could contaminate the putative M artian biosphere.
W hile dissent from the scientific community could potentially overcome
these concerns, at present the prospect o f deep drilling directly to any liquid
reservoirs remains far away for reasons o f cost and feasibility in addition to policy.
Rather, new approaches may necessarily reverse longstanding doctrine by expressly
avoiding the water while still addressing the driving question, that o f life on Mars.
A broad range o f such approaches present themselves, from Martian
magnetite (M cKay 1996, Thomas-Keprta 2002) to atmospheric methane
(Krashnopolsky 2004, Formisano 2004). But which path should be followed?
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Thanks to the contrast between its relative scarcity on Mars and its intrinsic
connection to known forms o f life, one biosignature in particular stands out like a
ribbon which no leprechaun could duplicate: Nitrogen. A strong argument for a
“Follow the Nitrogen” astrobiology strategy has been laid out by Capone (2006).
As discussed below, Capone et al recommend that future astrobiology
missions throughout the Solar System “search for the nitrogen; characterize and
quantify it; if its abundance and chemistry cannot be explained by abiotic processes,
do not leave until it is explained; and when it comes to sample return— bring back
anything that is enriched in nitrogen!”
Such a strategy o f following the nitrogen poses many challenges for Solar
System exploration, even when focusing only on Mars. Outside traces in its
atmosphere, no nitrogen has been found in situ on Mars. An oasis o f liquid water on
Mars would still be presumed sterile if no nitrogen— and therefore no nitrogen
containing organic compounds— were detected. In this way, nitrogen might be a
better target than the water itself.
To determine whether this is indeed the case, it will be necessary to better
understand the fundamental biogeochemical processes by which nitrogen enters the
geologic and corresponding areologic records, with an emphasis towards the
identification o f key distinguishing factors between biological and abiotic systems.
New means o f detecting living systems and their rem nants in extreme environments
on Earth and beyond must come into play. In addition, the drive to follow the
nitrogen is driven by many assumptions that are unavoidable given the scant
5
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knowledge o f nitrogen processes and inventories in the Solar System relative to more
detailed understanding on Earth.
A nitrogen-focused approach could be among the most promising in the
search for life on Mars, and in the broader effort to further understand life in the
Universe. Described here are several investigations using elemental analysis to
begin testing some o f the assumptions behind a “Follow the nitrogen” strategy, while
perhaps taking the next few steps down a path that could lead to a scientific pot of
gold.
Additional background: Differentiating Mars from Earth’s ancient record
The rarity o f nitrogen preservation in mineral form and its utility in the
terrestrial record has been recognized by Boyd (2001a). However, Boyd’s emphasis
on ammonium as a trace element capable o f surviving tectonic metamorphism
appears ill-suited to Mars. Lenardic (2004) suggests the cessation o f Mars plate
tectonics coincided with the formation o f the buoyant crust o f the southern highlands,
which collectively represent the oldest terrains on the planet. Even in these terrains,
magnetic lineations indicating nascent tectonics (Connemy 1999) are not widespread.
A strategy to follow the nitrogen on Mars should keep this in mind, as it allows a
broader range o f strategies. A nitrogen strategy for Mars does not need to limit itself
to ammonium, as many other nitrogen species and even nitrogen-containing organic
material may have survived through areologic history due to M ars’ lack of
appreciable tectonics.
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Beyond Sediments to Hydrothermal Sites
W ithout elaborating as to the necessary degree o f either condition, Boyd
(2001a) further suggests that both a high concentration o f am m onium and a
substantial circulation o f seawater through sediments are necessary for ammonium’s
exchange with potassium ions and subsequent ammonium enrichment. Hall (1989)
suggests one locality where this has occurred on Earth: Spilitized basalts associated
with oceanic hydrothermal systems. This suggests that in addition to clay deposits,
Martian hydrothermal localities could be a key target for following the nitrogen.
Despite thermal anomalies in the region o f the Hellas Basin suggested by
Hoffman (2003), ongoing hydrothermal activity has been largely ruled out. The
remnants o f such activity, however, are the subject o f intense search. Highlights
include:
• Estimations o f hydrothermal activity by Echaurren (2004) for both the
Argyre and Isisdis Planitia.
• Heilm an’s (2004) considerable success in identifying extant hot spring
deposits in Yellowstone National Park using aerial visible near infrared and
thermal infrared spectroscopy.
• Bishop’s (2004) addition o f Raman spectroscopy to this array of tools in the
search for hydrothermal sites.
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Strong Potential for Clay Investigations Revealed by Mars Express
While definitive identification o f hydrothermal sites on Mars remains elusive,
the most recent data from the Mars Express spacecraft bodes well for investigations
into Mars clays. Planetary scientists studying M ars have always had plenty of
“W here in the w orld...?” questions. W here’s the nitrogen? Where are the
carbonates? But at least one USGS publication with the title “Martian Mystery:
W here’s the Clay?” (Clark and Dalton 1995) has at long last had an answer to its
plaintive inquiry. This answer is particularly important given the possibility that
“clays are important to the formation o f life, perhaps as surfaces to which large
molecules could stick. If clays never formed in abundance on Mars, life may not
have been able to develop (Clark and Dalton 19 9 5 /” The role o f clays relative to
prebiotic chemistry could parallel that suggested for borax in the stabilization of
ribose (Ricardo 2004).
Fortunately, the search for phyllosilicates in the decade since Clark and
D alton’s concerns has been so successful and the implications so important that the
earliest and presumably most life-friendly o f M artian eras has now been dubbed the
“phyllocian (Bibring 2006).”
Bibring and the Mars Express team began their clay revelations by
identifying several regions containing hydrated phyllosilicates (2005). The most
common clay signature among these is nontronite, whose chemical formula of
Fe2(Al,Si)4 0 io(OH)2Nao.3 ■ nFfO (Klein 1999) does not contain a potassium ion for
exchange with ammonium. The presence o f other, potassium ion-containing clays
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was not ruled out, however, and the incorporation o f nontronite into future
experiments would allow for a control relative to clays with higher cation exchange
capacity. Ammonium exchange with ions other than potassium is less likely because
o f differing ionic radii and corresponding fits within the mineral matrix. Sodium’s
ionic radius is 190 picometers versus potassium’s 243 picometers, for instance.
Poulet et al (2006) were able to identify numerous other specific
phyllosilicates upon further analysis o f the Mars Express OM EGA data. These
include montmorillonite and chamosite ((Fe(II),Mg,Fe(III))5 Al(Si3Al)Oio(OH,0)8),
and while neither possesses a potassium ion for ammonium exchange, this growing
diversity lends credence to the possibility o f clays with suitably high cation exchange
capacity but in lower abundance, although it may also be o f significance that “no
serpentine clay.. .has been detected so far (Poulet 2 0 0 6 /”
It should also be noted that Bibring emphasizes the lack o f carbonates in the
OMEGA data. This lack, Bibring argues, suggests that the bulk o f M ars’ atmosphere
has been lost to space rather than the regolith. Given the elevated 1 5 N o f M ars’
atmosphere suggesting atmospheric escape (Bogard 2001), it is very possible to
extend this reasoning to nitrogen, as well, making the identification o f remaining
nitrogen sources all the more crucial to the question o f life on Mars.
The Nitrate Question
This proposal focuses on ammonium as the nitrogen species most likely to
demonstrate a clear-cut link to life. The most likely form o f nitrogen on Mars,
9
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however, is nitrate produced from such abiotic processes as the interaction of
lightning-produced N-species with liquid water (Mancinelli 2003). Substantial
nitrate deposits on Earth are isolated to the planet’s most M ars-like environments,
such as the Atacama Desert (McKay 2003) and Antarctic Dry Valleys (Michalski
2005).
The astrobiological implications o f the search for nitrate remain highly
relevant, however. In fact, the lack o f nitrates— which current observations
support— could suggest an early loss o f M ars’ nitrogen, which would presumably
cause greater hardship to any Mars biota. Such early loss is countered somewhat by
gas inclusion studies o f ALH84001, indicating that Mars had suffered much less
atmospheric loss in the earliest Noachian (Marti 2000)
On the other hand, the failure to detect nitrates thus far could indicate the
presence o f one or more denitrifying processes, which would have re-exposed Mars
nitrogen to atmospheric loss. Biological denitrification is the primary source of
nitrogen fractionation on Earth, as lighter isotopes are preferentially released back
into the atmosphere (Boyd 2001). In established terrestrial systems, this
fractionation is on the order of 81 5 N +6 to 7%o. On Mars, a much larger signal is
expected from Mars atmospheric loss, with 81 5 N enrichments on the order o f several
hundred %o, potentially masking any other sources o f fractionation, such as
biological activity. Given the lack o f evidence for both nitrates and ammonium, and
the added difficulty in directly linking nitrates to biology, a focus on ammonium is
considered reasonable.
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Abiotic sources of ammonium
Mancinelli (2003) points to the influx o f cometary and asteroidal materials as
one source o f abiotic ammonium on Mars. Such material could be identified as
exogenic by its potentially unusual isotopic ratios as suggested by Boyd (2001, after
Pizarello 1994) or by the accompanying presence o f mellitic acid and other
metastable products o f kerogen oxidation, which have been suggested as an end
result of carbonaceous meteoric influx for M ars by Benner (2001).
Mancinelli also points out the formation o f abiotic ammonium from the
reduction o f nitrite by Fe2+. W hile the >25°C temperature and relatively neutral pH
detailed by Summers (1993) for this process are not a very good match for the acidic
(Squyres 2004b) and most likely very cold waters o f Terra Meridiani, an awareness
and continuing re-evaluation o f this process is demanded by the presence o f Fe2+ in
the pyroxene and olivine phases revealed by the Opportunity Mossbauer
spectrometer (Klingelhofer 2004).
Experimental Approach
Elemental analysis was used to determine the nitrogen quantities in a range of
terrestrial samples selected to test assumptions and determine sensitivities relevant to
the formulation o f the “Follow the nitrogen” strategy. A FlashEA l 112 Automatic
Elemental Analyzer from CE Elantech was used to collect all data, after
spectroscopic studies with the Jet Propulsion Laboratory’s LUCINA instrument were
shown to be too inconsistent and difficult to interpret to be o f use. Samples ranging
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in size from as small as .011 mg to not more than 23 mg were weighed with a
microbalance, and were sealed within foil cups. The cups were then loaded into the
elemental analyzer’s auto sampler, along with the appropriate blanks and standards,
to be combusted and analyzed within a controlled atmosphere. At least three
standards were run for each batch o f samples, to create an appropriate standard curve
as close as possible to the expected results of the unknowns. If results from
unknown samples fell far from the sample curve, less accurate data could result.
12
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Chapter One: Elemental Analysis of Select Nitrogen Species
and Shewanella Oneidensis MR-1
A key first step in developing the CE Elantech elemental analyzer for
astrobiological investigations of nitrogen was the creation o f sensitivity series for
various nitrogen species. To establish a diverse data set, the sensitivity series
extended beyond ammonium and nitrate (specifically, ammonium chloride, NH4C1
and sodium nitrate, NaNOa). Also included was alanine (C3H7NO2), the second most
common amino acid based on its 7.8% showing in a sampling o f 1,150 proteins
(Doolittle 1989). While glycine as the simplest amino acid was most common in the
Miller-Urey experiment (1959), alanine was judged an acceptable representative o f
amino acids.
Adenine (C5H5N5) was included as a particularly nitrogen rich organic
molecule that is often described as one o f the most important due to its contributions
to DNA, RNA, ATP, and many vitamins and cofactors. Adenine is often mentioned
in discussions o f prebiotic chemistry (Miller 1995, Saladino 2004), although Shapiro
(1995) has cast doubt on how crucial its role may have been.
To connect this chemical data more directly to life, a dilution series of
Shewanella oneidensis MR-1 was also prepared. After inoculating 1 mL Luria-
Bertani liquid media with MR-1, the resulting liquid culture was pelletized after two
days. The LB was decanted, and the pellet was re-suspended, re-pelletized, and
suspended again a total o f three times in 200pL in Nanopure-filtered water to wash
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as much LB as possible from the microbes. Removal from their nutrient source was
also intended to arrest further growth.
The 200pL sample (Sample #1) was evenly divided into samples # la and #lb.
lOpL from # la was used to inoculate an LB agarose plate, after which the remaining
90pL was centrifuged and decanted. Sample # lb provided lOpL colony to 90pL of
Nanopure-water which became the next sample in the dilution series, sample #2.
Each step in the dilution series constituted a 10X dilution (lOpL into 90pi.). For
further colony counting, agarose plates were also inoculated with lOpL from samples
#2, #4, and #7. Laboratory grade sand was weighed into individual containers, into
which the remainder o f dilution series Samples #1 through #6 was pipetted. Control
sample #7, a blank, demonstrated that the sand’s background nitrogen content was
below detection limits. All samples including the #1 a pellet were then left to
desiccate for two days in preparation for elemental analysis.
W hile plates inoculated with Samples #1 and #2 were overgrown, it was
possible to count that inoculated with #4 (which had a dilution o f 1000X). It should
be noted that the control plate inoculated with blank sample #7 was free o f colonies.
An additional calculation o f cell density per micro liter was made based on the mass
o f the Sample #1 a pellet and the average mass o f Shewanella putrefaciens suggested
by Haas (2004), 1.37x10‘1 3 g/cell. Data were as follows:
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Nitrogen species measurement discussion
The sensitivity series indicate potential problems with the precision of any
single measurement o f nitrogen concentration, but they also set an encouragingly
low threshold for simple nitrogen detection with elemental analysis.
LB plate, 10p,L #4 inoculation
Colony count
(Quarter-plate)
Colony count
(total plate)
MR-1, lp L #4 MR-1, lpL #1
262 1048 105 104,800
Mass, Sample a pellet: 0.000088g
pL pre
desiccation
Mass 1 MR-1
(Haas 2004)
# MR-1 in pellet MR-1, lp L #1
90 1.37E-13 642,335,766 7,137,064
Average
3,620,932
Table 1: MR-1 concentration
pL
sample
# MR-1 Total
MR-1
(mg)
Total
sand
(mg)
Total
sample
(mg)
Subsample
m ass (mg)
MR-1
subsample
mass (mg)
Actual
N %
Act
C%
# lb 90 642,335,766 0.088000 116.000 116.088 19.387 0.014696 0 0.143
19.592 0.014852 0 0.141
#2 80 57,096,513 0.007822 177.000 177.008 19.077 0.000843 0 0.031
20.874 0.0009225 0 0
#3 90 6,423,358 0.000880 138.000 138.001 20.365 0.0001299 0 0
20.681 0.0001319 0 0
#4 80 570,965 0.000078 194.000 194.000 19.937 8.039E-06 0 0
21.998 8.87E-06 0 0
#5 90 64,234 0.000009 99.000 99.000 19.893 1.768E-06 0 0
21.806 1.938E-06 0 0
#6 100 7,137 0.000001 74.000 74.000 17.525 2.316E-07 0 0
10.096 1.334E-07 0 0
#7 100 0 0 98.000 98.000 20.526 0 0 0
20.195 0 0 0
# la
(pellet)
90 642335766 .088000 - .088000 0.088 0 0
Table 2: MR- dilution series sample preparation and results
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The results for all series largely confirm the detection threshold o f .01% or
lOOppm for nitrogen as provided by CE Elantech. Readings o f “0” should be read as
falling below this detection limit. The limiting factor in producing an absolute
minimum level o f nitrogen detection using the FlashEA l 112 proved to be the
accompanying microbalance combined with the ionic nature o f m any of the sample
salts. The smallest sample sizes attempted approached the mass o f a single crystal of
MR-1 subsample mass (mg) Actual N % Act C % C mass (mg)
0.014696 0 0.1437964 0.027878
0.014852 0 0.1414114 0.027705
Table 3: MR-1 Sample #1 j dilution series discrepancy highlights
Ammonium Chloride, 26.19% N by weight
Ammonium
Chloride (mg)
Weight %
N (act.)
Weight % N, normalized to 20
mg total sample size (actual)
Weight % N,
normalized to 20 mg
total sample size
(expected)
5.904 24.52% 7.24% 7.73%
2.289 26.01% 2.98% 3.00%
1.942 26.10% 2.53% 2.54%
0.434 26.48% 0.57% 0.57%
0.26 26.22% 0.34% 0.34%
0.211 26.66% 0.28% 0.28%
0.136 23.86% 0.16% 0.18%
0.125 25.24% 0.16% 0.16%
0.066 21.54% 0.07% 0.09%
0.057 21.03% 0.06% 0.07%
0.051 22.53% 0.06% 0.07%
0.037 23.68% 0.04% 0.05%
0.019 27.95% 0.03% 0.02%
0.019 0.00% 0.00% 0.02%
Table 4: Ammonium chloride series
ammonium chloride or sodium nitrate. This grain size limitation and the build-up of
electrostatic charge within individual crystals made accurate dilutions o f the sample
salts within NaCl prone to unacceptably high margins o f error. To maintain
16
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accuracy, samples were analyzed in pure form, but in decreasing mass. In addition
to the raw data, each reading was normalized to approximate the signal that would be
interpreted from a same amount o f nitrogen species but within a 20 mg total sample
size.
This technique allows conclusions regarding the utility o f elemental analysis
to astrobiology to be made more readily. It was not possible to reach the 1 to 19 ppm
(.0019%) threshold provided by Mancinelli (2003) for the estimated average
concentration o f nitrogen in the Martian crust. However, this could be viewed as a
positive, as it is not average concentrations o f nitrogen that are o f interest to “Follow
the nitrogen,” but anomalously high concentrations that cannot be explained by
abiotic processes (Capone 2006).
As such, the lower level detections o f nitrogen at levels equivalent to .01%
(100 ppm) fall within the range o f such largely abiotic finds as H all’s 200 ppm
spilitized basalts (1989). Perhaps most importantly, the .01% threshold is an order of
magnitude less than the lowest ammonium concentration (.24%) reported by Bishop
et al (2002) in their studies o f cation exchange in clays. Because o f this lower
detection threshold, there is almost certainly a place for elemental analysis of
FlashEAl 112’s ilk in the “Follow the nitrogen” arsenal, even if it is used in addition
to Bishop’s infrared reflectance spectroscopy and differential thermal analysis
techniques. This greater sensitivity could also be an additional argument for sample
return if instruments o f similar performance cannot be sufficiently miniaturized for
in situ analysis.
17
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Figure 1 : Ammonium Chloride Sensitivity Series
N % Ul6!3M
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Figure 2 : Ammonium chloride weight % N , normalized t o 2 0 m g total sample size
|en)ov
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Expected
Sodium Nitrate,
Sodium
nitrate (mg)
16.48% N by weight
Weight %
N Weight % N, normalized to 20
(actual) mg total sample size (actual)
Weight % N, normalized to
20 mg total sample size
(expected)
1.994 14.48% 1.44%
1.64%
0.987 14.97% 0.74%
0.81%
0.505 15.10% 0.38%
0.42%
0.328 14.74% 0.24%
0.27%
0.14 15.34% 0.11%
0.12%
0.089 15.09% 0.07%
0.07%
0.057 15.00% 0.04%
0.05%
0.03 16.66% 0.02%
0.02%
0.012 23.20% 0.01%
0.01%
Table 5: Sodium nitrate series
Alanine, 15.72% N by weight
Weight % N, normalized to
ine Weight % Weight % N, normalized to 20 20 mg total sample size
i N (actual) mg total sample size (actual) (expected)
2.160 15.06% 1.63%
1.70%
1.087 15.56% 0.85%
0.85%
0.653 15.33% 0.50%
0.51%
0.321 15.10% 0.24%
0.25%
0.173 14.94% 0.13%
0.14%
0.084 15.23% 0.06%
0.07%
0.056 15.76% 0.04%
0.04%
0.029 16.43% 0.02%
0.02%
0.016 19.03% 0.02%
0.01%
Table 6: Alanine series
Adenine ■(HCI)2, 40.82% N by weight
Weight % N, normalized to
Adenine Weight % Weight % N, normalized to 20 mg 20 mg total sample size
(mg)
N (actual) total sample size (actual) (expected)
2.124 34.34% 3.65%
4.34%
0.966 36.59% 1.77%
1.97%
0.451 37.54% 0.85%
0.92%
0.275 37.68% 0.52%
0.56%
0.121 36.40% 0.22%
0.25%
0.062 35.29% 0.11%
0.13%
0.052 37.30% 0.10%
0.11%
0.026 13.93% 0.02%
0.05%
0.022 40.88% 0.04%
0.04%
0.011 34.57% 0.02%
0.02%
Table 7: Adenine series
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Figure 3 : Sodium Nitrate Sensitivity Series
N % *46!s m
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Expected — • — Actual
Figure 4: Sodium nitrate weight % N , normalized t o 2 0 m g total sample size
|en)ov
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Expected
Figure 5 : Alanine Sensitivity Series
N % 1MBja/W
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Figure 6 : Alanine weight % N , normalized t o 2 0 m g total sample size
lenjov
24
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Expected
Figure 7 : Adenine Sensitivity Series
s O
o '
O
O
LO
O
O
LO
o
o
o
o
o
LO
CO
o
o
d
c o
o
o
LO
CN
N % JMBiaM
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Expected — ■—Actual
Figure 8 : Adenine weight % N , normalized t o 2 0 m g total sample size
jenjov
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Expected
A limited number o f trends can be observed in the plots seen in Figures 1-8.
For both ammonium chloride and adenine, deviation from the expected results
appears to increase while approaching and going below .1% equivalent
concentrations. The particularly notable deviation in the reading o f a sample o f .026
mg adenine was most likely exaggerated by the tiny quantities involved: The loss o f
a single crystal o f adenine between weighing and sampling at this stage could have
caused the deviation. Finally, adenine’s consistently lower-than-expected nitrogen
levels are possibly due to changes in the level o f hydration or amount of hydrogen
chloride in complex with the adenine while in storage.
Alanine and sodium nitrate appear to show similar trends in Figures 3 and 5,
in that their nitrogen levels a detected as lower than average until reaching their two
to three smallest samples, at which point their nitrogen levels quickly become higher
than expected. This could be an artifact o f the weighing procedure, in which a few
extra crystal grains at the smallest sample size could increase the apparent amount of
nitrogen within a sample.
Shewanella oneidensis MR-1 dilution series discussion
The data for the S. oneidensis MR-1 dilution series illustrates the added
complexities introduced when working with biological samples and their more
elaborate means o f preparation. First, it is necessary to point out inconsistencies in
determining a cell density in the liquid media. Adjusting for all dilutions, colony
counts from plating still arrived at a figure more than an order o f magnitude below
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that predicted from the mass o f the pellet o f pure MR-1. Rather than averaging such
disparate figures, the latter (roughly 7 million M R -l/pL in Sample #1) was chosen
for subsequent calculations in Table 2.
Regardless o f the actual cell density, the overriding conclusion is that
elemental analysis was in this case unable to detect the nitrogen signal in even a very
large number o f bacteria— Anywhere from 1.5 to 100 million MR-1 in Sample # lb
(which was mixed with sand), and roughly 6 times either o f those amounts in the
pure pellet o f Sample # la , which also tested negative for carbon.
It is encouraging that a carbon signal was seen in both subsamples o f #lb.
However, as Table 3 highlights, discrepancies cast a shadow on this result. This is
because the total mass o f carbon in each subsamples exceeds the total mass o f MR-1
expected to be present. This suggests a background source o f carbon, but none is
apparent in the control subsamples (#7) or those exposed to more dilute suspensions.
Still, the average result for the two subsamples o f Sample #2 give a carbon
content that is the expected factor o f ten less than the amount recorded for Sample #1,
providing some hope that the dilution series was not entirely compromised.
Limitations of elemental analysis
Clearly, elemental analysis o f biological samples requires sufficient repetition
to account for possible errors due to the additional complexity o f preparation. While
the sensitivity series o f nitrogen species show promise, they also cannot avoid one
fundamental shortcoming: The FlashEA l 112 instrument cannot differentiate
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between different nitrogen species. It can only reveal generic nitrogen levels. If
appropriately configured, carbon, sulfur, and oxygen levels can also be determined,
which could lead to more specific diagnosis for chemically pure samples, but for
general environmental samples elemental analysis will remain only a first step.
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Chapter Two: Preparing for Mars by searching for nitrogen on Earth
Before packing up the elemental analyzer into the nearest rocket and blasting
off, many terrestrial investigations will be necessary to validate the assumptions
behind following the nitrogen. A variety o f samples were analyzed, beginning with
source clays selected to illuminate the potential entrenchment o f ammonium in the
rock record through cation exchange. To contrast these w ith the nitrogen (or lack
thereof) in the rest o f the rock record, a selection o f sedimentary rocks spanning a
broad swath o f geologic history was also sampled.
Clay samples
Source clays were selected to parallel the work o f Bishop (2001). Due to its
prevalence among Mars clay minerals as indicated by M ars Express (Bibring 2005),
nontronite (both Nau-1 and Nau-2) replaced kaolinite as the endmember with the
least potential for bound ammonium for this round of studies, which retained
montmorillonite (SWy-2, (Al,Mg)g(Si4 0 io)4(OH)g • I 2H 2O), illite (IMt-1, “an alkali-
deficient m ica near the muscovite composition,” KAl2(AlSi3 0 io)(OH)2, but having
“less substitution o f A1 for Si, more water, and more substitution o f K by Ca and Mg
(Klein 1999)), and attapulgite (PF1-1, also known as palygorskite,
(Al,Mg)2(Si4 0 io)4(OH) • 4H20 ), after Bishop. Also after Bishop, samples were
obtained from the Clay Minerals Society, Source Clays Repository, as noted by the
standardized codes above (Costanzo 2001, Klein 1999).
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Thorough baseline studies o f the source clays remain available (Costanzo
2001), but room for additional work was evident. The elemental analysis o f Mermut
and Cano (2001) employed 1M ammonium solution, making it inappropriate for
nitrogen evaluations. The elemental analysis o f the source clays using inductively
coupled plasma-mass spectroscopy was limited to heavier elements than nitrogen
(Kogel and Lewis 2001). Likewise, thermal analyses (Guggenheim and van Groos
2001) did not address nitrogen and infrared studies (Madejova and Komadel 2001)
only mention in passing ammonium bands in Syn-1 synthetic mica-montmorillonite,
but do not extrapolate to relative abundance.
Cation exchange studies o f the source clays (Borden and Giese 2001) were of
interest due to their use o f ammonium acetate. Borden and Giese exposed their
source clays to 1M ammonium acetate during two three-day sessions, as opposed to
Bishop’s three sessions totaling twenty-four hours using 1M ammonium nitrate.
Cation exchange capacities o f source clays studied by Borden and Giese and also
analyzed here were (in meq/lOOg) 17.5 for palygorskite (PF-1, also referred to as
attapulgite) while montmorillonite (SWy-2) was at 85. This is consistent with
Bishop’s (2001) finding of greater ammonium emplacement within montmorillonite
than palygorskite.
The geologic background o f the source clays is well established by Moll
(2001). SWy-2 montmorillonite is from Cretaceous marine units from Wyoming.
PF1-1 Palygorskite is from the Dogtown Clay Member formed through the infilling
o f a sedimentary basin in the Triassic through Miocene near Gadsden County,
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Florida. Additional information regarding illite and both nontronite samples is
provided in the table below (Moll 2001).
Weight
(m g)
%N % c Additional Clay Repository
Information
(Moll 2001)
Swy-2 Montmorillonite (A) 19.687 0.000 0.253 Na-rich Montmorillonite, Crook
County, Wyoming, USA
Swy-2 Montmorillonite (B) 22.651 0.000 0.251
Swy-2 Montmorillonite (C) 20.957 0.000 0.257
Nau-1 Nontronite (A) 20.095 0.000 NA Green color, Al-enriched, From Uley
Mine, South Australia
Nau-1 Nontronite (B) 19.345 0.000 0.015
Nau-1 Nontronite (C) 20.854 0.000 0.005
Nau-2 Nontronite (A) 20.582 0.000 0.026 Brown color, Al-poor, contains
tetrahedral Fe, From Uley Mine,
South Australia
Nau-2 Nontronite (B) 20.203 0.000 0.000
IMt-2 Illite (A) 20.394 0.019 0.061 Silver Hill, Mont. (Cambrian shale)
IMt-2 Illite (B) 21.173 0.019 0.080
PF1-1 Palygorskite (A) 20.381 0.000 0.131 Also known as attapulgite, Gadsden
County, Florida, USA
PF1-1 Palygorskite (B) 20.762 0.000 0.113
Table 8: Source clays elemental analysis
Ancient sedimentary rock samples
The ancient samples were less standardized that the source clays, but included such
famous localities as the Burgess Shale (530Ma). Others included Neoproterozoic (1000 to
562Ma) banded iron formation from the Kingston Peak Formation (Death Valley region,
Weight (mg) %N %C C/N
Eocene Green River sed rock (A) 19.661 0.03 11.94 388.4
Eocene Green River sed rock (B) 21.465 0.02 11.50 565.4
Cambrian sed rock with wrinkle texture (A) 21.469 0.02 0.08 4.8
Cambrian sed rock with wrinkle texture (B) 20.438 0.02 0.08 3.9
Neoproterozoic Namibian sed rock (A) 22.448 0.04 0.32 8.2
Neoproterozoic Namibian sed rock (B) 20.673 0.03 0.32 9.7
Burgess Shale (A) 20.252 0.04 0.57 12.8
Burgess Shale (B) 21.171 0.05 0.57 12.3
Neoproterozoic BIF (A) 20.646 0.02 0.54 31.4
Neoproterozoic BIF (B) 21.023 0.01 0.56 43.9
Table 9: Ancient sample elemental analysis
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California) and Namibian sedimentary rock, known to contain compressions of cm-long,
mm-wide organic tubes. Cambrian sedimentary rock exhibiting wrinkled textures as
described by Bottjer and Hagadom (Bottjer 2005, Hagadom and Bottjer 1999 and 1997) and
noted in the Early Triassic by Pruss et al (2005) was also analyzed. The most recent sample
was an organic-rich carbonate from the lacustrine Green River Formation (Eocene, 48ma).
Discussion
What becomes immediately apparent upon examining both the source clays
and the ancient sam ples’ nitrogen content is a reversal o f expectations: The clays
whose cation exchange capacity was supposed to make them a safe haven for
nitrogen in an otherwise hostile mineralogical world were instead largely devoid o f it.
The selection o f sedimentary rock localities universally contained small but
repeatable quantities o f nitrogen, in strong contrast to expectations.
The exception to the source clays strike-out is illite, where it can be noted
that the detection o f .019% (190ppm) N was previously undetected by Bishop’s
control analysis using IR reflectance spectroscopy and differential thermal analysis
(2001). This is consistent with Bishop’s assessment o f illite as highly suitable for
ion exchange.
While the Neoproterozoic BIF was thought least likely to contain nitrogen—
to the point o f being considered an additional control— the minute traces found are in
hindsight less surprising. Orberger et al document “nitrogen and carbon in a BIF-
bearing hydrothermal Archean chert from Pilbara, W estern Australia (2006).”
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Related teams have found nitrogen and carbon including isotopic data relatively easy
to quantify in 3.5 Ga chert (Rouchon 2005), hydrothermal minerals from Paleozoic
black shales (Orberger 2005, Gallien 2004), and an additional Archean chert (Gallien
2003).
Still, the specific BIF sampled in this study is not known at present to have
experienced hydrothermal alteration, and it is still possible that its trace nitrogen
contents make a novel contribution to the argument against the original assumptions
o f nitrogen’s relative scarcity in the rock record.
Arguing against contamination: C/N ratios
Instrument contamination by the nitrogen species used in the sensitivity
series can be ruled out because the ancient samples were run prior to the nitrogen
species. Additional controls were provided by the source clay samples run in the
same batch as the ancient samples, as the source clays were similarly crushed and
homogenized with a mortar and pestle (cleaned between samples) and otherwise
received the same preparation as the ancient samples without showing any nitrogen
contamination.
If the carbon-free nitrogen species used in the sensitivity series can be ruled
out as possible contaminants, it would appear reasonable to assume that the carbon
and nitrogen within the ancient samples are linked as part o f the same traces o f
organic matter. For this reason, the ratio o f C/N was also included in Table 9, as it
appears reasonably consistent for each sample, while providing a greater range than
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the .01-.05% raw nitrogen readings. The C/N ratio appears distinct for each set of
samples, suggesting a different population o f organic matter for each. If the nitrogen
traces were due to contamination during retrieval or laboratory handling (by linger
oils, perhaps, despite the gloves worn during preparation), a consistent C/N ratio
might be expected across all samples. As the C/N ratio is consistent within samples
o f one locality rather than across all localities, the trace organics appear valid.
Implications for following the nitrogen
These results have significant implications for some aspects o f the “Follow
the nitrogen” strategy, in particular assumptions that relate to extrapolations between
Earth and Mars. While only featuring five localities, it appears significant that each
Earth locality had nitrogen traces o f .01% (lOOppm) or greater (up to .05%, or
500ppm), substantially above the background levels for Mars suggested by
Mancinelli (2003). It is presumed to be much more difficult to find such high
concentrations on Mars.
In addition, with the exception o f illite, the source clays were devoid of
nitrogen traces. If the source clays are taken as representative o f terrestrial
phyllosilicates, as the Source Clays Repository suggests, then clay minerals
specifically may not be as important or may be too roundabout a w ay o f following
the nitrogen. It m ay not be necessary to find first elevated concentrations o f
ammonium and then interpret these concentrations as biotic or abiotic. Rather, a
35
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simpler approach might be to tackle the sampling o f a wide variety o f M artian
sedimentary rocks head-on.
Aubrey (2006) makes an excellent case for the validity o f such an approach
even at the Opportunity rover’s current site in Terra Meridiani, by showing the
“detection o f organic material, including amino acids and their amine degradation
products, in ancient terrestrial sulfate minerals.” Indeed, with the lack o f M artian
tectonics, almost any sedimentary bed with traces o f possible life could easily be a
lagerstatte due to the lack o f metamorphism. Nitrogen m ay still be the key to finding
life on Mars, but clays are likely to prove essential to this strategy not for their cation
exchange capacity, but rather for their shining a beacon on the most ancient aqueous
deposits of M ars’ phyllocian era.
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Chapter Three: Following the nitrogen through Mars on Earth
With the knowledge gained from sensitivity series and comparison o f source
clays to the ancient samples, it was possible to apply elemental analysis to samples
collected in an analogue setting. A subset was selected from samples collected in the
fall o f 2002 during the Mars Desert Research Station Crew #7 rotation. This subset
included scrapings from a visibly green hypolith (Figure 13), orange (Figure 10) and
white lichens (Figure 11), a sandstone covered in an orange crust reminiscent o f
lichen but presumed to be abiotic (Figure 12), and sand from a dry stream bed that
served as a control. All samples were from the Stacy’s Cake locality adjacent to the
Mars Desert Research Station, itself located on Bureau o f Land M anagement acreage
between Capitol R eef and Arches National Parks near Hanksville, Utah. Below, the
author discusses the landscape with fellow crewmember Hillary Bowden.
Figure 9: First EVA at MDRS
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Elemental analysis of nitrogen for the discovery of life in a Mars analogue
The nitrogen content of the selected samples was very revealing:
Weight (mg) %N %C C/N
Control Sand (A) 20.382 0.000 0.279 -
Control Sand (B) 19.364 0.000 0.132 -
Homogenized W hite Lichen (A) 19.798 0.406 6.157 15.177
Homogenized W hite Lichen (B) 21.156 0.388 5.968 15.363
Orange Crust (A) 21.216 0.000 1.341 -
Orange Crust (B) 19.474 0.000 1.399 -
Homogenized Orange Lichen (A) 21.060 0.425 4.638 10.917
Homogenized Orange Lichen (B) 19.911 0.535 5.858 10.917
Table 10: Utah Mars analogue nitrogen and carbon results
Figure 10: Orange Lichen
Figure 11: White lichen
Figure 12: Sandstone with orange crust Figure 13: Opal with hypolith
38
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Discussion
W hile every sample contained carbon, nitrogen proved to be genuinely
diagnostic for differentiating biology from inorganic processes. The white lichen
contained roughly .4% nitrogen; the control sand had none. The orange lichen
averaged about .5% nitrogen; the orange crust on the sandstone had none, adding
greatly to the conclusion that it was the result o f chemical weathering and not living
processes. The lichen, on the other hand, might have been the discovery o f the
century.. .if it had been found one planet farther out.
It is true that the characteristic lichen surface textures were easily recognized
by the human eye, even through a plexiglass simulated space helmet. However,
elemental analysis as a means o f following the nitrogen will rem ain a potential tool
for the future o f astrobiology. A robotic eye on M ars may not be as sharp, and the
signs o f life will almost certainly be less readily apparent. In such conditions, a
deeper appreciation for the fundamental biochemistry o f known life and a
willingness to stubbornly follow its tracks will continue to be the first steps towards
greater understanding.
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Chapter Four: Looking to the future
W ith the Phoenix Mars Scout on deck for a 2007 departure and the Mars
Science Laboratory ready to rumble come 2009, it is important to plan future work in
continuing the development o f nitrogen as a biosignature.
Elemental analysis is necessarily only the first step in following the nitrogen.
As discussed above, Bishop (2002) outlines the use o f differential thermal analysis
and infrared reflectance spectroscopy for the study o f cation exchange between
ammonium and potassium ions within clay matrices. Earlier work (Boyd 1997)
suggests the use o f capacitance manometry, which might be particularly amenable to
isotopic studies. Both Raman spectroscopy and UV fluorescence are expected to be
particularly useful for Mars in situ investigations, and it will be desirable to further
Bishop’s work firstly through the adoption o f these instruments as the primary means
o f detection. Calibration o f UV and Raman techniques relative to Bishop’s methods
will provide a means to evaluate which strategy best “Follows the Nitrogen.”
UV Fluorescence
Fortunately, information from Turner Designs citing Holmes (1999)
establishes UV excitation on the order o f 360 nm in conjunction with suitable
reagents as an excellent means o f measuring ammonium concentrations at the
submicromolar level. The complex preparations and large sample volumes would
inhibit Holm es’ procedures for in situ planetary investigations, but are highly
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suitable for laboratory use. While untested in the search for clay-bound ammonium,
initial experiments could lay the necessary foundation.
Raman Spectroscopy
Bishop (2002) emphasizes spectral features at 3.06 and 7pm for the detection
using IR reflectance spectroscopy o f bound ammonium in clays. A determination as
to whether similar distinguishing features can be identified using Raman
spectroscopy will contribute to Villar and Edwards (2006) argument in favor of
Raman spectroscopy in astrobiology.
Establishing thresholds for abiotic nitrogen exchange and detection
Present knowledge o f Mars nitrogen is highlighted by its scarcity, with
nitrogen’s abundance in Mars solid materials falling below the threshold of all in situ
investigations to date, including that o f the Pathfinder APXS, the alpha mode of
which could detect elements o f z < Na (Foley 2003). Establishing the lowest
detectable levels o f cation exchange is important to extrapolating ammonium levels
in ancient environments. Bishop (2002) cites detection thresholds for clay-bound
ammonium by IR spectra on the order o f “a few” parts per thousand. It is o f interest
to meet or exceed this threshold using Raman spectroscopy, and secondly to address
a major difficulty in extrapolating Bishop’s work directly to Mars, that of
inordinately high ammonium concentrations.
Bishop compensated for 24 hour total incubation times with molar
concentrations o f ammonium. The minimum concentration o f ammonium at which
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cation exchange takes place is o f critical interest in re-establishing the utility o f clay-
bound ammonium as a biomarker, in light o f the conclusions o f Chapter Two.
Establishing thresholds for exchange and detection in biological systems
To make a stronger case for ammonium as a biosignature and guide for future
in situ investigations, it may be necessary to study the level o f cation interchange that
takes place in biological systems. A precedent for the study o f microbial redox
behaviors in clays such as nontronite is provided by the work o f Kim (2003), in
which microbial reduction o f Fe3+ was characterized. Extrapolating such results to
Mars suggests a number of model microorganisms:
• Acidophilic sulfate-reducing bacteria as studied by Kolmert (2001), which
might have been quite at home in any Meridiani Sea.
• Magneto tactic bacteria such as MV-1 as suggested by ALH84001 studies
(Thomas-Keprta 2002)
• Methanogenic archea as suggested by the presence o f methane in the Mars
atmosphere and by studies suggesting their survivability in Mars conditions
(Sears 2002).
• Numerous others, including potential isolates from parallel studies o f
terrestrial clay-dominated, N-limited environments, as discussed below.
While it m ay be feasible to study several laboratory systems featuring
different model microorganisms and even microbial communities, the most relevant
data will be that which can be most closely compared to abiotic controls. Since
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2 _ j_
abiotic ammonium formation has been linked to systems containing Fe and nitrite,
microorganisms adapted to such systems are suggested as the best models.
Specifically, Thiobacillus ferrooxidans would appear to be such an
appropriate model microbe. Studies o f its iron-oxidation by Lazaroff (1982) even
featured ammonium (albeit only as part o f the neutralizing agent ammonium
hydroxide), and more intriguingly observed the M ars-relevant mineral jarosite
amongst the precipitates.
Ongoing investigations o f iron-oxidizers at Mars analogues such as the Rio
Tinto (Fernandez-Remolar 2003) might also suggest new avenues to explore. If an
isolate that couples the oxidation of Fe2 + to Fe3+ to the reduction of nitrite to
ammonium can be obtained, this could serve as a biological pathway ideal for
comparison to abiotic systems. O f interest in studying overall cycling would be to
reciprocate the isolate’s ferrous iron oxidation with the ferric iron reduction o f an
organism such as Shewanella as described by Nealson (2002).
Furthermore, if pH differences between biological and abiotic systems cannot
be reconciled, the hypothesized geochemistry o f past aqueous environments such as
the Meridiani Sea could immediately rule out abiotic mechanisms. Alternatively, it
m ay be desirable to employ model organisms which minimally affect the
geochemistry relevant to abiotic ammonium formation.
43
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Distinguishing between cation exchange in abiotic vs. biological systems
In this phase o f future investigations, a synthesis o f previous work comparing
biological and abiotic systems is developed, with an emphasis on differences most
relevant to astrobiology. Again, capacitance manometry might be particularly useful
in identifying possible isotopic effects in biological systems relative to abiotic
controls.
Biochemical pathways associated with cation exchange within ecosystems
If unique behaviors or organisms relating to cation exchange are observed in
the course o f future investigations, it would be appropriate to examine the
biochemical pathways or genes with which they are associated. Inspiration is
provided by past work such as that by Atkinson (1991), in which genes and gene
products relating to nitrogen-limited growth were identified in Bacillus subtilis.
Additional insight comes from Podar (2006) in describing how microbes might vary
their ratios of such amino acids as arginine and lysine based on the scarcity of
nitrogen in the environment. It might even be possible that microbes use cation sites
in their environment to store species such as ammonium during times of scarcity.
Searching for biochemical pathways in this vein could confirm biological uniqueness
relative to abiotic systems.
44
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In situ nitrogen investigations in extreme environments
Another future research path might focus on the application o f knowledge
gained in the lab to in situ investigations, including instrument development and
integration o f findings with the latest data from ongoing missions such as the Mars
Exploration Rovers.
Analogues and integration of laboratory work with JPL instrument
development
Possible Mars analogue sites to which laboratory nitrogen investigations
could be linked range from H all’s (1989) spilitized basalts in southwest England, to
the Rio Tinto or the Atacama. Relevant sites closer to home include large stretches
o f the southwest desert, which AVIRIS (the Airborne Vis/IR Imaging Spectrometer)
data have shown to contain up to 20% clays by weight (Clark 1995), along with
other M ars-relevant minerals such as hematite, goethite, and jarosite. Sites in Utah,
where work described above at the M ars Desert Research Station was conducted,
have recently attracted attention for “blueberry” concretions similar to those which
have caused so much excitement at Meridiani (Chan 2004). Further sampling o f
clays and instrument testing at MDRS is suggested as a relevant and highly
accessible field exercise, which could take place in conjunction w ith the ongoing
Raman and UV fluorescence instrumentation programs and field investigations at
JPL.
45
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Conclusion: Looking to MER and Beyond
The second-class status that nitrogen investigations on M ars have thus far
received— and which future investigations must remedy— is well illustrated by the
final Pathfinder APXS results (Foley 2003). While the alpha-mode o f the APXS
ruled out the presence o f carbon at a level above .3% by weight, no similarly
concrete threshold could be drawn for the similarly undetected nitrogen because no
laboratory nitrogen sample was evaluated!
This neglect has carried over even into the M ER results. In the discussion of
Opportunity’s discovery o f jarosite (Klingelhofer 2004, Squyres 2004b), it is
repeatedly pointed out that the potassium ions o f the most common form of jarosite
are insufficiently abundant. However, specific m ention is only made of Na+ and
H30 + to make up the difference. The grouping o f all other possible cations under the
variable “X+1” glosses over the important fact that the presence o f ammonium
jarosite— if found— would constitute not only the first in situ discovery of non-
atmospheric Mars nitrogen, but potentially a major astrobiological breakthrough.
While ammonium jarosite precipitation studies (Music 1999) have generally
taken place at higher temperatures than are expected at Meridiani outside of
hydrothermal activity, Mossbauer spectra of said ammonium jarosite precipitates
(Music 1993) are largely consistent with Meridiani jarosite, featuring isomer shifts
o f .374-.404 mm/s and .39 respectively, and quadrupole splitting o f 1.085-1.103 and
1.22 (1.15 adjusting for temperature) mm/s respectively. Combined with a growing
understanding o f the mechanism and redox regions o f ammonium jarosite
46
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precipitation (Jiang 2004), there appears to be every reason to highlight— not gloss
over!— ammonium jarosite and other ammonium salts as Opportunity’s mission
continues.
Unfortunately, despite improvements in their x-ray modes, even the more
advanced M ER APXS systems are limited in their sensitivity to nitrogen by the
proximity o f the nitrogen and oxygen signals, as well as the small fraction of
nitrogen in the Mars atmosphere (Rieder 2003). Even if the entire weight percent o f
jarosite— constrained by mini-TES at the samples’ sites to be less that 5%— was
ammonium jarosite, the resulting weight percent o f ammonium (3.75% within the
mineral) would be barely .2% overall.
It m ay therefore be desirable to include precipitation studies in future
laboratory work, to test the relative affinity o f relevant cations (hydronium,
ammonium, sodium, potassium) for jarosite and other ammonium-inclusive minerals.
A precedent is set by the hydrometallurgical studies o f Dutrizac (1996a and b, 1997)
and Ellergsma (1993a and b). This would greatly help determine the likelihood o f
minerals such as ammonium jarosite at Meridiani.
As Opportunity continues its trek through the etched terrain and toward
Victoria Crater, the search for potassium salts and other X+ 1 minerals such as jarosite
that have the potential to contain ammonium should be prioritized. If sufficiently
higher concentrations o f such minerals are found, nitrogen concentrations could
creep into the realm o f detectability by M ER APXS. Failing outright detection, a
number o f questions could still be answered, including:
47
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• As our understanding o f M eridiani’s overall geochemistry evolves, what
constraints can be placed on nitrogen concentrations in the Meridiani aqueous
system?
• How might these constraints impact the potential for biological activity at
Meridiani?
• Did M eridiani’s liquid waters and ferrous iron ions interact with the nitrogen
in the Mars atmosphere, either at its current partial pressure o f . 151 mbar or
at some higher level? Or did an icy covering limit this interaction, and
therefore the availability o f atmospheric nitrogen sources to any potential
Meridiani biota?
Future laboratory and field work geared towards following the nitrogen may
answer these questions. The work performed here has contributed to an
understanding that will better guide future missions. Specifically, Capone et al’s
admonition to bring back “anything enriched in nitrogen” (2006) was shown to be a
worthy maxim, because elemental analysis was able to draw conclusions on the
biogenicity o f samples without regard for specific nitrogen species or whether they
were embedded in a particular clay matrix. Nitrogen signals encouraging more
detailed searches for past life were found throughout a sampling o f the terrestrial
record, and a similar signals on Mars would give hope for life there, as well. The
development o f a comprehensive “Follow the Nitrogen” strategy should continue.
After all, no matter how many ribbons may decorate the forest, the determination to
keep digging will eventually uncover the pot o f gold.
48
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Bibliography
Aharonson, O., M. T. Zuber, et al. (2001). “Statistics o f M ars’ topography from the
Mars Orbiter Laser Altimeter: Slopes, correlations, and physical Models.”
Journal o f Geophysical Research-Planets 106(E10): 23723-23735.
Arvidson, R. E., F. Poulet, et al. (2005). “Spectral Reflectance and Morphologic
Correlations in Eastern Terra Meridiani, M ars.” Science: 1109509.
Atkinson, M. R. and S. H. Fisher (1991). “Identification o f Genes and Gene-Products
W hose Expression Is Activated During Nitrogen-Limited Growth in Bacillus-
Subtilis.” Journal o f Bacteriology 173(1): 23-27.
Aubrey, A., H. J. Cleaves, et al. (2006). “Sulfate minerals and organic compounds on
M ars.” Geology 34(5): 357-360.
Baugh, W. M., F. A. Kruse, et al. (1998). “Quantitative geochemical mapping of
ammonium minerals in the southern Cedar M ountains, Nevada, using the
Airborne Visible Infrared Imaging Spectrometer (AVIRIS).” Remote Sensing
o f Environment 65(3): 292-308.
Benner, S. A., K. G. Devine, et al. (2000). “The missing organic molecules on
M ars.” Proceedings o f the National Academy o f Sciences o f the United
States o f America 97(6): 2425-2430.
Beran, A., J. Armstrong, et al. (1992). “Infrared and Electron-Microprobe Analysis
o f Ammonium-Ions in Hyalophane Feldspar.” European Journal o f
M ineralogy 4(4): 847-850.
Bibring, J. P., Y. Langevin, et al. (2006). “Global mineralogical and aqueous mars
history derived from OMEGA/Mars express data.” Science 312(5772): 400-
404.
Bibring, J.-P., Y. Langevin, et al. (2005). “Mars Surface Diversity as Revealed by
the OMEGA/Mars Express Observations.” Science: 1108806.
Bishop, J. L., A. Banin, et al. (2002). “Detection o f soluble and fixed NH4+ in clay
minerals by DTA and IR reflectance spectroscopy: a potential tool for
planetary surface exploration.” Planetary and Space Science 50(1): 11-19.
Bishop, J. L., E. Murad, et al. (2004). “M ultiple techniques for mineral identification
on Mars: a study o f hydrothermal rocks as potential analogues for
astrobiology sites on Mars.” Icarus 169(2): 311-323.
49
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Bogard, D. D., R. N. Clayton, et al. (2001). “M artian volatiles: Isotopic composition,
origin, and evolution.” Space Science Reviews 96(1-4): 425-458.
Borden, D. and R. F. Giese (2001). “Baseline studies o f The Clay Minerals Society
Source Clays: Cation exchange capacity measurements by the ammonia-
electrode method.” Clays and Clay M inerals 49(5): 444-445.
Bottjer, D. J. (2005). “Geobiology and the fossil record: eukaryotes, microbes, and
their interactions.” Palaeogeography Palaeoclimatology Palaeoecology
219(1-2): 5-21.
Boyd, S. R. (1997). “Determination o f the ammonium content of potassic rocks and
minerals by capacitance manometry: A prelude to the calibration o f FTIR
microscopes.” Chemical Geology 137(1-2): 57-66.
Boyd, S. R. (2001a). “Ammonium as a biomarker in Precambrian metasediments.”
Precambrian Research 108(1-2): 159-173.
Boyd, S. R. (2001b). “Nitrogen in future biosphere studies.” Chemical Geology
176(1-4): 1-30.
Boyd, S. R. and P. Philippot (1998). “Precambrian ammonium biogeochemistry: a
study o f the Moine metasediments, Scotland.” Chemical Geology 144(3-4):
257-268.
Boynton, W. V., W. C. Feldman, et al. (2002). “Distribution o f hydrogen in the near
surface o f Mars: Evidence for subsurface ice deposits.” Science 297(5578):
81-85.
Busigny, V., P. Cartigny, et al. (2003). “Ammonium quantification in muscovite by
infrared spectroscopy.” Chemical Geology 198(1-2): 21-31.
Capone, D., Radu Popa, Beverly Flood, and Kenneth Nealson (2006). “Follow the
nitrogen.” Science 312: 708-9.
Chan, M. A., B. Beitler, et al. (2004). “A possible terrestrial analogue for haematite
concretions on M ars.” Nature 429(6993): 731-734.
Christensen, P. R., J. L. Bandfield, et al. (2003). “Morphology and composition of
the surface o f Mars: M ars Odyssey THEMIS results.” Science 300(5628):
2056-2061.
Christensen, P. R., J. L. Bandfield, et al. (2003). “M orphology and composition of
the surface o f Mars: Mars Odyssey THEMIS results.” Science 300(5628):
2056-2061.
50
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Christensen, P. R., J. L. Bandfield, et al. (2000). “Detection o f crystalline hematite
mineralization on Mars by the Thermal Emission Spectrometer: Evidence for
near-surface water.” Journal of Geophysical Research-Planets 105(E4): 9623-
9642.
Clark, BC, B. A. (1979). “Volatiles in the M artian Regolith.” Geophysical Research
Letters 6(10): 811-814.
Clark, R., and J. D. (1995). Mars: M ineralogical Constraints and Comparison to
Earth. American Astronomical Society, Division o f Planetary Science,
Hawaii.
Cloutis, E. (2000). Spectral properties o f ferric iron- and ammonium-bearing
sulphate minerals and implications for Mars. Mineralogical Society of
America - Geological Society o f America Annual Meeting, Reno, NV.
Connemey, J. E. P., M. H. Acuna, et al. (1999). “Magnetic lineations in the ancient
crust o f M ars.” Science 284(5415): 794-798.
Corsetti, F. A., A. N. Olcott, et al. (2006). “The biotic response to neoproterozoic
snowball earth.” Palaeogeography Palaeoclimatology Palaeoecology 232(2-
4): 114-130.
Costanzo, P. A. and S. Guggenheim (2001). “Baseline studies o f The Clay Minerals
Society Source Clays: Preface.” Clays and Clay M inerals 49(5): 371-371.
David, L. (2006). “Mars Science Laboratory: Engineers, Scientists Tackle
Challenges.” Space.com.
Doolittle, R. (1989). Redundancies in protein sequences. Prediction o f Protein
Structures and the Principles o f Protein Conformation. G. Fasman. New York,
Plenum Press: 599-623.
Dutrizac, J. E. (1996a). “The effect of seeding on the rate o f precipitation o f
ammonium jarosite and sodium jarosite.” Hydrometallurgy 42(3): 293-312.
Dutrizac, J. E. (1997). “The behavior o f thallium during jarosite precipitation.”
Metallurgical and M aterials Transactions B-Process Metallurgy and Materials
Processing Science 28(5): 765-776.
Dutrizac, J. E., D. J. Hardy, et al. (1996b). “The behaviour o f cadmium during
jarosite precipitation.” Hydrometallurgy 41(2-3): 269-285.
51
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Echaurren, J. C. and A. C. Ocampo (2004). “Calculation and prediction o f
hydrotherm al zones and impact conditions on Argyre Planitia, M ars.”
M eteoritics & Planetary Science 39(8): A34-A34.
Elgersma, F., G. J. Witkamp, et al. (1993a). “Simultaneous Dissolution o f Zinc
Ferrite and Precipitation o f Ammonium Jarosite.” Hydrometallurgy 34(1):
23-47.
Elgersma, F., G. J. W itkamp, et al. (1993b). “Incorporation o f Zinc in Continuous
Jarosite Precipitation.” Hydrometallurgy 33(3): 313-339.
ESA (2005). “Green light for deployment o f ESA ’s Mars Express radar.” ESA.int.
F. Poulet, J.-P. B., J. Mustard, A. Gendrin, Y. Langevin, B.Gondet, N. Mangold
(2005). “Hydrated minerals on Mars as seen by M Ex-OMEGA.” Geophysical
Research Abstracts 7: 04778.
Felzer, B., P. Hauff, et al. (1994). “Quantitative Reflectance Spectroscopy of
Buddingtonite from the Cuprite M ining District, Nevada.” Journal o f
Geophysical Research-Solid Earth 99(B2): 2887-2895.
Femandez-Remolar, D. C., N. Rodriguez, et al. (2003). “Geological record o f an
acidic environment driven by iron hydrochemistry: The Tinto River system.”
Journal o f Geophysical Research-Planets 108(E7): -.
Foley, C. N., T. Economou, et al. (2003). “Final chemical results from the Mars
Pathfinder alpha proton X-ray spectrometer.” Journal o f Geophysical
Research-Planets 108(E12): -.
Formisano, V., S. Atreya, et al. (2004). “Detection of methane in the atmosphere of
M ars.” Science 306(5702): 1758-1761.
Gallien, J. P., B. Orberger, et al. (2004). “Nitrogen in biogenic and abiogenic
minerals from Paleozoic black shales: an NRA study.” Nuclear Instruments
& M ethods in Physics Research Section B-Beam Interactions with Materials
and Atoms 217(1): 113-122.
Gallien, J. P., B. Orberger, et al. (2003). “Mineralogy and geochemistry o f an
Archaean chert: In quest o f N-sites.” Geochimica Et Cosmochimica Acta
67(18): A115-A115.
Gendrin, A., N. M angold, et al. (2005). “Sulfates in Martian Layered Terrains: The
OMEGA/M ars Express View.” Science: 1109087.
52
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Grady, M. M., I. P. W right, et al. (1997). “A carbon and nitrogen isotope study o f
Zagami.” Journal o f Geophysical Research-Planets 102(E4): 9165-9173.
Guggenheim, S. and A. F. K. van Groos (2001). “Baseline studies o f The Clay
Minerals Society Source Clays: Thermal analysis.” Clays and Clay Minerals
49(5): 433-443.
Haas, J. R. a. A. N. (2004). “Effects o f aqueous complexation on reductive
precipitation o f uranium by Shewanella putrefaciens.” Geochemical
Transactions 5(3): 41.
Hagadom, J. W. and D. J. Bottjer (1997). “Wrinkle structures: M icrobially mediated
sedimentary structures common in subtidal siliciclastic settings at the
Proterozoic-Phanerozoic transition.” Geology 25(11): 1047-1050.
Hagadom, J. W. and D. J. Bottjer (1999). “Restriction o f a late neoproterozoic
biotope: Suspect-microbial structures and trace fossils at the Vendian-
Cambrian transition.” Palaios 14(1): 73-85.
Hall, A. (1989). “Ammonium in Spilitized Basalts o f Southwest England and Its
Implications for the Recycling o f Nitrogen.” Geochemical Journal 23(1): 19-
23.
Hall, A. (1999). “Ammonium in granites and its petrogenetic significance.” Earth-
Science Reviews 45(3-4): 145-165.
Head, J. W., M. Kreslavsky, et al. (1998). “Oceans in the past history of Mars: Tests
for their presence using Mars Orbiter Laser Altimeter (MOLA) data.”
Geophysical Research Letters 25(24): 4401-4404.
Head, J. W., D. Smith, et al. (1998). “Mars: Assessing evidence for an ancient
northern ocean with M OLA data.” Meteoritics & Planetary Science 33(4):
A66-A66.
Heilman, M. J. and M. S. Ramsey (2004). “Analysis o f hot springs and associated
deposits in Yellowstone National Park using ASTER and AVIRIS remote
sensing.” Journal o f Volcanology and Geothermal Research 135(1-2): 195-
219.
Hochleitner, R., N. Tarcea, et al. (2004). “Micro-Raman spectroscopy: a valuable
tool for the investigation o f extraterrestrial material.” Journal of Raman
Spectroscopy 35(6): 515-518.
Hoefen, T. M., R. N. Clark, et al. (2003). “Discovery o f olivine in the Nili Fossae
region o f M ars.” Science 302(5645): 627-630.
53
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Hoffman, N., and P. R. Kyle (2003). The Ice Towers o f Mt. Erebus as analogues o f
biological refuges on Mars. Sixth International Conference on Mars,
Pasadena, CA.
Holmes, R. M., A.Aminot, R.Kerouel, B.A.Hooker, B.J.Peterson (1999). “A simple
and precise method for measuring ammonium in marine and freshwater
ecosystems.” Can. J. Fish. Aquat. Sci. 56: 1801-1808.
Hovis, G. L., D. Harlov, et al. (2004). “Solution calorimetric determination of the
enthalpies o f formation o f NH4-bearing minerals buddingtonite and tobelite
(vol 89, pg 85, 2004).” American M ineralogist 89(11-12): 1838-1839.
Hubbard, G. S., F. M. Naderi, et al. (2002). “Following the water, the new program
for Mars exploration.” Acta Astronautica 51(1-9): 337-350.
Irion, R. (2002). “Astrobiology science conference - Astrobiologists try to ‘follow
the water to life’.” Science 296(5568): 647-648.
Jiang, H. and F. Lawson (2004). “Reaction mechanism for the formation of
ammonium jarosite: thermodynamic studies and experimental evidence.”
Transactions o f the Institution o f Mining and M etallurgy Section C-Mineral
Processing and Extractive M etallurgy 113(3): 175-181.
Karl, D., A. Michaels, et al. (2002). “Dinitrogen fixation in the w orld’s oceans.”
Biogeochemistry 57(1): 47.
Kim, J.-w., Y. Furukawa, et al. (2003). “Characterization o f Microbially Fe(III)-
Reduced Nontronite: Environmental Cell-Transmission Electron Microscopy
Study.” Clays and Clay Minerals 51(4): 382-389.
Kirchner, J. W. (1989). “The Gaia Hypothesis - Can It Be Tested.” Reviews of
Geophysics 27(2): 223-235.
Kirschvink, J. L., E. J. Gaidos, et al. (2000). “Paleoproterozoic snowball Earth:
Extreme climatic and geochemical global change and its biological
consequences.” Proceedings o f the National Academy o f Sciences o f the
United States o f America 97(4): 1400-1405.
Klein, C. a. S. Hurlbut, Jr. (1999). Manual o f Mineralogy. New York, John W iley &
Sons, Inc.
Klingelhofer, G., R. V. Morris, et al. (2004). “Jarosite and hematite at Meridiani
Planum from Opportunity’s Mossbauer spectrometer.” Science 306(5702):
1740-1745.
54
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Kogel, J. E. a. S. A. L. (2001). “Baseline Studies o f the Clay M inerals Society
Source Clays: Chemical Analysis by Inductively Coupled Plasma-Mass
Spectroscopy (ICP-MS).” Clays and Clay Minerals 49(5): 387-392.
Kolmert, A. and D. B. Johnson (2001). “Remediation o f acidic waste waters using
immobilised, acidophilic sulfate-reducing bacteria.” Journal o f Chemical
Technology and Biotechnology 76(8): 836-843.
Krai, T. A., C. R. Bekkum, et al. (2004). “Growth of methanogens on a mars soil
simulant.” Origins o f Life and Evolution o f the Biosphere 34(6): 615-626.
Krashnopolsky, V. A., J. P. Maillard, et al. (2004). “Detection o f methane in the
martian atmosphere: evidence for life?” Icarus 172(2): 537-547.
Krohn, M. D., C. Kendall, et al. (1993). “Relations o f Ammonium Minerals at
Several Hydrothermal Systems in the Western United-States.” Journal o f
Volcanology and Geothermal Research 56(4): 401-413.
Kruse, F. A., J. W. Boardman, et al. (2003). “Comparison o f airborne hyperspectral
data and EO-1 Hyperion for mineral mapping.” Ieee Transactions on
Geoscience and Remote Sensing 41(6): 1388-1400.
Kurama, H. and F. Goktepe (2003). “Recovery o f zinc from waste material using
hydrometallurgical processes.” Environmental Progress 22(3): 161-166.
Kustka, A. B., S. A. Sanudo-Wilhelmy, et al. (2003). “Iron requirements for
dinitrogen- and ammonium-supported growth in cultures o f Trichodesmium
(IMS 101): Comparison with nitrogen fixation rates and iron: carbon ratios of
field populations.” Limnology and Oceanography 48(5): 1869-1884.
Langevin, Y., F. Poulet, et al. (2005). “Sulfates in the North Polar Region o f Mars
Detected by OMEGA/Mars Express.” Science: 1109091.
Langevin, Y., F. Poulet, et al. (2005). “Summer Evolution o f the North Polar Cap of
Mars as Observed by OMEGA/ Mars Express.” Science: 1109438.
Lazaroff, N., W. Sigal, et al. (1982). “Iron Oxidation and Precipitation o f Ferric
Hydroxysulfates by Resting Thiobacillus-Ferrooxidans Cells.” Applied and
Environmental Microbiology 43(4): 924-938.
Lide, D., Ed. (2000). CRC Handbook o f Physics and Chemistry, 81st Edition 2000-
2001. Boca Raton, FL, CRC Press.
55
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Madejova, J. and P. Komadel (2001). “Baseline studies o f The Clay Minerals
Society Source Clays: Infrared methods.” Clays and Clay Minerals 49(5):
410-432.
Malin, M. C. and K. S. Edgett (2000). “Evidence for recent groundwater seepage and
surface runoff on M ars.” Science 288(5475): 2330-2335.
Mancinelli, R. L. (1996). “The search for nitrogen compounds on the surface of
M ars.” Advances in Space Research 18(12): 241-248.
Mancinelli, R. L., and Amos Banin (2003). “Where is the Nitrogen on M ars?”
International Journal o f Astrobiology 2(3): 217-225.
Mancinelli, R. L. and M. R. White (2001). “Inhibition o f denitrification by
ultraviolet radiation.” Life Sciences: Planetary Protection; Ozone and Uvb
Radiation Effects 26(12): 2041-2046.
Marais, D. J. D., L. J. Allamandola, et al. (2003). “The NASA astrobiology
roadmap.” Astrobiology 3(2): 219-235.
Marti, K. and K. J. M athew (2000). “Ancient M artian nitrogen.” Geophysical
Research Letters 27(10): 1463-1466.
McKay, C. P., E. I. Friedmann, et al. (2003). “Temperature and moisture conditions
for life in the extreme arid region o f the Atacama Desert: Four years of
observations including the El Nino o f 1997-1998.” Astrobiology 3(2): 393-
406.
McKay, D. S., Everett K. Gibson Jr., Kathie L. Thomas-Keprta, Flojatollah Vali,
Christopher S. Romanek, Simon J. Clemett, Xavier D. F. Chillier, Claude R.
Maechling, and Richard N. Zare (1996). “Search for Past Life on Mars:
Possible Relic Biogenic Activity in Martian M eteorite ALH84001.” Science:
924-930.
Mermut, A. R. a. A. F. C. (2001). “Baseline Studies o f the Clay Minerals Society
Source Clays: Chemical Analyses o f Major Elements.” Clays and Clay
Minerals 59(5): 381-386.
Michalski, G., J. G. Bockheim, et al. (2005). “Isotopic composition o f Antarctic Dry
Valley nitrate: Implications for NOy sources and cycling in Antarctica.”
Geophysical Research Letters 32(13): -.
Miller, S. L., Urey, Harold C. (1959). “Organic Compound Synthesis on the
Primitive Earth.” Science 130(3370): 245-251.
56
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Miller, S. L. and A. Lazcano (1995). “The origin o f life - Did it occur at high
temperatures?” Journal o f Molecular Evolution 41(6): 689-692.
Moll, W. F. (2001). “Baseline studies o f The Clay Minerals Society Source Clays:
Geological origin.” Clays and Clay Minerals 49(5): 374-380.
Murray, J. B., J. P. Muller, et al. (2005). “Evidence from the Mars Express High
Resolution Stereo Camera for a frozen sea close to M ars’ equator.” Nature
434(7031): 352-356.
Music, S., S. Popovic, et al. (1993). “Properties o f Precipitates Formed by
Hydrolysis o f Fe3+ Ions in Nh4fe(So4)2 Solutions.” Journal o f Colloid and
Interface Science 160(2): 479-482.
Music, S., G. P. Santana, et al. (1999). “Fe-57 Mossbauer, FT-IR and TEM
observations o f oxide phases precipitated from concentrated Fe(N03)(3)
solutions.” Croatica Chemica Acta 72(1): 87-102.
Mustard, J. F., F. Poulet, et al. (2005). “Olivine and Pyroxene Diversity in the Crust
o f M ars.” Science: 1109098.
NASA (2005). “N A SA ’s Twin Mars Rovers Continue Exploration.” Electronically
retrieved, NASA.gov.
Nealson, K. and W. Berelson (2003). “Layered microbial communities and the
search for life in the universe.” Geomicrobiology Journal 20(5): 451-462.
Nealson, K. H., A. Belz, et al. (2002). “Breathing metals as a w ay o f life: geobiology
in action.” Antonie Van Leeuwenhoek International Journal of General and
Molecular Microbiology 81(1-4): 215-222.
Neville, R. A., J. Levesque, et al. (2003). “Spectral unmixing o f hyperspectral
imagery for mineral exploration: comparison o f results from SFSI and
AVIRIS.” Canadian Journal o f Remote Sensing 29(1): 99-110.
Nielsen, E. (2004). “Mars express and M ARSIS.” Space Science Reviews 111(1-2):
245-262.
Orberger, B., D.L.Pinti, C. Wagner, J.P.Gallien, M. Fialin, L. and K. H. Daudin
(2006 (retrieved)). “Nitrogen and Carbon in a BIF-Bearing Hydrothermal
Archean Chert from Pilbara, Western Australia.” COSIS Abstracts.
Orberger, B., J. P. Gallien, et al. (2005). “Nitrogen and carbon partitioning in
diagenetic and hydrothermal minerals from Paleozoic Black Shales, (Selwyn
Basin, Yukon Territories, Canada).” Chemical Geology 218(3-4): 249-264.
57
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Patino, F., M. Cruells, et al. (2003). “Kinetics o f alkaline decomposition and
cyanidation of argentian ammonium jarosite in lime medium.”
Hydrometallurgy 70(1-3): 153-161.
Pizzarello, S. (2004). “Chemical evolution and meteorites: An update.” Origins of
Life and Evolution o f the Biosphere 34(1-2): 25-34.
Pizzarello, S., X. Feng, et al. (1994). “Isotopic Analyses o f Nitrogenous Compounds
from the Murchison M eteorite - Ammonia, Amines, Amino-Acids, and Polar
Hydrocarbons.” Geochimica Et Cosmochimica Acta 58(24): 5579-5587.
Podar, M. (2006). Personal communication. June 8th.
Poter, B., M. Gottschalk, et al. (2004). “Experimental determination of the
ammonium partitioning among muscovite, K-feldspar, and aqueous chloride
solutions.” Lithos 74(1-2): 67-90.
Poulet, F., J. P. Bibring, et al. (2005). “Phyllosilicates on M ars and implications for
early martian climate.” Nature 438(7068): 623-627.
Ramseyer, K., L. W. Diamond, et al. (1993). “Authigenic K-Nh4-Feldspar in
Sandstones - a Fingerprint o f the Diagenesis o f Organic-Matter.” Journal of
Sedimentary Petrology 63(6): 1092-1099.
Ricardo, A., M. A. Carrigan, et al. (2004). “Borate minerals stabilize ribose.”
Science 303(5655): 196-196.
Rieder, R., R. Gellert, et al. (2003). “The new Athena alpha particle X-ray
spectrometer for the M ars Exploration Rovers.” Journal o f Geophysical
Research-Planets 108(E12).
Rouchon, V., D. L. Pinti, et al. (2005). “NRA analyses o f N and C in
hydromuscovite aggregates from a 3.5 Ga chert from Kittys Gap, Pilbara,
Australia.” Nuclear Instruments & Methods in Physics Research Section B-
Beam Interactions with Materials and Atoms 231: 536-540.
Saladino, R., C. Crestini, et al. (2004). “Advances in the prebiotic synthesis of
nucleic acids bases: Implications for the origin o f life.” Current Organic
Chemistry 8(15): 1425-1443.
Salinas, E., A. Roca, et al. (2001). “Characterization and alkaline decomposition-
cyanidation kinetics o f industrial ammonium jarosite in NaOH media.”
Hydrometallurgy 60(3): 237-246.
58
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Schwertmann, U., J. Friedl, et al. (2000). “The effect o f clay minerals on the
formation o f goethite and hematite from ferrihydrite after 16 years’ ageing at
25 degrees C and pH 4-7.” Clay Minerals 35(4): 613-623.
Sears, D. W. G., P. H. Benoit, et al. (2002). “Investigation o f biological, chemical
and physical processes on and in planetary surfaces by laboratory
simulation.” Planetary and Space Science 50(9): 821-828.
Seu, R., D. Biccari, et al. (2004). “SHARAD: The MRO 2005 shallow radar.”
Planetary and Space Science 52(1-3): 157-166.
Shapiro, R. (1995). “The Prebiotic Role o f Adenine - a Critical Analysis.” Origins of
Life and Evolution o f the Biosphere 25(1-3): 83-98.
Shen YN, B. R. (2004). “The antiquity o f microbial sulfate reduction.” EARTH-
SCIENCE REVIEWS 64(3-4): 243-272.
Squyres, S. W., R. E. Arvidson, et al. (2004a). “The Opportunity Rover’s Athena
science investigation at Meridiani Planum, M ars.” Science 306(5702): 1698-
1703.
Squyres, S. W., J. P. Grotzinger, et al. (2004b). “In situ evidence for an ancient
aqueous environment at Meridiani Planum, M ars.” Science 306(5702): 1709-
1714.
Storrie-Lombardi, M. C., W. F. Hug, et al. (2001). “Hollow cathode ion lasers for
deep ultraviolet Raman spectroscopy and fluorescence imaging.” Review o f
Scientific Instruments 72(12): 4452-4459.
Storrie-Lombardi, M. C., A. I. Tsapin, et al. (1999). “Ultraviolet Raman
spectroscopy for in situ geobiological exploration o f M ars.” Abstracts o f
Papers o f the American Chemical Society 217: U844-U844.
Summers, D. P. and S. Chang (1993). “Prebiotic Ammonia from Reduction o f Nitrite
by Iron(Ii) on the Early Earth.” Nature 365(6447): 630-632.
Thomas-Keprta, K. L., S. J. Clemett, et al. (2002). “Magnetofossils from ancient
Mars: a robust biosignature in the Martian meteorite ALH84001.” Applied
and Environmental M icrobiology 68(8): 3663-3672.
Villar, S. E. J. and H. G. M. Edwards (2006). “Raman spectroscopy in astrobiology.”
Analytical and Bioanalytical Chemistry 384(1): 100-113.
59
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Wang, A., K. Kuebler, et al. (2004). “M ineralogy o f a M artian meteorite as
determined by Raman spectroscopy.” Journal o f Raman Spectroscopy 35(6):
504-514.
Ward, G. S., G. C. Cramm, et al. (1982). “Effect o f Ammonium Jarosite on Early
Life Stages o f a Saltwater Fish, Cyprinodon-Variegatus.” Marine Pollution
Bulletin 13(6): 191-195.
Weiss, B. P., D. L. Shuster, et al. (2002). “Temperatures on Mars from Ar-40/Ar-39
thermochronology o f ALH84001.” Earth and Planetary Science Letters
201(3-4): 465-472.
Wright, I. P., C. T. Pillinger, et al. (1992). “Nitrogen in Zagami.” Meteoritics 27(3):
309-309.
Yen, A. S., B. Murray, et al. (1999). “Stability o f hydroxylated minerals on Mars: A
study on the effects o f exposure to ultraviolet radiation.” Journal of
Geophysical Research-Planets 104(E11): 27031-27041.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission.
Appendix: The Mind of the Mars Analogue Explorer
To follow the nitrogen all the way to the actual Mars, it will be important to
monitor the adaptations in perspective that occur in an alien landscape:
November 16, 2002: Geobiologist's Personal Log, Mars Desert Research Station
The bright moon (surely a rare conjunction o f Phobos and D eim os) bathing cliff-
fa ces in p a le blue m ilk as w e hurry home from an EVA in the pressu rized rover. Our
arm ada o f ATVs m elting into the center o f a dusty violet w hirlpool as the dusk unifies the
distant hills and infinite sky.
A s w e enter the second w eek o f our crew rotation, w e have truly begun to stretch our
wings over the fa c e o f our little Mars. A s w e see fa rth er and push further, the sights grow
m ore bizarre, especially in the m ost alien light o f the day, that which signals the
approaching night. A t these times, rushing to fin ish this key task and that before the chill o f
space seeps down through the thin atm osphere — remember, w e are alm ost a mile high!—our
thoughts turn to what w as once the strange center o f our M artian world. That is, the
oversized tin can that is now, simply, “home. ” What a quick change!
M y feelin gs about the overall sim are evolving, too. There have been som e ups and
downs in my ability to suspend d isb elief like the K aw asaki arrivals. They opened up m ore o f
the alien landscape around us, but at the sam e time, cruising around on them— even in space
suits— is alm ost too much like what norm al p eo p le do out here, even if future astronauts w ill
use these things on M ars. It's the sam e w ay fo r many other details o f life out at the MDRS.
As time passes, the little glitches aw ay from the real M ars can creep in, as opposed to our
arrival days, when the newness made each nuance truly exotic, adding up to an easy
suspension o f disbelief.
61
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But the glitches creep in only until evening approaches. Then the late afternoon light
fan s the em bers o f the landscape. R eddish hues that m erely hinted o f M ars at m idday
crackle and com bust w ith it in the chilly bonfire o f sunset. A s the surroundings becom e m ost
alien, 1 rem em ber how the tin can that w as once alien has becom e home, and realize that I
am not having a short-circuit in m y imagination. Rather, I am going through a pro cess that
the real M artians w ill experience. Even they w ill start to f e e l less like they are living on the
monolithic, m ystery M ars o f childhood as they adapt, learn, and make it their home. I am left
to conclude that whether thrust into the desert or o ff the p la n et entirely, w eird is weird. A nd
fam iliarity is fam iliarity—even home. Just as we have com e to think o f the M ars D esert
Research Station as hom e... so sh all w e think o f Mars.
Figure 14: Overlooking Canyonlands National Park during sim
62
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Shannon, Derek Michael
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Elemental analysis as a first step towards "following the nitrogen" on Mars
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