astrobiology” an introduction to an obscure field of research · “astrobiology” an...
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“Astrobiology”an introduction to an obscure
field of research
Kai Finster
SAC & Bioscience
How is Astrobiology defined?
Astro- or Exo- or Planetary-biology?
= study of the origin, evolution, adaptation
and distribution of past and present life in the universe
including Earth.
= encompasses anthropology, astronomy, astrophysics,
biochemistry, biology, chemistry, cosmology, genetics,
geology, palaeontology, planetary science (philosophy
and theology). Monica. M. Grady, Geology Today 19:99-103. 2003.
Exploration along three lines
• In situ observations and experiments
• Study of Earth analogues
• Simulation experiments
In situ experiments
• Mars classic: The Viking experiments
Viking experiments
ALH84001- rocky bio-signatures?
McKay et al,
1996
ALH84001- rocky bio-signatures?
ALH84001- rocky bio-signatures?
Remote In situ observations
• Satellite observations: Mars-express
“Follow the water”
“Follow the water”
Boynton et al, 2002
“Follow the water”
Phoenix - ice underneath the surface
Trace gases in the atmosphere
• Methane on Mars - Why is that of interest?
Methane on MARS
Methane data Earth Mars
Atmospheric
concentration
1750 ppbv 10 ppbv
Life time in the
atmosphere (years)
10 600
Production pr. year
to keep a constant
atmospheric
concentration (tons)
515 millioner 125
Sources Prokaryotes in
cattle, termits, rice
paddies; abiotic
chemical reactions
Prokaryotes?
Water-rock
reactions
Methane in the Martian atmosphere
Methane in the Martian atmosphere,
and where it could originate from,
and what the implications are.
Study of Earth analogues
Focus on Astro”micro”biology.
Astromicrobiologist search for life in the
universe by studying life/microbes on earth.
How is this justified?
We find environments on Earth that can be
regarded as Analogues to extraterrestrial
habitats. Such as Mars!
What are analogues?
Definition: something that is similar to another thing.
Without being the thing.
What is considered an
Analogue -and to what?
We usually have two extraterrestrial
habitats in mind-
1. Mars
2. Europa
What is considered an
Analogue -and to what- some
examples ?
- Black smokers
- Deep biosphere
- Dry (cold) desserts
- Permafrost Soil
Black Smokers
• High pressure
• High temperature
• Chemolithotrophic
microbes
• Ancient
phylogenetic
lineages
• Cradle of Life
Deep Biosphere
• Survival for long
periods of time
• Low substrate
concentrations
• Chemolithotrophic
microbes
• No/little interference
with the surface
Problems with the AnaloguesAnalogues are embedded in the complex eco-system
Earth
-> protecting atmosphere
-> high temperature
-> a lot of organic matter/oxygenic photosynthesis
-> oxygen
-> complex food webs
-> complex microbial communities everywhere
-> about 4 billion years of evolution and interactions
between the biotic and the abiotic world
-> etc.
Simulation experiments
Biological Marssimulations
0
2
4
6
8
10
12
14
16
18
1950 - 59 1960 - 69 1970 - 79 1980 - 89 1990 - 99 2000 - 07
Time Intervals
Nu
mber
of
Exper
imen
ts
Prokarytic Cultures
Prokaryotic Communities
Organic Molecules
Eukaryotes
Virus
Marssimulation facility at the University of Aarhus
Table 1. Environmental conditions in the Mars simulation chamber and on the surface
of present-day Mars.
Parameter Sim.environment Present-day Marsa
Temperature range
(°C)b
-41 - +40 -123 - +25
Pressure range (mbar) 7.6 - 9.7 6.7 - 9.9c
UV radiation (nm) >200 >200
UV intensity at 239 nm
(W m-2 nm-1)
0.207 0.006d
Gas composition (%)
CO2 91.4 95.3
N2 4.8 2.7
Ar 2.8 1.6
O2 0.24 0.13
H2O 0.14 0.02
CO 0.16 0.07
Other 0.41 0.25
•aFrom Horneck .
•bAt the soil surface.
See Fig. 1.
•cFrom Tillman et al. .
•dAnnual average
intensity at 11.6° N
(Patel, M., Personal
communication).
Our Approach
Simulation experiments
Concentrations of individual amino acids as
function of depth
0.0 0.1 0.2 0.3 0.4 0.5 0.6
0-1.5
1.5-3
3-6
6-9
9-15
15-21
21-27
27-33
Control
Dep
th (
mm
)
[DNA] (µg gdw -1
)
DNA concentrations as a function of depth
Parameter Temperature
(ºC)
Pressure
(mbar)
UV radiation
(nm)
UV intensity dose Lamp Protection of
sample
Mars
half-life
(days)
Reference
DNA -41 - 40 8 200 - 1000 35 times Mars Hg-xenon,
135 W
Soil matrix
0 – 1.5 mm80 Present study
THAA -41 - 40 8 200 - 1000 35 times Mars See above See above 135 Present study
Aspartate in
THAA
-41 - 40 8 200 - 1000 35 times Mars See above See above 70 Present study
Arginine in
THAA
-41 - 40 8 200 - 1000 35 times Mars See above See above 150 Present study
Glycine in
THAA
-41 - 40 8 200 - 1000 35 times Mars See above See above 183 Present study
Cell numbera -41 - 40 8 200 - 1000 35 times Mars See above See above 35 Present study
Viable cellsb -41 - 40 8 200 - 1000 35 times Mars See above See above 46 Present study
CFU’sc 41 - 40 8 200 - 1000 35 times Mars See above See above 22 Present study
Glycine 21 ~10-7 190-325 1/12 of Mars Deuterium None 1.5 ten Kate et
al. 2006
Glycine 21 ~10-7 190-325 1/12 of Mars Deuterium None 1.5 See above
Glycine -63 7 190-325 1/12 of Mars Deuterium None 10 See above
Glycine 21 4 � 10-6 190-325 1/25 of Mars Deuterium None 0.9 ten Kate et
al. 2005
D-alanine 21 4 � 10-6 190-325 1/25 of Mars Deuterium None 0.1 ten Kate et
al. 2005
Conclusions and hypotheses
• UV effect in H1
• Reactive compounds in H1 + H2
• Freeze-thaw cycles H1 - H5
Exo-planets
What do I consider being
“relevant Astro”micro”biological
research topics”?
• Simulation experiments, which include the information on the abiotic conditions obtained from space missions and exploration
What do I consider being
“relevant Astro”micro”biological
research topics”?
• Simulation experiments, which include the information on the abiotic conditions
obtained from space missions and exploration
• De-contamination studies - planetary protection
What do I consider being
“relevant Astro”micro”biological
research topics”?• Simulation experiments, which include the information on the abiotic conditions
obtained from space missions and exploration
• De-contamination studies - planetary protection
• Analogues with respect to exoplanets: Atmosphere composition, processes and signatures.