Äîêóìåíò âçÿò èç êýøà ïîèñêîâîé ìàøèíû. Àäðåñ îðèãèíàëüíîãî äîêóìåíòà : http://www.iki.rssi.ru/conf/2009elw/presentations/presentations_pdf/session6/prieto-ballesteros_ELW.pdf Äàòà èçìåíåíèÿ: Mon Mar 2 19:59:23 2009 Äàòà èíäåêñèðîâàíèÿ: Tue Aug 18 05:58:41 2009 Êîäèðîâêà: Ïîèñêîâûå ñëîâà: landing

ASTROBIOLOGY OF EUROPA
O. Prieto-Ballesteros, J.A. Rodriguez Manfredi, Felipe GÑmez-GÑmez. Centro de AstrobiologÌa-INTA-CSIC, Ctra. Ajalvir km. 4, 28850 TorrejÑn de Ardoz, Madrid, Spain. Contact: prietobo@inta.es

International Workshop Europa Lander: science goals and experiments


Astrobiology: study of the origins,
distribution and future of Life in the Universe

It includes the searching of

potential habitable planetary objects in our Solar System as one of the
main goals
International Workshop Europa Lander: science goals and experiments


POTENTIAL HABITABILITY OF THE SOLAR SYSTEM Mars has been traditionally the main target for astrobiological exploration. Many missions to Mars Evidences of a warmer and wetter past: - flows - hydrated minerals ... Lessons from the exploration: Planetary Protection Biological Experiments Technology challenges FUTURE PLANETARY MISSIONS: ExoMars MSL AFL
International Workshop Europa Lander: science goals and experiments


STARTING THE ASTROBIOLOGICAL EXPLORATION OF THE OSS 1) Where do we look for life or answers about its origin? Potential habitable environments / Organic rich environments 2) What kind of life signals do we look for?. Extinct/extant life. 3) How could we detect them? Remote sensing vs. in situ measurements

International Workshop Europa Lander: science goals and experiments


1-WHERE) POTENTIAL HABITABLE ENVIRONMENTS
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and sustain life Energy sources (light, redox couples)

LIFE on Earth

Liquid water

Chemical Building blocks. and appropriate environment for complex organics

Evidences from previous missions High priority on the exploration of EUROPA

(+) Harbor liquid water ocean Meteorites and other objects could have brought carbon (even organics) Active body with energy Interface water/rock: chemical disequilibria

(-) Radiations are too strong on surface Extreme conditions pressure pH salinity absence of light

EJSM is the first step in the exploration of habitability ...
International Workshop Europa Lander: science goals and experiments


Evidences supporting the liquid water in the interior of Europa. CONFIRMATION OF THE PRESENCE AND CHARACTERIZATION ARE NEEDED
TECHNIQUE Theoretical study of tidal deformation and heating IMPLICATIONS Predicts that an ocean will persist once formed CHALLENGE Rheology of ice is poorly known, especially at tidal frequencies, so predictions are uncertain Might be explained by thin, cold, brittle ice "floating" on thick, warm, soft, easily deformed ice Even if water is implicated, it need not come from an ocean--there may be melting within the ice Is there any other possible conducting layer? Requires Europa orbiter

Observations of surface deformation, especially "chaotic" regions, rafting, cycloidal ridges, possible low viscosity surface flows NEAR Infrared spectroscopy suggesting salt deposits on surface Magnetic field evidence for an induction response Altimetry and gravity field with sufficient resolution to determine tidal variation

Suggests thin ice and highly mobilized ice, consistent with an underlying ocean

Salt could arise from sublimation of a salty water "eruption" Requires a near surface, global conducting layer, most readily explained by a salty ocean Clear determination of whether there is an ocean; information on ice thickness

Compiled by D. Stevenson (2000), Science 289, 1305-1307

International Workshop Europa Lander: science goals and experiments


Composition of the surface from spectral data. CLUES CONCERNING THE INTERIOR ENVIRONMENTAL CHEMISTRY (NUTRIENTS) SHOULD BE SEARCHING
Water Ice I is dominant (Pilcher et al. 1972, Clark and McCord, 1980, Clark 1981) Other identified materials: SO2 (Lane et al.,1981; Noll et al.,1995; Lane & Domingue,1997; Domingue & Lane,1998). CO2, (Smythe et al., 1998, Carlson 2001). H2O2,(Carlson et al 1999a) Amorphous H2O (Hansen & McCord, 2001) O2 (Hall et al., 1995, 1998; Spencer & Calvin, 2002) Na, K ions (Johnson et al., 2002) Hydrated species on the Dark terrains, distorted absorption features near 1.5 and 2.0 m. Candidates: Salt hydrates (McCord et al. 1998, 1999: Kargel et. al. 2000,
Dalton et al. 2005)

Sulfuric acid hydrates (Carlson et al. 1999b, 2002)

Conducting solution if salts are dissolved in the water ocean
International Workshop Europa Lander: science goals and experiments


Some planetary environments may be envisioned . Data sources: Spectroscopy, Geology/geophysics, Theoretical modeling
Environment Surface Physical-chemical characteristics
Water ice contaminated by hydrated minerals (salts or/and sulfuric acid hydrates), organics (?) Cold. Low pressure. Liquid water deficiency

Energy sources Extreme Radiation Oxidants

Terrestrial analog Polar ice surfaces

Subsurface

Ocean or aqueous reservoir (speculative) Seafloor or interface water/rock

Water ice contaminated by hydrated minerals. Clathrates?. Organics (?) from surface. Cold. Cryospheric pressure. Saline. and organics (?) from the surface Dissolved gases? Thermally stratified or mixed. Pressure dependent of the crust thickness. pH? Saline. Hydrothermal vents. Hot. High pressure. Rockwater interface. Salt deposits.

Oxidants (?) from surface

Polar ice surfaces

Oxidants (?) from the surface Methanogenesis Chemolithotrophy Methanogenesis Chemolithotrophy Thermal

Subglacial Antarctic lakes Saline lakes

Submarine hydrothermal vents Thermokarst?

International Workshop Europa Lander: science goals and experiments


2-WHAT) ASTROBIOLOGICAL MEASUREMENTS (BEFORE A MISSION WHICH REACHS THE POTENTIAL HABITABLE ENVIRONMENT)
RADIATION ON THE SURFACE ALTERS DRAMATICALLY OR DESTROY THE MATERIALS!! ONLY IF ANY BIOSIGNATURE IS ABUNDANT ON THE SURFACE, THEY CAN BE DETECTED REMOTELY

a) Key properties of the surface/ subsurface environment b) Local composition and features. Potential biosignatures arisen from the interior. Extinct life/Extant life

Terrestrial analog studies

Simulation experiments

International Workshop Europa Lander: science goals and experiments


a) Properties of the surface/subsurface environment.
- Characterization of the landing site. - Model the properties of the endogenous material
Comparison between surface/subsurface Access to less altered materials (melting the ice, for instance) Physical environmental constraints: pressure, temperature, radiation pH conductivity Environmental chemistry: nutrients organics (endogenous, exogenous) minerals, elements, isotopes Energy sources: heat flow, radiation
International Workshop Europa Lander: science goals and experiments


b) Detection of potential biosignatures
Structures. Size and shape may vary depending on environmental conditions (for instance starvation) Fossils Biominerals Organic chemistry/Biochemistry Biopolymers Fatty acids Nucleic acids Proteins Hydrocarbons, hopanes Amino acids Chirality Inorganic chemistry/ Isotopes Waste and metabolic products (silicates, carbonates) Environmental modifications induced by metabolic products
International Workshop Europa Lander: science goals and experiments


Some planetary environments may be envisioned . Data sources: Spectroscopy, Geology/geophysics, Theoretical modeling
Environment Surface Physical-chemical characteristics
Water ice contaminated by hydrated minerals (salts or/and sulfuric acid hydrates), organics (?) Cold. Low pressure. Liquid water deficiency

Energy sources Extreme Radiation Oxidants

Terrestrial analog Polar ice surfaces

Subsurface

Ocean

Seafloor

Water ice contaminated by hydrated minerals. Clathrates?. Organics (?) from surface.Cold. Cryospheric pressure. Saline. and organics (?) from the surface Dissolved gases? Thermally stratified or mixed. Pressure dependent of the crust thickness. pH? Saline. Hydrothermal vents. Hot. High pressure. Rockwater interface. Salt deposits.

Oxidants (?) from surface

Polar ice surfaces

Oxidants (?) from the surface Methanogenesis Chemolithotrophy Methanogenesis Chemolithotrophy Thermal

Subglacial Antarctic lakes Saline lakes

Submarine hydrothermal vents Thermokarst?

International Workshop Europa Lander: science goals and experiments


We have learnt from the terrestrial analog studies that life can survive in very extreme conditions. Some terrestrial microbes resist to: Radiation fluxes Impacts 30 kGy Pressures up to 100 MPa Range of pH= 0.5 ­ 11 Salinity Anoxic environments. Chemolithotrophy (H2, S° or Fe++ as energy in the absence of O2) International Workshop Europa Lander: science goals and experiments


radiation sulfur
O ) y+S O·M x(S 4 H SO 4+ n 2 nH 2O·H 2
z

nH2O·H2SO

4

Sz

salts
Terrestrial analogs also are useful for geochemical and cryopetrological modelling Endogenic origin of the salts is supported by: - dark materials are related to fractures - geochemical models It is compatible the presence of both sulfuric acid hydrates and salt hydrates in the surface of Europa. Acidity is produced by radiolysis at low temperature from the salty materials, although endogenic acid brines should not be totally rejected.
International Workshop Europa Lander: science goals and experiments


Crystallization of the Ocean brines under equilibrium vs. Flash frozen brines

From Marion (2001)

Fractional crystallization Flash freezing

mineral differentiation

endogenous acid mineral assemblage on surface

endogenous acid to neutral mineral assemblages International Workshop Europa Lander: science goals and experiments


Possible geochemistry of the ocean
Assuming the dark terrain materials are partly endogenous. We take examples of brines with different acidic character to make experiments about cristallization of cryomagmas: - Neutral. Example: Tirez lake - Acidic. Example: Rio Tinto

International Workshop Europa Lander: science goals and experiments


XRD Evaporated: hexahydrate + halite Lyophized: bischofite + halite
br ine Apr il 2006
lyophized evaporated -100ºC flash frozen evaporated

Same brine, different crystallization path (T, P), different spectra

%Reflectance 1400

1600

1800

2000

2200

2400

wavelengh mm
International Workshop Europa Lander: science goals and experiments


THE HIGH PRESSURE PLANETARY SIMULATION CHAMBER (HPPSC)
The equipment has two different chambers (both large volume cells): - MINchamber (2 cm3), for physico-chemical studies which can reaches pressures up to 10000 bar - BIOchamber (10 cm3), for biological experiments which has higher volume and can reaches up to 3000 bar

International Workshop Europa Lander: science goals and experiments


TECHNICAL CHARACTERISTICS OF HPPSC
The heating/cooling system is an integrated circuit of liquid nitrogen and electrical resistances. Both chambers can work in the temperature interval from 90 to 600 K. The whole system can be controlled automatically, being the pressure, the temperature and the rest of parameters registered while the experiment is running.

International Workshop Europa Lander: science goals and experiments


TECHNICAL CHARACTERISTICS OF HPPSC
Each chamber has four different ports to incorporate several sensors. They are used for making in situ analysis and to be able to monotorize the processes occurring during the changes of pressure and temperature. Currently, a raman spectrometer, and a video camera are installed on two ports using sapphire windows. Other sensors able to be incorporated for specific studies are those to measure magnetic susceptibility, electrical resistivity, and mass spectrometry.

International Workshop Europa Lander: science goals and experiments


EXAMPLES OF EXPERIMENTS RUNNING (BIOCHAMBER): Survival of microorganisms and preservation of biosignatures
The potential habitable environments in the interior of icy satellites are characterized by some extreme conditions. Microorganisms adapted to the deep interior habitats of icy satellites should be, at least, baro-tolerant and nonfotosynthetic. Scientific Questions - Adaptation of live organisms under pressure - Identify key factors determining piezoresistance in extremofile archea and eubacteriae, especially the piezoresistant proteins and the related genes - Influence of the previous factors on the origin of life Specific Goals - Study the processes of lipidic oxidation in cell membranes under pressure - Study cell membrane integrity and functionality under pressure -Modeling of the cell membrane behavior under pressure as liposomes of known and simple composition - Identification of proteins responsible for piezoresistance and the related genes

International Workshop Europa Lander: science goals and experiments


EXAMPLES OF EXPERIMENTS RUNNING: Survival of microorganisms and preservation of biosignatures
We have started using Escherichia coli for testing as a heterotrophic microorganism. This model was used for pressure resistance studies. Fresh media reinoculation techniques were used for survival capacity studies. This microorganism was subject to high pressure conditions (500, 1000 and 1800 bar). After high pressure conditions fresh media were inoculated for microorganism viability studies. Optical density was used for following the bacterial growth. Optic microscopy was used (see figures) for microbial counting.
Control 500 bar 1800 bar

International Workshop Europa Lander: science goals and experiments


EXAMPLES OF EXPERIMENTS RUNNING: Survival of microorganisms and preservation of biosignatures
T0 500
Optical density (AU)
2 1,5 1 0,5 0

T3 500
Optical density (AU)
2,5 2 1,5 1 0,5 0
0 280 160 12 0 20 0 24 0 32 0 40 80

2,5

0

40

80

20 0

120

16 0

240

Time (min )

28 0

32 0

Time (min)

T3 1000

T3 1800
Optical density (AU) 2,5 2 1,5 1 0,5 0

Optical density (AU)

2,5 2 1,5 1 0,5 0
0 12 0 16 0 20 0 24 0 28 0 32 0 40 80

40

80

0

16 0

20 0

24 0

28 0

Time (min)

12 0

Time (min)

Microorganisms from the 3 runs grow after exposure at high pressure, but less at 1800 bar International Workshop Europa Lander: science goals and experiments

32 0


3-HOW) IN SITU MEASUREMENTS

Suggested instruments for surface element: Astrobiology
Physico-chemical characterization of surface/subsurface Hydrochemistry (from the melting ice) Organic chemistry characterization Life detection

Temperature, radiation environment, pH, redox, conductivity

Elements, ions, inorganic molecules

Organic molecules

Biosignatures

Spectroscopic techniques Environmental multi-sensor Raman IR GCMS Molecular ecology techniques Metabolic test Imaginery Microscopy

Fluorescence

International Workshop Europa Lander: science goals and experiments