Julian Chela-FloresJulian Chela-FloresThe Abdus Salam ICTP, Trieste, ItaliaThe Abdus Salam ICTP, Trieste, Italiaandand Instituto de Estudios Avanzados, Caracas, Instituto de Estudios Avanzados, Caracas, Republica Bolivariana de VenezuelaRepublica Bolivariana de Venezuela

TThe Origins: how, when and where it all startedhe Origins: how, when and where it all started , , Accademia Nazionale dei Lincei. Centro Linceo Interdisciplinare “Beniamino Segre”, Accademia Nazionale dei Lincei. Centro Linceo Interdisciplinare “Beniamino Segre”, Roma, 22 May 2006Roma, 22 May 2006

Evolution of the universe: From Astrophysics to Astrobiology

Distinguishing Distinguishing between signatures of between signatures of past life and nonlifepast life and nonlife

Exploring the Solar System - Missions and TechniquesExploring the Solar System - Missions and TechniquesEGU 2008, Austria Center Vienna, Lecture Room 11; 15 April 2008: 9.15EGU 2008, Austria Center Vienna, Lecture Room 11; 15 April 2008: 9.15

AuthorsAuthors

Julian Chela-FloresJulian Chela-FloresThe Abdus Salam ICTP, Trieste, ItaliaThe Abdus Salam ICTP, Trieste, Italia

andandInstituto de Estudios Avanzados, Caracas, Instituto de Estudios Avanzados, Caracas,

Republica Bolivariana de VenezuelaRepublica Bolivariana de Venezuela

Narendra KumarNarendra KumarIndian Institute of Science,Indian Institute of Science,

Bangalore, IndiaBangalore, India

Joseph SeckbachJoseph SeckbachThe Hebrew University of JerusalemThe Hebrew University of Jerusalem

IsraelIsrael

Vinod TewariVinod TewariWadia Institute of Himalayan GeologyWadia Institute of Himalayan Geology

Dehradun, India.Dehradun, India.

Future missions to EuropaFuture missions to Europa

There is a possibility for returning to Europa There is a possibility for returning to Europa with both the LAPLACE mission,with both the LAPLACE mission,

The outline of LAPLACE has been The outline of LAPLACE has been summarised by summarised by Blanc, M. and the LAPLACE Blanc, M. and the LAPLACE consortium (2008). consortium (2008).

and the and the Europa Geophysical Explorer.Europa Geophysical Explorer.

Europa Geophysical Europa Geophysical ExplorerExplorer

HabitabilityHabitability

For For NASA's Science Mission DirectorateNASA's Science Mission Directorate habitabilityhabitability is also is also the focus of its Solar System Exploration Roadmap.the focus of its Solar System Exploration Roadmap.

““Is Europa habitable?”Is Europa habitable?” plays a prominent role in ESA’s plays a prominent role in ESA’s Cosmic Vision Plan for 2015-2025 that has been adopted for Cosmic Vision Plan for 2015-2025 that has been adopted for the LAPLACE mission. The other two Goals are related with the LAPLACE mission. The other two Goals are related with habitability:habitability:

What have been the conditions for the formation of the What have been the conditions for the formation of the Jupiter system? Jupiter system? How do they contribute to the possible How do they contribute to the possible emergence of life?emergence of life?

How does the Jupiter system work? How does the Jupiter system work? How does the system How does the system contribute to the conditions for habitability?contribute to the conditions for habitability?

Plan of the talkPlan of the talk

The patchy surface of Europa: The patchy surface of Europa: A major challenge in the exploration of EuropaA major challenge in the exploration of Europa..

Chemical elements on the surface of Antarctica and Europa.Chemical elements on the surface of Antarctica and Europa.

Biogeochemistry.Biogeochemistry.

A ‘fluctuation test’ for the exploration of Europa.A ‘fluctuation test’ for the exploration of Europa.

Instrumentation.Instrumentation.

Discussion.Discussion.

The patchy surface of Europa: The patchy surface of Europa: A major challenge in the exploration of EuropaA major challenge in the exploration of Europa

International Journal of Astrobiology (2006), 5, pp. 17-22 (Cambridge University Press).

Part IPart I

Ice-covered oceans over a silicate core:Ice-covered oceans over a silicate core:The cases of Europa and TitanThe cases of Europa and Titan

A hydrobotA hydrobot

Galileo revealed evidence for an internal ocean,Galileo revealed evidence for an internal ocean,

Horvath Horvath et alet al, 1997, 1997

but we argue that for determining the but we argue that for determining the habitability of Europahabitability of Europa, ,

waiting to enter the ocean by 2028 may be unnecessarywaiting to enter the ocean by 2028 may be unnecessary..

Endurance, 2008Endurance, 2008

Possible sources of the stainsPossible sources of the stains

External source:External source:

Ions may be implanted from the Jovian plasma. Ions may be implanted from the Jovian plasma.

Internal source:Internal source:

Sulfur may be due to cryovolcanism.Sulfur may be due to cryovolcanism.

Could the source be biogenic?Could the source be biogenic?

We discuss the use of mass spectrometry We discuss the use of mass spectrometry in the context of the available instrumentation.in the context of the available instrumentation.

Chemical elements on Chemical elements on the surface of the surface of

Antarctica and EuropaAntarctica and Europa

Part IIPart II

Antarctica’s Antarctica’s subglacial lakessubglacial lakes

Antarctica’s Antarctica’s Dry Valleys:Dry Valleys:

BeaconBeacon

Taylor Taylor

VictoriaVictoria

WrightWright

The Taylor (Dry) ValleyThe Taylor (Dry) Valley

Lake Hoare (9)Lake Hoare (9)

Lake Bonney (7)Lake Bonney (7)

A cross-section of the icy surface of Lake HoareA cross-section of the icy surface of Lake Hoare

Algal mat pieces on the surface of Lake Hoare

(Parker et al, Phycologia, 1982)(Parker et al, Phycologia, 1982)

Annual escape of sulfur (kg) Annual escape of sulfur (kg) by the loss of algal matsby the loss of algal mats

The Europa icy surfaceThe Europa icy surface (Spectrometer data from near IR) (Spectrometer data from near IR)

and ‘patchy’and ‘patchy’

albedo per pixelalbedo per pixel

High resolutionHigh resolution albedo imagealbedo image

Distribution of Distribution of non-ice componentnon-ice component

4 km/pixel4 km/pixel McCord McCord et al,et al, Science 280 (1998), 1242Science 280 (1998), 1242

Where should we land?Where should we land?

Part IIIPart III

BiogeochemistryBiogeochemistry

The delta The delta 3434S-parameterS-parameter

The meteorite coincides with the standard (st) terrestrial ratio of the The meteorite coincides with the standard (st) terrestrial ratio of the isotopes isotopes 3232S and S and 3434S. For a given sample (sa), we define with S. For a given sample (sa), we define with respect to this meteorite:respect to this meteorite:

The Canyon Diablo Meteorite (CDM) is a troilite (FeS), that was The Canyon Diablo Meteorite (CDM) is a troilite (FeS), that was found in Arizona:found in Arizona:

Sulfate-reducing bacteriaSulfate-reducing bacteria

Sulfate-reducing bacteriaSulfate-reducing bacteria

4H4H22 + H + H22SOSO44 –» H –» H22S + 4HS + 4H22O + 39 O + 39 kilocalorieskilocalories

The HThe H22S then combines with Fe in sediments to form grains of the S then combines with Fe in sediments to form grains of the

biogenic mineral pyrite.biogenic mineral pyrite.

Iron sulfide, FeS2

Unite H with S atoms from dissolved sulfate Unite H with S atoms from dissolved sulfate ( SO( SO44-2 -2 ))

of seawater to form hydrogen sulfide Hof seawater to form hydrogen sulfide H22S :S :

The sulfur isotopes are divided The sulfur isotopes are divided between biogenic minerals and between biogenic minerals and

sulfate mineralssulfate minerals Dissolved sulfate on Dissolved sulfate on

evaporation forms evaporation forms sulfate minerals sulfate minerals depleted of depleted of 3232S by 20 S by 20 per mil.per mil.

The HThe H22S given off by S given off by

the bacteria is enriched the bacteria is enriched in in 3232S by 20 per mil.S by 20 per mil.

Sulfur ions on Earth, meteorites and Sulfur ions on Earth, meteorites and the Moonthe Moon

Terrestrial

Meteoritic

Lunar

-40From measurements in From measurements in basins off California:basins off California:insoluble sulfide, mostly insoluble sulfide, mostly pyrite.pyrite.

Sulfate Sulfate coexisting with coexisting with

seawaterseawater

The deltaThe delta3434S-parameterS-parameter

Part IVPart IV

A ‘fluctuation test’ for the A ‘fluctuation test’ for the exploration of Europaexploration of Europa

The fluctuation test The fluctuation test (Luria and Delbruck)(Luria and Delbruck)

Luria first assumed that mutations in a growing bacterial culture could be acquired as a result of its exposure to virus (phage).

The observed number would then have very small very small fluctuationsfluctuations (slight deviations from the mean).

If this was the case, the number of resistant individuals would vary very little from one experiment to the next.

Can bacterial fluctuations be large?Can bacterial fluctuations be large?

Alternatively, Luria also assumed that a mutation can Alternatively, Luria also assumed that a mutation can occur before the bacterium was confronted with phage.occur before the bacterium was confronted with phage.

The number of resistant bacteria would depend on the The number of resistant bacteria would depend on the time elapsed since the mutation. The number of resistant time elapsed since the mutation. The number of resistant individuals shows individuals shows exponentially large fluctuationsexponentially large fluctuations..

The observed bacterial exponential growth suggests to The observed bacterial exponential growth suggests to detect such deviations from Gaussianity with detect such deviations from Gaussianity with higher order higher order statisticsstatistics..

InstrumentationInstrumentation

Part VPart V

Difficulties with the Difficulties with the the dust analyzersthe dust analyzers

3232S is isobaric (same m/z) with S is isobaric (same m/z) with 1616OO22. There would not have . There would not have

sufficient resolution with the current design to identify the sufficient resolution with the current design to identify the contributions from S and its interference with the Ocontributions from S and its interference with the O22 at m/z at m/z

32 and 34. 32 and 34.

The instrument required needs to count about 1x10The instrument required needs to count about 1x1066 sulfur ions to sulfur ions to gget a precision of +/- 5 per mil on the et a precision of +/- 5 per mil on the deltadelta3434S-S-

parameterparameter. So. So the likely ion counts is a key issue. the likely ion counts is a key issue.

The cloud generated around EuropaThe cloud generated around Europa

We expect it to mirror the large S-isotope deviations on We expect it to mirror the large S-isotope deviations on the surface. the surface.

Consequently, dust detectors in orbit should record Consequently, dust detectors in orbit should record similar similar non-Gaussian distributionsnon-Gaussian distributions as conjectured for as conjectured for the surface itself, with the surface itself, with non-non-vanishingvanishing cumulants cumulants of of order greater than 2.order greater than 2.

On the other hand, the contributions from the On the other hand, the contributions from the OO22 atmosphere should be described instead by a atmosphere should be described instead by a Gaussian Gaussian distributiondistribution with with vanishingvanishing cumulants cumulants of order greater of order greater than 2.than 2.

A possible instrument is a penetratorA possible instrument is a penetrator

A UK Consortium has already argued in favour of A UK Consortium has already argued in favour of landing with penetrators on the icy surface of Europa.landing with penetrators on the icy surface of Europa.

Penetrators are considered in the recent paper of Penetrators are considered in the recent paper of Blanc, M. and the LAPLACE consortium Blanc, M. and the LAPLACE consortium summarising summarising the mission.the mission.

In this case, if the Europan surface is to be probed In this case, if the Europan surface is to be probed with penetrators, MS would be a valuable alternative with penetrators, MS would be a valuable alternative for understanding the icy patches.for understanding the icy patches.

The mass constraints for MS on The mass constraints for MS on penetrators are severepenetrators are severe

120 x 60 mm; 500 g120 x 60 mm; 500 g

To illustrate that miniaturization To illustrate that miniaturization is not the main challenge, we point is not the main challenge, we point out suitable instrumentation:out suitable instrumentation:

• The current MS on Cassini The current MS on Cassini (Ion and neutral MS), and (Ion and neutral MS), and

•The work on miniaturised The work on miniaturised MS by Peter Wurz and co-MS by Peter Wurz and co-workers at the University of workers at the University of Bern.Bern.

DiscussionDiscussion

The use of MS is suggested for a dust analyzer and, if The use of MS is suggested for a dust analyzer and, if landers are possible, MS is also suggested for penetrators.landers are possible, MS is also suggested for penetrators.

The work of miniaturization of the instrumentation does The work of miniaturization of the instrumentation does not seem to be the greatest challenge in interpreting S-not seem to be the greatest challenge in interpreting S-isotopes either in orbit or on the icy surface of Europa.isotopes either in orbit or on the icy surface of Europa.

pdf files can be downloaded from:pdf files can be downloaded from:

http://www.ictp.it/~chelaf/ss16a.htmlhttp://www.ictp.it/~chelaf/ss16a.html