Session 7

Astrobiology: habitability, synthesis of organics in ice, and prebiotic chemistry in liquid water

09/11 – Monday


15:00 - 15:30 Habitability in our Solar System and Beyond (Nader Haghighipour)

  1. Nader Haghighipour (Institute for Astronomy, University of Hawaii)

The notion of habitability is defined based on the life as we know it. Since Earth is the only habitable planet known to humankind, the orbital and physical characteristics of Earth are used to define a habitable planet. That means, habitability is the characteristic of an environment which has similar properties as those of Earth, and the capability of developing and sustaining Earthly life. This statement implies that owing to the essential role that water plays on life on Earth, the definition of a habitable planet is tied to the presence of liquid water. This definition has strong connections to a variety of complex, interdependent processes. For instance, the surface temperature and pressure of a planet should allow for liquid water to exist. This is determined by the amount of irradiation that the planet receives from the star, and the response of the planet’s atmosphere. The latter delicately depends on the composition of the planet, and that in turn determines the heat transport mechanism, cloud presence, and many other atmospheric properties. The irradiation from the star is contingent on the type of the star and the planet’s orbital parameters. The atmospheric composition, on the other hand, depends on the in-gassing, out gassing, and escape histories of the planet. The in-gassing and out-gassing accounts are intrinsically connected to the interior dynamics of the planet, while atmospheric escape is related to a variety of thermal and non-thermal processes, which themselves are linked to the presence of a magnetic field. I will present a review of these processes and the role that they play in habitability of Earth. I will also present an overview of the current research on the extension of habitability to other planets, and discuss the prospect of detecting life both inside and outside of our solar system.

15:30 - 15:50 How can we observe the motion of habitability (Oleksandr Potashko)

  1. Oleksandr Potashko (Scientific Enterprise „Fractal”)
  2. Michel Viso (CNES)

We connect habitability with criteria of presence of life on heavenly bodies [1] – as having an atmosphere or volcanism. These criteria are applied to solid crust bodies. The solid bodies include planets and comets. What is in case of icy planets likes Europa, Callisto. The criteria is measure of surface changing – in consequence of erupsion. Enceladus is most clear object – it’s eruption is visible and under Cassini investigation.
Why atmosphere is criterion? We consider that life springs from volcano vicinity[2] mainly from underwater volcanoes because they can work stationary during few thousand years. Volcanoes create an atmospheres. Any atmosphere will disappear out of solar wind. So, an atmosphere is a result of volcanoes activity.
We may evaluate the Earth’s atmosphere by its density measurements. Now we need to measure atmospheres of Mars, Venus, Titan. It’s possible by means radio method used during Venus mapping. We propose to use ballooning to measure atmosphere density tied with attitude. Ballooning is prepared to use for investigating Mars, Venus, Titan(NASA). Once we would know atmosphere data of main atmosphere planets – Venus, Earth, Mars, Titan we would be able formulate criteria to evaluate an atmospheres of nonSolar planets, maybe tie to their isotopic abundance. Using atmosphere’s data, including historic meanings one may build spread of life through Solar system.
Besides, ballooning may give as some astrobiology data connected with comets[3].
We can suppose there are planetary cycles of weather and life in Solar system[4,5]. It might leads from the first planet Mercury to outer boundary. Mission Messenger observe “water ice and other frozen volatile materials in its permanently shadowed polar craters”(NASA). The evidences of cycles on the Earth are ice ages and global extinction.The same cycles we expect find on other atmospheric planets.
1. O. Potashko, „Criteria of presence of life on heavenly bodies” Int.conference ‘Meet the space Kraków’, 27-28 November 2014 Poland
2. O.Potashko “Volcanoes and Life: Life Arises Everywhere Volcanoes Appear” in ‘The Future of Life and the Future of our Civilization’ Springer 2006, pp 65-66
3. O.Potashko, M.Viso “Catching Comet’s Particles in the Earth’s Atmosphere by Using Balloons” 40th COSPAR Scientific Assembly. Held 2-10 August 2014, in Moscow, Russia, Abstract B0.6-5-14.
4. O.Potashko “Planetary cycles of life” in: 3-d Astrobiology Science Conference Astrobiology, NASA, Mar.28 to Apr. 1, 2004, Int. Journal of Astrobiology, Suppl., 2004,
5. O. Potashko “Propagation of life beyond the Earth” Geophysical Research Abstracts, Vol. 7, 01519, 2005 SRef-ID: 1607-7962/gra/EGU05-A-01519

15:50 - 16:10 Strategic Map for Exploring the Ocean-World Enceladus (Brent Sherwood)

  1. Brent Sherwood (Jet Propulsion Laboratory, California Institute of Technology)

Cassini’s discovery of jets emitting salty water from the interior of Saturn’s small moon Enceladus is one of its most astounding results to date. Measurements of organic species in the resulting plume, finding that the jet activity is valved by tidal stretching at apocrone, the modeled lifetime of E-ring particles, and gravitational inference of a long-lived, large water reservoir in contact with the rock core all indicate that Enceladus meets today’s textbook conditions for habitability: liquid water, biologically available elements, a source of energy, and longevity of conducive conditions. Enceladus is among the best places in our solar system to search for direct evidence of biomarkers.
Of those places, Enceladus also proffers the simplest access to the telltale molecules, ions, isotopes, and even potential cytofragments, due to its plume continuously expressing material from the ocean directly into space. In situ mass spectroscopy of the plume, plume sample return, in situ investigation of plume fallback deposits on the surface, direct sulcus and vent exploration, and eventually submarining exploration of the ocean can all be envisioned.
However, building a consensus to plan and fund elaborate in situ exploration of this ocean world will hinge on promising results revealed by new data. As with most strategic maps, the very first steps are pivotal.
Two mission concepts are obvious: 1) flythrough plume analysis by gas and particle mass spectrometers, essentially re-making the Cassini INMS and CDA measurements but with modern, high-resolution instruments; 2) collection of plume ice particles, dust, and gas upon Stardust-like flythrough, followed by their retrieval to Earth for comprehensive analysis in terrestrial laboratories.
These and other waypoints on an integrated strategic map each require unique capabilities and yield results important for setting priorities and making subsequent investments. However, overlaid on this logical sequence are important, mutually competing programmatic constraints: astrobiology pursuits at other ocean worlds and Mars, and spectroscopy of exoplanet atmospheres; cadence of realistic opportunities for mission selections and of formal science-community planning cycles via Decadal Surveys; and programmatic impatience to await interim results before vectoring investments in enabling capabilities. As with Mars, anticipation of interesting eventual results could be a key driver of strategic intent, able to withstand absence of validation for many years.
Enabling elements include: coherent sequence of science questions addressable by various type of mission; technologies that mature at the right time to enable both mission performance and approval (e.g., planetary protection); integrated concepts whose cost estimates survive review; community momentum and international partnerships.
Analysis of the strategic map yields a short list of specific decision pressure points for the next two decades. Using these opportunities the community may systematically prosecute the grand objective of finding and exploring an alien ecosystem within the working lifetime of today’s graduate students. If missed, however, progress toward an epochal age of ocean exploration will be episodic, haphazard, and slow. The windows for making significant advances are sparse, and much remains to be done to prepare to take advantage of them.

16:10 - 16:30

17:30 - 18:00 Geologic context and habitability of the fluvio-lacustrine environment revealed by the Curiosity rover at Gale crater, Mars (Nicolas Mangold)

  1. Nicolas Mangold (LPGNantes, CNRS and University Nantes, France)
  2. Sylvestre Maurice (IRAP, OMP, Univ Toulouse, France)
  3. Michel Cabanne (LATMOS, UPMC, Paris, France)
  4. John P. Grotzinger (Caltech/JPL, Pasadena, USA)
  5. Paul R. Mahaffy (NASA Goddard Space Flight Center Greenbelt, USA)
  6. Ashwin R. Vasavada (Caltech/JPL, Pasadena, USA)
  7. Roger C. Wiens and the MSL team (LANL, Los Alamos, USA)

Since its landing on the distal end of an alluvial fan identified from orbit, the Curiosity rover has analyzed a variety of sedimentary rocks of various grain sizes, from mudstones to conglomerates. At the location of Yellowknife Bay a fluvio-lacustrine origin of the bedrock was deduced from the facies, texture and chemistry of sediments (Grotzinger et al., 2014). Their analysis indicates a complex evolution in three main phases all requiring aqueous conditions: (i) Cross-beddings and rounded pebbles indicate that sandstones and conglomerates were deposited by fluvial flows. The similarity in chemistry between mudstones and sandstones shows genetic relationships between the finer and coarser components. Mudstones were likely formed by settling of the finer component of these detrital sediments in a standing body of water. (ii) ChemCam data on raised ridges crisscrossing the sediments show enrichment in Mg and Li due to a leaching of these mobile elements by circulating fluids (Léveillé et al., 2014). A specific type of clay minerals (ferroan Mg-saponite) detected by the CheMin instrument is interpreted to have formed by in-situ alteration of olivine (McLennan et al, 2014). Both Mg-related leaching features indicate substantial post-depositional alteration in aqueous conditions. (iii) Straight light-toned veins were deposited in fractures in the sediments well after their induration. ChemCam showed that they consist of Ca-sulfates (Nachon et al., 2014), likely formed in a late diagenetic environment with relatively mild water circulation at a later stage, well after rock cementation. Gale crater is usually dated Noachian and Hesperian boundary, i.e. 3.6 Ga. The alluvial fan within the Curiosity landing site ellipse was estimated to be from the Hesperian period (Grant et al., 2014), but most sediments analyzed could come from earlier fluvial episodes and related deposits. Overall, these rocks have recorded the conditions of the Martian surface at that time, providing information on overall Mars habitability during a time period that was warm enough for the presence of sustained liquid water. No carbon detection has been made so far by ChemCam (except for atmospheric CO2 contributions), eliminating any carbonates or abundant sources of organics. However, carbon was observed by the SAM instrument, and organics have been detected as molecules of chlorinated alkanes and chlorobenzene (Freissinet et al., 2014). Although there is no evidence that these molecules were once related to living organisms, their existence in sediments that were once formed in water in the presence of ingredients favorable to life (i.e., P, S, C) pleads in favor of a habitable environment. After 1000 sols on Mars, some of these conclusions can be expanded. The deposition of fluvial sediments is not limited to the landing site area and most of the sediments visited so far indicate an origin of sandstones by fluvial deposition, though with a larger diversity in composition. Sulfate veins are now found along the whole rover traverse (>10 km after 1000 sols on Mars) showing that this diagenetic episode is controlled by a regional process. Future rover investigations will further enlarge the context of formation of these sediments.

18:00 - 18:20 Evidences of volcanism on P67 (Oleksandr Potashko)

  1. Oleksandr Potashko (Scientific Enterprise “Fractal”)
  2. Evgen Shniukov (Department of Marine Geology and Sedimentary Ore Formation National Academy of Sciences of Ukraine)
  3. Michel Viso (CNES)

There are numerous evidences of volcanism on comet Churyumov-Gerasimenko P67.
1. Rivers of sand that was lava’s river.
2. the movement of the stones, forming stones in lines that testifies the movement of stones during lava’s flows.
3. One may points how lava’s flows intersect one after another

We consider that lava’s flows take place around perihelion. The mechanism of lava’s flowing is adhesion. Most of lava fractions leave the comet. Numerous lava’s emissions form a adhesive bed.
There are much organics during volcanic activity especially near the chimney, and near the lava exit.

18:20 - 18:40 Where is the Phosphorus in Cometary Volatiles? (Daniel Boice)

  1. Daniel Boice (Trinity University, Physics and Astronomy Department, One Trinity Place, San Antonio, TX 78212-7200, USA.)
  2. Amaury A. de Almeida (Universidade de São Paulo, IAG, Departamento de Astronomia, Rua do Matão, 1226, CEP 05508-090, São Paulo, SP, Brasil.)

Phosphorus is a key element in all living organisms but its role in life’s origin is not well understood. Phosphorus-bearing compounds have been observed in space, are ubiquitous in meteorites in small quantities, and have been detected as part of the dust component in comet Halley. However, searches for P-bearing species in the gas phase in cometary comae have been unsuccessful. We present results of the first quantitative study of P-bearing molecules in comets to identify likely species containing phosphorus. We found reaction pathways of gas-phase and photolytic chemistry for simple P-bearing molecules likely to be found in comets and important for prebiotic chemistry. We hope to aid future searches for this important element, possibly shedding light on issues of comet formation (time and place) and understanding prebiotic to biotic evolution of life. Additional details are given in the Session 4 (Water and Life in the Solar System) poster by de Almeida, Boice, and Andreazza.

Acknowledgements: We greatly appreciate support from FAPESP (São Paulo, Brasil) and the NSF Planetary Astronomy Program.