ASTROBIOLOGY ON MARS

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ASTROBIOLOGY ON MARS

• A. Horvath (1,2), T. Ganti (2), T. Pocs (2,3),
• S. Berczi (2,4), E. Szathmary (2,5)
• 1 Konkoly Observatory, H-1525 Budapest, POB 67.
  Hungary,
• 2 Collegium Budapest (Institute for Advanced
  Study), H-1014 Budapest, Szentháromság u. 2.,
  Hungary,
• 3 Eszterhazy K. College, Dept. Botany, H-3300
  Eger, POB. 43, Hungary,
• 4 Eötvös University, Dept. General Physics,
  H-1117 Budapest, Pazmany P. s. 1/a.
• 5 Eötvös University, Dept. Plant Taxonomy and
  Ecology, H-1117 Budapest, Pazmany P. s. 1/c,
  Hungary

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Introduction-I Dark dune spots (DDSs) are
annually recurring geomorphological features of
Martian dark dunes located between the South Pole
and 50 degrees latitude
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Introduction-II Frost cover first appears on
dark dunes in autumn. Defrosting gradually
advances during the second half of winter and
early spring when dark spots are formed.
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Introduction-III

• DDSs were first observed in narrow-angle MGS MOC
  images in years 1998 to 2001. By now, several
  thousand such formations have been identified.
• All of the observed features of DDS phenomenon
• can be explained by a
• biological hypothesis.

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Observations - I

• DDSs have an isotropic circular form and are
  superimposed on the local topography.
• i.e., they are small scale groove or hole
  structures
• of the frosted surface of snow/ice cover

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Observations - II

• The process
• of DDS formation
• begins below the
• frosted layer.
• DDSs are shallow
• crater-like holes in the layer of
  precipitated snow/ice.

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Observations - III

• On slopes,
• the spots are elongated downwards,
• taking
• ellipsoidal or
• fan-like shape or creek-like flows
• depending on
• the steepness
• of the slope.

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Observations - IV

• The spring configuration of DDSs appears as the
  summer configuration of light grey patches in the
  dark dune fields. There are localized causes for
  spot formation.
• We interpret the light grey patches as dried
  remnants of the materials causing the DDS
  spotting phenomenon.

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Observations - V

• DDSs have seasonal changes from winter to summer.

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Observations VI

• DDSs have a massive annual reappearanceon the
  same places. The dinamics of the reappearance
  depend on local meteorological condicions.

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Interpretation of the DDSs genesis Biological
hypothesis by Martian Surface Organisms (MSO)

• Organisms in the soil, below the ice, warm up by
  the absorption of sunlight and melt the water ice
  around them.
• The CO2 ice cover disappears in the DDS center,
  where the melting starts.
• When water evaporates the organisms dessicate and
  the dark naked soil becomes visible.

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MARS ODYSSEY data

• Efficient pigments
• water lens
• UV screening and
• insulation by ice layer
• liquid phase
• water is abundant in the soil
• several months for reproduction
• terrestrial analogues

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CBC on Earth

• In terrestrial conditions several types of
  bacterial communities adapted to extreme physical
  environments (dry deserts, Antarctic ice and dry
  valleys, etc.). The most general bacterial
  consortia on the Earth are the cryptobiotic
  crusts (CBC). CBC regularly occurs and forms
  continuous cover with brown, black or dark violet
  color in the semiarid and arid areas of the
  Earth, which devoid of higher vegetation.

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CBC in central Australia

• In the subtropical desert areas, like the red
  heart of central Australia we have found the
  largest areas of CBC in the flat depressions
  between rocky hills or sand dunes, where water is
  temporarily accumulated during the short rainy
  season.

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Desert varnish on Earth and probably on Mars

• Both Spirit and Opportunity probes found bright
  rocks with shining surface. Such type of surfaces
  also can be found in terrestrial desert rocks
  (called desert varnish).
• The phenomenon has two main interpretations.
• 1 the surface is polished by the wind
  transporting fine dust grains.
• 2 bright cover may be the secretion of algae.

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Conclusions 1

• There are candidates for recently existing forms
  of micro-organisms on Mars the terrestrial type
  cryptobiotic crust (CBC) composed mainly by
  cyanobacteria consortia and a similarly bacterial
  remnant biomarker, the desert varnish on bright
  polished surfaces.
• Meteorite investigations showed habitable
  environment for Martian micro-organisms inside
  the rocks (D. McKay, et al. 2004), however the
  phenomena found by our group (DDS, CBC, bright
  desert varnish) may show evidences of the
  projection of recent life phenomena to the
  surface also appeared.