Morphology of the M ar tian Dark Dune Spots - PowerPoint PPT Presentation

András Horváth

Konkoly Observatory,

TIT Budapest Planetarium,

planet@mail.datanet.hu

(Előadás az MTA Geonómiai Bizottságának Szádeczky-emlékülésén, 2003. okt. 21.-én)

• Tibor Gánti

emeritus professor of theoretical biology

• EörsSzathmáry,

biology professor, Eötvös University and permanent fellow of the Collegium Budapest, Szaniszló Bérczi,

associate professor, Eötvös University

• AlbertGesztesi,

dep.director, TIT Budapest Planetárium

Introduction-IDark dune spots (DDSs) are annually recurring geomorphological features of martian dark dunes located between the South Pole and –50 degrees latitude

Introduction-IIFrost cover first appears on dark dunes in autumn. They defrost towards the second half of winter and in spring, when dark spots are formed.

• 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 DDSs

can be explained by a

biological hypothesis.

• DDSs have an isotropiccircularform and are superimposed on the local topography,
• i.e., small scale groove structure
• of the frosted surface of snow/ice cover.

• The process

of DDS formation

beginsbelow the

frosted layer.

• DDSs are shallow

crater-like holes in the layer of precipitated snow/ice.

• On slopes,

the spots are elongateddownwards,

taking

ellipsoidal or

fan-like shape or creek-like flows

depending on

the steepness

of the slope.

• The spring configuration of DDSs appears as the summer configuration of light grey patches in the dark dunefields. There are localized causes forspotformation.

Observations - V

• DDSs have a seasonal changes

from winter to summer.

Observations – VIDDSs have a massiv annual reappearanceon the same places. The dinamics of the reappearance depend on local meteorological condicions.

• Organisms

on the soil,below the ice, warm up by theabsorption ofsunlight andmelt the water ice

around them.

The CO2 ice coverdisappears

in the center,

where the meltingstarts.

When water evaporates the organismsdessicate and

the dark naked soil

can be seen.

Efficient pigments –water lens

–UV screening and

insulation by ice layer

– liquid phase:

wateris abundant in the soil

–several months for reproduction

– terrestrial analogues

ConclusionIf the biogenic hypothesis is correct, it means that, at exceptional sites and under exceptional circumstances, photosynthetic organisms still dwell on the Martial surface.This claim will be substantiated as far as possible by the extensive use of the data obtained by the Mars Express mission.

Proposal for MARS EXPRESS – IMars Express coud provide imaging and spectroscoping observations for detailed study of the dynamics of DDSs on the selected areas (Pityusa Patera and Inca City region)