Chott el Jerid, Tunisia: Closest thing to Mars on Earth?

The field campaign has been organised by the Europlanet Research Infrastructure (RI).

Chott el Jerid is a seasonal lake that is completely dry for most of the year. Its sun-baked surface, composed of a hard crust of sodium chloride, conceals sources of underground water and the area has a vivid red colour due to the high iron content. This environment appears to resemble closely layered deposits of chloride salts discovered at Martian high latitudes by recent missions, such as Mars Odyssey, using data from Thermal Emission Imaging System (THEMIS), Mars Global Surveyor and Mars Reconnaissance Orbiter.

The Europlanet project, which links planetary scientists from more than 100 laboratories and institutes in Europe and around the world, offers scientists access to a range of planetary analogues -- places on Earth that resemble environments found on other planets and moons in our Solar System -- to test out instrumentation for future missions and to understand more about how geological systems observed on places like Mars and Titan are formed and evolve.

Chott el Jerid is a new site and before it can be made accessible to the wider planetary science community, a detailed analysis needs to be made of the geology, mineralogy, climate and microbiology of the area.

The team that will carry out this survey includes experts on geology, geobiology, geochemistry, sedimentology and planetary geology. The team is led by Dr Felipe Gómez from the Centro de Astrobiología (INTA-CSIC) in Madrid, in collaboration with Jamel Touir from Sfax University, a specialist on sedimentology of the Sabkhas (the Arabic name for salt flat deposits in deserts).

"We will be studying the similarities between Chott el Jerid Desert and mineral deposits on the surface of Mars. From an astrobiological point of view, it is extremely interesting to examine the biological cycles at a site with such low and salty water levels. We are going to be using geophysical sounding techniques to produce detailed three-dimensional maps of the sub-surface water, the geology and the biological distribution at the site. These will help us gain a detailed understanding of the processes that control the geology of the habitat and how this in turn controls the biology. We will also bring samples back to the laboratory to catalogue the biology at the different sub-habitats," said Dr Gómez.

The Europlanet team visited Chott el Jerid in November 2009 to map the key analogue sites. On the current trip, the team will drill down to a depth of three metres to study the structure and mineralogy beneath the surface and to collect samples for microbiological analysis.

In addition to opening up access to Chott el Jerid, Europlanet is preparing a further analogue site in an area of the Popigai crater in Siberia, the fourth largest and best exposed meteorite crater that has been found on Earth. Europlanet is also supporting scientists on future field campaigns to Mars analogue sites at Rio Tinto in Southern Spain and Ibn Battuta in Morocco, to Svalbard, an analogue Europa, and to the Kamchatka Peninsula in Siberia, Russia, which can serve as analogue for the surfaces of Titan, Europa and Mars, and as a study site for prebiotic conditions on Earth.

"This new site at Chottt el Jerid will be a unique facility for European planetary scientists. Access to these field sites and the other facilities, tools and services Europlanet offers, or is developing, will allow Europe to set the pace for the adventure of planetary science for the decades to come," said Dr Gómez.