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• 1 media/Riotintoagua_small.jpg 2016-05-05T09:07:10+00:00 Rio Tinto 11 image_header 2016-07-14T12:09:34+00:00 Rio Tinto, a river with deep red water flows through the world's largest pyritic belt in southwestern Spain. (Pyrite​ is "Fools Gold", an iron and sulfur containing mineral.)  Rio Tinto is the site of 5000 years of mining activity for copper, silver and gold.  Its waters are highly acidic (pH 1.7—2.5; note: Coca -Cola is ~ 2.5; battery acid ~1, and the smaller the value, the more acidic a liquid is), making it painful to touch, and rich in heavy metals. Nevertheless, scientist have collected well over 1000 forms of acidophile (acid loving) life living here, including bacteria, yeast, fungi, algae and protists. 
  
  The conditions of Rio Tinto are in many ways similar to the surface of Mars, where acidic and sulfur-rich conditions are documented in the geologic record (e.g. Meridiani Planum, the landing site of the Opportunity rover, also see next section), as well as present surface environment. Rio Tinto was therefore selected as a site for the Mars Analog Research and Technology Experiment (MARTE) project, a collaboration between the  Spanish Centro de Astrobiologia (CAB) and NASA. 
   
  What makes Rio Tinto so attractive is nicely summarize in FAQ of the project, dated from 2003:
   

  2. Why is searching for life at Rio Tinto a good analog for searching for life on Mars?
   
  Answer: The science of the MARTE experiment is an analog for searching for subsurface life on Mars. MARTE performs the scientific exploration of a previously unexplored subsurface site with the potential to support life. The experiment will attempt to determine whether subsurface life is present, and to characterize how this life obtains its energy. The search for life on Mars would be required to go through a similar process. NASA and CAB hope to use the MARTE experiment to guide development of equipment to be used to explore Mars.
   
  3. Why is Rio Tinto like Mars?
   
  Answer: The Rio Tinto is located in the Iberian Pyrite Belt, a large deposit of sulfide minerals that was formed in an ancient hydrothermal system. The presence of volcanoes and ground ice on Mars suggests that hydrothermal systems should have formed. Mars is rich in iron and sulfur, key ingredients in the formation of sulfide minerals. Basaltic volcanism appears to have been widespread on Mars. On Earth, sulfide minerals are made in hydrothermal systems associated with basaltic volcanism. Thus, mineral deposits like the ones that we are drilling into on MARTE may be found in the martian subsurface.
   
  4. Why Search for Subsurface Life at Rio Tinto?
   
  Answer: A surface ecosystem consisting of extremophile microbes has been identified in the Rio Tinto River. The term extremophiles refers to the fact that the microbes live in "extreme conditions" compared to the conditions that most organisms prefer. In the case of the Tinto River, the water is very acidic and has a low pH (pH=2.3 in most of the river). These acidic conditions in the river are a consequence of the oxidation of iron and sulfur minerals by water. Some of the microbes that live in the river obtain their metabolic needs from iron and sulfur minerals. These are chemoautotrophs, or organisms that live on chemical energy. The scientific objective of our experiment is to search for a similar ecosystem in the subsurface.
   
  5. How will the Rio Tinto experiment help in the exploration of Mars?
   
  Answer: This year's field experiment is focused on searching for life in the subsurface using conventional drilling, sample handling and sample analysis techniques. The results of this experiment will provide ground truth on the science and help guide the technology development for a future experiment in the MARTE project that will simulate a remote drilling mission on Mars. This future experiment will use a drill and sample handling system designed for a Mars mission.