Red River Drills for Mars
To develop techniques to drill into the surface of Mars to look for signs of life, NASA and Spanish scientists recently began drilling 150 meters (495 feet) into the ground near the source of the waters of the Rio Tinto, a river in southwestern Spain, part of a three-year effort that will include the search for underground life forms.
|Sulfide minerals on surface of ponded water, Rio Tinto region of Spain, July 2002
Credit: Carol Stoker, NASA Ames
During the Mars Analog Research and Technology Experiment (MARTE), scientists and engineers from NASA, U.S. universities and the Spanish Centro De Astrobiologia (Center for Astrobiology) hope to show how robot systems could look for life below Mars' surface. Scientists believe that liquid water may exist deep underground on Mars.
"The Rio Tinto area is an important analog to searching for life in liquid water, deep beneath the subsurface of Mars," said Carol Stoker, principal investigator of the three-year project and a scientist at NASA Ames Research Center in California's Silicon Valley.
Scientists say bacteria that are present in the very acidic Rio Tinto play a role in producing acid in the river, a byproduct of the metabolism of iron and sulfur minerals in the region. The Rio Tinto looks like deep red wine, because iron is dissolved in the highly acidic river water. Scientists hope to find similar bacteria deep underground at the Rio Tinto, where groundwater interacts with iron and sulfur minerals. These underground bacteria may subsist on chemicals and minerals under the surface, according to scientists.
The drilling is expected to yield samples that experts will analyze to gain knowledge about subsurface life forms at the site. Eventually, scientists will use this "ground truth' information to check the accuracy of later robotic efforts to identify life forms, organic compounds and minerals.
|Water sample from the river in which different eukaryotic cells (Heliozoa, diatoms, dinoflagelates) and prokaryotes (much more smaller) can be seen.
Credit: Dr. Ricardo Amils Pibernat
In later phases of the experiment, scientists at NASA facilities in the United States and at the Centro de Astrobiologia in Madrid will remotely operate a robotic drill and life-detection instruments, and will interpret the results, all via satellite, to simulate a mission to search for life on Mars.
The subsurface is the key environment for searching for life on other planets, according to MARTE scientists. "Life needs liquid water and a source of energy," Stoker said. "On Earth, most common life forms are at the surface where sunlight provides the energy, but liquid water occurs rarely at the martian surface, if at all. Liquid water is expected in the subsurface of Mars. So NASA plans to use robotic drilling to search for subsurface life. That is why we are testing the life-search strategy in the Rio Tinto, where subsurface water and chemical energy are expected to support life." Stoker added.
Scientists say evidence suggests the chemistry of the Rio Tinto and its biology may be the result of an underground biologically based chemical reactor fueled by organisms that do not need oxygen gas to survive. MARTE scientists believe such a system may exist in the subsurface of the Rio Tinto area, according to Ricardo Amils Pibernat, a biologist at the Centro de Astrobiologia and a specialist on the biology of the Rio Tinto. If found, this type of life would represent an entirely new subsurface life system, he said.
It is not precisely known how bacteria oxidize the ferrous iron. Scientists believe the process relies on both chemical and biological forces working together. Pibernat's team has collected about 1,300 different organisms, including archaea, yeast, fungi, and protists. The most abundant biomass in the river seems to be algae. Blooms of algae often coat the surface of the water, turning the red water green and producing bubbles of oxygen. Pibernat thinks it is strange how eukaryotic organisms like algae are able perform in such harsh conditions of acidity and heavy metal concentrations (Eukaryotes are organisms that have a DNA-holding nuclear membrane in their cells).
Searching for life in the subsurface of another planet will not only require drilling, but sample extraction and handling, as well as new technologies to identify biomarker compounds and search for living organisms, according to Stoker and her colleagues. "A biomarker compound is like a signature left by life," Stoker explained.
|Missions beyond Europa orbiters, like a probe to drill into the Europan oceans, may not have to go far into the ice to find evidence of life.
During the Rio Tinto campaign, the drill and the robotic system will bring cores of underground rock to the surface. There, a suite of remotely operated science instruments that simulate a Mars mission payload will analyze samples and search for signs of life or biomarkers. The Signs of Life Detector (SOLID) instrument, developed at the Centro de Astrobiología, will search for life in the samples using new technology derived from molecular biology. This instrument can detect not just whole organisms, but macromolecules or other life byproducts, said Gómez-Elvira.
Researchers from the Centro de Astrobiologia have suggested that the Tinto River also makes a good Europa analogy. Jupiter's moon Europa is thought to have an acidic, salty ocean under its outer layer of ice. Thus, the Tinto River could represent a unique biological setting also to investigate the possibility of sulfur-based life on Europa.
One of the largest deposits of sulfide minerals in the world is in the Rio Tinto region. Similar mineral deposits may well be found on Mars, according to the scientists. "There is a critical and immediate need for technology maturation for drilling that can be done during a field experiment on Earth to simulate a Mars mission," Stoker said.
"It is crucial to prepare for Mars exploration by understanding the relevant terrestrial environments where life persists," she added. "In addition to looking for evidence of subsurface life, we hope MARTE inspires students to pursue careers in science and engineering," Stoker said. A series of eight one-hour educational webcasts about MARTE will take place beginning on Sept. 29 and continue through October 15.
The Astrobiology Science and Technology for Exploring Planets [ASTEP] program at NASA Headquarters, Washington, is funding the project. The Spanish contribution to the project is supported by the Ministerio de Ciencia y Tecnologia, Comunidad de Madrid and the Instituto Nacional de Tecnica Aeroespacial (Ministerio de Defensa).
Related Web Pages
Online Robotics Course
Centro de Astrobiologia, Madrid
Life Under A Spanish Red River
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Sulfuric Acid Found on Europa
The Sulfuric Chemistry in the Terrestrial System of Tinto River and Europa: A comparison
Fossils of Pilbera