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.

During the Mars Analog Research and Technology Experiment (MARTE), scientists and engineers from NASA, U.S. universities and the Spanish Centro De Astrobiología (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.

In later phases of the experiment, scientists at NASA facilities in the United States and at the Centro de Astrobiología 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 Astrobiología 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.

"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 webcasts and their schedule are accessible at this Internet URL: http://robotics.nasa.gov/courses/fall2003 and http://www.cab.inta.es.

The Astrobiology Science and Technology for Exploring Planets 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).