AUSTIN, Texas—Scientists this week begin the final leg of a five-year, NASA-funded mission to reach the bottom of Cenote Zacatón in Mexico, the world's deepest known sinkhole.

No one has ever reached bottom and at least one diver has died in the attempt. Scientists want to learn more about Cenote Zacatón's physical dimensions, the geothermal vents that feed it and the forms of life that exist in its murky depths.

Cenote Zacaton, near the northeastern coast of Mexico, is the deepest known water-filled sinkhole in the world.

Previous expeditions tested the robotic probe that will make the dive. The Deep Phreatic Thermal Explorer, known as DEPTHX, is a tangerine-shaped submarine designed to survey and explore for life in extreme regions on Earth and potentially in outer space. During eight years of research at Zacatón, doctoral student Marcus Gary, who coordinates the DEPTHX mission, and hydrogeology professor Jack Sharp, both from The University of Texas at Austin's Jackson School of Geosciences, discovered the system's unusual hydrothermal nature is analogous to liquid oceans under the icy surface of Jupiter's moon Europa.

Technology developed to explore the sinkholes could be applied to future space probes of Europa, where scientists believe that deep cracks and holes in the ice offer a chance of finding extraterrestrial life.

Cenote Zacaton is located in the state of Tamaulipas close to the town of Aldama near the northeastern coast of Mexico.

The DEPTHX technology has also been approved for a new NASA mission to explore one of Antarctica's ice-bound polar lakes. Researchers believe ice-bound lakes hold clues to the origins of life on Earth.

William Stone of Stone Aerospace in Del Valle, Texas, is principal investigator on the project. The research team also includes robotics experts, engineers, geobiologists and geochemists from Carnegie Mellon University's Robotics Institute, Colorado School of Mines, Southwest Research Institute and Mexico's Universidad Autonama de Nuevo Leon and Universidad del Noreste.

Unique in the world of robotic explorers, DEPTHX is autonomous. The probe does not rely on instructions from humans to decide where to go or what to do. Using software developed by Carnegie Mellon graduate student Nathaniel Fairfield, DEPTHX creates 3D maps of previously unexplored areas as it swims along and then uses those same maps to navigate back to the surface.

The mission's progress can be monitored at two Web sites: geology.com, where a science writer from The University of Texas at Austin's Jackson School of Geosciences will maintain a daily blog of the mission beginning May 16, and the Robotics Institute's DEPTHX Web site, www.frc.ri.cmu.edu/depthx, which will feature daily updates, images and graphics beginning May 15.

Editors: Print-resolution photos from past and ongoing DEPTHX missions are available at http://www.jsg.utexas.edu/news/rels/051407b.html. Updates will be posted during the March expedition.

For more information about the Jackson School, contact J.B. Bird at jbird@jsg.utexas.edu, 512-232-9623.