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Robo-explorer goes deep

After a successful deep-water test, an autonomous robot is gearing up to go where no machine - or human, for that matter - has gone before. It's all part of an experiment that could set the stage for seeking life on Europa, an ice-covered moon of Jupiter.

Stone Aerospace
The DEPTHX autonomous robot looks like an 8-foot-
wide orange mushroom packed with electronics.

The autonomous underwater robot is called the Deep Phreatic Thermal Explorer, or DEPTHX for short. The contraption looks like an 8-foot-wide (2.5-meter-wide), 2,860-pound (1.2-metric-ton) orange mushroom - but it has the tools and the smarts to swim down to the depths of a water-filled cavern, create its own maps of the area, then come back up with scientific samples.

This month, DEPTHX successfully explored a 377-foot-deep (115-meter-deep) sinkhole in eastern Mexico, called La Pilita, as a warm-up to an even bigger expedition planned in May: DEPTHX will be dropped into what's thought to be the world's deepest sinkhole, Mexico's El Zacaton, and could descend hundreds of yards (meters) into a dark region no diver has been able to reach. (One diver died trying to plumb Zacaton's depths back in 1994.)

DEPTHX is built to find its own way around an underwater cave without any tethers, guidance or communication from above. That autonomy is what distinguishes DEPTHX from remotely operated vehicles - such as the Alvin submersible robot, which made such a splash in the search for the Titanic.

"The difference between this and an ROV is like the difference between an airplane and a car," said Bill Stone, principal investigator for DEPTHX and the head of Texas-based Stone Aerospace. "This is designed for unexplored territory, where there is no external navigating."

But autonomous navigation is just half of DEPTHX's mission, Stone told me. The other half is what Stone calls "science autonomy" - that is, the robot's ability to identify targets of scientific interest and bring 'em back alive. DEPTHX can check the salinity, acidity, conductivity and chemical content of the water around it, and follow the "scent" to a hydrothermal vent or a microbial mat. It can even look for color variations that signal the presence of organisms. Then it can extend a mechanical arm with a coring mechanism, grab a sample and bring it up to the surface.

The samples from La Pilita's depths have not yet been analyzed - but DEPTHX microbiologist John Spear, an assistant professor of environmental science and engineering at the Colorado School of Mines, expects that those samples will contain several new phyla, or divisions, of bacteria.

"If that's the case, that will be the first robotically cataloged, previously unknown division," Stone said.

The Mexican sinkholes, also known as cenotes, are just the first targets for DEPTHX. Stone Aerospace and the other partners in the project - including the Colorado School of Mines, Carnegie Mellon University, the Southwest Research Institute, the University of Texas at Austin, the University of Colorado and the University of Arizona's Lunar and Planetary Laboratory - are already planning to build a more robust robot for exploring Antartica's subsurface lakes.

The ultimate goal is to produce a breed of robots that can be sent to Europa or other moons where liquid water may exist beneath a miles-deep layer of ice. The mother probe would melt its way through the ice and release a nuclear-powered base station into the water below. DEPTHX's grandchildren would then fan out from the base and look for undersea samples bearing the signatures of alien organisms.

Along with Mars, Europa offers one of the best opportunities in the solar system for finding extraterrestrial life. "That's why this is so important," Stone said.

He said the Europa project could get off the ground in seven to 10 years - if only NASA had the money. NASA has allocated $5 million for the DEPTHX project so far, but all that cash has been spent, Stone said.

"Effectively, we're out of money and running on overhead," he told me. "There are a few of us, including myself, who haven't been paid in six or seven months. ... The budget was about $5 million, and we're probably a quarter of a million over that. It's the same at some of the other institutions involved in this."

Despite the tight budgets, Stone and his colleagues are proud of what they've done and intend to keep on doing it - with potential funding from NASA as well as the National Science Foundation and international partners. "They could not have paid Lockheed Martin half a billion to do what we did," he said.

For more about DEPTHX, check out the Carnegie Mellon University news release, the project Web page at CMU's Field Robotics Center, the DEPTHX page at the University of Texas, Stone Aerospace's press kit (which includes video clips of the robot in action) and this report from Popular Science.