CHICAGO – A NASA robot tested last winter in an icy Wisconsin lake will complete a monthlong underwater mission in Antarctica today, having explored dark, deep waters frozen off from the outside world tens of thousands of years ago.

Managed by a team from Texas and Chicago, the robot has hit its marks while patrolling Lake Bonney, a body of water locked under 15 feet of ice. The Antarctic lake is the nearest thing on Earth to outer space, and scientists hope lessons learned there will inform a future hunt for life in the ice-covered oceans of Jupiter's frozen moon Europa.

The robot overcame some technical surprises to gather information on the lake's internal structure and spot a colony of microbes unlike any seen before.

Scientists named the robot ENDURANCE (for Environmentally Non-Disturbing Under-ice Robotic ANtarctiC Explorer) in a nod to the ship Sir Ernest Shackleton was forced to abandon on his failed Antarctic expedition a century ago.

The device patrols under the ice like a $5 million Roomba robotic vacuum cleaner while a pair of scientists with tracking antennas follow it across the ice above. A fiber-optic cable is its lifeline to University of Illinois researchers.

ENDURANCE was built by Stone Aerospace in Austin from a design used for Mexican waters. When it first explored cold water in February at Lake Mendota in Madison, Wis., the sonar was iffy, thrusters balked, and it barely found its way back to the starting point.

But in Antarctica, it motored flawlessly to all its destinations – determining its own routes underwater, evading obstructions and returning by dead reckoning to the team of relieved scientists.