A yeti has been spotted roving the Antarctic ice sheet. It doesn’t much resemble the ferocious Abominable Snowman of Tibetan legend, nor the fuzzy white giant with razor-sharp teeth and blue face made famous in the claymation classic “Rudolph the Red-Nosed Reindeer.” This model rolls across the frozen landscape and, rather than pose a threat to humankind, is making Arctic and Antarctic explorations safer and less expensive. Yeti is a self-guided polar robot that uses ground-penetrating radar to map what lies beneath the ice — often, a crevasse waiting to claim lives and expensive equipment. Yeti’s radar can penetrate down about 15 yards into the ice. The March/April issue of the Journal of Field Robotics describes the vehicles and their deployments in northern Greenland and across 1,031 miles from McMurdo Station in Antarctica to the South Pole. Researchers [professors Laura Ray and James Lever] plan to use the robot’s hazard-mapping abilities to develop algorithms for other machines operating in remote locales, but Yeti is proving useful in other ways as well. The robot was recently used to map ice caves on the slopes of Antarctica’s Mount Erebus, the world’s southernmost active volcano.