First in a three-part series.
SUMMIT STATION, Greenland -- The midnight sun is shining on the Greenland ice sheet, and Yeti Robot is out for a spin.
The probe's chunky tires crunch a trail through the snow, then jerk to a stop. A blue plastic sled carrying a ground-penetrating radar crashes into Yeti's boxy black chassis, still tied to the robot by nylon ropes.
Yeti's handlers try to diagnose the problem. The robot is swinging too wide on its right turns, straying from the path programmed into its onboard GPS. The engineers confer. Seconds later, Yeti is again whizzing toward the horizon.
It's the first day of this year's field tests, and the researchers are eager to show off their prize pupil. If all goes well, battery-powered Yeti and its close relative -- a solar-powered version called Cool Robot -- could one day expand scientists' access to Earth's poles and enhance their ability to study how climate change is speeding the melt of Greenland's ice sheet.
The robots are part of a new breed of autonomous rovers, submarines, ocean gliders and unmanned aircraft designed to go places scientists can't, to handle jobs that are too dangerous or too costly for researchers to undertake themselves.
"It's expensive to put researchers in the field," said Jim Lever, a mechanical engineer at the Army's Cold Regions Research and Engineering Laboratory who helped develop Yeti and Cool Robot with colleagues at Dartmouth College and the University of New Hampshire. "You have a logistics train to support them."
That logistics train includes the U.S. Air Force's ski-equipped LC-130 cargo planes, which ferry personnel, scientific equipment, food and other basic supplies to the National Science Foundation's research camps in Greenland and Antarctica. The flight that brought Yeti's handlers to the summit of Greenland's ice sheet in mid-July carried everything from a fresh supply of weather balloons to a crate of cantaloupes.
Hauling stuff and finding the crevasse
But those flights can't deliver all the supplies it takes to keep NSF's far-flung polar research camps operating. Twice a year -- once at each pole -- the agency sends teams of station staff on overland treks to deliver fuel and other cargo to prepare remote outposts in Greenland and Antarctica for their busy summer research seasons.
Case tractors drag huge cargo sleds along the ice, journeys that normally take weeks to complete. It's a dangerous job. Teams must watch for crevasses in polar ice, using radar hanging on a boom about 20 feet in front of the lead tractor.
"If you see a crevasse, you have a couple of seconds to stop the vehicle," said Laura Ray, a professor at Dartmouth's Thayer School of Engineering who helped create Yeti and Cool Robot. "As you can imagine, that's a fairly fatiguing, stressful job."
Ray and her colleagues say Yeti could help make those supply treks safer. The robot, outfitted with a ground-penetrating radar, could take over the job of scouting for crevasses -- and interpret those data on the fly. The current version of Yeti is constructed from $25,000 worth of parts, including military-rated, ultralight batteries that can travel 10 to 15 kilometers before they need to be recharged.
"There are things that Yeti can cross that the big vehicle can't because it's so heavy," Ray said. "If there's a crevasse hidden by a snow bridge, Yeti won't fall through because it's so light. ... At some point, we hope NSF will see this as a fairly valuable logistics vehicle that saves money in the long run."
But before Yeti can take the job, it must undergo more tests, like this year's field trials on the summit of the Greenland ice sheet.
Engineers Tom Lane and Suk Joon Lee, who graduated from Dartmouth in May, had planned to spend eight days at Summit Station testing the rover's ability to follow preprogrammed paths as it used an instrument package developed by UNH scientists to measure the pollution plume produced by the camp's diesel generator.
Yeti also carried an onboard computer and signal processing board, a ground-penetrating radar and an ultra-precise GPS to plot its path forward and map small ice ridges, called sastrugi, that resemble tiny frozen sand dunes.
"We're just trying to prove a robot is able to collect data humans would collect," Lane said, a few hours after he and Lee landed on the ice sheet and unpacked Yeti from its travel crate. "Our goal is to use autonomous robots to drag a variety of scientific equipment."
Over the next seven days, the two engineers' work was cut short by bad weather and altitude sickness, but Ray, who supervised their work on Yeti over the past year, said she's happy with the robot's progress. Yeti was able to execute a "square wave" pattern of repeating north-east-north-west turns and aced test trips of 3 to 4 kilometers.
Charging ahead, 24 hours a day
That experience will aid Ray's team as they develop an improved version of Yeti's solar-powered sibling, Cool Robot, which they believe is more suited to collecting data for scientists studying the poles.
"It can drive as long as the sun is up, and in the polar regions in summertime, the sun is up 24 hours a day," Lever said. "So you can considerably extend the reach of science parties out into the continent [of Antarctica] or onto the Greenland ice cap by using a robot that's solar-powered."
The researchers hope to send Cool Robot on a long test journey in 2013, perhaps to accompany NSF's annual supply trek across Greenland's ice. To prepare, they're redesigning Cool Robot's solar panel box to make it lighter and reshaping the robot's overall profile to help it resist being overturned by strong winds.
"Our goal is for any scientist that needs to collect data to be able to borrow one of these robots, or buy one," Lane said. "They can go day and night at the same speed. They don't make errors like humans do."
Still, the team behind Yeti Robot and Cool Robot doesn't think that its rovers -- or other machines -- will ever completely supplant humans at the poles.
"I don't think we'll ever replace scientists in the field," Lever said. "The intention is to expand their reach."
Correction: A previous version incorrectly referred to Dartmouth University; the institution is named Dartmouth College.