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January 18, 2000
Search for Meteorites Enlists a Novel Recruit
DiagramNomad on the Ice
By WARREN E. LEARY
umans have long ventured to Antarctica to study and make discoveries on the icy continent. Now, a new breed of explorer -- a metallic robot crammed with wires and electronics -- is poised to add its name to the annals of polar history: Nomad, the meteorite hunter.
Nomad, a four-wheeled machine built by Carnegie Mellon University's Robotics Institute in Pittsburgh, is in Antarctica to see if it can discover something without human assistance. The achievement would be a first for a robot.
Josh Landis for The New York TimesBen Shamah, an engineer at Carnegie Mellon University, puts the robot Nomad through its paces at Williams Field, the icy airfield near McMurdo Station, Antarctica.
The machine is designed to search rock-strewn areas of ice that are known to harbor meteorites and pick out the objects that fell from space from among ordinary rocks and stones. Nomad's builders believe that the robot has enough intelligence to sort out information from its sensors and choose the rocks composed of extraterrestrial material, a job normally done by humans experienced in meteorite detection. They hope Nomad will discover at least one new meteorite on its own.
Dr. William L. Whittaker, the principal researcher on the Nomad project, said past exploration robots, like those sent into space or far down in deep oceans, had been drones that simply transmitted information for humans to evaluate.
"Until now, explorative robots have taken pictures, gathered data and returned what they viewed to scientists who made judgments and decisions," Dr. Whittaker said.
"This time, Nomad will make its own judgments and inferences about the rocks that it encounters. If successful, it will be viewed as machine intelligent behavior."
Nomad and a half dozen engineers and graduate students who are supporting its mission arrived in December at McMurdo Station, the main United States base in Antarctica. The 1,600-pound robot, outwardly about the size of a Volkswagen Beetle, was taken by helicopter a week ago to its testing area 180 miles northwest of the base for three weeks of field trials. After initial delays caused by severe, windy weather, the crew set up Nomad's instruments and conducted demonstration runs of the robot prior to beginning the actual trials.
Nomad is powered by a gasoline-driven generator that supplies electricity for its computers, communications, scientific instruments, high-resolution digital camera and propulsion. Each of its four metal wheels, covered with metal-studded snow tires, is powered by a separate electric motor. The vehicle, which can expand its chassis to go over obstacles 40 inches tall or use its laser range finder to help go around them, is designed to move at about 1.5 feet per second as it surveys an area.
Dr. Dimitrios Apostolopoulos, a systems scientist at the Robotics Institute, who is project manager for Nomad, said the robot would test its skills under increasingly challenging conditions. Some parts of the test area are flat ice sheets studded with occasional, distinct rocks while others are moraines, dense concentrations of rock and rubble deposited by glaciers.
When it sees a good candidate, the robot will move in for detailed examination with instruments on the end of a movable arm, including a close-up mini-camera that will look at it from different angles. Nomad will touch the rock several times with a reflection spectrometer, which shines a light on the object and analyzes the spectrum of the reflected light to tell what elements are present. Then the robot will use a metal detector to sense the presence of iron, a major component of some meteorites, and do computations to classify the sample.
If Nomad decides a rock is a meteorite, the robot will radio the object's exact location to the researchers using coordinates calculated by the satellite-based Global Positioning System. Later, people will retrieve the specimen to confirm or refute Nomad's findings.
"Of the hundreds or thousands of rocks Nomad looks at, we hope to get detailed readings on 150 or so," Dr. Apostolopoulos said. "Nomad will not only say if a rock is a meteorite or not, but it also should be able to tell what type of terrestrial rock it is. It's more than a yes-or-no decision."
The project, which has so far cost about $3.5 million, is sponsored by the National Aeronautics and Space Administration's Office of Space Science, which is interested in sending intelligent robot explorers to other planets. On distant worlds, where the simplest, round-trip radio communication can take hours, it would be impossible for humans on Earth to guide a robot. Scientists need robots that can fend for themselves in unknown, hostile environments and that are smart enough to recognize and assess the unexpected.
Engineers at Carnegie Mellon felt that Antarctica would not only be a good place to test such robots in a distant, harsh environment, but also offered an opportunity to demonstrate their ability to do useful work. Conditions on the continent make it a reservoir for meteorites, and robots could help human searchers make their limited time there more productive.
"Robots are tools, not toys," Dr. Whittaker said. "Their success will depend upon them proving themselves and selling the concept of their usefulness."
Hundreds of researchers, including meteorite hunters, descend upon Antarctica at this time of the year, taking advantage of the frigid continent's brief summer to study and explore. Since 1969, scientists from the United States and Japan have collected more than 20,000 meteorites near certain Antarctic mountain ranges where they have been preserved in the ice for thousands of years. Glacial movements gradually concentrate the space rocks in discrete areas and push them to the surface, where experienced searchers can recognize them by their unique outer characteristics.
Meteorites collected in Antarctica not only include remnants from the formation of the solar system billions of years ago, but also pieces of the Moon and Mars that were blasted away by impacts with asteroids and comets. A controversial Antarctic meteorite discovered in 1984 originated on Mars and is believed by some scientists to contain evidence of primitive microscopic life.
Nomad is being tested at Elephant Moraine, a prime meteorite collection site on the east Antarctic plateau. Elephant Moraine, so named because it looks like a small elephant with a long trunk, has yielded more than 2,000 meteorite specimen during seven previous visits, going back more than 15 years, by researchers with the Antarctic Search for Meteorites, or Ansmet, program.
Ansmet, sponsored by the National Science Foundation, has collected more than 10,000 meteorites over the past 23 years and made them available to researchers worldwide. Two members of the Ansmet group who have been searching other meteorite sites this season are to join the robot team to help verify Nomad's findings.
Nomad and its instruments, which will be taken by helicopter to the moraine, have been tested on several trial runs over the past two years, but this expedition marks the first time the robot is expected to operate completely on its own and deliver useful results.
In the summer of 1997, Nomad made a 130-mile trek across a section of the Atacama Desert in northern Chile while being remotely operated by researchers in Pittsburgh and at NASA's Ames Research Center in California. Later in 1997, and again in 1998, engineers went to the Patriot Hills area of Antarctica to test components and then the completed vehicle under close human control.
Dr. Apostolopoulos said the Nomad team decided not to take along any spare parts for major systems, eliminating the possibility of doing any major mechanical work in the field. "This is a conscious decision that forced us to work on reliability, to make the robot rugged," he said. "We have to make the case that it will work in space, where there won't be any mechanics around to fix it if something goes wrong."
Dr. Ralph P. Harvey of Case Western Reserve University, who directs the Ansmet exploration operations in Antarctica, said that having Nomad work in a well-explored area, where most easy samples have been retrieved, will be a true test of the technology. Dr. Harvey said the human eye and brain were the best instruments for detecting meteorites among similar-looking rocks, and he did not see machines replacing humans as primary spotters. However, he said, robots could have a supplemental role in cleaning up samples left behind after a human search.
"Robots don't lose their concentration and are happy to do jobs that are repetitive and difficult, allowing humans to do something else that might be more exciting and profitable," Dr. Harvey said.
"If Nomad finds meteorites that we might not recover otherwise, because other sites have a higher priority, then this is a great boon. Nomad will be doing real work rather than simply demonstrating some technology."
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