Mapping Antarctica

Antarctica was on the map long before anyone ever laid eyes on it．Nearly 2，400years ago，ancient Greek philosophers such as Aristotle believed that a great continent must exist at the bottom of the world．They thought it was needed to balance out the continents at the top of the world．In the 1500s，mapmakers often included a fanciful continent they referred to as Terra Incognita （Latin for"unknown land"） at the bottom of their maps．But it was not until the 1800s----after explorers had sighted and set foot on Antarctica----that mapmakers got down to the business of really mapping the continent，which is one-and-a-half times the size of the U．S．．

While the coastline could be mapped by ships sailing around the continent，it took airplanes----and later，satellites----to chart Antarctica's vast interior （内陆）．That job continues today．And it is a job that can still require a mapmaker，or cartographer，to put on boots and head out into the wild．

Cole Kelleher is familiar with that．He is a cartographer with the Polar Geospatial Center （PGC），which is based at the University of Minnesota and has a staff at McMurdo Station．PGC teamed up with Google to use the company's Trekker technology to capture images of Antarctica for the Internet giant's popular feature，Street View．A Trekker camera，which is the size of a basketball，is set about two feet above a backpack．The camera records images in all directions．"It weighs about 50pounds．I was out for two and a half days，hiking 10to 12hours each day，"says Kelleher．It was hard work，but really an incredible experience．"According to Kelleher there are plans to use the technology to create educational apps for museums．

The PGC staff at McMurdo Station provides highly specialized mapmaking services for the U．S．Antarctic Program．For one project，Kelleher used satellite images to map huge cracks in the ice．That helped a team of researchers know whether they could safely