On a big white cruise ship, 140 tourists have paid thousands of dollars for a rare first-hand tour of Antarctica. Humans didn't set foot on the continent until about 200 years ago, but now, it draws more than 50,000 visitors a year. Why are people going today -- and how does this journey compare to the famous "Heroic Age" trek by Ernest Shackleton about a century before? PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders