Watch Modern Marvels Season 10 Episode 73 Online

In 2003, with Mars closer to Earth than it had been in 60,000 years, scientists launched three life-seeking planetary landers. If the long journeys prove successful, all should be hard at work on the Red Planet's surface by January 2004. NASA's EM Spirit /EM and EM Opportunity /EM and the European Space Agency's EM Beagle 2 /EM represent the pinnacle in the history of the search for extraterrestrial life. Leading scientists, who believe life may exist beyond Earth, explain skepticism about ETs having visited Earth.