Surer signs of life: A better class of tools for detecting signs of life on other planets and moons

When they reached Mars' surface in 1976, NASA's two Viking landers touched down with a gentle thud. At 7 feet tall, 10 feet long, and weighing around 1,300 pounds, these spacecraft--the first U.S. mission to successfully land on the Martian surface--looked like overgrown pill bugs.