If all goes as planned, Curiosity, NASA's nuclear-powered rover, will touch down early Monday morning in the 96-mile-wide Gale Crater on the fourth planet from the sun.
The goal is to collect soil samples that scientists hope will finally settle the question of whether there is or ever was life on the red planet.
And "if all goes as planned" is the key phrase because even NASA officials admit that a safe touchdown for Curiosity is the hardest mission they've ever attempted. The mission is scheduled to last for two years.
- Pat Duggins, author of "Trailblazing Mars." He writes about space for "Modern Weekly" magazine in China
This program aired on August 3, 2012.