2004 - NASA successfully lands two Mars rovers.

After parachuting through the atmosphere and bouncing to a stop using giant air bags, the Mars rover Spirit lands on the Red Planet near Gusev Crater. Spirit’s twin, Opportunity, lands on the opposite side of Mars near Meridiani Planum. NASA unveiled this photograph in February 2004 of Opportunity's robotic arm as it stretched over the surface of Mars, marking the first day of the joint $820 million mission when both unmanned spacecraft were in full swing. (© AP Images)