Considered some of the pinnacles of Mars exploration and study for the Mars NASA missions, Spirit and Opportunity landed on January 2004, carrying a multitude of scientific instruments that seeked to continue the search for hospitable environments for primitive life. They performed studies on the geology and atmosphere of the planet, with the eventual decision that there has been evidence of past life on Mars at one time.
A different approach was used for these rovers than many others, as here they used three methods to cushion the landing: parachutes, a set of rockets, and a final cluster of air cushions that would allow the rovers to end upright on the surface. While they were initially intended to only work for a month and a half, Spirit lost connection with Earth after six years, and Opportunity still works after twelve years, more than fifty times the original planned duration, giving NASA some of the best value for its money it has ever seen in a rover. The rovers have studied various craters, subterranean changes in the planet that will allow scientists to better determine if Mars has a liquid core, and searched for fossils and other carbon compounds that would hint at life.