Interest in our neighboring planet, Mars, has ebbed and flowed ever since Percival Lowell claimed to discover canals on its surface from his telescopic observations in the 19th century. The first spacecraft flybys of the 1960s indicated a forbidding surface similar to the Moon. However, images from later missions orbiting the planet showed dry river channels, deltas, and possibly former oceans. In 2004, the Opportunity rover discovered sediments that had precipitated from standing water long ago, and the Phoenix polar lander uncovered ice during its mission in 2008, all clearly showing that Mars was once a wet planet.
With its watery past, current questions have shifted to whether life might have been present, and how habitable the former climate was. Evidence suggests that at least during some epochs, the water on Mars was quite acidic, and as the planet became colder, remaining liquid water was highly saline. Neither of these are ideal conditions for life, however, work in the last decade has shown that extremophile life forms exist even in the most inhospitable conditions on Earth. Previous Mars rovers had no direct way to detect or study carbon—the building block of life. To address this, NASA is launching its biggest rover yet, packed with new instruments to begin its quest on the surface of the Red Planet. Lift-off is scheduled for November 26th.
Visit these websites for more information about the Curiosity Mars Rover: