The idea that Mars once had oceans is a controversial one: It's been proposed before, and formations that look like shorelines have been found in images from a variety of spacecraft.
Now scientists, after analyzing data from the European Space Agency's Mars Express mission, have concluded that the northern plains of Mars may have had an ocean.
MORE: http://lightyears.blogs.cnn.com/2012/02/06/mars-may-have-had-oceans/?hpt=us_t5
See also...
The Ancient Oceans of Mars
http://abcnews.go.com/Technology/slideshow/photos-final-frontier-1884336
Mars 'super-drought' may make red planet too dry for alien life
http://www.cbsnews.com/8301-205_162-57372059/mars-super-drought-may-make-red-planet-too-dry-for-alien-life/?tag=cbsnewsSectionContent.10
NASA's Juno Spacecraft Refines Its Path to Jupiter
http://www.sciencedaily.com/releases/2012/02/120206145903.htm
