Images taken by NASA’s Mars Reconnaissance Orbiter(MRO) spacecraft show that Mars potentially, had a huge ocean. If the ocean on the northern hemisphere existed, it would have covered as much as one-third of the planet’s surface.  According to the VOA website, using the Orbiter images, “scientists from the California Institute of Technology found ridge-like features known as inverted channels that are evidence that there was once an ocean floor on Mars.”  The images show what appear to be an ancient river delta.  Lead study author Roman DiBiase, postdoctoral scholar at Caltech said, “This is probably one of the most convincing pieces of evidence of a delta in an unconfined region – and a delta points to the existence of a large body of water in the northern hemisphere of Mars.”  Co-author of the study, Mike lamb said, “scientists have long hypothesized that the northern lowlands of Mars are a dried-up ocean bottom, but no one yet has found the smoking gun.”  The Curiosity Rover has found evidence of water covering the surface, including rocks smoothed by water.  On earth, rivers and streams spread out as they empty into lakes and oceans. The same appears to have been the case on the now dry surface of Mars.  “In our work and that of others, including the Curiosity rover, scientists are finding a rich sedimentary record on Mars that is revealing its past environments, which include rain, flowing water, rivers, deltas, and potentially oceans,” Lamb revealed to the media. “Both the ancient environments on Mars and the planet’s sedimentary archive of these environments are turning out to be surprisingly Earth-like.”  While scientists admit this in not 100% conclusive of an ocean on Mars, the mounting evidence appears to be pointing in that direction.