Mars Was Once All Wet Date: 11.29.2001 This is a composite image illustrating what Mars would look like today if it still had the massive amount of water researchers believe was present at its formation. If the primordial Martian ocean still existed, it would cover large areas of the planet, represented by the blue regions.
Although Mars is now very dry, scientists observing the Martian atmosphere with NASA's Far Ultraviolet Spectroscopic Explorer (FUSE) spacecraft, combined with other research, estimate that Mars could have been born with more water in proportion to its mass than the Earth. If the initial quantity of water on Mars could have been evenly distributed across the planet somehow, it would have been equivalent to a global Martian ocean at least three-quarters of a mile (1.25 kilometers) deep. This is 1.3 times more water per mass than the Earth.
The image was made by taking the estimated ancient Martian water supply and calculating how extensive the coverage would be if it were in the form of an ocean that could flood the low-lying regions on Mars today. An elevation map of the Martian landscape was created from a topographic survey by NASAs Mars Global Surveyor (MGS) spacecraft, and a computer artist filled in the ancient Martian ocean. Note that the ocean covers much of the northern hemisphere of Mars, which is a vast basin according to the MGS survey.
