Mars ocean theory

The Mars ocean theory states that nearly a third of the surface of Mars was covered by an ocean of liquid water early in the planet's geologic history. This ocean is called Paleo-Ocean or Oceanus Borealis ( ).  It  would have filled the basin Vastitas Borealis in the northern hemisphere. This region lies 4–5 km (2.5–3 miles) below the mean planetary elevation. It would have existed approximately 4.1–3.8 billion years ago. Evidence for this ocean includes geographic features resembling ancient shorelines, and the chemical properties of the Martian soil and atmosphere. Early Mars would have required a denser atmosphere and warmer climate to allow liquid water to remain at the surface.

 Other explanations 
Not all scientists agree that this ocean really existed. The Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (HiRISE) has discovered large boulders on the site of the ancient seabed, which should contain only fine sediment. The boulders could have been dropped by icebergs, a process common on Earth. The interpretations of some features as ancient shorelines has been challenged.

A study published in September 2021 compared potassium isotopes found in rocks from various bodies. The study  suggests that the surface gravity on Mars was too low to keep enough water to form a large ocean.

There are other explanations of how the surface gullies and channels were created include wind erosion, liquid carbon dioxide, and liquid methanol.

Confirmation or refutation of the Mars ocean hypothesis awaits additional observational evidence from future Mars missions.

 Related pages 



 Terraforming of Mars – Hypothetical modification of Mars that would include a large northern ocean

 References 

Category:Mars