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Evidence for an Ancient Martian Ocean

13 Jul 2020, 16:00 UTC
Evidence for an Ancient Martian Ocean
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Was Mars once partially covered in ancient seas? A recent study has found new evidence to support the Mars ocean hypothesis.
Signs Point to Seas
A map of Mars’s topography created by the Mars Orbiter Laser Altimeter shows two distinct southern and northern hemispheres. Click to enlarge. [NASA/JPL/GSFC/MOLA. Map by Emily Lakdawalla]The debate about large bodies of water on Mars has raged for decades.
The discovery of the Martian dichotomy — a ~30 km difference in height between the lower, smooth northern hemisphere and higher, heavily cratered southern hemisphere — was an early indication that the northern hemisphere may once have been underwater.
Long, unbroken features identified as potential ancient shorelines were spotted on Mars as early as the 1970s by the Viking orbiters, further supporting a picture of vast past oceans.
And dozens of further clues have piled up: signs of stream channels and river deltas, indications of past rainfall, hints of historical tsunamis from asteroid impacts, atmospheric signatures that point to a past abundant water supply — the list goes on.
In this proposed map of an ancient ocean on Mars, underwater regions are indicated in white, and the above- and below-water regions are separated by a proposed ...

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