Water Flowed on Mars

Welcome to Intricate Osuga Valles

The search for water on Mars keeps turning up evidence that something wet once flowed across its surface. Images like this one from the Mars Express orbiter show streamlined islands and narrow gorges that were carved out by fast-moving water sometime in the distant past. This one shows a region near the Vallis Marineris canyon complex that splits the mid-section of the planet. Captured on December 7th, 2013 by the Mars Express cameras, this view is of the Osuga Valles region. It’s an outflow channel that emanates from a region of what planetary scientists call chaotic terrain (that is, chaotic landscapes disrupted in some way).

Flow features on Mars
A perspective view of Osuga Valles on Mars, showing braided river valleys that once carried water across the surface. Courtesy ESA/Mars Express.

The search for water on Mars keeps turning up evidence that water once flowed across its surface. Images like this one from the Mars Express orbiter show streamlined islands and narrow gorges that were carved out by fast-moving water sometime in the distant past. This one shows a region near the Vallis Marineris canyon complex that splits the mid-section of the planet. Captured on December 7th, 2013 by the Mars Express cameras, this view is of the Osuga Valles region. It’s an outflow channel that emanates from a region of what planetary scientists call chaotic terrain (that is, chaotic landscapes disrupted in some way).

So, what caused this scene? The most likely explanation is an episode of chaotic flooding (extremely heavy flash flooding) that sent water and rocks and mud rushing across the landscape and carving out these channels and gullies. The geologic evidence here suggests that there were likely several bouts of flooding, creating these grooved valley floors and islands.

The floodwaters rushed along, emptying into a deep depression of chaotic terrain. Planetary scientists not only want to know what caused these episodes of flooding, but where the water went. Did it flow underground? Pond in a lake for awhile? If so, what happened to it after that?

There’s so much we don’t know yet about the ‘lifetime’ of water on Mars. One hypothesis is that much of the Mars water inventory escaped to space. That’s a possibility that the Mars Maven mission is going to study once it arrives at the Red Planet later this year. If that did happen, then there should be some evidence in the atmosphere that tells scientists about how much water may have escaped. It’s very likely that some water did rush underground, and could exist as subsurface permafrost or in deep aquifers underground.

Think about that as you look at Mars in the late evening skies this month. It’s an easy one to spot in the east, not far from the bright star Spica, in the constellation Virgo. Mars is at its closest to us right now and is a bright, lovely sight in the evening sky. Check it out!

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