What does today's Mars announcement really mean?

Posted by David Eicher
on Monday, September 28, 2015

Dark, narrow streaks on martian slopes such as these at Hale Crater stretch the length of a football field and are believed to have been caused by flowing liquid water. // NASA/JPL-Caltech/Univ. of Arizona
Today, the astronomy world has been rocked by a major announcement on Mars and the existence of flowing water on the planet’s surface. What does this finding really mean?

It’s very significant, even if clues and signs for this kind of temporary surface water, high in salt content, have been around for a while. We now have clear evidence of summertime flows of briny water on the surface.

One of the great questions in planetary science centers on martian water. Lots of evidence exists that abundant water flowed on Mars in the ancient past. What transformed Mars from a wet planet to a dry one? No one yet knows. Most of the remaining water is locked up in ice, in the polar caps, below the planet‘s surface and all around the martian soil.

Spacecraft evidence points to lots of water as ice or liquid brines below the surface. But to find strong evidence for seasonal water flowing on the planet’s surface in the present day is amazing. The temperatures and pressures on current Mars suggest this would be awfully hard to do. And it’s the salty nature of the water that helps make it possible. The current flows of water appear when temperatures rise above –10° F (–23° C).

For many years, NASA and others in the space exploration game have “followed the water” in the quest for assessing the rarity of life in the universe. From what we now understand, water is necessary for life — or at least the kind of life we’re familiar with.

This is another major step in understanding that properties that make life on Earth possible are perhaps not quite as rare as we might have thought.

Could microbes exist in the salty martian water? Yes. But we will not likely know whether they exist now, or whether they ever did exist, until a sampling mission studies not only surface water, but also drills into the martian aquifers and carefully studies what they contain, other than H2O and a variety of salts.

Stay tuned.

Follow David J. Eicher on Twitter: www.twitter.com/deicherstar

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