If it were possible to transport ourselves back in time about 3.5 billion years, Mars would look very different than it does now, and thanks to NASA’s Curiosity rover, we know that water did indeed exist at one time on the red planet, EarthSky reports:
“Curiosity scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, announced another new study about Mars water, published in the peer-reviewed journal Nature Geoscience. A statement about the new work painted a vivid picture of Mars, billions of years ago:
‘Imagine ponds dotting the floor of Gale Crater, the 100-mile-wide (150-kilometer-wide) ancient basin that Curiosity is exploring. Streams might have laced the crater’s walls, running toward its base. Watch history in fast forward, and you’d see these waterways overflow then dry up, a cycle that probably repeated itself numerous times over millions of years.’
“That is the landscape described by Curiosity scientists …”
A new paper from NASA which was published in the journal Nature Geoscience lays out a fascinating theory that the Gale Crater, which was likely formed as the result of a massive ancient impact, once contained small streams that formed a sort of oasis that featured shallow and salty pools of water:
“The deposits serve as a watermark created by climate fluctuations as the Martian environment transitioned from a wetter one to the freezing desert it is today.”
Or, as lead author William Rapin noted in a statement:
“We went to Gale Crater because it preserves this unique record of a changing Mars. Understanding when and how the planet’s climate started evolving is a piece of another puzzle: When and how long was Mars capable of supporting microbial life at the surface?”
Life at the microbial level is the building block needed before any advanced lifeforms can appear, as the Earth proves. We know that evolution began in the oceans and then progressed from there, meaning that the same could have been true on Mars at a time in the distant past.
Rapin and his co-authors also describe what they found thanks to Curiosity on a formation that has been dubbed Sutton Island:
“… the team already knew the area had intermittent drier periods. But the Sutton Island salts suggest the water also concentrated into brine.
“Typically, when a lake dries up entirely, it leaves piles of pure salt crystals behind. But the Sutton Island salts are different: For one thing, they’re mineral salts, not table salt. They’re also mixed with sediment, suggesting they crystallized in a wet environment – possibly just beneath evaporating shallow ponds filled with briny water.”
Sutton Island, Rapin added, can best be compared to saline lakes found in South America:
“Given that Earth and Mars were similar in their early days, Rapin speculated that Sutton Island might have resembled saline lakes on South America’s Altiplano [in west-central South America, the place where the Andes are widest]. Streams and rivers flowing from mountain ranges into this arid, high-altitude plateau lead to closed basins similar to Mars’ ancient Gale Crater. Lakes on the Altiplano are heavily influenced by climate in the same way as Gale.
“During drier periods, the Altiplano lakes become shallower, and some can dry out completely. The fact that they’re vegetation-free even makes them look a little like Mars.”
Curiosity’s latest data has also led Rapin’s team to realize that a cycle of wet-to-dry conditions has existed on Mars for billions of years. Project Scientist Ashwin Vasavada of JPL remarked:
“As we climb Mount Sharp, we see an overall trend from a wet landscape to a drier one. But that trend didn’t necessarily occur in a linear fashion. More likely, it was messy, including drier periods, like what we’re seeing at Sutton Island, followed by wetter periods…”
For now, we now know that billions of years ago there was briny water on the surface of Mars, and that means the conditions for life once existed. That alone makes Curiosity and the Mars mission a huge success.
Here’s more on Gale Crater and Mars:
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