Space

Earth-like Soil on Mars Reveals Red Planet was Possibly Warm and Wet in the Past

Catherine Griffin
First Posted: Jul 18, 2014 07:35 AM EDT

What was Mars like in the ancient past? That's a question that scientists continue to grapple with as NASA's Curiosity rover continues its trek across the Red Planet. Now, one scientist says that soil deep within a crater dating to some 3.7 billion years ago and imaged by the rover contains evidence that Mars was once much warmer and wetter.

The Martian landscape is littered with loose rocks from impacts or layered by catastrophic floods; this is in stark contrast to the smooth contours of the soils that soften landscapes on Earth. Yet recent images from Curiosity of Gale Crater reveal Earth-like soil profiles with cracked surfaces lined with sulfate and ellipsoidal hollows.

"The pictures were the first clue, but then all the data really nailed it," said Gregory Retallack, a geologist with the University of Oregon, in a news release. "The key to this discovery has been the superb chemical and mineral analytical capability of the Curiosity rover, which is an order of magnitude improvement over earlier generations of rovers. The new data show clear chemical weathering trends, and clay accumulation at the expense of the mineral olivine, as expected in soils on Earth. Phosphorus depletion within the profiles is especially tantalizing, because it attributed to microbial activity on Earth."

In fact, surface cracks in the deeply buried soils suggest typical soil clods. In addition, vesicular hollows, or rounded holes, and sulfate concentrations are both features of desert soils on Earth.

That's not to say that this proves that there was once life on Mars. Instead, it does reveal that the Red Planet was wetter and warmer than expected; this would technically make it more habitable. That said, more exploration will be needed before scientists can draw any firm conclusions.

The findings are published in the journal Geology.

See Now: NASA's Juno Spacecraft's Rendezvous With Jupiter's Mammoth Cyclone

More on SCIENCEwr