Water on Mars - page 3

Roving 'Round the Berry Bowl

In 2004, Mars Rover Opportunity stumbled on an interesting find as it roamed around the Meridiani Planum region: clusters of marble-sized spheres embedded in outcrop rocks. Steve Squyres, principal investigator for the Mars Exploration Rover Mission, commented that the spheres "looked like blueberries in a muffin," and the name stuck.

This image, taken by the Mars Exploration Rover Opportunity's panoramic camera, is an approximate true-color rendering of the "Berry Bowl," a rock in the "Eagle Crater" outcrop that contains pebble-like hematite spherules. (Image credit: Mars Exploration Rover Mission, JPL, NASA)

The "blueberries" - which are actually more gray than blue - lie scattered throughout an outcrop area named "Berry Bowl" not far from Opportunity's landing site. Analysis by Opportunity's Mossbauer Spectrometer showed that the "blueberries" contain the iron-bearing mineral hematite. On Earth, hematite often forms in a wet environment, and deposits of gray hematite are found in areas where there has been standing water or hot springs, such as in Yellowstone National Park.

Interestingly, the Martian blueberries have a counterpart on Earth. Even before the hematite spheres were discovered on Mars, geologists studied similar features in the redrock canyon regions of southern Utah, where minerals precipitated from groundwater seeping through Navajo Sandstone millions of years ago. If the Martian blueberries formed in a similar manner, then the vast plains of Meridiani Planum may indeed have a wet history.

Hematite Utah
Marble-like hematite concretions, very similar to the "blueberries" photographed on Mars, litter the Navajo Sandstone surface in southern Utah's Grand Staircase-Escalante National Monument. (Image credit: Brenda Beitler Bowen)

Flash Floods on Mars?

On Earth, a powerful thunderstorm can dump large amounts of water into a dry stream bed in a relatively short time period. These sudden, localized floods occur most often in dry, desert areas, such as the southwestern United States. The sun-parched ground is unable to absorb such a large volume of rain, so the water runs rapidly over the land surface, producing a localized flood event called a flash flood. A flash flood can turn an otherwise dry stream channel into a rapidly moving wall of turbulent water that can carry away most everything in its path, including vehicles and even entire houses.

Fremont Flood
In summer 2003, a flash flood on the Fremont River roared through Utah's Capitol Reef National Park, flooding the park's main road and stranding visitors for several hours. (Image credit: Laurie J. Schmidt)

Some scientists believe that flash floods may periodically occur on Mars. Imagery from the Mars Orbiter Camera shows the presence of gullies and stream channels on the Martian surface - features that are similar to those left by flash floods in Earth's desert regions. One hypothesis for the existence of these features is that during Mars' early history, asteroid impacts may have triggered brief periods of warmer, wetter climate. Large impacts could have melted ice beneath the Martian surface and thrown water vapor into the atmosphere, which, in turn, would have fallen to the ground as rain. The resulting torrential downpours would have produced rivers and flooding and may have carved out the channels, valleys, and gullies we now see on the surface of Mars.

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