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Rock on Mars may have been formed 'like applejack liquor'

October 11, 2012|By Jon Bardin
  • The rock dubbed "Jake Matijevic," above, is under study by the Mars rover Curiosity. The red dots show where the ChemCam laser took readings, and the purple circles show where the spectrometer APSX trained its view.
The rock dubbed "Jake Matijevic," above, is under study by the… (NASA/JPL-Caltech/MSSS )

NASA researchers revealed surprising details from the preliminary analysis of a rock on the surface of Mars: The rock has both an unexpected mineral content and a potentially strange geological history. The results were discussed during a press conference on Thursday.

The rock was named "Jake Matijevic" by the researchers, after a former chief engineer on the Curiosity rover project who died in August.

The results came from two different tools onboard the rover: The ChemCam, which uses a laser to probe the chemical content of a sample from a distance, and APXS, a spectrometer that also can be used to understand the elemental chemistry of rocks.

The rock, referred to by the scientists as "Jake" for short, is an igneous rock shaped like a pyramid. Within Jake, ChemCam discovered an array of different mineral signatures in different locations, suggesting a diverse chemical makeup. Some parts of the rock were high in iron and titanium, while others were high in silicon, aluminum, sodium and potassium. APXS confirmed the results.

The makeup of the rock is surprising because rocks analyzed in past rover missions had different compositions, with less sodium and potassium than early Curiosity samples have shown. This suggests the area the rover is in is quite geologically different than the regions studied in the past.

Perhaps most compelling about Jake is the way it may have formed. Edward Stolper, a geologist on the team from Caltech, says that when he tried to match the makeup of Jake to his database of "tens of thousands of igneous rocks from Earth," the closest match was an unusual but well-known type of rock that forms on oceanic islands like Hawaii.

The way those rocks formed may provide clues to how Jake formed. Stolper says the rock variety on Earth forms "much like applejack liquor." The liquor was made in colonial times by putting the raw booze in a barrel, and placing it out in the cold. The water in the applejack would rise to the top and freeze, crystallizing into ice. This could be removed, and the process repeated, creating a more pure alcohol.

Similarly, Jake may have been formed when rock melted into magma, which generates a liquid that crystallizes out certain minerals -- perhaps leading to its strange mineral makeup.

Importantly, Stolper said that the process only occurs on Earth when the magma had a high percentage of water dissolved into it. If the same process were taking place on Mars, it might mean quite a bit of water was once in the area.

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