A fascinating thing to come from NASA's Mars Science Laboratory mission since it landed inside Gale Crater on Aug. 5 is how familiar this region of Mars looks. The mountains look like they belong in Arizona and the surrounding plain appears to have once been a flowing river.
And now, mission managers have announced that even the mineralogy of soil samples bare a striking resemblance to the volcanic soil you'd find in one particular location on Earth.
Over the past few weeks, Curiosity has been scooping samples of soil from a sandy patch in a location known as "Rocknest." The rover's scooper - called the Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) - has been undergoing the long process of giving itself a Martian ‘dust bath' (collecting a sample, shaking and then dumping the soil to remove any Earthly contaminants) and most recently deposited a small sample into one of its on board laboratories.
The Chemistry and Mineralogy (CheMin) instrument was then used to carry out X-ray diffraction on the sample. This was the first time X-ray diffraction has ever been done on another planet.
The technique works by firing a beam of X-rays through a sample that has been previously sieved to remove any large lumps. The largest grain allowed into the CheMin instrument is no bigger than twice the width of a human hair - 150 micrometres.
As the X-rays blast through the grains of Mars soil, they are scattered, or diffracted, at varying angles depending on the minerals present. The technique can also detect the alignment of atoms inside the particles, giving scientists an idea as to whether crystalline structures present.
"We had many previous inferences and discussions about the mineralogy of Martian soil," said David Blake of NASA Ames Research Center in Moffett Field, Calif., the principal investigator for CheMin, during Tuesday's press briefing. "Our quantitative results provide refined and in some cases new identifications of the minerals in this first X-ray diffraction analysis on Mars."
In the diffraction "fingerprint" from the X-ray analysis (shown top), the scientists detected feldspar, olivine and pyroxene - all of which are basaltic minerals that originate from volcanic activity. These types of minerals are typically found on the Hawaiian islands.
"So far, the materials Curiosity has analyzed are consistent with our initial ideas of the deposits in Gale Crater, recording a transition through time from a wet to dry environment," added David Bish of Indiana University in Bloomington, co-investigator on the CheMin experiment. "The ancient rocks, such as the conglomerates, suggest flowing water, while the minerals in the younger soil are consistent with limited interaction with water."
Indeed, MSL scientists know that Curiosity has landed in an ancient dry riverbed, providing us with a huge advantage in the pursuit of understanding the wet past of Mars and its potential for harboring habitats suitable for (past or present) microbial life.
Curiosity will now drop a sample of soil into another instrument - the Sample Analysis at Mars (SAM) instrument - to assess whether the dust and sand at Rocknest contain organic carbon-based compounds that may reveal the planet's potential for supplying the building blocks of life.
Source: JPL News
Image: The first analysis of X-ray diffraction on Martian soil by the Chemistry and Mineralogy (CheMin) experiment. The soil sample, taken from a wind-blown deposit within Gale Crater, where the rover landed, is similar to volcanic soils in Hawaii. Credit: NASA/JPL-Caltech/Ames