Curiosity finds similarities between soil of Mars and soil of Hawaii

The first X-ray view of Martian soil, taken by the Chemistry and Mineralogy (CheMin) instrument on Curiosity. The mineralogy is similar to volcanic soil in Hawaii. Credit: NASA / JPL-Caltech / Ames

When one thinks about Mars, probably the last thing that comes to mind is a tropical paradise. Mars is just the opposite – cold, dry and barren. But as the saying goes, “the devil is in the details.” It turns out that in some ways, Mars actually does have some things in common with the warm, sandy climes of Earth, according to new results released yesterday in a Curiosity rover press briefing.

Curiosity just finished its first X-ray examination of the Martian soil at its landing site (and the first such test done by any planetary mission), and found that its mineralogical composition is very similar to the volcanic soils of Hawaii. The analysis was done by the Chemistry and Mineralogy (CheMin) instrument on the rover.

CheMin is a smaller version of the very same laboratory instruments on Earth, which use X-ray diffraction to identify minerals with a high degree of precision.

The soil sample revealed the presence of crystalline feldspar, pyroxenes and olivine mixed with amorphous (non-crystalline) material.

According to David Blake, principal investigator for CheMin, “We had many previous inferences and discussions about the mineralogy of Martian soil. Our quantitative results provide refined and in some cases new identifications of the minerals in this first X-ray diffraction analysis on Mars.”

The results help to understand the origin of the fine-grained soil and dust that covers much of Mars’ surface due to wind. This material is younger than the conglomerate rocks also being studied by Curiosity. The dust is spread globally by dust storms, while the sandy soil tends to form locally.

Comparison of these rocks and the dust provides a look at how the older, wetter Mars transformed into the cold, dry planet we see today. The rocks formed during a time when liquid water was present, but the younger dust and soil has had little if any interaction with water.

As noted by CheMin co-investigator David Bish, “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. The ancient rocks, such as the conglomerates, suggest flowing water, while the minerals in the younger soil are consistent with limited interaction with water.”

Later, Curiosity will use CheMin to examine the material in the layered sedimentary deposits of the nearby foothills of Mount Sharp, a primary target for study, which may be related to other water-formed features in the area such as the old streambeds and associated alluvial fans.

“Our team is elated with these first results from our instrument,” said Blake. “They heighten our anticipation for future CheMin analyses in the months and miles ahead for Curiosity.”

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