curiosity soil
October 30, 2012

NASA Curiosity Rover Sends Back First Mars Soil Data

Lee Rannals for — Your Universe Online

NASA announced on Tuesday the first analysis of Martian soil by the Chemistry and Mineralogy (CheMin) experiment on NASA's Curiosity rover.

The soil sample taken during Curiosity's third scoop on October 15 revealed the presence of crystalline feldspar, pyroxenes and olivine mixed with some amorphous (non-crystalline) material.

NASA said that the soil sample taken within Gale Crater resembles what could be found in volcanic soils in Hawaii on Earth.

"Much of Mars is covered with dust, and we had an incomplete understanding of its mineralogy," David Bish, CheMin co-investigator with Indiana University in Bloomington, said in a press release. "We now know it is mineralogically similar to basaltic material, with significant amounts of feldspar, pyroxene and olivine, which was not unexpected. Roughly half the soil is non-crystalline material, such as volcanic glass or products from weathering of the glass."

Curiosity first delivered the soil sample to its ChemMin instrument for X-ray diffraction analysis on October 17 (Sol 71).

By directing an X-ray beam at a sample and recording how X-rays are scattered, the instrument was able to help identify and quantify minerals on Mars for the first time.

"Our team is elated with these first results from our instrument," David Blake, principal investigator for CheMin, said in the press release. "They heighten our anticipation for future CheMin analyses in the months and miles ahead for Curiosity."

NASA believes that the soil sample analyzed by the CheMin instrument is likely a blend of globally distributed dust and larger sand-sized particles derived from local sources.

The space agency said during a teleconference on Tuesday that it plans on keeping Curiosity at this Rocknest spot on Mars for another week or so.

Blake said that engineers had to shrink the size of Curiosity's CheMin instrument from the industry standard Refrigerator size, to a shoebox size. This instrument is a compact X-ray diffraction instrument that is about 10 inches on each side.

CheMin is equipped with a charged couple device (CCD), which detects both the position and energy of each X-ray photon. The technology in this CCD was originally developed by NASA and has become widely used in commercial digital cameras.

"Our quantitative results provide refined and in some cases new identifications of the minerals in this first X-ray diffraction analysis on Mars," Blake said in the release.

When soil is delivered to CheMin, it is funneled into one of the windowed areas in the cell assemblies. These cell pairs act like a tuning fork, vibrating at 2,000 times per second.

When particles are vibrated, they flow like liquid, and this movement enables the instrument's X-ray beams to hit all of the grains in random orientations over time.

Implementing the powder vibration system was a crucial step in enabling small portable X-ray diffraction instruments because many of the moving parts in conventional X-ray diffraction instruments could be eliminated.

"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," Bish said. "The ancient rocks, such as the conglomerates, suggest flowing water, while the minerals in the younger soil are consistent with limited interaction with water."

Scientists have used an X-ray diffraction instrument to examine the paintings on the west wall in the tomb of King Tutankhamen. The commercial instrument used in situations like this derived from technology developed for the CheMin.

NASA said once Curiosity departs Rocknest, it will continue its journey towards Glenelg.

Curiosity has been stationed at Rocknest for nearly a month now, and during its time there it was able to perform its first scoop of Martian soil.