PIA05469: Salty Martian Rock
Target Name: Mars
Is a satellite of: Sol (our sun)
Mission: Mars Exploration Rover (MER)
Spacecraft: Opportunity
Instrument: Alpha Particle X-ray Spectrometer
Rock Abrasion Tool (RAT)
Product Size: 1920 x 1080 pixels (width x height)
Produced By: JPL
Full-Res TIFF: PIA05469.tif (597 kB)
Full-Res JPEG: PIA05469.jpg (161.6 kB)

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Original Caption Released with Image:
These plots, or spectra, show that a rock dubbed "McKittrick" near the Mars Exploration Rover Opportunity's landing site at Meridiani Planum, Mars, has higher concentrations of sulfur and bromine than a nearby patch of soil nicknamed "Tarmac." These data were taken by Opportunity's alpha particle X-ray spectrometer, which produces a spectrum, or fingerprint, of chemicals in martian rocks and soil. The instrument contains a radioisotope, curium-244, that bombards a designated area with alpha particles and X-rays, causing a cascade of reflective fluorescent X-rays. The energies of these fluorescent X-rays are unique to each atom in the periodic table, allowing scientists to determine a target's chemical composition.

Both "Tarmac" and "McKittrick" are located within the small crater where Opportunity landed. The full spectra are expressed as X-ray intensity (logarithmic scale) versus energy. When comparing two spectra, the relative intensities at a given energy are proportional to the elemental concentrations, however these proportionality factors can be complex. To be precise, scientists extensively calibrate the instrument using well-analyzed geochemical standards.

Both the alpha particle X-ray spectrometer and the rock abrasion tool are located on the rover's instrument deployment device, or arm.

Image Credit:
NASA/JPL/Cornell/Max Planck Institute

Image Addition Date:
2004-03-02