Looking for Salts on Mars
Looking for Salts on Mars
ESP_034309_1485  Science Theme: Composition and Photometry
Why are scientists interested in areas that contain salts on Mars? Simply put, salts usually form by evaporation of liquid water. Most salts can easily dissolve in water, and if that water evaporates away completely, the salt is left behind as a deposit or residue. The larger the amount of salts initially dissolved, the larger the salt deposit left behind when the water evaporates. So when scientists look for regions on Mars that have noticeable salt deposits, they are effectively looking for areas that may have contained liquid water in the past.

A few years ago, a group of scientists found more than 600 locations on Mars that may contain chloride salts, which could be very similar to common table salt. Since then, scientists have been using the HiRISE camera to look at these locations more closely and they have found out that many of these locations are very similar to dried lakes on Earth, which are sometimes called “playas” or “salt pans.” Many such playas can be visited in California and Arizona such as the Racetrack playa and the Death Valley National Park.

In this image, the chlorides have a bright appearance and are covered by other dark materials. Interestingly, the bright deposits also display cracks that form polygonal patterns very similar to common mud cracks, which may be another indication that these deposits formed when salty waters evaporated away. Studying these regions in detail can help scientists understand when and how the weather conditions on Mars may have changed.

Written by: Ramy El-Maarry  (15 January 2014)
Acquisition date
20 November 2013

Local Mars time

Latitude (centered)

Longitude (East)

Spacecraft altitude
253.5 km (157.5 miles)

Original image scale range
50.7 cm/pixel (with 2 x 2 binning) so objects ~152 cm across are resolved

Map projected scale
50 cm/pixel and North is up

Map projection

Emission angle

Phase angle

Solar incidence angle
67°, with the Sun about 23° above the horizon

Solar longitude
52.2°, Northern Spring

For non-map projected images
North azimuth:  97°
Sub-solar azimuth:  48.8°
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Black and white
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non-map           (91MB)

IRB color
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Merged IRB
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Merged RGB
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RGB color
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B&W label
Color label
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EDR products

IRB: infrared-red-blue
RGB: red-green-blue
About color products (PDF)

Black & white is 5 km across; enhanced color about 1 km
For scale, use JPEG/JP2 black & white map-projected images

All of the images produced by HiRISE and accessible on this site are within the public domain: there are no restrictions on their usage by anyone in the public, including news or science organizations. We do ask for a credit line where possible:
NASA/JPL/University of Arizona

NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Mars Reconnaissance Orbiter for NASA’s Science Mission Directorate, Washington. The HiRISE camera was built by Ball Aerospace and Technology Corporation and is operated by the University of Arizona.