MRO CRISM - MSL Landing Site Selection

This web site contains links to CRISM browse products, pre-PDS release data products, reference information, and resources related to CRISM data acquisition and analysis in support of MSL landing site selection.

(1) MRO Support of MSL Landing Site Selection:

The MRO project and the CRISM, HiRISE, and CTX science and operations teams support the MSL landing site selection process through the acquisition of high resolution panchromatic, multispectral, and hyperspectral orbital remote sensing data. The first MSL landing site selection workshop was held in May, 2006. At that workshop 30+ candidate landing sites were proposed by the Mars science community. Since then, more sites have been proposed based on new findings from CRISM, OMEGA, and TES, bringing the grand total of proposed landing sites to 46. Between the start of the MRO Primary Science Phase (November, 2006) and the second MSL landing site selection workshop (October, 2007), MRO has surveyed each of the initial candidate sites (and most of the ones suggested later) with nested high spatial resolution CRISM, HiRISE, and CTX observations centered at sites' coordinates.

(2) An Overview of CRISM Observations of the Candidate MSL Landing Sites:

The characteristics of the standard CRISM data acquisition modes and resulting data products are listed in the table below. The MSL candidate landing site survey campaign has resulted in the acquisition of at least one high quality Full Resolution Targeted (FRT) observation for each of the initial candidate sites. Many of the candidate sites are of great scientific interest irrespective of the MSL landing site selection process. As a result additional CRISM hyperspectral coverage is clustered around those sites with previously known mineralogical diversity.

CRISM also acquires multispectral survey (MSP) data of the candidate landing sites as a natural consequence of the ongoing global mapping (multispectral survey) campaign.

(3) An Overview of CRISM Browse Images of Candidate MSL Landing Sites:

This early release of special products that will be archived to the Planetary Data System consists of map-projected versions of CRISM images. The many spectral channels in CRISM data have been condensed to 7 thematic color images that show spectral variations related to the types of minerals present. The seven versions of the data show:

• Enhanced visible color
• Indicators of oxidized iron (ferric) minerals formed when water interacted with crustal rocks
• Infrared surface brightness, or albedo
• Indicators of iron- and magnesium- containing igneous minerals formed by volcanic processes
• Indicators of hydrated (water-containing) minerals, typically though not always sulfates, formed when water interacted with crustal rocks
• Indicators of clay-like (phyllosilicate) minerals formed when water interacted with crustal rocks
• Indicators of water or carbon dioxide ice on the surface or in the atmosphere over each site

There are two types of CRISM browse products:

1. 3x3 degree maps derived from low spatial resolution CRISM multispectral mapping data. Each set of browse product maps is centered on a candidate landing site and overlain on THEMIS daytime IR data
   
   
2. Map-projected high resolution browse products derived from CRISM hyperspectral targeted data.

The browse products are organized by candidate landing site. For each site there is the multispectral context map and one or more targeted observations designated by a product ID. For example, one of the targeted observations for the Aeolis Fan Delta site is FRT000064CE. "FRT" specifies the type of observations from the table above, and "000064CE" is the unique hexidecimal identifier or target ID associated with a target.

The targeted and  multispectral map browse products for each site can be accessed by clicking on the site name or the site location in the table below. The targeted observation browse products are arranged in a matrix where each column is a different CRISM observation and each row is a different browse version of the image.

Map Projection Standards for the Browse Products

Multispectral Mapping Browse Products: The multispectral browse product context maps span 3x3 degrees in planetary central angle. Each map is in an equirectangular projection at 256 pixels per degree, referenced to the nearest equator-ward 5 degree increment in latitude. For example, the center latitude of projection for a site at 2 degrees north is 0 degrees; the center latitude of projection for a site at 7 degrees north is 5 degrees north. At the center latitude of projection, 1 pixel corresponds to 231.53 meters.

Targeted Observation Browse Products: All of the images are in simple cylindrical projection at 3072 pixels per degree, with the center latitude of the projection at the equator. 3072 pixels per degree was chosen because it approximates the native resolution of CRISM data, and is at the same time a whole multiple of 256 pixels per degrees (the scale of most Mars global data products). At the equator, 1 pixel in a map-projected targeted browse product is 19.294 meters.

There are three versions of each browse image:

*.png files
*.ll.png files, which have a latitude/longitude grid
*.tif files, GeoTIFF files

In addition, the locations of the CRISM images are provided in *.lbl text files. These indicate the location of the corners of the no-grid CRISM images (*.png) in E longitude and latitude, the resolution of the pixel at the center of the image, and the projection (cylindrical) used to generate these products.

Visible and Near-infrared (VNIR) Browse Products

Information in CRISM's 107 VNIR wavelengths (at 0.36-1.05 microns) is represented as two browse products.

The first is a false color red-green-blue (file name: vnir_rgb) image that has been optimally stretched to the dynamic range of all the CRISM data obtained at all the MSL landing site. These data were corrected for photometeric effects, that is, differences in local solar time and the angle of sunlight to the surface. This correction was performed by dividing the brightness of Mars' surface at each wavelength ("I/F") by cosine of the solar incidence angle (angle of sunlight to local vertical).

The second false color image (file name: vnir_fem) provides information related to iron minerals. This is derived from spectral data that have been corrected for photometric effects. The parameter data have also been 'flattened' (a complex median filtering process) to reduce the effect of detector noise.

*See Data Product SIS for detailed formulas.

Infrared (IR) Browse Products

Information in CRISM's 438 IR wavelengths (at 1.00-3.92 microns) is represented as five browse products.

The first IR browse product (file name: ir_ira) shows I/F at 1330 nm. It provides a good representation of IR albedo. It has been corrected for photometric effects.

The second IR browse product (file name: ir_maf) shows information related to mafic mineralogy, that is, the mineralogy of unaltered igneous minerals such as olivine and pyroxene. It is derived from data corrected for photometric effects, and for effects of atmospheric gases. (This was done by dividing the spectrum of each pixel by a scaled spectrum of the atmosphere, derived from comparing the summit and base of Olympus Mons.) The parameter data have also been 'flattened'.

*See Data Product SIS for detailed formulas.

The third IR browse product (file name: ir_phy) shows information related to hydroxylated minerals including phyllosilicates. It is also derived from the data corrected for atmospheric and photometric effects, and has been flattened.

*See Data Product SIS for detailed formulas.

The fourth IR browse product (file name: ir_hyd) shows information related to bound water in minerals, usually sulfates but in some cases phyllosilicates, hydrated glass, or possibly zeolite. It is also derived from spectral data corrected for atmospheric and photometric effects, and has been flattened.

*See Data Product SIS for detailed formulas.

The fifth and final IR browse product (file name: ir_ice) shows information related to water or carbon dioxide frost or ice. It too is derived from data corrected for atmospheric and photometric effects, and has been flattened.

*See Data Product SIS for detailed formulas.

Interpreting the Browse Products

CRISM browse products are intended for data visualization and not detailed quantitative analysis. However, every effort was made in the construction of the browse products to preserve useful information and the dynamic range of the original calibrated data. In addition, the mapping information specified on this page and in the table below is sufficient to register the brose images with other data sets. Typically registration errors are about 200 m or less.

Compositional information on the surface is concentrated in four of the browse products (vnir_fem, ir_maf, ir_phy, and ir_hyd). Not all of the sites exhibit spectral evidence for mineralogical diversity. If a location is covered in dust, it appears red in vnir_fem and bland in the other products. Sites with diversity in igneous mineralogy will appear interesting in ir_maf. Sites with minerals formed by interaction of crustal rocks with liquid water will appear interesting in ir_phy and ir_hyd.

None of the sites is expected to have permanent water ice on the surface. Location that had water ice clouds at the time of observation will appear slightly blue-green in ir_ice.

(4) Links to CRISM Browse Images of Candidate MSL Landing Sites

Click on the name of a site below to see CRISM images covering it or located nearby to view the high resolution browse images.

Click on location to view the context images for that site.

(5) Archive of pre-PDS Release CRISM Standard Data Products for Candidate MSL Landing Sites:

To facilitate the systematic evaluation of the MSL candidate landing sites, the CRISM team is providing the community pre-PDS release calibrated data (TRDR data products) and backplanes with geometric and photometric information (DDR data products) for observations within a 3x3 degree (178-km) box surrounding each MSL candidate landing site.

The CRISM Targeted Reduced Data Record (TRDR) products provided here have been processed with the latest version of the CRISM calibration pipeline and supercede all prior versions, including those delivered to the PDS through September 2007.

Researchers unfamiliar with CRISM data products are encouraged to check out the CRISM Data Product Software Interface Specification.

Reference Documents:

CRISM Targeted Reduced Data Record (TRDR) and Derived Data Record (DDR) PDS Catalog Files:

• TRDR PDS Catalog
• DDR PDS Catalog

CRISM Calibration Data Records (CDRs):

Selected calibration files (CDRs) can be used to retrieve the wavelength of each CRISM channel and to correct the data for atmospheric gas absorptions. A brief description of the contents of each CDR directory can be found here.

• Atmospheric Transmission Model CDRs
• Detector Wavelength Array CDRs
• Standard Wavelength CDRs

(6) Additional Resources:

MSL Landing Site Selection Committee Contacts:

CRISM MSL Landing Site Selection Contacts: