MRO CRISM Along Track Oversampled Observation Log Maximum Likelihood Processed S Data

CRISM (Compact Reconnaissance Imaging Spectrometer) derived product types

Instrument: MRO Compact Reconnaissance Imaging Spectrometer for Mars

PDS4 Bundle: urn:nasa:pds:crism_ato_s_iof_lmlDOI: 10.17189/9nmk-g896

The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) is one of the instruments on board the NASA Mars Reconnaissance Orbiter (MRO) that began operations in 2006 (Murchie et al., 2007). CRISM consists of a pair of push-broom hyperspectral imaging spectrometers operating from 0.362 to 3.92 μm, with a 6.55 nm spectral spacing. The columns of the detectors correspond to columns in CRISM sensor space hyperspectral image cubes. Each image band in the sensor space cubes corresponds to data for a particular wavelength. The S spectrometer operates from 0.362 to 1.02 μm, and the L spectrometer from 1.02 to 3.92 μm. CRISM can operate in various modes, as defined in Murchie et al., (2007), and in the CRISM Software Interface Specification (SIS) Document (Murchie, Guinness, Slavney, 2022). The instrument can also be adjusted in an along track direction to provide nadir-looking views of the surface or a set of observations at varying emergence angles to probe atmospheric and surface scattering and absorption characteristics. Beginning in 2011, a new observing mode was implemented that provided overlapping coverage of the same areas on Mars, producing along track oversampled (ATO) observations. CRISM ATO Observations for S data hyperspectral image cubes are processed using a log maximum likelihood (LML) approach to retrieve the best estimate of I/F (spectral radiance on sensor divided by solar spectral radiance at the observation time) in the presence of Poisson noise. The LML processing also generated map-projected I/F spectral cubes at 12 m/pixel, taking advantage of the data overlap associated with the along-track oversampling, i.e., the overlap allowed a form of “super resolution” processing.

This ATO bundle contains several collections, one for each type of ATO basic product, along with browse, document, and miscellaneous collections. ATO basic products are stored in physical folders based on individual ATO scenes. There is one folder for each ATO scene. Each ATO basic product has three parts: the PDS4 XML label, the ATO image file, and an ENVI (Environment for Visualizing Images) header file. For the ATO archive, the image products include both sensor-space and map-projected versions of the I/F cubes. Each image type is briefly described in below table with the sensor space and map projection type descriptions combined. Map-projected products are indicated by the letter “p” in the product code. The codes of products whose creation involved applying LML processing contain “lml,” as opposed to “nlml” for those whose creation did not. Those containing spectral summary parameters contain “_param.” For more information about CRISM ATO S data products, see the User’s Guide.

Example Listing of Archive Basic Products

Product Code	Product_Type in ODE	Description	PDS4 Collection (The link is to the collection inventory data file.)
nlml	NLML	ATO S data sensor space product without log maximum likelihood (LML) processing	urn:nasa:pds:crism_ato_s_iof_lml:data_nlml
nlmlp	NLMLP	ATO S data map-projected version of the nlml sensor space product	urn:nasa:pds:crism_ato_s_iof_lml:data_nlmlp
lml	LML	ATO S data sensor space LML noise-abated product.	urn:nasa:pds:crism_ato_s_iof_lml:data_lml
lmlp	LMLP	ATO S data LML regularized and noise-abated map projected product	urn:nasa:pds:crism_ato_s_iof_lml:data_lmlp
lml_param	LMLPAR	ATO S data LML regularized and noise-abated spectral parameter product	urn:nasa:pds:crism_ato_s_iof_lml:data_lml_param
lmlp_param	LMLPPAR	ATO S data LML regularized and noise-abated map-projected spectral parameter product	urn:nasa:pds:crism_ato_s_iof_lml:data_lmlp_param

More information can be found in:

The User’s Guide.for the MRO CRISM ATO observation log maximum likelihood processed s data products
Murchie, S., Arvidson, R., Bedini, P., Beisser, K., Bibring, J. P., Bishop, J., Wolff, M. (2007). Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on Mars Reconnaissance Orbiter (MRO). Journal of Geophysical Research E: Planets, 112(5), 1–57. https://doi.org/10.1029/2006JE002682.
Murchie, S. L., Guinness, E., Slavney, S. (2022). CRISM Data Product Software Interface Specification, Version 1.3.7.6, 288 p. Planetary Data System Standards Reference, JPL D-7669, Part 2, V 1.18.0.0, 2022.