Archiving the MSL Curiosity Rover Mastcam Multispectral Reflectance Data Set

Project: Research project

Description

The Mars Science Laboratory Curiosity rover carries a dual camera multispectral imaging system called Mastcam that has been imaging the Martian surface and atmosphere in 12 unique spectral bandpasses (including broadband RGB) between 400-1100 nm since the rover landed in Gale crater in August, 2012. The high spatial resolution color and multispectral imaging capabilities of Mastcam provide an important operational resource used tactically to help choose specific drive paths and regions for more detailed in situ analyses and/or drilling. Mastcam multispectral data also enable a limited tactical assessment of the composition and/or mineralogy of the landing site and traverse for scientific assessment purposes. Examples include the assessment of the dust cover of rock surfaces, detection of weak hydration features in mineral-filled veins, and the assessment of the crystallinity of ferric oxide phases like hematite.

Mastcam images are presently only being archived to the PDS as calibrated radiance-on-sensor, simply scaled to an estimate of radiance factor or I/F (where I is the measured radiance, and pi*F is equal to the estimated solar irradiance at the top of the Martian atmosphere at the time of the observation), without using any information from the onboard Mastcam calibration target. In principle, the archived I/F data can be used to compare 12-color Mastcam "spectra" to laboratory reflectance spectra of rocks and minerals, for the purposes of detecting specific phases and/or attempting to model their relative abundances. However, in reality, the PDS archived Mastcam data do not correct for the significant and time-variable spectral influence of the dusty Martian atmosphere on the derived colors of the surface, nor are they calibrated to radiance using calibration target images or the latest pre-flight and in-flight calibration data sets (e.g., flatfields, radiance coefficients). The result is that users who attempt to create their own reflectance spectra from archived Mastcam radiance data sets end up with spectra that deviate substantially from previous telescopic, orbital, lander, and rover multispectral measurements of Mars. The Mastcam PI and team have no plans to archive higher-fidelity Mastcam I/F data sets.

Thus, we propose to create and archive in the PDS an accurate set of Mastcam images calibrated to I/F for use in laboratory comparisons and spectral abundance/mixture modeling studies. Our primary goal is to produce and validate data calibrated to an absolute reflectance accuracy of <10%, and a relative band-to-band precision of <2%. A critical part of our approach and methodology will be to use the onboard Mastcam calibration target as a reference. Past experience with MER and MPF images calibrated using similar onboard calibration targets shows that relative calibration via the target corrects for most of the spectral influence of the Martian atmosphere and generates spectra that can be directly compared to laboratory and theoretical reflectance modeling results.

Our work is relevant to the objectives of the PDART program as a Data Product Generation program that would generate and archive higher-order, properly-validated data products than those that currently exist within the PDS. Source data would be the existing raw Mastcam EDRs archived in the PDS, and outputs would be robustly calibrated and validated RDRs that provide accurate estimates of radiance factor and approximate Lambert albedo in each Mastcam filter.

Our team has substantial experience with the previous creation and archiving of I/F data sets from MPF and MER, and with the modeling work needed to properly calibrate the Mastcam data sets. We have also been actively involved in the acquisition of the Mastcam images and their tactical calibration, and so are intimately familiar with the starting data set for this project. We have discussed the project with the Geosciences Node and they have agreed to archive the data set.

StatusActive
Effective start/end date5/16/175/15/20

Funding

  • NASA: Goddard Space Flight Center: $465,775.00

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radiance
reflectance
calibration
Martian atmosphere
Mars
flight
modeling
mineral
crystallinity
hydration
rock
hematite
crater
irradiance
albedo
relative abundance
mineralogy
spatial resolution
drilling
oxide