Science Theme: Composition and Photometry 
Science theme lead: Matthew Chojnacki  
View images in this theme  
Composition and Photometry
One of the novel aspects of HiRISE is the high-resolution color capability. The imaging spectrometer, CRISM, is the main tool on MRO for the investigation of the spectrophotometric properties of the surface, but the spatial resolution is limited to about 18 meter per pixel.

In regions where compositional diversity has been found (e.g. Mawrth Vallis, Nili Fossae, Valles Marineris), HiRISE’s color images are being used to map compositional units at scales below that of CRISM. This has proven to be extremely powerful in assessing the spatial relationships between different units and of particular importance for the investigation of potential landing sites for Mars Science Laboratory (MSL) rover mission.

Many of the images acquired within the composition and photometry theme are therefore strongly linked to CRISM targets of interest and have either been acquired as joint targets or as “ridealongs” on CRISM high priority targets in the latter phases of the planning cycles. Surfaces containing water-alternated minerals, such as phyllosilicates (i.e, clays), carbonates, and chlorides, have been shown to be particularly colorful. HiRISE images show that heterogeneity in the color of these regions frequently persists down to the meter scale, which suggests that, in some places, processes may be best elucidated by mapping this heterogeneity below the resolution limit of CRISM using HiRISE color.

Relevant papers describing HiRISE color
Delamere, W.A., Tornabene, L.L., McEwen, A.S., Becker, K., Bergstrom, J.W., Bridges, N.T., Eliason, E.M., Gallagher, D., Herkenhoff, K.E., Keszthelyi, L., 2010. Color imaging of Mars by the High Resolution Imaging Science Experiment (HiRISE). Icarus 205, 38–52.

McEwen, A. et al., 2010. The High Resolution Imaging Science Experiment (HiRISE) during MRO’s Primary Science Phase (PSP). Icarus 205, 2‐37.