Radiometic calibration and data processing for the ExoMars Pancam instrument through compension for atmospheric and dposited dust

The PanCam instrument will be the 'science eyes' of the ExoMars rover, providing colour, stereo and multispectral wide-angle panoramic images, and high-resolution colour images from Mars. In order to fulfil its potential and further scientific knowledge of the Mars environment, the raw images returned will require radiometric processing and calibration before they are ready for use. Two levels of data processing will be implemented for different timescales: primary data processing for short term tactical planning; secondary data processing for longer term strategic planning. Primary radiometric processing will provide data within minutes as required for tactical planning. The primary radiometric data processing pipeline will form part of the Automatic Data-processing Pipeline running on a computer at the Rover Operation and Control Centre; processing will trigger automatically as soon as data is available. Primary data processing will correct camera behaviour and artefacts characterised during pre-launch calibration and post-launch observations. It will also generate first order derived data products such as approximate colour images and reflectance measurements. These will be used directly by the tactical planning team and fed into the geometric processing pipeline for the generation of 3D data products. Secondary radiometric processing will generate data products on a timescale of the order of hours to days for strategic planning. The secondary data processing pipeline will form part of the data processing analysis and visualisation toolkit run on the PanCam workstation at the ROCC by the PanCam operations team. The processing pipeline will require some user input to check model fitting, adjust parameters and take measurements. Training in how to use the toolkit will be provided to the PanCam operations team. Secondary radiometric data processing will use measurements of the PanCam Calibration Target to characterise and compensate for the incident solar illumination spectrum (effectively white balance correction), airborne and deposited dust. Derived data products from secondary data processing will include true colour images, false colour and enhanced images, accurate reflectance measurements, deposited dust optical depth and atmospheric optical depth. These data will be used directly for strategic planning and initial scientific interpretation and can be fed into geometric processing for the generation of refined 3D data products. Calibration coefficients generated during secondary processing will be used to refine primary data processing on subsequent sols.