Summary

The iMars project focused on developing tools and value-added datasets to massively increase the exploitation of space-based data from NASA and ESA Mars mission imaging and 3D data beyond the PI teams. iMars has added significant value by creating more complete and fused 3D models of the surface from multi-resolution co-registered stereo all co-registered to a global reference system derived from laser altimetry and has shown how these 3D models can be employed to create a set of co-registered imaging data through time, permitting a much more comprehensive interpretation of the Martian surface to be made.

Emphasis was placed on the co-registration of multiple datasets from different space agencies and orbiting platforms around Mars and their synergistic use to discover what surface changes have occurred since NASA's Viking Orbiter spacecraft first went into orbit around Mars forty years ago.

iMars brought together the best expertise in Europe for the processing of Martian orbital data within a single environment for handling, visualising and interpreting these data. The ESA Mars Express High Resolution Camera (HRSC) provided the 3D mapping products used as base data (for around 50% of the surface), where possible. When CTX stereo products are also available over the same areas as HRSC (for around 20% of the surface), then the CTX products can be co-registered with HRSC and CTX 3D mapping products can be employed as the base data for higher resolution images such as MOC-NA and HiRISE. A Co-registered Ames Stereo Pipeline using Gotcha Optimisation (CASP-GO) was developed for large-scale production of CTX 3D mapping products and small area production of HiRISE products. Some 5,300 CTX stereo products have been processed using cloud computing provided by Microsoft Azure® covering about 20% of the Martian surface. In iMars, standards were set for the production and dissemination of HRSC mosaiced products, which are easier to utilise for co-registration than individual strips and have better internal geometry. A fully automated Auto-Coregistration and Orthorectification (ACRO) system was developed to operate on a linux cluster without any manual intervention. Around 15,000 NASA images (out of the ≈400,000 acquired with resolution of ≤100m) were processed using the ACRO system covering around 4% of the surface. New HRSC 3D mapping products were produced for the South Polar Residual Cap area and the unfunded (by iMars) PhD student is working on applying the same approach to the North Polar cap in collaboration with another iMars partner. ACRO products have therefore been processed as well as multi-resolution DTMs from CTX and HiRISE. All the 3D mapping products have been analysed qualitatively by visual inspection and the ACRO processing includes calculating internal quality metrics, which is used to flag bad products.

An automated data mining algorithm was developed to find scene fragments where single or multiple instances of change are detected. This used supervised classification initially with planetary science labelled inputs but will in the near future employ mass public participation from a shortly-to-be-launched citizen science programme under the auspices of Zooniverse. A great deal of effort was placed on determining the optimum Human Factors for incentivising and motivating such participants. Each additional set of a minimum of 10 identifications and notations will be further employed to improve the classification (standing it is believed at around 50%) and the data mining applied to new areas by non-EU funded students at Masters and PhD level. The key to public dissemination is the iMars webGIS system which has been developed to allow experts and members of the public to examine different parts of the planet for changes as well as perform geomorphological and geological research. Dissemination of the underlying products will take place through ESA PSA (for HRSC products) and NASA PDS (for NASA ACRO and CASP-GO 3D mapping products).

The iMars base data can be used by the ESA ExoMars Trace Gas Orbiter 2016 and subsequent ESA missions to provide the necessary inputs for the selection of a future landing site for the ESA ExoMars 2020 rover and for any Mars Sample Return missions in the 2020s.

It will greatly extend the use of the archived data by providing mapped and co-registered images.



Prof. Jan-Peter Muller

Coordinator, iMars

Head of Imaging, UCL-MSSL