The Geography of Oxia Planum 01 Geography and Quad Grids

This data set provides a grid of quads and projection information to be used for rover operations and the informal geographic naming convention for the regional geography of Oxia Planum. Both subject to update prior to the landed mission.

Contents

This data set contains 4 shapefiles and 1 zipped folder.

OxiaPlanum_GeographicFeatures_2021_08_26. Point shapefile with the names of geographic features last updated at the date indicated

OxiaPlanum_GeographicRegions_2021_08_26. Polygon shapefile with the outlines of geographic regions fitted to the master quad grid and last updated at the date indicated.

OxiaPlanum_QuadGrid_1km. Polygon shapefile of 1km quad that will be used for ExoMars rover mission

OxiaPlanum_Origin_clong_335_45E_18_20N. The center point of the Oxia Planum as defined by the Rover Operations and Control center and origin point used for the Quad grid

CRS_PRJ_Equirectangular_OxiaPlanum_Mars2000.zip. Zip folder containing the projection information use for all the data associated with this study. These are saved in the ESRI projection (.prj) and well know text formal (.wkt)

Guide to individual files

File name (example) Description

OxiaPlanum_QuadGrid_1km.cpg Text display information

OxiaPlanum_QuadGrid_1km.dbf Database file

OxiaPlanum_QuadGrid_1km.prj Projection information

OxiaPlanum_QuadGrid_1km.sbx Spatial index file

OxiaPlanum_QuadGrid_1km.shp Shape file data <-Open this data in GiS with the other supporting files in the same directory

OxiaPlanum_QuadGrid_1km.shp.xml Symbolisation information

OxiaPlanum_QuadGrid_1km.shx Geoprocessing history

These data are provided with the following projection:

Equirectangular_Mars_Oxia_Planum, Projection = Equidistant_Cylindrical, Datum = D_Mars_2000 Spheroid, Central meridian = 335.45

Quad grid and contours

The quad grid was created using the ArcPro 2.7 Grid Index Features Tool (Esri, 2021). The grid is a 121 × 120 array of 1000 m × 1000 m quads labelled ‘A1’ in the South West to ‘DP120’ in the North East. The grid covers the entire CTX mosaic and the lower left corner of quad BD50 coincides with the centre of the ROCC projection system at 335.45°E 18.20°N. Topographic contours were created at 25 m intervals from a CTX DEM down sampled to 100 m/pixel, with contours shorter than 1500 m in length were removed. Contours were smoothed using the PAEK algorithm at a tolerance of 200 m (USGS & MRCTR GIS Lab, 2018).

Geographic regions

A common geographical division and naming system for the Oxia Planum region is needed to allow ExoMars team members to communicate efficiently. Identifying and naming geographical locations and zones provides a spatial context for detailed observations, strategic planning and operations, and hypotheses testing.

Differentiating geographic regions

We divide Oxia Planum into 30 regions (Figure 2 and Table 3 from Fawdon et al 2021). This system of regions is a formalisation of the geographic differentiation demanded by discussions since the initial suggestion of Oxia Planum as a landing site in 2014 (ESA & The ExoMars 2018 Landing Site Selection Working Group (LSSWG), 2014) Each region is defined by a combination of topographic and or albedo changes in the HRSC and CTX data and that have needed to be talked about. Regions are smaller closer to the center of the landing site or where topography and albedo are more variable. This reflects the need to increase the fidelity of discussion where the rover is more likely to land or there are likely to have been more active geomorphic processes. As such these regions capture features pertaining to hypotheses about the paleo-environments being developed by the RSOWG and provide a natural framework to explore Oxia Planum.

Naming geographic regions

The regions were named in three ways: a number, a unique identifier, and a descriptive term. Unique identifiers were drawn from a list of Roman imperial and senatorial provinces at the largest geographic extent of the Roman empire in 117AD. This scheme was chosen because it has geographic and cultural ties throughout Europe and provides an appropriate number and variety of names. The descriptive terms (e.g., Planum, Lacus, etc) are those used in planetary toponomy (IAU, 1979). Names were selected to reflect the geography of the region (e.g., Caledonia has high elevation terrain in the northwest, Aegyptus has a large channel feature). Geographic locations within regions are also named. These names were drawn from a wider list of Roman towns or other relevant geographic locations with suitable, but process-agnostic, descriptive term (e.g., Alexandria Tholus named after the city in the ‘Aegyptus’ imperial province). These conventions have the capacity to expand this list as exploration of Oxia Planum continues.

Although IAU recognised features (e.g., Malino crater) have also been included, all other names are informal. Informal naming of local features has been performed by previous Mars Rover mission teams. As has occurred during previous missions, some names will probably be replaced with formal IAU designations as the mission progresses.