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Home , Tooting (crater)

MARTIAN DATABASE : TOWARDS A COMPLETION FOR D > 100M A. Lagain1, G.K. Benedix1,*, C. Norman2 , K. Chai3, S. Meka3, P.A. Bland1, J. Paxman2, M.C. Towner1, and S. Anderson1. 1School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia ([email protected]), 2School of Civil and Mechanical Engineering, Curtin University, Perth, WA, Australia, 3Curtin Institution of Computation, Curtin University, Perth, WA, Australia, *Dept of Earth and Planetary Sciences, WA Museum, Perth WA, Australia.

Using of the beta01 version of the MurrayLab global MOTIVATION CTX mosaic (NASA/JPL/MSSS/The Murray Lab) DETECTION ON CTX IMAGES Impact craters constitute the major tool of “celestial geologist” to decipher the history of planetary surfaces.  tedious mapping and morphological inspection of a large number of circular features to distinguish true and primary impact craters from other surface features LOCAL SCALE  local variation of the cratering density require the mapping of small craters, much more numerous • (a) Detection on CTX mosaic covering the Arandas crater Robbins and Hynek (2012) database [1] 1. By using the most complete manual catalog of Martian craters ( ), we built a Crater Detection Algorithm (CDA) trained on the (D=25km, 42oN, 15oW, ) ejecta blanket [2,3,4]. THEMIS imagery (100m/px) between 1.2 and 4 crater radii. Removing detected craters 2. In this study, we evaluate the accuracy of the CDA by applying it over the entire THEMIS mosaic between 65 degrees of North and . located on bad quality CTX images. Cratering density map 3. We apply our CDA over the CTX mosaic (NASA/JPL/MSSS/The Murray Lab) at 5m/px and compare some CSFDs extracted on several areas on with the manual reveal over-cratering area. database.

• (b) Building of Thiessen polygons associated to the crater DETECTIONS ON THE THEMIS MOSAIC population. • Calculation of the ideal polygon size: • CDA applied on the THEMIS mosaic (100m/px) between 65o N/S 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁 𝑜𝑜𝑜𝑜 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 a b c • Robbins database = 363,895 entries • Automatic database = 328,833 entries • (c) All detections whom the associated polygon is less than • Underestimation of the CDA (in blue on the map) compared to the manual ~1/3 of the size of the ideal polygon are considered as database focused at immediate vicinity of large primary impact craters that have secondaries. produced kilometric secondary craters. • Using the Hartmann (2005) [7] chronology model and • Overestimation of the CDA (in red on the map) compared to the manual CraterStats II (Michael, 2010) [8] for the age derivation. Manual database focused on areas with high concentration of volcanic counting Automatic (/Elysium//Lunae Planum) (Utopia and periglacial counting Planitia) features. • (d) CSFD of supposed secondaries + supposed primaries give a model age twice as high as the manual count • (e) CSFD of primaries give a model age underestimated of only 13% than a manual count (Lagain et al., 2019b) [9] ! d e

REGIONAL SCALE • Detection on CTX mosaic covering the impact crater region.

• 60,000 detections over 4 tiles of the CTX mosaic, o o corresponding to an area of 8 x 8 . Fig a • Comparison of model ages measured by Parker et al. Difference between manual catalogue and the automatic database in 100km2 cell. (2010) [10] on four areas. Fig b Black circles are large primary impact craters that have produced a large portion of kilometric secondary craters on Mars (Robbins, 2014 [5]; Lagain et al., 2019a [6]). • All CSFDs shown here are extracted from the CDA Example of impact craters overlaid to the THEMIS day IR mosaic, in blue : detection by the detection. The same diameter range and chronology Fig d • Global CSFD comparison shows a good match between the manual database CDA, in red, compiled by Robbins & Hynek (2012) [1]. model (Hartmann & , 2001) [11] have been used and the automated detection for diameter between 1.2km and 60km to fit an isochron with each CSFD. • Lack of detections below 1.2km due to the low resolution of THEMIS imagery MISSED CRATERS Fig c • Model ages displayed in red are from Parker et al. (2010) [10]. • Differences in model ages do not exceed ±3%.

GLOBAL SCALE • Detection over the CTX mosaic on a latitudinal band between 45o N/S (~ 80% of craters D>1km are located on this area (Robbins & Hynek, 2012) [1]).

• ~ 17 Millions of craters detected with D>50m • The size frequency distribution of the automatic Gap due to bad quality images database fit well that of the manual database between Incremental representation of the CSFD of the manual and the automatic database. 1 and 10 km. MATCHED CRATERS • Possibility to explore young features on Mars (Tooting, Mojave…) Latitude and diameter of craters missed by the CDA Tooting Missed craters: FUTURE WORK • ~15% of craters compiled by Robbins are not detected by the CDA between 45o N/S, a large proportion of them are representing by large craters (D>6km) • Cleaning false detection and secondary craters clusters corresponding either to complex craters or degraded craters. from the database by analysing the spatial cratering distribution Matched craters : • Small deviation of the centroid coordinate between the automated detection • Merge databases for different diameter size range and the manual database : no more than ±10 pixels Difference in number of pixels between the automatic detection and the Robbins’ database • General trend to an overestimation of the diameter : ~5 pixels • Building a web interface for your crater request ! Acknowledgements References We are greatful to the MurrayLab team for their particular helpful work in the building of the CTX [1] Robbins, S. and Hynek, B. (2012) JGR, 117, E05004. [2] Norman, C.J. et al. (2018) Planetary Science Information and Data Analytics Conference, St. Louis, MO, Abstr #6002. [3] Benedix, G.K., et al. (2018) 49th LPSC, #2202. [4] Benedix, G.K., et al. (2019) 50th LPSC, #2140. [5] Robbins, S. & Hynek, B. (2014), The secondary crater population of Mars, Earth and Planetary Science Letters, 400, 66-76, doi: 10.1016/j.epsl.2014.05.005. [6] Lagain, A. et al. (2019) Icarus, under review. [7] Hartmann, W.K. (2005) mosaic and make it available. This work is supported by Australian Research Council (FT170100024), Martian cratering 8: Isochron refinement and the chronology of Mars, Icarus, doi:10.1016/j.icarus.2004.11.023. [8] Michael, G.G. & Neukum, G. (2010), Planetary surface dating from crater size frequency distribution measurements: Partial resurfacing the Curtin University and by resources provided by the Pawsey Supercomputing Centre with funding events and statistical age uncertainty, Earth and Planetary Science Letters, 294, 223-229. [9] Lagain, A. et al. (2010) Planetary and Space Science (under review). [10] Parker, M.P. et al. (2010), 3D structure of the Gusev Crater region. Earth and Planetary from the Australian Government and the Government of Western Australia. Science Letters, 294, 411-423, doi: 10.1016/j.epsl.2010.01.013. [11] Hartmann, W.K. and Neukum, G.G. (2001), Cratering chronology and the evolution of Mars, Space Science Reviews, 96: 165-194.