Since its arrival in early 2006, various instruments aboard NASA's Mars Reconnaissance Orbiter (MRO) have been collecting a variety of scientific and engineering data from orbit around Mars. Among these is the Shallow Radar (SHARAD) instrument, supplied by Agenzia Spaziale Italiana (ASI) and designed for subsurface sounding in the 15–25 MHz frequency band. As of this writing, MRO has completed more than 46,000 nearly polar orbits of Mars, 30% of which have included active SHARAD data collection. By 2009, a sufficient density of SHARAD coverage had been obtained over the polar regions to support 3D processing and analysis of the data. Using tools and techniques commonly employed in terrestrial seismic data processing, we have processed subsets of the resulting collection of SHARAD observations covering the north and south polar regions as SHARAD 3D volumes, imaging the interiors of the north and south polar ice caps known, respectively, as Planum Boreum and Planum Australe. After overcoming a series of challenges revealed during the 3D processing and analysis, a completed Planum Boreum 3D volume is being used currently for scientific research. Lessons learned in the northern work fed forward into our 3D processing and analysis of the Planum Australe 3D volume, currently under way. We discuss our experiences with these projects and present results and scientific insights stemming from these efforts.
References
Andrews-Hanna, J. C. ,M. T. Zuber , andW. B. Banerdt , 2008, The Borealis basin and the origin of the martian crustal dichotomy: Nature, 453, no. 7199, 1212–1215, http://dx.doi.org/10.1038/nature07011.CrossrefWeb of ScienceGoogle ScholarBierson, C. J. ,R. J. Phillips ,I. B. Smith ,S. E. Wood ,N. E. Putzig ,D. Nunes , andS. Byrne , 2016, Stratigraphy and evolution of the buried CO2 deposit in the Martian south polar cap: Geophysical Research Letters, 43, no. 9, 4172–4179, http://dx.doi.org/10.1002/2016GL068457.CrossrefWeb of ScienceGoogle ScholarBiondi, B. L. , 2006, Downward-continuation Methods, in 3D seismic imaging: SEG Investigations in Geophysics 14, 51–64, http://dx.doi.org/10.1190/1.9781560801689.ch5.Google ScholarBrothers, T. C. ,J. W. Holt , andA. Spiga , 2015, Planum Boreum basal unit topography, Mars: Irregularities and insights from SHARAD: Journal of Geophysical Research, 120, no. 7, 1357–1375, http://dx.doi.org/10.1002/2015JE004830.Web of ScienceGoogle ScholarCampbell, B. A. , andR. J. Phillips , 2014, Mars Reconnaissance Orbiter Shallow Radar radargram data, MRO-M-SHARAD-5-RADARGRAM-V1.0, http://pds-geosciences.wustl.edu/mro/mro-m-sharad-5-radargram-v1/mrosh_2001/.Google ScholarCampbell, B. A. ,G. A. Morgan ,N. E. Putzig ,J. L. Whitten ,J. W. Holt , andR. J. Phillips , 2015, Enhanced radar visualization of structure in the south polar deposits of Mars:46th Lunar and Planetary Science Conference, Abstract 2366 , http://www.hou.usra.edu/meetings/lpsc2015/pdf/2366.pdf, accessed 8 December 2016.Google ScholarCampbell, B. A. ,N. E. Putzig ,F. J. Foss II , andR. J. Phillips , 2014, SHARAD signal attenuation and delay offsets due to the Martian ionosphere: IEEE Geoscience and Remote Sensing Letters, 11, no. 3, 632–635, http://dx.doi.org/10.1109/LGRS.2013.2273396.CrossrefWeb of ScienceGoogle ScholarCampbell, B. A. ,N. E. Putzig ,L. M. Carter , andR. J. Phillips , 2011, Autofocus correction of phase distortion effects on SHARAD echoes: IEEE Geoscience and Remote Sensing Letters, 8, no. 5, 939–942, http://dx.doi.org/10.1109/LGRS.2011.2143692.CrossrefWeb of ScienceGoogle ScholarChristian, S. ,J. W. Holt ,S. Byrne , andK. E. Fishbaugh , 2013, Integrating radar stratigraphy with high resolution visible stratigraphy of the north polar layered deposits, Mars: Icarus, 226, no. 2, 1241–1251, http://dx.doi.org/10.1016/j.icarus.2013.07.003.CrossrefWeb of ScienceGoogle ScholarClifford, S. M. ,D. Crisp ,D. A. Fisher ,K. E. Herkenhoff ,S. E. Smrekar ,P. C. Thomas ,D. D. Wynn-Williams , et al., 2000, The state and future of Mars polar science and exploration: Icarus, 144, no. 2, 210–242, http://dx.doi.org/10.1006/icar.1999.6290.CrossrefWeb of ScienceGoogle ScholarDundas, C. M. , andL. P. Keszthelyi , 2013, Modeling steam pressure under martian lava flows: Icarus, 226, no. 1, 1058–1067, http://dx.doi.org/10.1016/j.icarus.2013.06.036.CrossrefWeb of ScienceGoogle ScholarDundas, C. M. ,S. Byrne ,A. S. McEwen ,M. T. Mellon ,M. R. Kennedy ,I. J. Dunbar , andL. Saper , 2014, HiRISE observations of new impact craters exposing Martian ground ice: Journal of Geophysical Research, 119, no. 1, 109–127, http://dx.doi.org/10.1002/2013JE004482.Web of ScienceGoogle ScholarEhlmann, B. L. , andC. S. Edwards , 2014, Mineralogy of the Martian surface: Annual Review of Earth and Planetary Sciences, 42, no. 1, 291–315, http://dx.doi.org/10.1146/annurev-earth-060313-055024.CrossrefWeb of ScienceGoogle ScholarFishbaugh, K. E. , andJ. W. Head III , 2005, Origin and characteristics of the Mars north polar basal unit and implications for polar geologic history: Icarus, 174, no. 2, 444–474, http://dx.doi.org/10.1016/j.icarus.2004.06.021.CrossrefWeb of ScienceGoogle ScholarGrima, C. ,W. Kofman ,J. Mouginot ,R. J. Phillips ,A. Hérique ,D. Biccari ,R. Seu , andM. Cutigni , 2009, North polar deposits of Mars: Extreme purity of the water ice: Geophysical Research Letters, 36, no. 3, no. L03203, n/a, http://dx.doi.org/10.1029/2008GL036326.CrossrefWeb of ScienceGoogle ScholarHeavens, N. G. ,M. I. Richardson ,A. Kleinböhl ,D. M. Kass ,D. J. McCleese ,W. Abdou ,J. L. Benson ,J. T. Schofield ,J. H. Shirley , andP. M. Wolkenberg , 2011, Vertical distribution of dust in the Martian atmosphere during northern spring and summer: High-altitude tropical dust maximum at northern summer solstice: Journal of Geophysical Research, 116, no. E01007, http://dx.doi.org/10.1029/2010JE003692.Google ScholarHolt, J. W. ,A. Safaeinili ,J. J. Plaut ,J. W. Head ,R. J. Phillips ,R. Seu ,S. D. Kempf , et al., 2008, Radar sounding evidence for buried glaciers in the southern mid-latitudes of Mars: Science, 322, no. 5905, 1235–1238, http://dx.doi.org/10.1126/science.1164246.CrossrefWeb of ScienceGoogle ScholarHolt, J. W. ,K. E. Fishbaugh ,S. Byrne ,S. Christian ,K. Tanaka ,P. S. Russell ,K. E. Herkenhoff ,A. Safaeinili ,N. E. Putzig , andR. J. Phillips , 2010, The construction of Chasma Boreale on Mars: Nature, 465, no. 7297, 446–449, http://dx.doi.org/10.1038/nature09050.CrossrefWeb of ScienceGoogle ScholarLandis, M. E. ,S. Byrne ,I. J. Daubar ,K. E. Herkenhoff , andC. M. Dundas , 2016, A revised surface age for the North Polar Layered Deposits of Mars: Geophysical Research Letters, 43, no. 7, 3060–3068, http://dx.doi.org/10.1002/2016GL068434.CrossrefWeb of ScienceGoogle ScholarLevin, S. A. , andF. J. Foss II , 2014, Downward continuation of Mars SHARAD data:84th Annual International Meeting, SEG, Expanded Abstracts , 3821–3825, http://dx.doi.org/10.1190/segam2014-1295.1.AbstractGoogle ScholarMcEwen, A. S. ,C. M. Dundas ,S. S. Mattson ,A. D. Toigo ,L. Ojha ,J. J. Wray ,M. Chojnacki ,S. Byrne ,S. L. Murchie , andN. Thomas , 2014, Recurring slope lineae in equatorial regions of Mars: Nature Geoscience, 7, no. 1, 53–58, http://dx.doi.org/10.1038/ngeo2014.CrossrefWeb of ScienceGoogle ScholarMilkovich, S. M. , andJ. J. Plaut , 2008, Martian south polar layered deposit stratigraphy and implications for accumulation history: Journal of Geophysical Research, 113, no. E6, no. E6, E06007, http://dx.doi.org/10.1029/2007JE002987.CrossrefGoogle ScholarOjha, L. ,M. B. Wilhelm ,S. L. Murchie ,A. Mcewen ,J. J. Wray ,J. Hanley ,M. Massé , andM. Chojnacki , 2015, Spectral evidence for hydrated salts in recurring slope lineae on Mars: Nature Geoscience, 8, no. 11, 829–832, http://dx.doi.org/10.1038/ngeo2546.CrossrefWeb of ScienceGoogle ScholarPhillips, R. J. ,M. T. Zuber ,S. E. Smrekar ,M. T. Mellon ,J. W. Head ,K. L. Tanaka ,N. E. Putzig , et al., 2008, Mars north polar deposits: stratigraphy, age, and geodynamical response: Science, 320, no. 5880, 1182–1185, http://dx.doi.org/10.1126/science.1157546.CrossrefWeb of ScienceGoogle ScholarPhillips, R. J. ,B. J. Davis ,K. L. Tanaka ,S. Byrne ,M. T. Mellon ,N. E. Putzig ,R. M. Haberle , et al., 2011, Massive CO2 ice deposits sequestered in the south polar layered deposits of Mars: Science, 332, no. 6031, 838–841, http://dx.doi.org/10.1126/science.1203091.CrossrefWeb of ScienceGoogle ScholarPicardi, G. ,D. Biccari ,R. Seu ,J. Plaut ,W. T. K. Johnson ,R. L. Jordan ,A. Safaeinili , et al., 2004, MARSIS: Mars advanced radar for subsurface and ionosphere sounding, in Mars express: A European mission to the red planet, European Space Agency Special Publication: ESA SP, 1240, 51–69.Google ScholarPlaut, J. J. , 2005, An inventory of impact craters on the Martian south polar layered deposits:Presented at Lunar and Planetary Science XXXVI, Abstract 2319 .Google ScholarPlaut, J. J. ,A. Safaeinili ,J. W. Holt ,R. J. Phillips ,J. W. Head III ,R. Seu ,N. E. Putzig , andA. Frigeri , 2009, Radar evidence for ice in lobate debris aprons in the mid-northern latitudes of Mars: Geophysical Research Letters, 36, no. 2, no. L2203, n/a, http://dx.doi.org/10.1029/2008GL036379.CrossrefWeb of ScienceGoogle ScholarPutzig, N. E. ,R. J. Phillips ,B. A. Campbell ,J. W. Holt ,J. J. Plaut ,L. M. Carter ,A. F. Egan ,F. Bernardini ,A. Safaeinili , andR. Seu , 2009, Subsurface structure of Planum Boreum from Mars Reconnaissance Orbiter shallow radar soundings: Icarus, 204, no. 2, 443–457, http://dx.doi.org/10.1016/j.icarus.2009.07.034.CrossrefWeb of ScienceGoogle ScholarSchultz, P. H. ,R. S. Harris ,S. J. Clemett ,K. L. Thomas-Keprta , andM. Zarate , 2015, Preserved flora and organics in impact melt breccia: Geology, 43, 635–638, http://dx.doi.org/10.1130/G35343.1.Google ScholarSeu, R. ,R. J. Phillips ,G. Alberti ,D. Biccari ,F. Bonaventura ,M. Bortone ,D. Calabrese , et al., 2007a, Accumulation and erosion of Mars' south polar layered deposits: Science, 317, no. 5845, 1715–1718, http://dx.doi.org/10.1126/science.1144120.CrossrefWeb of ScienceGoogle ScholarSeu, R. ,R. J. Phillips ,D. Biccari ,R. Orosei ,A. Masdea ,G. Picardi ,A. Safaeinili , et al., 2007b, SHARAD sounding radar on the Mars Reconnaissance Orbiter: Journal of Geophysical Research, 112, no. E5, no. E05505, 1–18, http://dx.doi.org/10.1029/2006JE002745.CrossrefWeb of ScienceGoogle ScholarSmith, D. E. ,M. T. Zuber ,H. V. Frey ,J. B. Garvin ,J. W. Head ,D. O. Muhleman ,G. H. Pettengill , et al., 2001, Orbiter laser altimeter: Experiment summary after the first year of global mapping of Mars: Journal of Geophysical Research, 106, no. E10, no. E10, 23689–23722, http://dx.doi.org/10.1029/2000JE001364.CrossrefWeb of ScienceGoogle ScholarSmith, I. B. , andJ. W. Holt , 2010, Onset and migration of spiral troughs on Mars revealed by orbital radar: Nature, 465, no. 7297, 450–453, http://dx.doi.org/10.1038/nature09049.CrossrefWeb of ScienceGoogle ScholarSmith, I. B. , andJ. W. Holt , 2015, Spiral trough diversity on the north pole of Mars, as seen by Shallow Radar (SHARAD): Journal of Geophysical Research, 120, no. 3, 362–387, http://dx.doi.org/10.1002/2014JE004720.Web of ScienceGoogle ScholarSmith, I. B. ,N. E. Putzig ,R. J. Phillips , andJ. W. Holt , 2016, A record of Martian ice ages: Science, 352, no. 6289, 1075–1078, http://dx.doi.org/10.1126/science.aad6968.CrossrefWeb of ScienceGoogle ScholarStolt, R. H. , 1978, Migration by Fourier transform: Geophysics, 43, no. 1, 23–48, http://dx.doi.org/10.1190/1.1440826.AbstractWeb of ScienceGoogle ScholarTanaka, K. L. ,J. A. P. Rodriguez ,J. A. Skinner Jr. ,M. C. Bourke ,C. M. Fortezzo ,K. E. Herkenhoff ,E. J. Kolb , andC. H. Okubo , 2008, North polar region of Mars: Advances in stratigraphy, structure, and erosional modification: Icarus, 196, no. 2, 318–358, http://dx.doi.org/10.1016/j.icarus.2008.01.021.CrossrefWeb of ScienceGoogle ScholarTaner, M. T. ,F. Koehler , andR. E. Sheriff , 1979, Complex seismic trace analysis: Geophysics, 44, no. 6, 1041–1063, http://dx.doi.org/10.1190/1.1440994.AbstractWeb of ScienceGoogle ScholarWray, J. J. ,S. T. Hansen ,J. Dufek ,G. A. Swayze ,S. L. Murchie ,F. P. Seelos ,J. R. Skok ,R. P. Irwin III , andM. S. Ghiorso , 2013, Prolonged magmatic activity on Mars inferred from the detection of felsic rocks: Nature Geoscience, 6, no. 12, 1013–1017, http://dx.doi.org/10.1038/ngeo1994.CrossrefWeb of ScienceGoogle ScholarZurek, R. W. , andS. E. Smrekar , 2007, An overview of the Mars Reconnaissance Orbiter (MRO) science mission: Journal of Geophysical Research, 112, no. E05S01, 1–22, http://dx.doi.org/10.1029/2006JE002701.Google Scholar
