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Jawin ER, Campbell BA, Whitten JL, Morgan GA. The Lateral Continuity and Vertical Arrangement of Dust Layers in the Martian North Polar Cap From SHARAD Multiband Data. GEOPHYSICAL RESEARCH LETTERS 2022; 49:e2022GL099896. [PMID: 36245892 PMCID: PMC9542121 DOI: 10.1029/2022gl099896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 08/15/2022] [Accepted: 08/19/2022] [Indexed: 06/16/2023]
Abstract
Interpretation of radar sounder reflections to infer the structure and composition of the martian polar caps depends on whether bright returns correspond to single packed dust layers or a more finely layered structure. Reflections from multiple layers can create strong resonant scattering (interference) effects that impact analyses of radargram reflectors and inference of dielectric contrast. We identify resonant behavior for an areally extensive reflector in the north polar layered deposits from Shallow Radar data processed in two frequency bands. Echo strength varies by ∼2 dB between subband reflections across a region ∼400 km in extent, with the stronger echo shifting abruptly from the high- to low-frequency band outside the central region of Gemina Lingula. This behavior can arise from resonant scattering between two layers of dust (0.3-0.6 m thick) separated by 0.5-3 m of ice. Such layering requires there be little postdepositional aeolian activity to preserve layer thickness and spacing.
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Affiliation(s)
- Erica R. Jawin
- Smithsonian InstitutionNational Air and Space MuseumWashingtonDCUSA
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2
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Recursive Enhancement of Weak Subsurface Boundaries and Its Application to SHARAD Data. REMOTE SENSING 2022. [DOI: 10.3390/rs14061525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sedimentary layers are composed of alternately deposited compositions in different periods, reflecting the geological evolution history of a planet. Orbital radar can detect sedimentary layers, but the radargram is contaminated by varying background noise levels. Traditional denoising methods, such as median filter, have difficulty dealing with such kinds of noise. We propose a recursive signal enhancement scheme to identify weak reflections from intense background noise. Numerical experiments with synthetic data and SHARAD radargrams illustrate that the proposed method can enhance the clarity of the radar echoes and reveal delicate sedimentary structures previously buried in the background noise. The denoising result presents better horizontal continuity and higher vertical resolution compared with those of the traditional methods.
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3
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Liquid Water Detection under the South Polar Layered Deposits of Mars—a Probabilistic Inversion Approach. REMOTE SENSING 2019. [DOI: 10.3390/rs11202445] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Liquid water was present on the surface of Mars in the distant past; part of that water is now in the ground in the form of permafrost and heat from the molten interior of the planet could cause it to melt at depth. MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) has surveyed the Martian subsurface for more than fifteen years in search for evidence of such water buried at depth. Radar detection of liquid water can be stated as an inverse electromagnetic scattering problem, starting from the echo intensity collected by the antenna. In principle, the electromagnetic problem can be modelled as a normal plane wave that propagates through a three-layered medium made of air, ice and basal material, with the final goal of determining the dielectric permittivity of the basal material. In practice, however, two fundamental aspects make the inversion procedure of this apparent simple model rather challenging: i) the impossibility to use the absolute value of the echo intensity in the inversion procedure; ii) the impossibility to use a deterministic approach to retrieve the basal permittivity. In this paper, these issues are faced by assuming a priori information on the ice electromagnetic properties and adopting an inversion probabilistic approach. All the aspects that can affect the estimation of the basal permittivity below the Martian South polar cap are discussed and how detection of the presence of basal liquid water was done is described.
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Orosei R, Lauro SE, Pettinelli E, Cicchetti A, Coradini M, Cosciotti B, Di Paolo F, Flamini E, Mattei E, Pajola M, Soldovieri F, Cartacci M, Cassenti F, Frigeri A, Giuppi S, Martufi R, Masdea A, Mitri G, Nenna C, Noschese R, Restano M, Seu R. Radar evidence of subglacial liquid water on Mars. Science 2018; 361:490-493. [PMID: 30045881 DOI: 10.1126/science.aar7268] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 06/20/2018] [Indexed: 11/02/2022]
Abstract
The presence of liquid water at the base of the martian polar caps has long been suspected but not observed. We surveyed the Planum Australe region using the MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) instrument, a low-frequency radar on the Mars Express spacecraft. Radar profiles collected between May 2012 and December 2015 contain evidence of liquid water trapped below the ice of the South Polar Layered Deposits. Anomalously bright subsurface reflections are evident within a well-defined, 20-kilometer-wide zone centered at 193°E, 81°S, which is surrounded by much less reflective areas. Quantitative analysis of the radar signals shows that this bright feature has high relative dielectric permittivity (>15), matching that of water-bearing materials. We interpret this feature as a stable body of liquid water on Mars.
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Affiliation(s)
- R Orosei
- Istituto di Radioastronomia, Istituto Nazionale di Astrofisica, Via Piero Gobetti 101, 40129 Bologna, Italy.
| | - S E Lauro
- Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
| | - E Pettinelli
- Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
| | - A Cicchetti
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
| | - M Coradini
- Agenzia Spaziale Italiana, Via del Politecnico, 00133 Roma, Italy
| | - B Cosciotti
- Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
| | - F Di Paolo
- Istituto di Radioastronomia, Istituto Nazionale di Astrofisica, Via Piero Gobetti 101, 40129 Bologna, Italy
| | - E Flamini
- Agenzia Spaziale Italiana, Via del Politecnico, 00133 Roma, Italy
| | - E Mattei
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
| | - M Pajola
- Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica, Vicolo Osservatorio 5, 35122 Padova, Italy
| | - F Soldovieri
- Consiglio Nazionale delle Ricerche, Istituto per il Rilevamento Elettromagnetico dell'Ambiente, Via Diocleziano 328, 80124 Napoli, Italy
| | - M Cartacci
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
| | - F Cassenti
- Dipartimento di Ingegneria dell'Informazione, Elettronica e Telecomunicazioni, Università degli Studi di Roma "La Sapienza," Via Eudossiana 18, 00184 Roma, Italy
| | - A Frigeri
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
| | - S Giuppi
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
| | - R Martufi
- Dipartimento di Ingegneria dell'Informazione, Elettronica e Telecomunicazioni, Università degli Studi di Roma "La Sapienza," Via Eudossiana 18, 00184 Roma, Italy
| | - A Masdea
- E.P. Elettronica Progetti, Via Traspontina 25, 00040 Ariccia (RM), Italy
| | - G Mitri
- International Research School of Planetary Sciences, Università degli Studi "Gabriele d'Annunzio," Viale Pindaro 42, 65127 Pescara (PE), Italy
| | - C Nenna
- Danfoss Drives, Romstrasse 2 - Via Roma 2, 39014 Burgstall - Postal (BZ), Italy
| | - R Noschese
- Istituto di Astrofisica e Planetologia Spaziali, Istituto Nazionale di Astrofisica, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
| | - M Restano
- Serco, c/o ESA Centre for Earth Observation, Largo Galileo Galilei 1, 00044 Frascati (RM), Italy
| | - R Seu
- Dipartimento di Ingegneria dell'Informazione, Elettronica e Telecomunicazioni, Università degli Studi di Roma "La Sapienza," Via Eudossiana 18, 00184 Roma, Italy
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Putzig NE, Smith IB, Perry MR, Foss FJ, Campbell BA, Phillips RJ, Seu R. Three-dimensional radar imaging of structures and craters in the Martian polar caps. ICARUS 2018; 308:138-147. [PMID: 29749975 PMCID: PMC5937288 DOI: 10.1016/j.icarus.2017.09.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Over the last decade, observations acquired by the Shallow Radar (SHARAD) sounder on individual passes of the Mars Reconnaissance Orbiter have revealed the internal structure of the Martian polar caps and provided new insights into the formation of the icy layers within and their relationship to climate. However, a complete picture of the cap interiors has been hampered by interfering reflections from off-nadir surface features and signal losses associated with sloping structures and scattering. Foss et al. (2017) addressed these limitations by assembling three-dimensional data volumes of SHARAD observations from thousands of orbital passes over each polar region and applying geometric corrections simultaneously. The radar volumes provide unprecedented views of subsurface features, readily imaging structures previously inferred from time-intensive manual analysis of single-orbit data (e.g., trough-bounding surfaces, a buried chasma, and a basal unit in the north, massive carbon-dioxide ice deposits and discontinuous layered sequences in the south). Our new mapping of the carbon-dioxide deposits yields a volume of 16,500 km3, 11% larger than the prior estimate. In addition, the radar volumes newly reveal other structures, including what appear to be buried impact craters with no surface expression. Our first assessment of 21 apparent craters at the base of the north polar layered deposits suggests a Hesperian age for the substrate, consistent with that of the surrounding plains as determined from statistics of surface cratering rates. Planned mapping of similar features throughout both polar volumes may provide new constraints on the age of the icy layered deposits. The radar volumes also provide new topographic data between the highest latitudes observed by the Mars Orbiter Laser Altimeter and those observed by SHARAD. In general, mapping of features in these radar volumes is placing new constraints on the nature and evolution of the polar deposits and associated climate changes.
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Affiliation(s)
- Nathaniel E Putzig
- Planetary Science Institute, 1546 Cole Boulevard, Suite 120, Lakewood, CO 80401, USA
| | - Isaac B Smith
- Planetary Science Institute, 1546 Cole Boulevard, Suite 120, Lakewood, CO 80401, USA
| | - Matthew R Perry
- Planetary Science Institute, 1546 Cole Boulevard, Suite 120, Lakewood, CO 80401, USA
| | - Frederick J Foss
- Freestyle Analytical and Quantitative Services, LLC, 2210 Parkview Drive, Longmont, CO 80504, USA
| | - Bruce A Campbell
- Smithsonian Institution, MRC 315, Center for Earth and Planetary Studies, National Air and Space Museum, 4th and Independence Ave, SW, Washington, DC 20560, USA
| | - Roger J Phillips
- Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Washington University in St. Louis, MO 63130, USA
| | - Roberto Seu
- Sapienza University of Rome, DIET Department, Via Eudossiana, 18, 00184 Rome, ITALY
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6
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Smith IB, Putzig NE, Holt JW, Phillips RJ. An ice age recorded in the polar deposits of Mars. Science 2016; 352:1075-8. [PMID: 27230372 DOI: 10.1126/science.aad6968] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/19/2016] [Indexed: 11/02/2022]
Abstract
Layered ice deposits at the poles of Mars record a detailed history of accumulation and erosion related to climate processes. Radar investigations measure these layers and provide evidence for climate changes such as ice advance and retreat. We present a detailed analysis of observational data showing that ~87,000 cubic kilometers of ice have accumulated at the poles since the end of the last ice age ~370,000 years ago; this volume is equivalent to a global layer of ~60 centimeters. The majority of the material accumulated at the north pole. These results provide both a means to understand the accumulation history of the polar deposits as related to orbital Milankovitch cycles and constraints for better determination of Mars' past and future climates.
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Affiliation(s)
- Isaac B Smith
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA.
| | - Nathaniel E Putzig
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - John W Holt
- University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas, J. J. Pickle Research Campus, Austin, TX 78758, USA
| | - Roger J Phillips
- Planetary Science Division, Southwest Research Institute, Boulder, CO 80302, USA. McDonnell Center for the Space Sciences and Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA
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7
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Phillips RJ, Davis BJ, Tanaka KL, Byrne S, Mellon MT, Putzig NE, Haberle RM, Kahre MA, Campbell BA, Carter LM, Smith IB, Holt JW, Smrekar SE, Nunes DC, Plaut JJ, Egan AF, Titus TN, Seu R. Massive CO
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Ice Deposits Sequestered in the South Polar Layered Deposits of Mars. Science 2011; 332:838-41. [DOI: 10.1126/science.1203091] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- Roger J. Phillips
- Planetary Science Directorate, Southwest Research Institute, Boulder, CO 80302, USA and Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA
| | - Brian J. Davis
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - Kenneth L. Tanaka
- Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA
| | - Shane Byrne
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA
| | - Michael T. Mellon
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA
| | - Nathaniel E. Putzig
- Department of Space Studies, Southwest Research Institute, Boulder, CO 80302, USA
| | - Robert M. Haberle
- Space Science and Astrobiology Division, National Aeronautics and Space Administration (NASA) Ames Research Center, Moffett Field, CA 94035, USA
| | - Melinda A. Kahre
- Bay Area Environmental Research Institute/NASA Ames Research Center, Moffett Field, CA 94035, USA
| | - Bruce A. Campbell
- Center for Earth and Planetary Studies, Smithsonian Institution, Washington, DC 20013, USA
| | - Lynn M. Carter
- Science and Exploration Directorate, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - Isaac B. Smith
- Institute for Geophysics, Jackson School of Geosciences, University of Texas, Austin, TX 78758, USA
| | - John W. Holt
- Institute for Geophysics, Jackson School of Geosciences, University of Texas, Austin, TX 78758, USA
| | - Suzanne E. Smrekar
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Daniel C. Nunes
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Jeffrey J. Plaut
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
| | - Anthony F. Egan
- Department of Space Operations, Southwest Research Institute, Boulder, CO 80302, USA
| | - Timothy N. Titus
- Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA
| | - Roberto Seu
- Department of Information Engineering, Electronics and Telecommunications, Sapienza University of Rome, 18-00184 Rome, Italy
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Nunes DC, Smrekar SE, Fisher B, Plaut JJ, Holt JW, Head JW, Kadish SJ, Phillips RJ. Shallow Radar (SHARAD), pedestal craters, and the lost Martian layers: Initial assessments. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010je003690] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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9
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Stillman DE, Grimm RE. Radar penetrates only the youngest geological units on Mars. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2010je003661] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Nunes DC, Smrekar SE, Safaeinili A, Holt J, Phillips RJ, Seu R, Campbell B. Examination of gully sites on Mars with the shallow radar. ACTA ACUST UNITED AC 2010. [DOI: 10.1029/2009je003509] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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11
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Onset and migration of spiral troughs on Mars revealed by orbital radar. Nature 2010; 465:450-3. [PMID: 20505722 DOI: 10.1038/nature09049] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 03/11/2010] [Indexed: 11/08/2022]
Abstract
The landscape of the north polar layered deposits of Mars (NPLD) is dominated by a pinwheel array of enigmatic spiral troughs. The troughs have intrigued planetary scientists since the Mariner 9 spacecraft returned the first close-up image in 1972, but conclusive evidence of their origin has remained elusive. Debate continues regarding all aspects of the troughs, including the possibility that they have migrated, their age in relation to the current NPLD surface, and whether they are fundamentally erosional or constructional features. The troughs are probably related to climatic processes, yet the nature of this relationship has remained a mystery. Previous data characterizing only the exposed NLPD surface were insufficient to test these hypotheses. Here we show that the central spiral troughs initiated after deposition of three-quarters of the NPLD, quickly reached a stable morphology and migrated approximately 65 kilometres poleward and 600 metres in altitude over the past two million years or so. Our radar stratigraphy rules out hypotheses of erosional incision post-dating deposition, and instead largely validates an early hypothesis for constructional trough migration with wind transport and atmospheric deposition as dominant processes. These results provide hard constraints for palaeo-climate models and a new context for evaluating imagery, spectral data, and now radar sounding data, the better to understand the link between orbital parameters and climate, the role of climate in shaping the polar ice of Mars, and eventually, the age of the polar deposits themselves.
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Holt JW, Fishbaugh KE, Byrne S, Christian S, Tanaka K, Russell PS, Herkenhoff KE, Safaeinili A, Putzig NE, Phillips RJ. The construction of Chasma Boreale on Mars. Nature 2010; 465:446-9. [PMID: 20505721 DOI: 10.1038/nature09050] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 03/10/2010] [Indexed: 11/09/2022]
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Seu R, Phillips RJ, Biccari D, Orosei R, Masdea A, Picardi G, Safaeinili A, Campbell BA, Plaut JJ, Marinangeli L, Smrekar SE, Nunes DC. SHARAD sounding radar on the Mars Reconnaissance Orbiter. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006je002745] [Citation(s) in RCA: 206] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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