10 research outputs found
Science results from sixteen years of MRO SHARAD operations
In operation for >16 years to date, the Mars Reconnaissance Orbiter (MRO) Shallow Radar (SHARAD) sounder
has acquired data at its nominal 300–450 m along-track and 3-km cross-track resolution covering >55% of the
Martian surface, with nearly 100% overlap in coverage at that scale in the polar regions and in a number of
smaller mid-latitude areas. While SHARAD data have opened a new window into understanding the interior
structures and properties of Martian ices, volcanics, and sedimentary deposits up to a few kilometers in depth,
they have also led to new revelations about the deeper interior and the behavior of the planet’s ionosphere. Here
we summarize the data collected by SHARAD over this time period, the methods used in the analysis of that data,
and the resulting scientific findings. The polar data are especially rich, revealing complex structures that
comprise up to several dozen reflecting interfaces that extend to depths of 3 km, which inform the evolution of
Martian climate in the late Amazonian period. SHARAD observations of mid-latitude lobate debris aprons and
other glacier-like landforms detect strong basal reflections and low dielectric loss, confirming that they are icerich
debris-covered glaciers. In other mid-latitude terrains, SHARAD data demonstrate the presence of widespread
ground ices, likely at lower concentrations. SHARAD signals also probe non-icy materials, mapping out
stacked lava flows, probing low-density materials thought to be ash-fall deposits, and occasionally penetrating
sedimentary deposits, all of which reveal the structures and interior properties diagnostic of emplacement
processes. SHARAD signals are impacted by their passage through the Martian ionosphere, revealing variations
in time and space of the total electron content linked with the remanent magnetic field. Advanced techniques
developed over the course of the mission, which include subband and super-resolution processing, coherent and
incoherent summing, and three-dimensional (3D) radar imaging, are enabling new discoveries and extending the
utility of the data. For 3D imaging, a cross-track spacing at the nominal 3-km resolution is more than sufficient to
achieve good results, but finer spacing of 0.5 km or less significantly improves the spatially interpolated radar
images. Recent electromagnetic modeling and a flight test show that SHARAD’s signal-to-noise ratio can be
greatly improved with a large (~120â—¦) roll of the spacecraft to reduce interference with the spacecraft body. Both
MRO and SHARAD are in remarkably fine working order, and the teams look forward to many more years in
which to pursue improvements in coverage density, temporal variability in the ionosphere, and data quality that
promise exciting new discoveries at Mars
Clutter Detection and Surface/Subsurface Slope Determination by Combination of Repeat-Pass Sounder Orbits Applied to SHARAD Data
Nadir-looking low-frequency radar sounders cannot easily resolve off-nadir surface returns from the subsurface nadir echoes. Cross-track surface echoes (also named "clutter ") with time delays synchronized with subsurface returns are renowned for being a major challenge for scientists, as they can affect the analysis of orbital radar sounders data. We present a method for clutter discrimination and surface/subsurface slope estimation using data acquired from radar sounders in closely spaced repeated orbits configuration. The method takes advantage of cross-track signal migration to discriminate off-nadir clutter from subsurface signal returns received at the nadir. The migration of the off-nadir signals is also used to determine the clutter direction of arrival (DOA) as well as the surface/subsurface cross-track slopes. The effectiveness of the method has been proven on the Mars Reconnaissance Orbiter (MRO)'s Shallow Radar (SHARAD) dataset and provides a proof-of-concept demonstration for the surface clutter discrimination when radar sounders repeated-passes data are available
National Astronomy Meeting 2019 Abstract Book
The National Astronomy Meeting 2019 Abstract Book. Abstracts accepted and presented, including both oral and poster presentations, at the Royal Astronomical Society's NAM2019 conference, held at Lancaster University between 30 June and 4 July 2019
Mars Workshop on Amazonian and Present Day Climate : June 18–22, 2018, Lakewood, Colorado
The Mars workshop is intended as the first of many meetings to promote the exchange of knowledge and ideas regarding the last 3 Ga of martian polar and climate history, including its environment and processes.Organizers: Planetary Science Institute, NASA Mars Program Office, Lunar and Planetary Institute, Universities Space Research Association, Conveners: Isaac Smith, Planetary Science Institute, Serina Diniega, Jet Propulsion Laboratory, California Institute of Technology, Science Organizing Committee: Than Putzig, Planetary Science Institute [and 8 others]PARTIAL CONTENTS: Geomorphological Evidence of Local Presence of Ice-Rich Deposits in Terra Cimmeria, Mars / S. Adeli, E. Hauber, G. Michael, P. Fawdon, I. B. Smith, and R. Jaumann--Middle Amazonian Accumulations of Ice-Rich Dust in the Mid-Latitudes of Mars / D. M. H. Baker--Thermal Properties of the North Polar Residual Cap / J. Bapst, S. Byrne, J. L. Bandfield, and P. O. Hayne--Correlation of the Visible and Radar Stratigraphic Records of Mars’ NPLD / P. Becerra, D. Nunes, I. B. Smith, M. M. Sori, Y. Brouet, and N. Thomas--Tagging Dust and Water in the NASA Ames Mars GCM: A New Global Vision of the Martian Climate / T. Bertrand, M. A. Kahre, R. J. Wilson, and A. Kling--The Mass Balance of Mars’ Spiral Troughs / A. M. Bramson, S. Byrne, J. Bapst, and I. B. Smith--Time Evolution of Swiss Cheese Terrains in the Martian South Polar Cap / V. F. Chevrier, M. S. Fusco, K. Farnsworth, J. P. Knightly, and A. Yazdani
The Sixth International Conference on Mars Polar Science and Exploration : September 5-9, 2016, Reykjavik, Iceland
The conference is designed to pull together the current state of Mars polar research from many fields, including geology, atmospheric, and climate sciences.European Geophysical Union
Icelandic Meteorological Office
International Association of Cryospheric Sciences
Lunar and Planetary Institute (LPI)
NASA Mars Program Office
Planetary Science Institute
Southwest Research Institute
Université de Nantes
University of Iceland in ReykjavikConference Organizing Committee, Isaac Smith, Convener, Southwest Research Institute [and 7 others] ; Science Organizing Committee, Wendy Calvin, University of Nevada [and 13 others
Effects of the passage of Comet C/2013 A1 (Siding Spring) observed by the Shallow Radar (SHARAD) on Mars reconnaissance orbiter
The close passage of Comet C/2013 A1 (Siding Spring) to Mars provided a unique opportunity to observe the interaction of cometary materials with the Martian ionosphere and atmosphere using the sounding radar SHARAD (SHAllow RADar) aboard Mars Reconnaissance Orbiter. In two nightside observations, acquired in the 10 h following the closest approach, the SHARAD data reveal a significant increase of the total electron content (TEC). The observed TEC values are typical for daylight hours just after dawn or before sunset but are unprecedented this deep into the night. Results support two predictions indicating that cometary pickup O+ ions, or ions generated from the ablation of cometary dust, are responsible for the creation of an additional ion layer
Ionosphere of Mars: data calibration and analysis, and modelling
Tesis inĂ©dita de la Universidad Complutense de Madrid, Facultad de Ciencias FĂsicas, Departamento de FĂsica de la Tierra, AstronomĂa y AstrofĂsica I, leĂda el 17/06/2014Depto. de FĂsica de la Tierra y AstrofĂsicaFac. de Ciencias FĂsicasTRUEunpu
Workshop on Radar Investigations of Planetary and Terrestrial Environments : February 7-10. 2005, Houston, Texas
Focuses on the capabilities of radar sounding and imaging systems to address issues such as: the subsurface geology and distribution of water on the Earth, Moon, Mars, and Europa, investigating the paleohydrology of planetary surfaces and identifying potential subsurface habitats capable of sustaining primitive life forms.Sponsored by: Lunar and Planetary Institute, National Aeronautics and Space Administration, Jet Propulsion Laboratory, Southwest Research Institute.Conveners: Essam Heggy., Lunar and Planetary Institute, Stephen Clifford, Lunar and Planetary Institute, Tom Farr, Jet Propulsion Laboratory, Cynthia Dinwiddie, Southwest Research Institute, Bob Grimm, Southwest Research Institute.PARTIAL CONTENTS: The Goldstone Solar System Radar: 1988-2003 Earth-based Mars Radar Observations / A. F. C. Haldemann, K. W. Larsen, R. F. Jurgens, and M A. Slade--Mapping Subsurface Stratigraphy and Anomalies in Iron-rich Volcanoclastics Using Ground-penetrating Radar: Potential for Shallow Sounding on Mars / E. Heggy, S. Clifford, R. Grimm, S. Gonzalez, D. Bannon, and D. Wyrick--Dielectric Map of the Martian Surface / E. Heggy and A. Pommerol--Surface Clutter Removal in Airborne Radar Sounding Data from the Dry Valleys, Antarctica / J. W. Holt, D. D. Blankenship, D. L. Morse, M E. Peters, and S. D. Kempf--Comparing Transient Electromagnetics and Low Frequency Ground Penetrating Radar for Sounding of Subsurface Water in Mars Analog Environments / J. A. Jernsletten and E. Heggy--The MARSIS Radar, Signal Simulation and Interpretation Using MOLA Topography Data / W. Koftnan, J. F. Nouvel, A. Herique, and J.-E. Martelal--A Phase Signature for Detecting Wet Structures in the Shallow Subsurface of Mars Using Polarimetric P-band SAR / Y: Lasne, Ph. Paillou, and J.-M Matezieux--Experimental Validation of the Mono and Bistatic Operating Mode of a GPR Dedicated to the Martian Subsurface Exploration / A. Le Gall, V. Ciorlelli, J. J. Berthelier, R. Ney, F. Dolon, and S. Bonoime
Cumulative index to NASA Tech Briefs, 1986-1990, volumes 10-14
Tech Briefs are short announcements of new technology derived from the R&D activities of the National Aeronautics and Space Administration. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This cumulative index of Tech Briefs contains abstracts and four indexes (subject, personal author, originating center, and Tech Brief number) and covers the period 1986 to 1990. The abstract section is organized by the following subject categories: electronic components and circuits, electronic systems, physical sciences, materials, computer programs, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences