Dr. Essam Heggy
Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA
Studying the geophysical evolutions of planets and the envir...
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Academic Career Length
26Years (2001-Present)
(Calculated once Scilit publication data is synced: current year − year of first publication + 1)
Representative Publications
View All Publications6 April 2007 in Science
Journal Article
JPJeffrey J. Plaut
Jeffrey J. Plaut
GPGiovanni Picardi
Giovanni Picardi
ASAli Safaeinili
Ali Safaeinili
AIAnton B. Ivanov
Anton B. IvanovSMSarah M. Milkovich
Sarah M. Milkovich
PEPeter Edenhofer
Peter Edenhofer
+18
The ice-rich south polar layered deposits of Mars were probed with the Mars Advanced Radar for Subsurface and Ionospheric Sounding on the Mars Express orbiter. The radar signals penetrate deep into the deposits (more than 3.7 kilometers). For most of the area, a reflection is detected at a time delay that is consistent with an interface between the deposits and the substrate. The reflected power from this interface indicates minimal attenuation of the signal, suggesting a composition of nearly pure water ice. Maps were generated of the topography of the basal interface and the thickness of the layered deposits. A set of buried depressions is seen within 300 kilometers of the pole. The thickness map shows an asymmetric distribution of the deposits and regions of anomalous thickness. The total volume is estimated to be 1.6 × 10 6 cubic kilometers, which is equivalent to a global water layer approximately 11 meters thick.
23 December 2005 in Science
Journal Article
GPGiovanni Picardi
Giovanni Picardi
JPJeffrey J. Plaut
Jeffrey J. PlautDBDaniela Biccari
Daniela Biccari
OBOrnella Bombaci
Ornella Bombaci
DCDiego Calabrese
Diego CalabreseEZEnrico Zampolini
Enrico Zampolini
+28
The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.
30 May 2008 in Science
Journal Article
RPRoger J. Phillips
Roger J. PhillipsMZMaria T. Zuber
Maria T. Zuber
SSSuzanne E. Smrekar
Suzanne E. Smrekar
MMMichael T. Mellon
Michael T. Mellon
JHJames W. Head
James W. Head
Lucia Marinangeli +21
The Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter has imaged the internal stratigraphy of the north polar layered deposits of Mars. Radar reflections within the deposits reveal a laterally continuous deposition of layers, which typically consist of four packets of finely spaced reflectors separated by homogeneous interpacket regions of nearly pure ice. The packet/interpacket structure can be explained by approximately million-year periodicities in Mars' obliquity or orbital eccentricity. The observed ∼100-meter maximum deflection of the underlying substrate in response to the ice load implies that the present-day thickness of an equilibrium elastic lithosphere is greater than 300 kilometers. Alternatively, the response to the load may be in a transient state controlled by mantle viscosity. Both scenarios probably require that Mars has a subchondritic abundance of heat-producing elements.
31 July 2015 in Science
Journal Article
WKWlodek Kofman
Wlodek KofmanAHAlain Herique
Alain HeriqueYBYves Barbin
Yves Barbin
JBJean-Pierre Barriot
Jean-Pierre Barriot
VCValérie Ciarletti
Valérie CiarlettiJZJakob Van Zyl
Jakob Van Zyl
+20
The Philae lander provides a unique opportunity to investigate the internal structure of a comet nucleus, providing information about its formation and evolution in the early solar system. We present Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) measurements of the interior of Comet 67P/Churyumov-Gerasimenko. From the propagation time and form of the signals, the upper part of the “head” of 67P is fairly homogeneous on a spatial scale of tens of meters. CONSERT also reduced the size of the uncertainty of Philae’s final landing site down to approximately 21 by 34 square meters. The average permittivity is about 1.27, suggesting that this region has a volumetric dust/ice ratio of 0.4 to 2.6 and a porosity of 75 to 85%. The dust component may be comparable to that of carbonaceous chondrites.
2 July 2010 in Journal of Geophysical Research
Journal Article
SCStephen M. Clifford
Stephen M. CliffordJLJeremie Lasue
Jeremie Lasue
Essam HeggyJBJoséphine Boisson
Joséphine Boisson
PMPatrick McGovern
Patrick McGovern
MMMichael D. Max
Michael D. Max
21 October 2023 in Nature Communications
Journal Article
Roohollah NooriMMMohsen Maghrebi
Mohsen Maghrebi
SJSøren Jessen
Søren JessenSBSayed M. Bateni
Sayed M. Bateni
Essam HeggyAAAmir Aghakouchak
Amir Aghakouchak +4
Groundwater recharge feeds aquifers supplying fresh-water to a population over 80 million in Iran—a global hotspot for groundwater depletion. Using an extended database comprising abstractions from over one million groundwater wells, springs, and qanats, from 2002 to 2017, here we show a significant decline of around −3.8 mm/yr in the nationwide groundwater recharge. This decline is primarily attributed to unsustainable water and environmental resources management, exacerbated by decadal changes in climatic conditions. However, it is important to note that the former’s contribution outweighs the latter. Our results show the average annual amount of nationwide groundwater recharge (i.e., ~40 mm/yr) is more than the reported average annual runoff in Iran (i.e., ~32 mm/yr), suggesting the surface water is the main contributor to groundwater recharge. Such a decline in groundwater recharge could further exacerbate the already dire aquifer depletion situation in Iran, with devastating consequences for the country’s natural environment and socio-economic development.
About Me
Dr. Essam Heggy is a Research Scientist at the Microwave Systems, Sensors and Imaging Lab (MiXIL), at the Viterbi School of Engineering in the University of Southern California and an affiliate of the Radar Science and Engineering Section (3340) at NASA’s Jet Propulsion Laboratory. Heggy obtained his MSc. and Ph.D. in 1999 and 2002 with distinguished honors from the Paris VI University in France (UPMC-Sorbonne). His research uses radar surface and subsurface characterization methods to understand water evolution in Earth’s arid environments and planetary surfaces. His research particularly focuses on understanding volatile evolution in the North African Sahara and Arabian Peninsula, as well as Mars, the Moon, Jovian Icy satellites and Near-Earth Objects. His work involves probing structural, hydrological, and volcanic elements in terrestrial and planetary environments using different types of radar imaging and sounding techniques as well as measuring the electromagnetic properties of rocks in the radar frequency range. Heggy’s research expertise spans from laboratory electromagnetic characterization of terrestrial samples and planetary analog materials, radar sounding of aquifers in hyper-arid environments, SAR and InSAR image analysis, GPR surveys in desertic, volcanic and ice-rich environments, FDTD numerical simulations of wave propagation, and data analysis of different terrestrial and planetary radar missions.