Radar autofocus algorithm incorporating terrain knowledge for correction of Mars' ionospheric distortion in MARSIS observations

McMichael, Joseph G.; Gim, Y.; Arumugam, Darmindra D.; Plaut, J. J.

doi:10.1109/radar.2017.7944326

Cited by 7 publications

(4 citation statements)

References 7 publications

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“…We used dayside and nightside SHARAD observations produced by US Instrument Team members which are publicly available on the NASA Planetary Data System. All clutter simulations and reprocessed MARSIS radargrams (McMichael et al., 2017) used in our survey are available on the Colorado SHARAD Processing System (Putzig et al., 2016).…”

Section: Methodsmentioning

confidence: 99%

“…In this study, we investigate the subsurface of a region of interest near the Acraeus Mons volcano in the Tharsis Volcanic Province using observations from the SHAllow RADar (SHARAD) instrument onboard the Mars Reconaissance Orbiter (Seu et al., 2007) and from the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard Mars Express (McMichael et al., 2017; Picardi et al., 2004). Using radar sounding, we probe the subsurface to map the extent and thickness of the volcanic deposits that are present and measure other material properties that can be related to composition such as permittivity and bulk density.…”

Section: Introductionmentioning

confidence: 99%

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New Insights Into Subsurface Stratigraphy Northwest of Ascraeus Mons, Mars, Using the SHARAD and MARSIS Radar Sounders

et al. 2022

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The Tharsis Montes volcanoes on Mars are the source of laterally extensive lava flows and other volcanic deposits generating a complex stratigraphy throughout the Tharsis Volcanic Province. We use SHAllow RADar (SHARAD) and Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) observations in a region northwest of Ascraeus Mons to determine the composition, density, thickness, and spatial distribution of these emplaced volcanic materials. We identified subsurface reflectors along 43 SHARAD and five MARSIS observations. Reflectors in the volcanic plains are interpreted to be sequences of basaltic lava flows with interspersed pyroclastic material, dust, or regolith during a hiatus in activity. Others correspond to the base of three major flow fields. Several plain reflectors were detected by both MARSIS and SHARAD. Other notable reflectors were identified near Ascraeus' flank where lava buried glacially derived sediment. We derived thickness and other material properties for flows using their distinct topographic boundary visible in the radar images. Permittivity ranged from 7.0 to 11.2 corresponding to lava flow densities of 3.20–3.52 g/cm3. Flow thicknesses ranged from 19.8 to 60.2 m. Loss tangents were low for the flow fields ranging from 0.024 to 0.043. Loss tangents in the plains ranged from 0.010 to 0.076. Higher loss tangents correspond to lossier regions that may have higher concentrations of radar absorbing minerals like hematite. Surface roughness controls where reflectors are detected. SHARAD detects the base of three out of the four flow fields in this region with muted surface roughness from dust mantling and erosion.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New Insights Into Subsurface Stratigraphy Northwest of Ascraeus Mons, Mars, Using the SHARAD and MARSIS Radar Sounders

et al. 2022

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“…10.1029/2021GL093618 2 of 10 ;McMichael et al, 2017). 2,682 and 10,981: MARSIS observes bright reflections (between the white arrows, green on top right) that exist at the thickest portions of the cap and extend to the margins -an impossible scenario for a localized heat source that melts basal water ice (see Supporting Information S1) (Plaut et al, 2007).…”

Section: Supporting Informationmentioning

confidence: 99%

“…Figure 1. Depth corrected Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) observations and locations at the South Polar Layered Deposits (SPLD;McMichael et al, 2017). 2,682 and 10,981: MARSIS observes bright reflections (between the white arrows, green on top right) that exist at the thickest portions of the cap and extend to the margins -an impossible scenario for a localized heat source that melts basal water ice (see Supporting Information S1)(Plaut et al, 2007).…”

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confidence: 99%

A Solid Interpretation of Bright Radar Reflectors Under the Mars South Polar Ice

Lalich

Rezza

Horgan

et al. 2021

Geophysical Research Letters

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Mars has been the subject of speculation regarding the presence of liquid water for well over a century (Lowell, 1895;Lowell & Lockyer, 1906), and this hypothesis persisted until the Mariner missions visited the planet for the first time in the 1960s and found the planet to be dry, rocky, and mostly covered with impact-induced craters (McCauley et al., 1972). Numerous outflow channels were observed, but with higher resolution and better coverage from the Viking missions, they turned out to be ancient and dry (Baker, 1982). As a result of these robotic investigations, discussions of current liquid water on Mars moved into the subsurface, where temperature and pressure regimes could plausibly lead to melting of ice (Clifford, 1993), potentially at the poles (Clifford, 1987). It was primarily for this reason that the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument (MARSIS) was sent to Mars, as specifically noted in a paper describing the instrument: "The primary scientific objective of the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS), which will be on board Mars Express mission scheduled for launch in 2003, is to map the distribution and depth of the liquid water/ice interface in the upper kilometres of the crust of Mars." (Picardi et al., 2004).In 2018, after more than a decade of acquiring observations and examining subsurface reflections (or the lack thereof), a candidate liquid detection was found beneath a portion of the south polar layered deposits (SPLD, Orosei et al., 2018). Orosei et al. (2018) reported anomalously bright MARSIS radar reflections near a region around 81°S, 193°E (Figure 1), in which the subsurface reflection was brighter than the surface

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Characteristics of the Basal Interface of the Martian South Polar Layered Deposits

Khuller

Plaut

2021

Geophysical Research Letters

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We expand on previous studies of the South Polar Layered Deposits' (SPLD) basal interface using data acquired by the Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) to obtain detailed maps of elevation, topography, and reflected radar power. Using these maps, we derive the thickness (ranging from 0 to 3.7 km) and volume of the SPLD (∼1.60 × 106 km3). While most basal interfaces reflect less power than the average SPLD surface, areas with basal echo power exceeding that of the surface are widespread throughout the SPLD, including at the location of potential subglacial water bodies in Ultimi Scopuli. The occurrence of these high basal echo power signatures appears to be largely frequency independent in MARSIS data. While the cause of the relatively high basal echo power values is uncertain, our observations suggest that this behavior is widespread, and not unique to Ultimi Scopuli.

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Radar autofocus algorithm incorporating terrain knowledge for correction of Mars' ionospheric distortion in MARSIS observations

Cited by 7 publications

References 7 publications

New Insights Into Subsurface Stratigraphy Northwest of Ascraeus Mons, Mars, Using the SHARAD and MARSIS Radar Sounders

New Insights Into Subsurface Stratigraphy Northwest of Ascraeus Mons, Mars, Using the SHARAD and MARSIS Radar Sounders

A Solid Interpretation of Bright Radar Reflectors Under the Mars South Polar Ice

Characteristics of the Basal Interface of the Martian South Polar Layered Deposits

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