Mars Global Surveyor Bistatic Radar Probing of the MPL/DS2 Target Area

Simpson, R. A.; Tyler, G. L.

doi:10.1006/icar.2001.6629

Cited by 4 publications

(5 citation statements)

References 16 publications

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“…The theoretical value of δf ~2 Hz is therefore the lower limit of the differential Doppler shift between the surface echo and direct signal, under the assumptions that (1) the position and rotational velocity of the echo site on Vesta are well-represented by a point on the surface, and (2) Dawn’s orbital velocity is constant. Our calculation is consistent with the expectation of a small frequency separation due to Dawn’s low orbital velocity that is orders of magnitude smaller than observed in typical orbital BSR experiments at larger planetary bodies—such as for the orbital BSR experiment by the Mars Global Surveyor spacecraft, which detected radar reflections from the martian surface that were separated by as much as 10 kHz from the received direct signal 8 .…”

Section: Resultssupporting

confidence: 90%

“…Over the past decades, orbital BSR experiments have been used to assess the textural (and in some cases, dielectric) properties of the surfaces of terrestrial bodies such as Mercury 2 , Venus 3 , the Moon 4 – 6 , Mars 7 , 8 , Saturn’s moon Titan 9 , and now comet 67P/CG 10 . In contrast to most orbital BSR experiments, Dawn’s HGA beam intersected Vesta’s surface at grazing angles of incidence near 89° and in a microgravity environment with substantial variability in its gravity field 11 , leading to a low and variable orbital velocity and hence a more challenging detection of the Doppler-shifted surface echo (hereafter simply referred to as the “surface echo”).…”

Section: Introductionmentioning

confidence: 99%

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Orbital bistatic radar observations of asteroid Vesta by the Dawn mission

2017

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We present orbital bistatic radar observations of a small-body, acquired during occultation by the Dawn spacecraft at asteroid Vesta. The radar forward-scattering properties of different reflection sites are used to assess the textural properties of Vesta’s surface at centimeter-to-decimeter scales and are compared to subsurface hydrogen concentrations observed by Dawnʼs Gamma Ray and Neutron Detector to assess potential volatile occurrence in the surface and shallow subsurface. We observe significant differences in surface radar reflectivity, implying substantial spatial variations in centimeter-to-decimeter-scale surface roughness. Our results suggest that unlike the Moon, Vesta’s surface roughness variations cannot be explained by cratering processes only. In particular, the occurrence of heightened hydrogen concentrations within large smoother terrains (over hundreds of square kilometers) suggests that potential ground-ice presence may have contributed to the formation of Vesta’s current surface texture. Our observations are consistent with geomorphological evidence of transient water flow from Dawn Framing Camera images.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Orbital bistatic radar observations of asteroid Vesta by the Dawn mission

2017

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“…So far all the observations of solid CO 2 on Mars were performed in the higher part of the electromagnetic spectrum, i.e. in the infrared [ Klassen et al , 1999; Hansen , 1999] and microwave ranges [ Simpson and Tyler , 2001], although future missions will perform measurements in the MHz range using orbiting radar capable to probe the subsurface at depth [ Picardi et al , 1999; Biccari et al , 2001]. Furthermore, future lander missions might involve the sounding of the Martian subsurface with Ground‐Probing Radar or with other electrical or electromagnetic geophysical methods.…”

Section: Introductionmentioning

confidence: 99%

Frequency and time domain permittivity measurements on solid CO₂ and solid CO₂–soil mixtures as Martian soil simulants

Pettinelli

2003

J. Geophys. Res.

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[1] Permittivity and conductivity measurements were performed to assess the dielectric behavior of solid CO 2 (i.e., CO 2 ice, snow, and powder) and solid CO 2 /soil mixtures. For comparison, some dielectric measurements were also conducted on H 2 O ice, dry glass beads, glass beads saturated with water, drained glass beads, and frozen drained glass beads. The measurements were performed in the frequency domain (20 Hz to 1 MHz) using a capacitive cell (Parallel Plate Capacitor) and in the time domain using a transmission line (Time Domain Reflectometry). The data obtained with both techniques have shown that solid CO 2 has a permittivity value that ranges between 1.4 and 2.1 as a function of density, values that distinguish it from H 2 O ice. In contrast, H 2 O ice, dry glass beads, frozen (drained) glass beads, and dry volcanic sand all have very similar permittivity values, and thus they cannot be clearly distinguished at higher frequencies. Data have also shown that a high volume fraction of solid CO 2 significantly reduces the permittivity value of a soil. Furthermore, almost all the samples tested in this work seem to behave like low loss materials, having a conductivity which is generally equal to or lower than 10 À6 Sm À1 at the highest frequency (and smaller values at lower frequencies). Finally, TDR measurements and data from some dielectric models were compared in order to assess the capability of these models to predict the permittivity of a granular multiphase material.

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“…. Example of the differential Doppler shift (δf ) or frequency separation between the direct signal and BSR surface echoes for two different missions(Simpson & Tyler 2001;Palmer et al 2017). The δf for the Mars Global Surveyor's BSR observations on the left is several orders of magnitude larger than the δf for Dawn BSR at Vesta owing to the much slower spacecraft orbital velocity around a small body, which is accounted for by PARSE when suggesting reasonable processing parameters for a given mission.…”

mentioning

confidence: 99%

“…The δf for the Mars Global Surveyor's BSR observations on the left is several orders of magnitude larger than the δf for Dawn BSR at Vesta owing to the much slower spacecraft orbital velocity around a small body, which is accounted for by PARSE when suggesting reasonable processing parameters for a given mission. (Plots are adapted fromSimpson &Tyler 2001 andPalmer et al 2017. )…”

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confidence: 99%

Processing and Analysis for Radio Science Experiments (PARSE): Graphical Interface for Bistatic Radar

2022

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Opportunistic bistatic radar (BSR) observations of planetary surfaces can probe the textural and electrical properties of several solar system bodies without needing a dedicated instrument or additional mission requirements, providing unique insights into volatile enrichment and supporting future landing, anchoring, and in situ sampling. Given their opportunistic nature, complex observation geometries, and required radiometric knowledge of the received radio signal, these data are particularly challenging to process, analyze, and interpret for most planetary science data users, who can be unfamiliar with link budget analysis of received echoes. The above impedes real-time use of BSR data to support mission operations, such as identifying safe landing locations on small bodies, as was the case for the Rosetta mission. To address this deficiency, we develop an open-source graphical user interface—Processing and Analysis for Radio Science Experiments (PARSE)—that assesses the feasibility of performing BSR observations and automates radiometric signal processing, power spectral analysis, and visualization of DSN planetary radio science data sets acquired during mission operations or archived on NASA’s Planetary Data System. In this first release, PARSE automates the processing chain developed for Dawn at Asteroid Vesta, streamlining the detection of DSN-received surface-scatter echoes generated as the spacecraft enters/exits occultations behind the target. Future releases will include support for existing Arecibo data sets and other Earth-based radio observatories. Our tool enables the broader planetary science community, beyond planetary radar signal processing experts, to utilize BSR data sets to characterize electrical and textural properties of planetary surfaces. Such tools are becoming increasingly important as the number of space missions—and subsequent opportunities for orbital radio science observations—continue to grow.

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Mars Global Surveyor Bistatic Radar Probing of the MPL/DS2 Target Area

Cited by 4 publications

References 16 publications

Orbital bistatic radar observations of asteroid Vesta by the Dawn mission

Orbital bistatic radar observations of asteroid Vesta by the Dawn mission

Frequency and time domain permittivity measurements on solid CO₂ and solid CO₂–soil mixtures as Martian soil simulants

Processing and Analysis for Radio Science Experiments (PARSE): Graphical Interface for Bistatic Radar

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Mars Global Surveyor Bistatic Radar Probing of the MPL/DS2 Target Area

Cited by 4 publications

References 16 publications

Orbital bistatic radar observations of asteroid Vesta by the Dawn mission

Orbital bistatic radar observations of asteroid Vesta by the Dawn mission

Frequency and time domain permittivity measurements on solid CO2 and solid CO2–soil mixtures as Martian soil simulants

Processing and Analysis for Radio Science Experiments (PARSE): Graphical Interface for Bistatic Radar

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Frequency and time domain permittivity measurements on solid CO₂ and solid CO₂–soil mixtures as Martian soil simulants