Density variations within the south polar layered deposits of Mars

Li, Junlun; Andrews-Hanna, J. C.; Sun, Youshun; Phillips, R. J.; Plaut, J. J.; Zuber, M. T.

doi:10.1029/2011je003937

Cited by 18 publications

(18 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thus, the model results lead us to conclude that recent magmatism may offer a plausible explanation for enhanced heat flux. Gravity inversions intriguingly suggest a positive density anomaly near the region, which could be associated with subsurface structure in the crust involving magmatism (Li et al, 2012), but future higher-resolution gravity data would be needed to convincingly test this possible association.…”

Section: 1029/2018gl080985mentioning

confidence: 99%

Water on Mars, With a Grain of Salt: Local Heat Anomalies Are Required for Basal Melting of Ice at the South Pole Today

Sori

Bramson

2019

Geophysical Research Letters

View full text Add to dashboard Cite

Recent analysis of radar data from the Mars Express spacecraft has interpreted bright subsurface radar reflections as indicators of local liquid water at the base of the south polar layered deposits (SPLD). However, the physical and geological conditions required to produce melting at this location were not quantified. Here we use thermophysical models to constrain parameters necessary to generate liquid water beneath the SPLD. We show that no concentration of salt is sufficient to melt ice at the base of the SPLD in the present day under typical Martian conditions. Instead, a local enhancement in the geothermal heat flux of >72 mW/m2 is required, even under the most favorable compositional considerations. This heat flow is most simply achieved via the presence of a subsurface magma chamber emplaced 100 s of kyr ago. Thus, if the liquid water interpretation of the observations is correct, magmatism on Mars may have been active extremely recently.

show abstract

Section: 1029/2018gl080985mentioning

confidence: 99%

Water on Mars, With a Grain of Salt: Local Heat Anomalies Are Required for Basal Melting of Ice at the South Pole Today

Sori

Bramson

2019

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…This type of ice, usually called dirty ice, is uncommon on Earth as the amount of grain content in meteoric ice is negligible (usually lower than 1%) [ Petit et al, ]. Conversely, dirty ice is common in planetary materials, as demonstrated by recent measurements on the Martian polar caps [ Plaut et al ., ; Li et al, ] and by observations performed on the icy Galilean satellite surfaces [ Moore et al, ; Pappalardo et al, ]. The literature on dielectric measurements of dirty ice analogs is fairly limited and relatively recent.…”

Section: Dielectric Properties Of Hydrates and Icy Mixturesmentioning

confidence: 99%

Dielectric properties of Jovian satellite ice analogs for subsurface radar exploration: A review

Pettinelli

Cosciotti

Paolo

et al. 2015

Reviews of Geophysics

View full text Add to dashboard Cite

The first European mission dedicated to the exploration of Jupiter and its icy moons (JUpiter ICy moons Explorer-JUICE) will be launched in 2022 and will reach its final destination in 2030. The main goals of this mission are to understand the internal structure of the icy crusts of three Galilean satellites (Europa, Ganymede, and Callisto) and, ultimately, to detect Europa's subsurface ocean, which is believed to be the closest to the surface among those hypothesized to exist on these moons. JUICE will be equipped with the 9 MHz subsurface-penetrating radar RIME (Radar for Icy Moon Exploration), which is designed to image the ice down to a depth of 9 km. Moreover, a parallel mission to Europa, which will host onboard REASON (Radar for Europa Assessment and Sounding: Ocean to Near-surface) equipped with 9MHz and 60MHz antennas, has been recently approved by NASA. The success of these experiments strongly relies on the accurate prediction of the radar performance and on the optimal processing and interpretation of radar echoes that, in turn, depend on the dielectric properties of the materials composing the icy satellite crusts. In the present review we report a complete range of potential ice types that may occur on these icy satellites to understand how they may affect the results of the proposed missions. First, we discuss the experimental results on pure and doped water ice in the framework of the Jaccard theory, highlighting the critical aspects in terms of a lack of standard laboratory procedures and inconsistency in data interpretation. We then describe the dielectric behavior of extraterrestrial ice analogs like hydrates and icy mixtures, carbon dioxide ice and ammonia ice. Building on this review, we have selected the most suitable data to compute dielectric attenuation, velocity, vertical resolution, and reflection coefficients for such icy moon environments, with the final goal being to estimate the potential capabilities of the radar missions as a function of the frequency and temperature ranges of interest for the subsurface sounders. We present the different subsurface scenarios and associated radar signal attenuation models that have been proposed so far to simulate the structure of the crust of Europa and discuss the physical and geological nature of various dielectric targets potentially detectable with RIME. Finally, we briefly highlight several unresolved issues that should be addressed, in near future, to improve our capability to produce realistic electromagnetic models of icy moon crusts. The present review is of interest for the geophysical exploration of all solar system bodies, including the Earth, where ice can be present at the surface or at relatively shallow depths.

show abstract

“…It can be seen in Figure 3 that the occurrence of

in the absence of water-bearing materials is possible only for a dielectric constant below that of water ice, leaving CO

ice as the main possible constituent of surface material ( Table 1 ). However, CO

ice is considered to be a minor component of the Southern polar cap of Mars [ 54 ], and it has not been detected outside the polar regions. By contrast, in the absence of appreciable attenuation within the surface material, brine would produce strong reflections even if the permittivity of surface material was that of basaltic rocks ( Table 1 ).…”

Section: Radar Sounding and Subsurface Water Detectionmentioning

confidence: 99%

The Global Search for Liquid Water on Mars from Orbit: Current and Future Perspectives

Orosei

Ding

et al. 2020

Life

View full text Add to dashboard Cite

Due to its significance in astrobiology, assessing the amount and state of liquid water present on Mars today has become one of the drivers of its exploration. Subglacial water was identified by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) aboard the European Space Agency spacecraft Mars Express through the analysis of echoes, coming from a depth of about 1.5 km, which were stronger than surface echoes. The cause of this anomalous characteristic is the high relative permittivity of water-bearing materials, resulting in a high reflection coefficient. A determining factor in the occurrence of such strong echoes is the low attenuation of the MARSIS radar pulse in cold water ice, the main constituent of the Martian polar caps. The present analysis clarifies that the conditions causing exceptionally strong subsurface echoes occur solely in the Martian polar caps, and that the detection of subsurface water under a predominantly rocky surface layer using radar sounding will require thorough electromagnetic modeling, complicated by the lack of knowledge of many subsurface physical parameters. Higher-frequency radar sounders such as SHARAD cannot penetrate deep enough to detect basal echoes over the thickest part of the polar caps. Alternative methods such as rover-borne Ground Penetrating Radar and time-domain electromagnetic sounding are not capable of providing global coverage. MARSIS observations over the Martian polar caps have been limited by the need to downlink data before on-board processing, but their number will increase in coming years. The Chinese mission to Mars that is to be launched in 2020, Tianwen-1, will carry a subsurface sounding radar operating at frequencies that are close to those of MARSIS, and the expected signal-to-noise ratio of subsurface detection will likely be sufficient for identifying anomalously bright subsurface reflectors. The search for subsurface water through radar sounding is thus far from being concluded.

show abstract

Density variations within the south polar layered deposits of Mars

Cited by 18 publications

References 35 publications

Water on Mars, With a Grain of Salt: Local Heat Anomalies Are Required for Basal Melting of Ice at the South Pole Today

Water on Mars, With a Grain of Salt: Local Heat Anomalies Are Required for Basal Melting of Ice at the South Pole Today

Dielectric properties of Jovian satellite ice analogs for subsurface radar exploration: A review

The Global Search for Liquid Water on Mars from Orbit: Current and Future Perspectives

Contact Info

Product

Resources

About