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Eos ◽  
2022 ◽  
Vol 103 ◽  
Author(s):  
Kimberly Cartier
Keyword(s):  

Sometimes ocean dynamics are a drag.


2021 ◽  
Vol 13 (24) ◽  
pp. 5097
Author(s):  
Michael T. Bland ◽  
Randolph L. Kirk ◽  
Donna M. Galuszka ◽  
David P. Mayer ◽  
Ross A. Beyer ◽  
...  

Jupiter’s moon Europa harbors one of the most likely environments for extant extraterrestrial life. Determining whether Europa is truly habitable requires understanding the structure and thickness of its ice shell, including the existence of perched water or brines. Stereo-derived topography from images acquired by NASA Galileo’s Solid State Imager (SSI) of Europa are often used as a constraint on ice shell structure and heat flow, but the uncertainty in such topography has, to date, not been rigorously assessed. To evaluate the current uncertainty in Europa’s topography we generated and compared digital terrain models (DTMs) of Europa from SSI images using both the open-source Ames Stereo Pipeline (ASP) software and the commercial SOCET SET® software. After first describing the criteria for assessing stereo quality in detail, we qualitatively and quantitatively describe both the horizontal resolution and vertical precision of the DTMs. We find that the horizontal resolution of the SOCET SET® DTMs is typically 8–11× the root mean square (RMS) pixel scale of the images, whereas the resolution of the ASP DTMs is 9–13× the maximum pixel scale of the images. We calculate the RMS difference between the ASP and SOCET SET® DTMs as a proxy for the expected vertical precision (EP), which is a function of the matching accuracy and stereo geometry. We consistently find that the matching accuracy is ~0.5 pixels, which is larger than well-established “rules of thumb” that state that the matching accuracy is 0.2–0.3 pixels. The true EP is therefore ~1.7× larger than might otherwise be assumed. In most cases, DTM errors are approximately normally distributed, and errors that are several times the derived EP occur as expected. However, in two DTMs, larger errors (differences) occur and correlate with real topography. These differences primarily result from manual editing of the SOCET SET® DTMs. The product of the DTM error and the resolution is typically 4–8 pixel2 if calculated using the RMS image scale for SOCET SET® DTMs and the maximum images scale for the ASP DTMs, which is consistent with recent work using martian data sets and suggests that the relationship applies more broadly. We evaluate how ASP parameters affect DTM quality and find that using a smaller subpixel refinement kernel results in DTMs with smaller (better) resolution but, in some cases, larger gaps, which are sometimes reduced by increasing the size of the correlation kernel. We conclude that users of ASP should always systematically evaluate the choice of parameters for a given dataset.


2021 ◽  
Author(s):  
Natalie Wolfenbarger ◽  
Jacob Buffo ◽  
Krista Soderlund ◽  
Donald Blankenship
Keyword(s):  

2021 ◽  
Vol 13 (17) ◽  
pp. 3476
Author(s):  
Paul Schenk ◽  
Chloe Beddingfield ◽  
Tanguy Bertrand ◽  
Carver Bierson ◽  
Ross Beyer ◽  
...  

The topography of Neptune’s large icy moon Triton could reveal important clues to its internal evolution, but has been difficult to determine. New global digital color maps for Triton have been produced as well as topographic data for <40% of the surface using stereogrammetry and photoclinometry. Triton is most likely a captured Kuiper Belt dwarf planet, similar though slightly larger in size and density to Pluto, and a likely ocean moon that exhibited plume activity during Voyager 2′s visit in 1989. No surface features or regional deviations of greater than ±1 km amplitude are found. Volatile ices in the southern terrains may take the form of extended lobate deposits 300–500 km across as well as dispersed bright materials that appear to embay local topography. Limb hazes may correlate with these deposits, indicating possible surface–atmosphere exchange. Triton’s topography contrasts with high relief up to 6 km observed by New Horizons on Pluto. Low relief of (cryo)volcanic features on Triton contrasts with high-standing massifs on Pluto, implying different viscosity materials. Solid-state convection occurs on both and at similar horizontal scales but in very different materials. Triton’s low relief is consistent with evolution of an ice shell subjected to high heat flow levels and may strengthen the case of an internal ocean on this active body.


Author(s):  
Anthony Haag ◽  
Oliver Burch ◽  
Damian Ineichen ◽  
Philippe Block ◽  
Francesco Ranaudo
Keyword(s):  

Icarus ◽  
2021 ◽  
Vol 364 ◽  
pp. 114466
Author(s):  
Ondřej Čadek ◽  
Klára Kalousová ◽  
Jakub Kvorka ◽  
Christophe Sotin
Keyword(s):  

2021 ◽  
Author(s):  
Martin Kihoulou ◽  
Klára Kalousová ◽  
Ondřej Souček ◽  
Ondřej Čadek
Keyword(s):  

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