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The evolution of a young ocean within Mimas

The fractured, young surfaces on confirmed ocean worlds such as Europa and Enceladus suggest that ocean-bearing moons with relatively thin overlying ice shells should be easy to identify. Hence, the discovery that Mimas’ rotation state is best explained by an internal ocean seems challenging to reconcile with its heavily cratered surface. Previous studies have shown that an internal ocean is compa
A. R. Rhoden, M. E. Walker, M. L. Rudolph, Michael T. Bland, Michael Manga

A new database of giant impacts over a wide range of masses and with material strength: A first analysis of outcomes

In the late stage of terrestrial planet formation, planets are predicted to undergo pairwise collisions known as giant impacts. Here, we present a high-resolution database of giant impacts for differentiated colliding bodies of iron–silicate composition, with target masses ranging from 1 × 10−4M⊕ up to super-Earths (5 M⊕). We vary the impactor-to-target mass ratio, core–mantle (iron–silicate) frac
Alexandre Emsenhuber, Erik Asphaug, Saverio Cambioni, Travis S. J. Gabriel, Stephen R. Schwartz, Robert E. Melikyan, C. Adeene Denton

Measuring erosional and depositional patterns across Comet 67P's imhotep region

Comet 67P/Churyumov-Gerasimenko displays a pronounced hemispherical dichotomy in surface morphology, where the southern hemisphere exhibits more erosional features than the northern hemisphere due to receiving much greater solar radiation. Consequently, it is generally assumed that particles are ejected from the southern hemisphere through sublimation and a significant fraction eventually descends
Abhinav S. Jindal, Samuel P. D. Birch, Alexander G. Hayes, F. P. Özyurt, A. Issah, S. Moruzzi, N. M. Barrington, Jason M. Soderblom, Randolph L. Kirk, R. Marschall, J.-B. Vincent

Evolution of a lake margin recorded in the Sutton Island member of the Murray formation, Gale crater, Mars

This study uses data from the Mars Science Laboratory Curiosity rover to document the facies of the Sutton Island member of the Murray formation, interpret paleoenvironments, and establish key stratigraphic transitions at Gale crater. Two facies associations were identified: Facies Association 1 (FA1) and Facies Association 2 (FA2). Individual facies in FA1 include planar-laminated mudstone with m
Samantha Gwizd, Christopher M. Fedo, John P. Grotzinger, Steve G. Banham, Frances Rivera-Hernandez, Sanjeev Gupta, Kathryn M. Stack, Lauren A. Edgar, Ashwin R. Vasavada, Joel M. Davis, Linda C. Kah

The lunar cratering chronology

This chapter provides an introduction to crater-size frequency distribution (CSFD) measurements and presents a review of the work performed on dating lunar geological units using CSFDs since the last New Views of the Moon volume (2006), including various volcanic and tectonic features, as well as individual impact craters. At the end of the chapter, implications for the new CSFD age determinations
Harald Hiesinger, Carolyn H. Van der Bogert, G. Michael, N. Schmedemann, W. Iqbal, Stuart J. Robbins, B. Ivanov, J.-P. Williams, M. Zanetti, J. Plescia, Lillian R. Ostrach, James W. Head III

Lunar mare basaltic volcanism: Volcanic features and emplacement processes

Volcanism is a fundamental process in the geological evolution of the Moon, providing clues to the composition and structure of the mantle, the location and duration of interior melting, the nature of convection and lunar thermal evolution. Progress in understanding volcanism has been remarkable in the short 60-year span of the Space Age. Before Sputnik 1 in 1957, the lunar farside was unknown, th
James W. Head III, Lionel Wilson, Harald Hiesinger, Carolyn H. Van der Bogert, Yuan Yuan Chen, James L. Dickson, Lisa Gaddis, Junichi Haruyama, Lauren Jozwiak, Erica Jawin, Chunlai Li, Jianzhong Liu, Tomokatsu Morota, Debra H. Needham, Lillian R. Ostrach, Carle M. Pieters, Tabb C. Prissel, Yuqi Qian, Lei Qiao, Malcolm R. Rutherford, David R. Scott, Jennifer L. Whitten, Long Xiao, Feng Zhang, Ouyang Ziyuan

Moon-forming impactor as a source of Earth’s basal mantle anomalies

Seismic images of Earth’s interior have revealed two continent-sized anomalies with low seismic velocities, known as the large low-velocity provinces (LLVPs), in the lowermost mantle. The LLVPs are often interpreted as intrinsically dense heterogeneities that are compositionally distinct from the surrounding mantle. Here we show that LLVPs may represent buried relics of Theia mantle material (TMM)
Qian Yuan, Mingming Li, Steven J. Desch, Byeongkwan Ko, Hongping Deng, Edward J. Garnero, Travis S. J. Gabriel, Jacob A. Kegerreis, Yoshinori Miyazaki, Vincent Eke, Paul D. Asimow

Relationship between explosive and effusive volcanism in the Montes Apenninus region of the Moon

Lunar Pyroclastic Deposits (LPDs) are sites of explosive volcanism and often occur in areas of effusive volcanism on the Moon. On Earth, it has been observed that most volcanism has both effusive and explosive phases, whereas on the Moon, these two types of volcanism have typically been considered separately. We hypothesize that the relationship between explosive and effusive volcanism on the Moon
Lori M Pigue, Kristen A. Bennett, Briony H.N. Horgan, Lisa Gaddis

Analyzing spatial distributions and alignments of pitted cone features in Utopia Planitia on Mars

Martian geomorphology and surface features provide links to understanding past geologic processes such as fluid movement, local and regional tectonics, and feature formation mechanisms. Pitted cones are common features in the northern plains basins of Mars. They have been proposed to have formed from upwelling volatile-rich fluids, such as magma or water-sediment slurries. In this study, we map th
Mackenzie M. Mills, Alfred S. McEwen, Amanda N. Hughes, Ji-Eun Kim, Chris Okubo

The inevitability of large shallow craters on Callisto and Ganymede: Implications for crater depth-diameter trends

Complex craters with diameters (D) ≥ 40 km on Callisto and Ganymede are shallower than would be expected from simply extrapolating the depth-diameter trend from smaller (D ≤ 40 km) craters. This unusual depth-diameter (d-D) trend, and associated changes in crater morphology, have been hypothesized to result from rheological transitions, including the existence of an ocean, within the moons' ice sh
Michael T. Bland, Veronica Bray

Evidence for fine-grained material at lunar red spots: Insights from thermal infrared and radar data sets

Lunar red spots are small spectrally red features that have been proposed to be the result of non-mare volcanism. Studies have shown that a number of red spots are silicic, and are spectrally distinct from both highlands and mare compositions. In this work, we use data from LRO Diviner, Mini-RF, and Arecibo to investigate the material properties of 10 red spots. We create albedo maps using Diviner
Benjamin Byron, Catherine Elder, Timothy Glotch, Paul Hayne, Lori M Pigue, Joshua T. S. Cahill

Exploring the interior of Europa with the Europa Clipper

The Galileo mission to Jupiter revealed that Europa is an ocean world. The Galileo magnetometer experiment in particular provided strong evidence for a salty subsurface ocean beneath the ice shell, likely in contact with the rocky core. Within the ice shell and ocean, a number of tectonic and geodynamic processes may operate today or have operated at some point in the past, including solid ice con
James Roberts, William B. McKinnon, Catherine Elder, Gabriel Tobie, John Biersteker, Duncan Young, Ryan S. Park, Gregor Steinbrügge, Francis Nimmo, Samuel Howell, Julie C. Castillo-Rogez, Morgan Cable, Jacob Abrahams, Michael T. Bland, Chase Chivers, Corey Cochrane, Andrew Dombard, Carolyn M. Ernst, Antonio Genova, Christopher Gerekos, Christopher R. Glein, Camilla Harris, Hamish Hay, Paul O. Hayne, Matthew Hedman, Hauke Hussmann, Xianzhe Jia, Krishan Khurana, Walter Kiefer, Randolph L. Kirk, Margaret Kivelson, Justin D. Lawrence, Erin J. Leonard, Jonathan Lunine, Erwan Mazarico, Thomas B. McCord, Alfred S. McEwen, Carol Paty, Lynnae Quick, Carol A. Raymond, Kurt Retherford, Lorenz Roth, Abigail Rymer, Joachim Saur, Kirk Scanlan, Dustin Schroeder, David Senske, Wencheng Shao, Krista Soderlund, Elizabeth Spiers, Marshall Styczinski, Paolo Tortora, Steven Vance, Michaela Villarreal, Benjamin Weiss, Joseph Westlake, Paul Withers, Natalie Wolfenbarger, Bonnie J. Buratti, Haje Korth, Robert Pappalardo, Interior Thematic Working Group