Publications (38)
Uranus Flagship Science-Driven Tour Design: Community Input Poll
Amy Simon, Ian Cohen, Matthew Hedman +3
The highest priority Planetary Flagship from the Planetary Science and Astrobiology Decadal Survey is the Uranus Orbiter and Probe. This mission enables broad, cross-disciplinary s…
Joint dynamical-geophysical evidence for a limit cycle in the Galilean moons
Amirhossein Bagheri, Steven Vance, Jim Fuller +5
Io, Europa, and Ganymede orbit in the Laplace mean-motion resonance, where their orbital and thermochemical evolution are strongly coupled [1-5]. Forced eccentricities sustain tida…
Mean radius and shape of Pluto and Charon from New Horizons images
Francis Nimmo, Orkan M Umurhan, Carey M Lisse +15
Approach images taken by the LORRI imaging system during the New Horizons spacecraft encounter have been used to determine the mean radii and shapes of Pluto and Charon. The primar…
Ocean tidal heating in icy satellites with solid shells
Isamu Matsuyama, Mikael Beuthe, Hamish C. F. C. Hay +2
As a long-term energy source, tidal heating in subsurface oceans of icy satellites can influence their thermal, rotational, and orbital evolution, and the sustainability of oceans.…
Impact-induced melting during accretion of the Earth
Jellie de Vries, Francis Nimmo, H. Jay Melosh +3
Because of the high energies involved, giant impacts that occur during planetary accretion cause large degrees of melting. The depth of melting in the target body after each collis…
Radiogenic Heating and its Influence on Rocky Planet Dynamos and Habitability
Francis Nimmo, Joel Primack, Sandra M. Faber +2
The thermal evolution of rocky planets on geological timescales (Gyr) depends on the heat input from the long-lived radiogenic elements potassium, thorium, and uranium. Concentrati…
Distribution of Europium in The Milky Way Disk; Its Connection to Planetary Habitability and The Source of The R-Process
Evan M. Carrasco, Matthew Shetrone, Francis Nimmo +3
The energy provided in the radioactive decay of thorium (Th) and uranium (U) isotopes, embedded in planetary mantles, sustains geodynamics important for surface habitability such a…
Non-synchronous rotation on Europa driven by ocean currents
Yosef Ashkenazy, Eli Tziperman, Francis Nimmo
It has been suggested that the ice shell of Jupiter's moon Europa may drift non-synchronously due to tidal torques. Here we argue that torques applied by the underlying ocean are a…
Isotopic evidence of long-lived volcanism on Io
Katherine de Kleer, Ery C. Hughes, Francis Nimmo +4
Jupiter's moon Io hosts extensive volcanism driven by tidal heating. The isotopic composition of Io's inventory of volatile elements, including sulfur and chlorine, reflects its ou…
Uranus Study Report: KISS
Mark Hofstadter, Ravit Helled, David J. Stevenson +27
Determining the internal structure of Uranus is a key objective for planetary science. Knowledge of Uranus's bulk composition and the distribution of elements is crucial to underst…
Oxygen False Positives on Habitable Zone Planets Around Sun-Like Stars
Joshua Krissansen-Totton, Jonathan J. Fortney, Francis Nimmo +1
Oxygen is a promising exoplanet biosignature due to the evolutionary advantage conferred by harnessing starlight for photosynthesis, and the apparent low likelihood of maintaining…
Tidal dissipation of binaries in asteroid pairs
Laurent Pou, Francis Nimmo
Tidal dissipation in a celestial body can be used to probe its internal structure. Tides govern the orbital evolution of binary systems and therefore constraints on the interior of…
Investigating tidal stripping of a pre-existing moon as the origin of Saturn's young icy rings
Yifei Jiao, Francis Nimmo, Jack Wisdom +1
The origin of Saturn's rings has been debated for decades. Measurements from Voyager and Cassini have suggested that the rings could be as young as ~100 Myr and composed of nearly…
The Geology of Pluto and Charon Through the Eyes of New Horizons
Jeffrey M. Moore, William B. McKinnon, John R. Spencer +38
NASA's New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Pluto's encounter hemisphere shows ongoing surface geological activity centered on a vast basin…
A mushy source for the geysers of Enceladus
Colin R. Meyer, Jacob J. Buffo, Francis Nimmo +5
Enceladus is a primary target for astrobiology due to the plume ejecta measured by the Cassini spacecraft and the inferred subsurface ocean sustained by tidal heating. S…
Nucleosynthetic Pt isotope anomalies and the Hf-W chronology of core formation in inner and outer solar system planetesimals
Fridolin Spitzer, Christoph Burkhardt, Francis Nimmo +1
The 182Hf-182W chronology of iron meteorites provides crucial information on the timescales of accretion and differentiation of some of the oldest planetesimals of the Solar System…
Comparing NASA Discovery and New Frontiers Class Mission Concepts for the Io Volcano Observer (IVO)
Christopher W. Hamilton, Alfred S. McEwen, Laszlo Keszthelyi +31
Jupiter's moon Io is a highly compelling target for future exploration that offers critical insight into tidal dissipation processes and the geology of high heat flux worlds, inclu…
Origin of moderately volatile elements in Earth inferred from mass-dependent Ge isotope variations among chondrites
Elias Wölfer, Christoph Burkhardt, Francis Nimmo +1
The bulk silicate Earth (BSE) is depleted in moderately volatile elements, indicating Earth formed from a mixture of volatile-rich and -poor materials. To better constrain the orig…
A Recipe for Geophysical Exploration of Enceladus
Anton I. Ermakov, Ryan S. Park, Javier Roa +13
Orbital geophysical investigations of Enceladus are critical to understanding its energy balance. We identified key science questions for the geophysical exploration of Enceladus,…
Persephone: A Pluto-System Orbiter and Kuiper Belt Explorer
Carly Howett, Stuart Robbins, Bryan J. Holler +40
Persephone is a NASA concept mission study that addresses key questions raised by New Horizons' encounters with Kuiper Belt objects (KBOs), with arguably the most important being "…
Mechanisms and timing of carbonaceous chondrite delivery to the Earth
Francis Nimmo, Thorsten Kleine, Alessandro Morbidelli +1
The nucleosynthetic isotope signatures of meteorites and the bulk silicate Earth (BSE) indicate that Earth consists of a mixture of "carbonaceous" (CC) and "non-carbonaceous" (NC)…
True Polar Wander of Lava Worlds
Wanying Kang, Francis Nimmo, Feng Ding
As one of the most detectable types of terrestrial planets, lava worlds are highly prioritized targets for exoplanet atmosphere characterization since their atmospheres may reveal…
The thermal-orbital evolution of the Earth-Moon system with a subsurface magma ocean and fossil figure
Brynna G. Downey, Francis Nimmo, Isamu Matsuyama
Various theories have been proposed to explain the Moon's current inclined orbit. We test the viability of these theories by reconstructing the thermal-orbital history of the Moon.…
A Collective Trigger for Widespread Planetesimal Formation Revealed by Accretion Ages
James Bryson, Hannah Sanderson, Francis Nimmo +4
The formation of planetesimals was an integral part of the cascading series of processes that built the terrestrial planets. To illuminate planetesimal formation, here we develop a…
Long-Term Evolution of the Saturnian System
Matija Äuk, Maryame El Moutamid, Giacomo Lari +5
Here we present the current state of knowledge on the long-term evolution of Saturn's moon system due to tides within Saturn. First we provide some background on tidal evolution, o…
An Investigation of Libration Heating and the Thermal State of Enceladus's Ice Shell
Wencheng D. Shao, Francis Nimmo
Tidal dissipation is thought to be responsible for the observed high heat loss on Enceladus. Forced librations can enhance tidal dissipation in the ice shell, but how such libratio…
HST/ACS Observations of Europa's Atmospheric UV Emission at Eastern Elongation
Joachim Saur, Paul D. Feldman, Lorenz Roth +7
We report results of a Hubble Space Telescope (HST) campaign with the Advanced Camera for Surveys to observe Europa at eastern elongation, i.e. Europa's leading side, on 2008 June…
Reassessing Sub-Neptune Structure, Radii, and Thermal Evolution
Yao Tang, Jonathan J. Fortney, Francis Nimmo +3
We present a novel python-based 1D sub-Neptune evolution model that emphasizes the thermal evolution and potential solidification of the rock/iron core and the structure of the rad…
Was Venus Ever Habitable? Constraints from a Coupled Interior-Atmosphere-Redox Evolution Model
Joshua Krissansen-Totton, Jonathan J. Fortney, Francis Nimmo
Venus's past climate evolution is uncertain. General circulation model simulations permit a habitable climate as late as ~0.7 Ga, and there is suggestive-albeit inconclusive-eviden…
Physicochemical Controls on the Compositions of the Earth and Planets
Paolo A. Sossi, Remco C. Hin, Thorsten Kleine +2
Despite the fact that the terrestrial planets formed from the protoplanetary disk, their compositions show marked departures from that of solar nebula condensates. Metallic cores f…
Large-scale cryovolcanic resurfacing on Pluto
Kelsi N. Singer, Oliver L. White, Bernard Schmitt +22
The New Horizons spacecraft returned images and compositional data showing that terrains on Pluto span a variety of ages, ranging from relatively ancient, heavily cratered areas to…
Thermal-orbital evolution of Eris
Ryunosuke Akiba, Francis Nimmo
The large Kuiper Belt object (KBO) Eris is nearly as big as Pluto and has a small moon, Dysnomia. Constraints on the system's spin and orbit characteristics were recently used to a…
New insights on Titan's interior from its obliquity
Benoit Noyelles, Francis Nimmo
We constructed a 6-degrees of freedom rotational model of Titan as a 3-layer body consisting of a rigid core, a fluid global ocean, and a floating ice shell. The ice shell exhibits…
Convection in a volatile nitrogen-ice-rich layer drives Pluto's geological vigor
William B. McKinnon, Francis Nimmo, Teresa Wong +61
The vast, deep, volatile-ice-filled basin informally named Sputnik Planum is central to Pluto's geological activity[1,2]. Composed of molecular nitrogen, methane, and carbon monoxi…
Constraints on terrestrial planet formation timescales and equilibration processes in the Grand Tack scenario from Hf-W isotopic evolution
Nicholas G. Zube, Francis Nimmo, Rebecca Fischer +1
We examine 141 N-body simulations of terrestrial planet late-stage accretion that use the Grand Tack scenario, coupling the collisional results with a hafnium-tungsten (Hf-W) isoto…
Resonant stratification in Titan's global ocean
Benjamin Idini, Francis Nimmo
Titan's ice shell floats on top of a global ocean revealed by the large tidal Love number registered by Cassini. The Cassini observation exceeds the predicted…
Did the terrestrial planets of the Solar System form by pebble accretion?
Alessandro Morbidelli, Thorsten Kleine, Francis Nimmo
The dominant accretion process leading to the formation of the terrestrial planets of the Solar System is a subject of intense scientific debate. Two radically different scenarios…
Inclination damping on Callisto
Brynna G. Downey, Francis Nimmo, Isamu Matsuyama
Callisto is thought to possess a subsurface ocean, which will dissipate energy due to obliquity tides. This dissipation should have damped any primordial inclination within 1 Gyr -…