Europa's ocean translates interior tidal heating patterns to the ice-ocean boundary

The authors thank the University of Texas Institute of Geophysics and Jackson School of Geosciences for funding.The circulation in Europa's ocean determines the degree of thermal, mechanical and chemical coupling between the ice shell and the silicate mantle. Using global direct numerical simulations, we investigate the effect of heterogeneous tidal heating in the silicate mantle on rotating thermal convection in the ocean and its consequences on ice shell thickness. Under the assumption of no salinity or ocean-ice shell feedbacks, we show that convection largely transposes the latitudinal variations of tidal heating from the seafloor to the ice, leading to a higher oceanic heat flux in polar regions. Longitudinal variations are efficiently transferred when boundary-driven thermal winds develop, but are reduced in the presence of strong zonal flows and may vanish in planetary regimes. If spatially homogeneous radiogenic heating is dominant in the silicate mantle, the ocean's contribution to ice shell thickness variations is negligible compared to tidal heating within the ice. If tidal heating is instead dominant in the mantle, the situation is reversed and the ocean controls the pole-to-equator thickness contrast, as well as possible longitudinal variations.Publisher PDFPeer reviewe

An Investigation of Ceratomyxa shasta sporulation following death of itsChinook salmon host

As pre-spawning mortality (PSM) in Chinook salmon in the Willamette River Valley becomes a more defined and examined area of study, more focus is granted to not only preserving the health of these fish, but also expanding knowledge concerning various pathogens that utilize the salmon as hosts and may be associated with PSM. One such parasite, a myxozoan named Ceratomyxa shasta, has been known to be extremely detrimental to salmon health, yet little literature exists concerning what exactly happens to this parasite once the salmon die. This thesis briefly outlines the complexity regarding this parasite’s relationship with the Chinook salmon, offers some context to transmission dynamics, and explores a recent investigation conducted over the course of the 2013-2014 academic year to determine the capability of Ceratomyxa shasta to live, continue to develop, and sporulate following the death of one of its hosts, the Chinook salmon

Experimental and Simulation Efforts in the Astrobiological Exploration of Exooceans

The icy satellites of Jupiter and Saturn are perhaps the most promising places in the Solar System regarding habitability. However, the potential habitable environments are hidden underneath km-thick ice shells. The discovery of Enceladus’ plume by the Cassini mission has provided vital clues in our understanding of the processes occurring within the interior of exooceans. To interpret these data and to help configure instruments for future missions, controlled laboratory experiments and simulations are needed. This review aims to bring together studies and experimental designs from various scientific fields currently investigating the icy moons, including planetary sciences, chemistry, (micro-)biology, geology, glaciology, etc. This chapter provides an overview of successful in situ, in silico, and in vitro experiments, which explore different regions of interest on icy moons, i.e. a potential plume, surface, icy shell, water and brines, hydrothermal vents, and the rocky core

Keys of a Mission to Uranus or Neptune, the Closest Ice Giants

Uranus and Neptune are the archetypes of "ice giants", a class of planets that may be among the most common in the Galaxy. They are the last unexplored planets of the Solar System, yet they hold the keys to understand the atmospheric dynamics and structure of planets with hydrogen atmospheres inside and outside the solar system

Planetary Exploration Horizon 2061 Report, Chapter 3: From science questions to Solar System exploration

This chapter of the Planetary Exploration Horizon 2061 Report reviews the way the six key questions about planetary systems, from their origins to the way they work and their habitability, identified in chapter 1, can be addressed by means of solar system exploration, and how one can find partial answers to these six questions by flying to the different provinces to the solar system: terrestrial planets, giant planets, small bodies, and up to its interface with the local interstellar medium. It derives from this analysis a synthetic description of the most important space observations to be performed at the different solar system objects by future planetary exploration missions. These observation requirements illustrate the diversity of measurement techniques to be used as well as the diversity of destinations where these observations must be made. They constitute the base for the identification of the future planetary missions we need to fly by 2061, which are described in chapter 4. Q1- How well do we understand the diversity of planetary systems objects? Q2- How well do we understand the diversity of planetary system architectures? Q3- What are the origins and formation scenarios for planetary systems? Q4- How do planetary systems work? Q5- Do planetary systems host potential habitats? Q6- Where and how to search for life?Comment: 107 pages, 37 figures, Horizon 2061 is a science-driven, foresight exercise, for future scientific investigation

New Frontiers-class Uranus Orbiter: Exploring the feasibility of achieving multidisciplinary science with a mid-scale mission

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The case for a New Frontiers-class Uranus Orbiter:System science at an underexplored and unique world with a mid-scale mission

Current knowledge of the Uranian system is limited to observations from the flyby of Voyager 2 and limited remote observations. However, Uranus remains a highly compelling scientific target due to the unique properties of many aspects of the planet itself and its system. Future exploration of Uranus must focus on cross-disciplinary science that spans the range of research areas from the planet's interior, atmosphere, and magnetosphere to the its rings and satellites, as well as the interactions between them. Detailed study of Uranus by an orbiter is crucial not only for valuable insights into the formation and evolution of our solar system but also for providing ground truths for the understanding of exoplanets. As such, exploration of Uranus will not only enhance our understanding of the ice giant planets themselves but also extend to planetary dynamics throughout our solar system and beyond. The timeliness of exploring Uranus is great, as the community hopes to return in time to image unseen portions of the satellites and magnetospheric configurations. This urgency motivates evaluation of what science can be achieved with a lower-cost, potentially faster-turnaround mission, such as a New Frontiers–class orbiter mission. This paper outlines the scientific case for and the technological and design considerations that must be addressed by future studies to enable a New Frontiers–class Uranus orbiter with balanced cross-disciplinary science objectives. In particular, studies that trade scientific scope and instrumentation and operational capabilities against simpler and cheaper options must be fundamental to the mission formulation