Jacob Buffo

Dartmouth College · Department of Engineering Sciences

The freezing point of water is negatively dependent on pressure; therefore in any ocean without external forcing it is warmest at the surface and grows colder with depth. Below floating ice on Earth (e.g., ice shelves or sea ice), this pressure dependence combines with gradients in the ice draft to drive an ice redistribution process termed the “ic...

The formation mechanism of Europa’s large chaos terrain (>∼100 km diameter) and associated lenticulae (<∼10 km diameter) has been debated since their observations by the Galileo spacecraft. Their geomorphology and distribution suggest there may be reservoirs of saline liquid water 1–3 km beneath the surface—the “shallow water” model—generated by in...

Non‐ice impurities within the ice shells of ocean worlds (e.g., Europa, Enceladus, Titan, Ganymede) are believed to play a fundamental role in their geophysics and habitability and may become a surface expression of subsurface ocean properties. Heterogeneous entrainment and distribution of impurities within planetary ice shells have been proposed a...

Bright basal reflectors in radargram from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) of the Martian south polar layered deposits (SPLD) have been interpreted to be evidence of subglacial lakes. However, this interpretation is difficult to reconcile with the low Martian geothermal heat flow and the frigid surface tempera...

Several worlds in our solar system are thought to hold oceans of liquid water beneath their frozen surfaces. These subsurface ice and ocean environments are promising targets in the search for life beyond Earth, but they also present significant new technical challenges to planetary exploration. With a focus on Jupiter’s moon Europa, here we (1) id...

Liquid water is a critical component of habitability. However, the production and stability of surficial liquid water can be challenging on planets outside the Habitable Zone and devoid of adequate greenhouse warming. On such cold, icy exoEarths, basal melting of regional, global ice sheets by geothermal heat provides an alternative means of formin...

Liquid water is a critical component of habitability. However, the production and stability of surficial liquid water can be challenging on planets outside the Habitable Zone and devoid of adequate greenhouse warming. On such cold, icy exo-Earths, basal melting of regional/global ice sheets by geothermal heat provides an alternative means of formin...

Brine systems in Europa's ice shell have been hypothesized as potential habitats that could be more accessible than the sub‐ice ocean. We model the distribution of sub‐millimeter‐scale brine pockets in Europa's ice shell. Through examination of three habitability metrics (water activity, ionic strength, and salinity), we determine that brine pocket...

The composition of impurities in ice controls the stability of liquid water and thus the distribution of potential aqueous habitats. We present a framework for modeling the brine volume fraction in impure water ice as a function of temperature and bulk ice salinity, inspired by models originally developed for sea ice. We applied this framework to e...

Although the nature of the early Martian climate is a matter of considerable debate, the presence of valley networks (VN) provides unambiguous evidence for the presence of liquid water on Mars' surface. A subaerial fluvial origin of VN is at odds with the expected phase instability of near-surface water in the cold, dry Late Noachian climate. Furth...

Enceladus is a primary target for astrobiology due to the salty plume ejecta measured by the Cassini spacecraft and the inferred subsurface ocean sustained by tidal heating. Sourcing the plumes via a direct connection from the ocean to the surface requires a fracture through the entire ice shell ($\sim$10 km). Here we explore an alternative mechani...

Accreted ice retains and preserves traces of the ocean from which it formed. In this work, we study two classes of accreted ice found on Earth-frazil ice, which forms through crystallization within a supercooled water column, and congelation ice, which forms through directional freezing at an existing interface-and discuss where each might be found...

We present thermophysical, biological, and chemical observations of ice and brine samples from five compositionally diverse hypersaline lakes in British Columbia's interior plateau. Possessing a spectrum of magnesium, sodium, sulfate, carbonate, and chloride salts, these low-temperature high-salinity lakes are analogs for planetary ice-brine enviro...

Liquid water is a critical component of habitability. However, the production and stability of surficial liquid water can be challenging on planets devoid of adequate greenhouse warming. On such cold, icy exo-Earths, basal melting of regional/global ice sheets by geothermal heat provides an alternative means of forming liquid water. Here, we model...

Titan is a chemically rich world that provides a natural laboratory for the study of the origin of life. Titan’s atmospherically derived C x H y N z molecules have been shown to form amino acids when mixed with liquid water, but the transition from prebiotic chemistry to the origin of life is not well understood. Investigating this prebiotic enviro...

Ocean worlds have been identified as high‐priority astrobiology targets due to the link between life and liquid water. Young surface terrain on many icy bodies indicates that they support active geophysical cycles that may facilitate ocean‐surface transport that could provide observables for upcoming missions. Accurately interpreting spacecraft obs...

The highly modified surface of Europa's ice shell hides a global, salty ocean that may hold conditions favorable for life, and cycles in the ice shell likely impact those conditions by allowing material transfer between the surface and subsurface ocean. The Galileo spacecraft observed a number of young geologic features that indicated Europa's ice...

Long-lived hydrothermal systems are prime targets for astrobiological exploration on Mars. Unlike magmatic or impact settings, radiogenic hydrothermal systems can survive for >100 million years because of the Ga half-lives of key radioactive elements (e.g., U, Th, and K), but remain unknown on Mars. Here, we use geochemistry, gravity, topography da...

From orbit, the visibility of Titan’s surface is limited to a handful of narrow spectral windows in the near-infrared (near-IR), primarily from the absorption of methane gas. This has limited the ability to identify specific compounds on the surface—to date Titan’s bulk surface composition remains unknown. Further, understanding of the surface comp...

Heat flow measurements are important for our understanding of planetary interior composition, structure, and evolution. In the absence of direct measurement, a first‐order estimate of a planet's interior heat flow can be made by modeling the lithosphere's viscoelastic response to stress exerted by large surface loads. Here, we model the Martian lit...

We investigate the structure and evolution of multiphase ice-ocean interfaces (‘mushy layers’) and the implications for the geophysics and habitability of ice-ocean worlds. Understanding the potential diversity of these multiphase layers across solar system bodies provides insight into the potential rates and mechanisms of heat and solute transport...

From orbit, the visibility of Titan's surface is limited to a handful of narrow spectral windows in the near-infrared (near-IR), primarily from the absorption of methane gas. This has limited the ability to identify specific compounds on the surface -- to date Titan's bulk surface composition remains unknown. Further, understanding of the surface c...

In explaining extensive evidence for past liquid water, the debate on whether Mars was primarily warm and wet or cold and arid 4 billion years (Ga) ago has continued for decades. The Sun’s luminosity was ~30% lower 4 Ga ago; thus, most martian climate models struggle to elevate the mean surface temperature past the melting point of water. Basal mel...

Compositional heterogeneities within Europa's ice shell likely impact the dynamics and habitability of the ice and subsurface ocean, but the total inventory and distribution of impurities within the shell are unknown. In sea ice on Earth, the thermochemical environment at the ice‐ocean interface governs impurity entrainment into the ice. Here, we s...

A growing number of satellites in the outer solar system likely have global oceans beneath their outer icy shells. While the presence of liquid water makes these ocean worlds compelling astrobiological targets, the exchange of heat and materials between the deep interior and the surface also plays a critical role in promoting habitable environments...

Landslides are among the most widespread geologic features on Ceres. Using data from Dawn's Framing Camera, landslides were previously classified based upon geomorphologic characteristics into one of three archetypal categories, Type 1(T1), Type 2 (T2), and Type 3 (T3). Due to their geologic context, variation in age, and physical characteristics,...

Abstract #P21E-3402, 2018AGUFM.P21E3402L

Sea ice seasonally to interannually forms a thermal, chemical, and physical boundary between the atmosphere and hydrosphere over tens of millions of square kilometers of ocean. Its presence affects both local and global climate and ocean dynamics, ice shelf processes, and biological communities. Accurate incorporation of sea ice growth and decay, a...

Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun that play an important role in space weather. Faraday rotation (FR) is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME. FR observations of a source near the Sun can provide informati...

Updated and continued analysis of SIMPLE project field data.

Exploration of the furthest reaches of our planet, as well as other planetary bodies, typically requires the use of robotic platforms due to the extreme environments encountered. Some of the harshest conditions on earth are found in Antarctica and require the use of autonomous underwater vehicles (AUVs) to explore remote and hazardous areas beneath...

Coronal mass ejections (CMEs) are large-scale eruptions of plasma from the Sun that play an important role in space weather. Faraday rotation (FR) is the rotation of the plane of polarization that results when a linearly polarized signal passes through a magnetized plasma such as a CME. FR observations of a source near the Sun can provide informati...

Earth’s thick ice shelves provide an important analog for the physicochemical, and potentially microbial, characteristics of icy worlds such as Europa.

The Icefin vehicle is a novel, custom under-ice unmanned underwater vehicle. This vehicle was designed for polar sub-ice deployment and was deployed to McMurdo, Antarctica in November of 2014. An overview of the unique vehicle design is presented here, along with a summary of the deployment testing in Antarctica. Lessons learned from this deploymen...

Many competing models for the coronal heating and acceleration mechanisms of the high-speed solar wind depend on the solar magnetic field and plasma structure in the corona within heliocentric distances of 5R(circle dot). We report on sensitive Very Large Array (VLA) full-polarization observations made in 2011 August, at 5.0 and 6.1 GHz (each with...

Proposed mechanisms for coronal heating and acceleration of the fast solar wind, such as Joule heating by coronal currents or dissipation of Alfvén waves, depend on the magnetic field structure and plasma characteristics of the corona within heliocentric distances of 5 solar radii. Faraday rotation observations can provide unique information on the...

In a recent paper Savage et al. 2013, ApJ 765, 42, we reported the results of our investigation of the super bubble associated with the Rosette Nebula (NGC 2244). We made linear polarization measurements of 23 extra-galactic radio sources whose lines of sight passed through or close to the Rosette Nebula. The observations were made at frequencies o...

Many competing models for the coronal heating and acceleration mechanisms of the high-speed solar wind depend on the solar magnetic field and plasma structure in the corona within heliocentric distances of 5 R ?. We report on sensitive Very Large Array (VLA) full-polarization observations made in 2011 August, at 5.0 and 6.1?GHz (each with a bandwid...

Identifying and understanding (1) the coronal heating mechanism and (2) the acceleration mechanism for the high-speed solar wind are two of the most important modern problems in solar physics. Many competing models of the high-speed solar wind depend on the solar magnetic field inside heliocentric distances of 5 solar radii. We report on sensitive...

Coronal Mass Ejections (CMEs) are one of the most important solar phenomena in affecting conditions on Earth. There is not a consensus as to the physical mechanisms responsible for ejecting CME material from the solar atmosphere. Measurements that specify basic physical properties close to the Sun, when the CME is still evolving, should be useful i...

Turbulence may play an important role in a number of interstellar processes. One of these is heating of the interstellar gas, as the turbulent energy is dissipated and changed into thermal energy of the gas, or at least other forms of energy. There have been very promising recent results on the mechanism for dissipation of turbulence in the Solar W...