Shannon MacKenzie
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View article: Ramparts around Lakes on Titan Impact Winds and Methane Evaporation
Ramparts around Lakes on Titan Impact Winds and Methane Evaporation Open
Understanding the lake–atmosphere interactions on Titan is crucial to answering some of Titan’s long-standing scientific questions, such as the unexpectedly high methane abundance close to the surface, or the “magic islands” that appear on…
View article: NASA's Dragonfly Rotorcraft Lander Mission to Titan
NASA's Dragonfly Rotorcraft Lander Mission to Titan Open
NASA’s fourth New Frontiers mission, Dragonfly (Turtle & Lorenz 2024), will land a robotic octocopter on Saturn’s moon Titan in 2034 to study its prebiotic chemistry, constrain its habitability, and search for potential chemical biosignatu…
View article: Exploring Enceladus’ Plume in Polarization
Exploring Enceladus’ Plume in Polarization Open
From Cassini’s in situ and remote sensing characterizations, we know that Enceladus’ plume is made of primarily water vapor and ice particles (e.g. Waite et al. 2006, 2009, 2017; Postberg et al. 2011). Salts and organics make up the rest o…
View article: Potential Spectral Signatures in the Visible Spectra of the Enceladus Plume
Potential Spectral Signatures in the Visible Spectra of the Enceladus Plume Open
A plume of both vapor and small particles constantly erupts from the South Polar Terrain on Saturn’s moon Enceladus. The particle component of this plume consists primarily of particles composed very pure water ice, but Cassini’s in situ i…
View article: Surface Phase Function Behavior and Deviation from Lambertian Across Titan's Tropics
Surface Phase Function Behavior and Deviation from Lambertian Across Titan's Tropics Open
Titan has one of the least understood surfaces in the entire Solar System, due largely to its thick haze-filled atmosphere that is opaque at many wavelengths of light. Some exceptions exist, such as eight spectral windows in the near-infra…
View article: Understanding Titan’s Chemical Factory: An Analysis of VIMS Occultation Data
Understanding Titan’s Chemical Factory: An Analysis of VIMS Occultation Data Open
Background/Motivation:Titan’s atmosphere is an organic factory, producing high-order hydrocarbons from the photolysis of methane by solar ultraviolet radiation [Lavvas et al. 2008]. These organics aggregate together to form tholins, which …
View article: Impacts on Ocean Worlds Are Sufficiently Frequent and Energetic to Be of Astrobiological Importance
Impacts on Ocean Worlds Are Sufficiently Frequent and Energetic to Be of Astrobiological Importance Open
Evidence for the beneficial role of impacts in the creation of urable or habitable environments on Earth prompts the question of whether meteorite impacts could play a similar role at other potentially urable/habitable worlds like Enceladu…
View article: Toward Prebiotic Chemistry on Titan: Impact Experiments on Organic Haze Particles
Toward Prebiotic Chemistry on Titan: Impact Experiments on Organic Haze Particles Open
Impacts are critical to producing the aqueous environments necessary to stimulate prebiotic chemistry on Titan’s surface. Furthermore, organic hazes resting on the surface are a likely feedstock of biomolecules. In this work, we conduct im…
View article: Pharmacoinformatics-enabled Interventions Improved Care Coordination and Identified Pharmacy-Related Safety Issues in a Multicultural Medicare Population
Pharmacoinformatics-enabled Interventions Improved Care Coordination and Identified Pharmacy-Related Safety Issues in a Multicultural Medicare Population Open
Background Compared to White populations, multicultural older adults experience more gaps in preventive care (e.g., vaccinations, screenings, chronic condition monitoring), social determinants of health barriers (e.g., access to care, lang…
View article: Cassini Bistatic Radar Observations of Titan's Seas: Results about Dielectric Properties and Capillary Waves Detection
Cassini Bistatic Radar Observations of Titan's Seas: Results about Dielectric Properties and Capillary Waves Detection Open
Between 2006 and 2016, the Cassini spacecraft carried out 13 bistatic radar observations of the surface of Saturn's largest moon, Titan. Unmodulated right circularly polarized radio signals were transmitted by the spacecraft to the moon…
View article: Science Objectives for Flagship-Class Mission Concepts for the Search for Evidence of Life at Enceladus
Science Objectives for Flagship-Class Mission Concepts for the Search for Evidence of Life at Enceladus Open
Cassini revealed that Saturn's Moon Enceladus hosts a subsurface ocean that meets the accepted criteria for habitability with bio-essential elements and compounds, liquid water, and energy sources available in the environment. Wheth…
View article: The Case for a New Frontiers–Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission
The Case for a New Frontiers–Class Uranus Orbiter: System Science at an Underexplored and Unique World with a Mid-scale Mission Open
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 t…
View article: Science goals and new mission concepts for future exploration of Titan’s atmosphere, geology and habitability: titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON)
Science goals and new mission concepts for future exploration of Titan’s atmosphere, geology and habitability: titan POlar scout/orbitEr and in situ lake lander and DrONe explorer (POSEIDON) Open
View article: Applying monitoring data to measure and improve rehabilitation performance at four mine sites in the Pilbara region of Western Australia
Applying monitoring data to measure and improve rehabilitation performance at four mine sites in the Pilbara region of Western Australia Open
Atlas Iron Pty Ltd (Atlas) rehabilitated four iron ore projects in the Pilbara region of Western Australia between 2013 and 2017.Rehabilitation works at each project have involved reshaping and revegetation works on waste rock landforms (W…
View article: Enceladus as a potential oasis for life: Science goals and investigations for future explorations
Enceladus as a potential oasis for life: Science goals and investigations for future explorations Open
View article: Science Goals and Objectives for the Dragonfly Titan Rotorcraft Relocatable Lander
Science Goals and Objectives for the Dragonfly Titan Rotorcraft Relocatable Lander Open
NASA’s Dragonfly mission will send a rotorcraft lander to the surface of Titan in the mid-2030s. Dragonfly's science themes include investigation of Titan’s prebiotic chemistry, habitability, and potential chemical biosignatures from both …
View article: Solving the Alhazen–Ptolemy Problem: Determining Specular Points on Spherical Surfaces for Radiative Transfer of Titan’s Seas
Solving the Alhazen–Ptolemy Problem: Determining Specular Points on Spherical Surfaces for Radiative Transfer of Titan’s Seas Open
Given a light source, a spherical reflector, and an observer, where on the surface of the sphere will the light be directly reflected to the observer, i.e., where is the specular point? This is known as the Alhazen–Ptolemy problem and find…
View article: Titan: Earth-like on the Outside, Ocean World on the Inside
Titan: Earth-like on the Outside, Ocean World on the Inside Open
Thanks to the Cassini–Huygens mission, Titan, the pale orange dot of Pioneer and Voyager encounters, has been revealed to be a dynamic, hydrologically shaped, organic-rich ocean world offering unparalleled opportunities to explore prebioti…
View article: The Case for a Return to Enceladus
The Case for a Return to Enceladus Open
The plume of Enceladus provides access to fresh material from a habitable, subsurface ocean. We summarize in this white paper the evidence for Enceladus’ ocean and its habitability, identify constraints and outstanding questions on the det…
View article: New Frontiers-class Uranus Orbiter: Exploring the feasibility of achieving multidisciplinary science with a mid-scale mission
New Frontiers-class Uranus Orbiter: Exploring the feasibility of achieving multidisciplinary science with a mid-scale mission Open
View article: Returning Samples from Enceladus for Life Detection
Returning Samples from Enceladus for Life Detection Open
Evidence suggests that Saturn’s icy moon Enceladus has a subsurface ocean that sources plumes of water vapor and ice vented to space from its south pole. In situ analyses of this material by the Cassini spacecraft have shown that the ocean…
View article: The Importance of Further Studies and Missions to Understand Cryovolcanism
The Importance of Further Studies and Missions to Understand Cryovolcanism Open
View article: Enabling the Next Frontiers in Astrobiology — Ocean and Ice Worlds Explorations with a Radioisotope Power System Inside a Pressure Vessel
Enabling the Next Frontiers in Astrobiology — Ocean and Ice Worlds Explorations with a Radioisotope Power System Inside a Pressure Vessel Open
View article: New Frontiers Titan Orbiter
New Frontiers Titan Orbiter Open
As one of two planetary objects (other than Earth) that have solid surfaces,thick atmospheres, and astrobiological significance, Titan, like Mars, merits ongoing studywith multiple spacecraft. We propose that a Titan orbiter dedicated to g…
View article: Responsiveness to Discovery
Responsiveness to Discovery Open
2. This white paper provides an initial discussion of example shifts from Vision & Voyages Decadal Survey recommendations, pros and cons of such shifts, and possible means of handling responsiveness to discovery in implementing Decadal Sur…
View article: Ocean Worlds: A Roadmap for Science and Exploration
Ocean Worlds: A Roadmap for Science and Exploration Open
The Outer Planets Assessment Group (OPAG) formed the Roadmaps to Ocean Worlds (ROW) group to 1) assemble the scientific framework guiding the exploration of Ocean Worlds over the next several decades; 2) to design a roadmap(s) to explore t…
View article: Selection and Characteristics of the Dragonfly Landing Site near Selk Crater, Titan
Selection and Characteristics of the Dragonfly Landing Site near Selk Crater, Titan Open
The factors contributing to the initial selection of a dune site near the Selk impact structure on Titan as the first landing site for the Dragonfly mission are described. These include arrival geometry and aerodynamic/aerothermodynamic co…
View article: Solving the Alhazen-Ptolemy Problem: Determining Specular Points on\n Spherical Surfaces for Radiative Transfer of Titan's Seas
Solving the Alhazen-Ptolemy Problem: Determining Specular Points on\n Spherical Surfaces for Radiative Transfer of Titan's Seas Open
Given a light source, a spherical reflector, and an observer, where on the\nsurface of the sphere will the light be directly reflected to the observer,\ni.e. where is the the specular point? This is known as the Alhazen-Ptolemy\nproblem, a…
View article: Returning Samples From Enceladus for Life Detection
Returning Samples From Enceladus for Life Detection Open
Evidence suggests that Saturn's icy moon Enceladus has a subsurface ocean that sources plumes of water vapor and ice vented to space from its south pole. In situ analyses of this material by the Cassini spacecraft have shown that the ocean…
View article: The root of anomalously specular reflections from solid surfaces on Saturn’s moon Titan
The root of anomalously specular reflections from solid surfaces on Saturn’s moon Titan Open