D. A. Brain
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View article: The Exospace Weather Frontier
The Exospace Weather Frontier Open
Space weather is among the most powerful and least understood forces shaping planetary atmospheres. We observe its effects directly on Solar System bodies through atmospheric escape, chemical disruption, cometary tails, and auroral display…
View article: Magnetohydrodynamic Study of Mars’s Response to Short-term Solar Wind Dynamic Pressure Enhancements
Magnetohydrodynamic Study of Mars’s Response to Short-term Solar Wind Dynamic Pressure Enhancements Open
As a weakly magnetized planet, Mars interacts directly with the highly variable solar wind, where small-scale and short-duration structures are ubiquitous. Among solar wind parameters, dynamic pressure, as the dominant external pressure, p…
View article: Energy Conservation for Stellar Wind Mass-Loading: Atmospheric Ion Escape
Energy Conservation for Stellar Wind Mass-Loading: Atmospheric Ion Escape Open
We construct an analytical paradigm called ‘Particles in a Box’ to study the interaction between the solar wind and terrestrial ionospheres. Using energy flux conservation, we derive how wind deceleration drives magnetic pile-up and quanti…
View article: Comparing plasma measurements at Mars during close conjunctions of MAVEN and Mars Express
Comparing plasma measurements at Mars during close conjunctions of MAVEN and Mars Express Open
Introduction: Mars lacks an intrinsic global magnetic field, unlike Earth. Instead, the solar wind interacts directly with the upper atmosphere, creating an induced magnetic field that is much weaker compared to a global magnetic field. Lo…
View article: Deriving IMF Properties From Mars Express Heavy Pickup Ion Measurements
Deriving IMF Properties From Mars Express Heavy Pickup Ion Measurements Open
We present Mars Express (MEX) observations of heavy pickup ions (HPUI) at Mars and a new method to derive interplanetary magnetic field (IMF) properties. The MEX HPUI measurements were organized using the upstream IMF directions measured b…
View article: Interplanetary Hydrogen Observations of the Emirates Ultraviolet Spectrometer Onboard the Emirates Mars Mission
Interplanetary Hydrogen Observations of the Emirates Ultraviolet Spectrometer Onboard the Emirates Mars Mission Open
The Emirates Mars Ultraviolet Spectrometer (EMUS) aboard the Emirates Mars Mission (EMM) has been studying backscattered interplanetary hydrogen (interplanetary hydrogen (IPH)) Lyman emissions with dedicated observation strategies viz., U‐…
View article: First direct observations of atmospheric sputtering at Mars
First direct observations of atmospheric sputtering at Mars Open
Billions of years ago, Mars’ ability to sustain liquid water waned as the solar wind and radiation began to erode the atmosphere. Sputtering is an atmospheric escape process that may have been dominant during earlier epochs of our Sun acco…
View article: Multipoint Observations of Magnetic Reconnection in the Martian Magnetotail Triggered by an Interplanetary Magnetic Field Rotation
Multipoint Observations of Magnetic Reconnection in the Martian Magnetotail Triggered by an Interplanetary Magnetic Field Rotation Open
The induced magnetosphere of Mars is highly dynamic, driven by both the upstream solar wind and the planet’s crustal magnetic fields. This variability can occur on timescales much shorter than a single spacecraft orbit, making it difficult…
View article: Piercing the Martian Veil: A Statistical Study of Interplanetary Magnetic Field Reach Through Ionospheric Pressure Balance
Piercing the Martian Veil: A Statistical Study of Interplanetary Magnetic Field Reach Through Ionospheric Pressure Balance Open
Mars, being a small planet with a tenuous atmosphere, does not have a sharp boundary between regions dominated by solar wind plasma and planetary plasma. Instead, this transition is typically extended, allowing the interplanetary magnetic …
View article: Comprehensive Comparison of Two Global Multi‐Species MHD Models of Mars
Comprehensive Comparison of Two Global Multi‐Species MHD Models of Mars Open
Understanding the interaction between Mars and the solar wind is crucial for comprehending the atmospheric evolution and climate change on Mars. To gain a comprehensive understanding of the Martian plasma environment, global numerical simu…
View article: Atmospheric ion escape and solar wind deposition as a function of planetary radius
Atmospheric ion escape and solar wind deposition as a function of planetary radius Open
We explore the ability of an unmagnetized planet to retain an atmosphere as a function of its radius. We use a particle-in-cell hybrid code to simulate the global plasma interaction of unmagnetized terrestrial planets at 1 au under average…
View article: Source of Drift-dispersed Electrons in Martian Crustal Magnetic Fields
Source of Drift-dispersed Electrons in Martian Crustal Magnetic Fields Open
Mars lacks a global intrinsic dipole field but possesses localized crustal fields, making it unique in the solar system. Recent observations revealed that electrons can be injected into the crustal fields, and exhibit drift-dispersed burst…
View article: Atmospheric Escape From Earth and Mars: Response to Solar and Solar Wind Drivers of Oxygen Escape
Atmospheric Escape From Earth and Mars: Response to Solar and Solar Wind Drivers of Oxygen Escape Open
Habitability at the surface of a planet depends on having an atmosphere long enough for life to develop. The loss of atmosphere to space is an important component in assessing planetary surface habitability. Current models of atmospheric e…
View article: Statistical Analysis of Discrete Aurora on Mars: Variability with Magnetic Topology, Local Time and Season
Statistical Analysis of Discrete Aurora on Mars: Variability with Magnetic Topology, Local Time and Season Open
We present a comprehensive study of the nightside discrete electron aurora phenomenon on Mars, utilizing observations from EMUS onboard EMM. The oxygen emission at 130.4 nm is by far the brightest FUV auroral emission line observed at Mars…
View article: EMM EMUS Observations of FUV Aurora on Mars: Dependence on Magnetic Topology, Local Time, and Season
EMM EMUS Observations of FUV Aurora on Mars: Dependence on Magnetic Topology, Local Time, and Season Open
We present a comprehensive study of the nightside aurora phenomenon on Mars, utilizing observations from EMUS onboard Emirates Mars Mission. The oxygen emission at 130.4 nm is by far the brightest FUV auroral emission line observed at Mars…
View article: Variability of Atomic Hydrogen Brightness in the Martian Exosphere: Insights From the Emirates Ultraviolet Spectrometer on Board Emirates Mars Mission
Variability of Atomic Hydrogen Brightness in the Martian Exosphere: Insights From the Emirates Ultraviolet Spectrometer on Board Emirates Mars Mission Open
The Emirates Mars Ultraviolet Spectrometer (EMUS), aboard the Emirates Mars Mission (EMM), has been conducting observations of ultraviolet emissions within the Martian exosphere. Taking advantage of the distinctive orbit of the EMM around …
View article: Atmospheric Retention on Demagnetized Earth
Atmospheric Retention on Demagnetized Earth Open
It is commonly claimed that Earth's intrinsic magnetic field protects its atmosphere from being stripped away by the solar wind. We test this claim by analyzing the stability of Earth's atmosphere in the case that the geomagnetic field is …
View article: Characteristics of plasma boundaries with large density gradients and their effects on Kelvin–Helmholtz instability
Characteristics of plasma boundaries with large density gradients and their effects on Kelvin–Helmholtz instability Open
Boundaries between space plasmas occur in numerous contexts and scales, from astrophysical jets to planetary magnetospheres. Mass and momentum transport across boundaries poses a fundamental problem in magnetospheric physics. Kelvin–Helmho…
View article: Solar and Solar Wind Energy Drivers for O<sup>+</sup> and O2+ ${\mathrm{O}}_{2}^{+}$ Ion Escape at Mars
Solar and Solar Wind Energy Drivers for O<sup>+</sup> and O2+ ${\mathrm{O}}_{2}^{+}$ Ion Escape at Mars Open
Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular ox…
View article: Exoplanet Magnetic Fields
Exoplanet Magnetic Fields Open
Planetary magnetic fields are important indicators of planetary processes and evolution, from a planet's outer core to its surface (if it possesses one) to its atmosphere and near-space environment. Magnetic fields are most directly measur…
View article: Exploring Mars discrete aurora with synoptic images and movies from EMM EMUS
Exploring Mars discrete aurora with synoptic images and movies from EMM EMUS Open
Benefiting from a large orbit and high sensitivity, the Emirates Mars mission EMUS instrument has provided the first opportunity to synoptically and regularly image Mars’ discrete FUV auroral oxygen emission at 130.4 and 135.6 nm.…
View article: The Solar Wind: A net source or sink for terrestrial mass?
The Solar Wind: A net source or sink for terrestrial mass? Open
Shortly after the solar wind was first measured by the Second Soviet Cosmic Rocket (Luna 2) in 1959, planetary scientists immediately began wondering if it might be a source of mass for terrestrial atmospheres; perhaps even providing the E…
View article: Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars
Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars Open
Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular ox…
View article: EMM EMUS Observations of Hot Oxygen Corona at Mars: Radial Distribution and Temporal Variability
EMM EMUS Observations of Hot Oxygen Corona at Mars: Radial Distribution and Temporal Variability Open
We present the first observations of the dayside coronal oxygen emission in far ultraviolet (FUV) measured by the Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM). The high sensitivity of EMUS is provid…
View article: The Martian Ionospheric Response to the Co‐Rotating Interaction Region That Caused the Disappearing Solar Wind Event at Mars
The Martian Ionospheric Response to the Co‐Rotating Interaction Region That Caused the Disappearing Solar Wind Event at Mars Open
An unusually low density solar wind event was observed in December 2022 moving past both Earth and Mars. The source was traced back to a coronal hole and active region on the Sun's surface. The resulting solar wind lead to the development …
View article: Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars
Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars Open
Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular ox…
View article: Atmospheric Escape from Earth and Mars: Solar and Solar Wind Drivers of Oxygen Escape
Atmospheric Escape from Earth and Mars: Solar and Solar Wind Drivers of Oxygen Escape Open
We derive oxygen escape rates from Earth as a function of solar wind parameters from a reanalysis of Dynamics Explorer 1 data.• O + escape from Earth varies by a factor of 2 as a function of the solar wind magnetic field component aligned …
View article: Discrete Aurora at Mars: Insights Into the Role of Magnetic Reconnection
Discrete Aurora at Mars: Insights Into the Role of Magnetic Reconnection Open
Discrete aurora are sporadic emissions of light originating in Mars upper atmosphere. We report nadir imaging observations from MAVEN's Imaging UltraViolet Spectrograph which identify the conditions which trigger electron precipitation cau…
View article: EMM EMUS Observations of Hot Oxygen Corona at Mars: Radial Distribution and Temporal Variability
EMM EMUS Observations of Hot Oxygen Corona at Mars: Radial Distribution and Temporal Variability Open
We present the first observations of the dayside coronal oxygen emission in far ultraviolet (FUV) measured by the Emirates Mars Ultraviolet Spectrometer (EMUS) onboard the Emirates Mars Mission (EMM).The high sensitivity of EMUS is providi…
View article: Evidence for Magnetic Reconnection as the Precursor to Discrete Aurora at Mars
Evidence for Magnetic Reconnection as the Precursor to Discrete Aurora at Mars Open
Discrete aurora at Mars are characterized as localized, short‐lasting ultraviolet emissions on the nightside. They are caused by the precipitation of accelerated electron along open magnetic field lines and their collision with the Martian…