Explanipedia

Ion Reflection From the Martian Bow Shock Open

J. S. Halekas, D. L. Mitchell, C. Mazelle, J. R. Espley, Jacob Fruchtman · 2025

We utilize Mars Atmospheric and Volatile EvolutioN (MAVEN) observations to study reflected ions upstream from the Martian bow shock. We conduct back‐tracing of trajectories to separate ions in velocity space and quantify the reflected ion …

Role of ULF Waves in Reforming the Martian Bow Shock Open

Chi Zhang, Chuanfei Dong, Terry Z. Liu, C. Mazelle, Savvas Raptis , et al. · 2025

Understanding the nature of planetary bow shocks is beneficial for advancing our knowledge of solar wind interactions with planets and fundamental plasma physics processes. Here, we utilize data from the Mars Atmosphere and Volatile Evolut…

Global Energy Transport and Conversion in the Solar Wind-Mars Interaction: MAVEN Observations Open

Chi Zhang, Chuanfei Dong, Hongyang Zhou, J. S. Halekas, Xinmin Li , et al. · 2025

Ion velocity distributions upstream from the Martian bow shock: Recent results from MAVEN Open

C. Mazelle, K. Meziane, Cyril Simon Wedlund, C. Bertucci, J. S. Halekas , et al. · 2025

The region upstream from the bow shock of Mars is rich in different particle populations along with the associated physical processes. The MAVEN Solar Wind Ion Analyzer (SWIA) measures ion velocity distributions with unprecedented time and…

Field‐Aligned Proton Beams Upstream of the Martian Bow Shock: First Observations Open

K. Meziane, C. Mazelle, Cyril Simon Wedlund, J. S. Halekas, A. M. Hamza , et al. · 2025

We report fast sunward‐propagating energetic proton field‐aligned beams (FABs) observed about one Mars radius upstream of the Martian bow shock, recorded by the Solar Wind Ion Analyzer instrument on the MAVEN spacecraft. The velocity distr…

First direct observations of atmospheric sputtering at Mars Open

Shannon Curry, Takuya Hara, J. G. Luhmann, François Leblanc, R. Jolitz , et al. · 2025

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…

Predicting CO Cameron‐Band Auroral Emission at Venus Using VEx Electron Observations Open

Shaosui Xu, R. A. Frahm, Yingjuan Ma, D. L. Mitchell, J. G. Luhmann , et al. · 2025

Various types of auroral emissions have been observed at (partially) magnetized planets (e.g., Earth, Jupiter, and Mars). Auroral emissions have also been observed at Venus, an unmagnetized planet, by the Pioneer Venus Orbiter (PVO) and gr…

Observational Characteristics of Electron Distributions in the Martian Induced Magnetotail Open

Chi Zhang, Chuanfei Dong, Hongyang Zhou, Jan Deca, Shaosui Xu , et al. · 2025

Mars's magnetotail represents a unique case within the solar system, embodying both intrinsic and induced magnetic fields. Yet, the electron dynamics within this region have remained largely unexplored. Utilizing nine years of electron and…

Multipoint Observations of Magnetic Reconnection in the Martian Magnetotail Triggered by an Interplanetary Magnetic Field Rotation Open

Yuanzheng Wen, J. S. Halekas, Han‐Wen Shen, Abigail Azari, D. A. Brain , et al. · 2025

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…

Effects of Upstream Drivers on Magnetic Topology at Venus Open

Shaosui Xu, R. A. Frahm, Yingjuan Ma, J. G. Luhmann, D. L. Mitchell , et al. · 2025

Although Venus appears to present a predominantly ionospheric obstacle to the solar wind, the magnetic connectivity between the solar wind and the Venus ionosphere, or magnetic topology, is important for characterizing the Venus space envi…

Observation of Electric Field Enhancement at Ion Composition Boundary at Mars and Its Relation to Oxygen Acceleration Open

С. Д. Шувалов, L. Andersson, K. G. Hanley, J. S. Halekas, D. L. Mitchell , et al. · 2025

Direct electric field measurements during certain ionosphere‐magnetosheath transitions on the dayside of Mars reveal a presence of localized (20 km thickness along vertical direction) strong (40 mV/m) electric field located at the solar wi…

Space Weather Induces Changes in the Composition of Atmospheric Escape at Mars Open

K. G. Hanley, D. L. Mitchell, R. J. Lillis, C. M. Fowler, J. P. McFadden , et al. · 2024

Mars' dayside ionosphere is maintained primarily by ionization from solar ultraviolet photons and subsequent chemical reactions, with small contributions from other mechanisms such as impact ionization and charge exchange. In December 2023…

Application of a Scale Normalization Technique for High Resolution Analysis of the Magnetosheath at Mars Open

Jacob Fruchtman, J. S. Halekas, F. G. Eparvier, J. Gruesbeck, C. Mazelle , et al. · 2024

In order to study spatial distributions of global magnetosheath structures, physicists often rely upon spatial binning, whereby space is divided into cells, each filled with the average value of all spacecraft measurements within that cell…

C<sup>+</sup> 133.5 nm Emission Mechanisms on Mars Revealed by the MAVEN Observations Open

Shotaro Sakai, Hiromu Nakagawa, Justin Deighan, Sonal Jain, Kei Masunaga , et al. · 2024

C + emission is generated by electron impact, dissociative ionization, photoionization, and resonant scattering with carbon-related atoms, molecules, and ions in the Martian ionosphere and thermosphere. The contribution of each mechanism t…

On the Temporal Variability of High‐Altitude Reflection Potential Structures (HARPS) Open

A. Glocer, G. Collinson, Rachel Conway, Aroh Barjatya, R. Michell , et al. · 2024

High Altitude Reflection Potential Structures (HARPS) with typical magnitudes of a few tens of volts have been frequently detected above Earth's sunlit polar cap. They are thought to be electrostatic structures forming between 1 to several…

Characterization of Fuel and Cladding In and Near the Pellet-Pellet Gap of a High-Burnup Pressurized Water Reactor Fuel Rod Open

Rose Montgomery, Bruce Balkcom Bevard, Jason Harp, Tyson Jordan, Stephanie Curlin , et al. · 2024

At TopFuel 2021, we reported on metallographic examinations of a high burnup ZIRLO-clad spent fuel rod operated at the North Anna Power Station having a 3-mm gap between pellets at an elevation of ~1,403 mm. The rod was sectioned axially a…

Electron Energization by Ion Density Enhancement in the Martian Magnetotail—MAVEN Observations Open

Shaosui Xu, D. L. Mitchell, J. S. Halekas, J. P. McFadden, C. M. Fowler , et al. · 2024

It has been long observed at Mars that electron fluxes are enhanced during the tail current sheet crossings, of which the cause is not well understood. We use a novel approach to reveal one of the electron energization mechanisms with obse…

Source of Drift-dispersed Electrons in Martian Crustal Magnetic Fields Open

Chi Zhang, Hongyang Zhou, Chuanfei Dong, Yuki Harada, M. Yamauchi , et al. · 2024

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…

Two‐Spacecraft Observations of Asymmetric Martian Bow Shock: Conjunctions of Tianwen‐1 and MAVEN Open

Long Cheng, Yuming Wang, R. J. Lillis, J. S. Halekas, B. Langlais , et al. · 2024

The Martian bow shock has been extensively studied through magnetic field and plasma instrument observations from various Mars space missions. However, prior investigations primarily involve statistical analyses based on single spacecraft …

Closed magnetic topology in the Venusian magnetotail and ion escape at Venus Open

Shaosui Xu, D. L. Mitchell, P. L. Whittlesey, A. Rahmati, R. Livi , et al. · 2024

A Virtual Solar Wind Monitor at Mars With Uncertainty Quantification Using Gaussian Processes Open

Abigail Azari, Ellianna S. Abrahams, Facundo Sapienza, J. S. Halekas, John B. Biersteker , et al. · 2024

Single spacecraft missions do not measure the pristine solar wind continuously because of the spacecrafts' orbital trajectory. The infrequent spatiotemporal cadence of measurement fundamentally limits conclusions about solar wind‐magnetosp…

Progress in Understanding North American Monsoon Using a Climate Model Open

Ehsan Erfani, D. L. Mitchell · 2024

The North American Monsoon is a seasonal shift in the large-scale circulation that supplies 60-80% of annual rainfall in northwestern Mexico and 30-40% in the US southwest. Regional climate models have shown that summer precipitation predi…

Characterizing Precipitation Behaviors of H<sup>−</sup> in the Martian Atmosphere Open

Sarah Henderson, J. S. Halekas, R. Jolitz, D. L. Mitchell, C. Mazelle , et al. · 2024

Solar wind protons can charge exchange with the extensive hydrogen corona of Mars, resulting in a significant flux of energetic neutral atoms (ENAs). As these solar wind hydrogen ENAs precipitate into the upper atmosphere, they can experie…

The Martian Ionospheric Response to the Co‐Rotating Interaction Region That Caused the Disappearing Solar Wind Event at Mars Open

Skylar Shaver, Lincoln Solt, L. Andersson, J. S. Halekas, L. K. Jian , et al. · 2024

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 …

Evidence for a Current System and Potential Structure in the Martian Magnetotail Open

Murti Nauth, D. L. Mitchell, C. M. Fowler, Imke de Pater, Abigail Azari · 2024

We present a case study of plasma and magnetic field observations in the Martian magnetotail using data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission during an orbit when the spacecraft was in the optical shadow, past the…

Disappearing Solar Wind at Mars: Changes in the Mars‐Solar Wind Interaction Open

C. M. Fowler, Skylar Shaver, K. G. Hanley, L. Andersson, J. McFadden , et al. · 2024

On 26 December 2022 the solar wind density dropped by over an order of magnitude and remained low for about a day. We have utilized in‐situ plasma measurements made by the Mars Atmosphere and Volatile EvolutioN mission to determine how thi…

The Day the Solar Wind Disappeared at Mars Open

J. S. Halekas, Skylar Shaver, Abigail Azari, C. M. Fowler, Yingjuan Ma , et al. · 2023

In December 2022, an extremely low‐density solar wind stream encountered first the Earth and then Mars, shortly after the radial alignment of the two planets (i.e., Mars opposition). As the low‐density stream passed Mars, the properties of…

Open Magnetic Fields in the Martian Magnetosphere Revealing Dipole-like Intrinsic Magnetic Fields at Mars Open

Shaosui Xu, J. G. Luhmann, D. L. Mitchell, Tristan Weber, D. A. Brain , et al. · 2023

Mars’s magnetosphere is hybrid, having contributions from both an induced magnetosphere like Venus and the localized crustal magnetic fields. However, the planetary fields also include large-scale, more global components. In this study, we…

MAVEN H- Data (2014-2023) Open

Sarah Henderson, J. S. Halekas, R. Jolitz, D. L. Mitchell, C. Mazelle , et al. · 2023

These data were primarily obtained from the Neutral Gas and Ion Mass Spectrometer (NGIMS), Solar Wind Ion Analyzer (SWIA), and Solar Wind Electron Analyzer (SWEA) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. These…

MAVEN H- Data (2014-2023) Open

Sarah Henderson, J. S. Halekas, R. Jolitz, D. L. Mitchell, C. Mazelle , et al. · 2023

These data were primarily obtained from the Neutral Gas and Ion Mass Spectrometer (NGIMS), Solar Wind Ion Analyzer (SWIA), and Solar Wind Electron Analyzer (SWEA) onboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. These…

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