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Plasma sheet convection is a key element of storm‐time plasma dynamics in the magnetosphere. While decades of observations have advanced our understanding of convection in general, specifically storm‐time convection remains poorly understood. Using data from ISAS/NASA's Geotail and NASA's MMS, this study characterizes plasma sheet magnetic flux transport across the magnetotail during numerous storms (both recovery and main phases) and contrasts these observations with those from quiet times. Our findings confirm the well‐documented enhancement of the convection electric field during geomagnetic storms. Beyond that, our results reveal a significant dawn‐dusk asymmetry. At dawn, the elevated convection is realized via relatively faster flows while at dusk, through a stronger northward magnetic field. These findings suggest a complex feedback loop between plasma sheet convection and ring current buildup, whereby the latter asymmetrically inflates the magnetotail on the dusk side, shifting the reconnection site and subsequently enhanced earthward flows toward dawn. Plain Language Summary: Strong solar activity creates major disruptions of the Earth's magnetic field known as geomagnetic storms. These major disturbances of near‐Earth space can impact essential technologies like GPS systems and power grids. Our research used data from two space missions, ISAS/NASA's Geotail and NASA's MMS, to study how particles and magnetic fields move in space around Earth during such storms. We compared storm periods to calm times and evaluated the differences. During geomagnetic storms, we found that charged particles transport more magnetic flux due to stronger electric field. We further noted a significant difference between the dawn (morning) and dusk (evening) sectors on the nightside of the near‐Earth space environment. During storm times, plasma moves faster on the dawn side, while the magnetic field is stronger on the dusk side. This discovery reveals that plasma movement and energy buildup during storms are more complex than we thought. The energy buildup on the dusk side pushes plasma movement more toward the dawn side. Understanding these details helps us better predict the impacts of geomagnetic storms on Earth's space environment, which can improve our ability to protect our technology and infrastructure. Key Points: Convection electric field is elevated across the plasma sheet during storms, but convection properties are different between dawn and duskDawn magnetic flux transport during storm time is statistically associated with relatively faster flowsDusk magnetic flux transport during storm times is statistically associated with more dipolar magnetic fields [ABSTRACT FROM AUTHOR]

Plasma Depletion Events (PDEs) are characterized by abrupt, localized reductions in ionospheric plasma density at least by an order of magnitude decrease. These events are observed over a limited range of altitudes, typically spanning a few tens of kilometers. We use Mars Atmosphere and Volatile Evolution spacecraft data to investigate the properties and possible formation mechanism of daytime PDEs, typically observed at altitudes above 250 km. We show, using two example events and statistical analysis, that the depletion events are associated with electrostatic fluctuations and increased electron temperatures. The events are further accompanied by enhanced fluxes of suprathermal electrons and light energetic ions. These are indicative of local plasma heating, possibly mediated by the electrostatic fluctuations. The heated plasma may eventually escape from the depletion region through the ambipolar diffusion. Plain Language Summary: The Martian ionosphere, consisting of ions and electrons, is embedded in the planet's thin atmosphere. Density variations in the ionosphere, occurring on both large and small scales, can significantly impact the atmospheric loss process on Mars. One particular type of these ionospheric anomalies involves sudden reductions in ion density, often by tenfold or more. Although we have a basic understanding of these depletion events, their detailed characteristics and origins are not yet fully understood. We use data from various instruments onboard the Mars Atmosphere and Volatile Evolution spacecraft to investigate these phenomena, particularly on the dayside. We find that these depletion events are accompanied by increased electron temperatures and enhanced electric field fluctuations, while the magnetic field remains virtually unchanged. These observations suggest localized plasma heating within the depleted region. Furthermore, the fluxes of energetic light ions (mostly protons) and electrons are increased during the events. This increase in energetic particles could potentially serve as the energy source driving the heating process. We propose that the depletion events form when the heated ionospheric plasma escapes from the heated region. Key Points: Large scale plasma density depletions in the Martian dayside ionosphere are linked with electrostatic fluctuationsIncreased electron temperatures, enhanced suprathermal electron fluxes, and energetic light ions are observed within the depleted regionsLocal plasma heating possibly drives electron escape, forming an ambipolar field and causing plasma depletions through ambipolar diffusion [ABSTRACT FROM AUTHOR]

The design, characteristics, and performance of a CubeSat magnetometer board (Quad-Mag) equipped with four PNI RM3100 magnetometers is presented. The low size, weight, power, and cost of the RM3100 enables the inclusion of four sensors on a single board, allowing a potential factor of two reduction in the noise floor established for an individual sensor via oversampling with multiple sensors. The instrument experimentally achieved a noise floor of 5.345 nT (individual axis), averaging across each axis of the four magnetometers, at a 65 Hz sampling rate. This approaches the previously theoretically established limit for the system of 4.37 nT at 40 Hz. A single on-board, Texas Instrument MSP430 microcontroller handles synchronization of the magnetometers and facilitates data collection through a simple UART-based command interface to host system. The Quad-Mag system has a mass of 59.05 g and total power consumption of 23 mW while sampling and mW while idle. The Quad-Mag enables 1 nT magnetic field measurements at 1 Hz using commercial-off-the-shelf sensors for space applications. [ABSTRACT FROM AUTHOR]

A new sensor for measuring low-amplitude magnetic fields that is ideal for small spacecraft is presented. The novel measurement principle enables the fabrication of a low-cost sensor with low power consumption and with measuring capabilities that are comparable to recent developments for CubeSat applications. The current magnetometer, a software-modified version of a commercial sensor, is capable of detecting fields with amplitudes as low as 8.7 nT at 40 Hz and 2.7 nT at 1 Hz, with a noise floor of 500 pT/√(Hz) @ 1 Hz. The sensor has a linear response to less than 3 % over a range of ±100 000 nT. All of these features make the magneto-inductive principle a promising technology for the development of magnetic sensors for both space-borne and ground-based applications to study geomagnetic activity. [ABSTRACT FROM AUTHOR]