The standard linear fluid theory of Farley and Buneman predicts that kinetic physics are required to avoid the artificial growth of smaller structures. We explore the possibility of simulating the Farley–Buneman instability using, for the first time, a fully fluid five-moment model. This is the first time a fully fluid model has been used to simulate the Farley–Buneman instability. The results obtained with both models are qualitatively consistent with the ones from kinetic simulations.

The solar cycle affects the H₂O concentration in the upper mesosphere mainly in two ways: directly through photolysis and, at the time and place of NLC formation, indirectly through temperature changes. The H₂O–Lyman-α response is modified by NLC formation, resulting in a positive response at the ice formation region (due to the temperature change effect on the ice formation rate) and a negative response at the sublimation zone (due to the photolysis effect).

Earth’s space environment is populated with charged particles. The energetic ones are trapped around Earth in radiation belts. Orbiting spacecraft that cross their region can accumulate charges on their internal surfaces, leading to hazardous electrostatic discharges. This paper showcases the SafeSpace safety prototype, which aims to warn satellite operators of probable incoming hazardous events by simulating the dynamics of the electron radiation belts from their origin at the Sun.

In this work, we analyzed and compared measurements of electron fluxes in the radiation belts from two instruments with different orbits. In the outer belt, where the altitude difference is the largest between the two instruments, we find that the observations are in good agreement, except during geomagnetic storms, during which fluxes at low altitudes are much lower than at high altitudes. In general, both at low and high altitudes, the correlation between the instruments was found to be good.

The solar wind is in a plasma state and can exhibit a range of phenomena like waves and instabilities. One observed phenomenon in the solar wind is magnetic holes (MHs). They are localized depressions in the magnetic field. We studied the motion of MHs using the multispacecraft ESA Cluster mission. We derived their velocities in the solar wind frame and found that both linear and rotational MHs are convected with the solar wind.

The relation between electron, ion and neutral temperatures in the lower thermosphere–ionosphere (LTI) is key to understanding the energy balance and transfer between species. However, their simultaneous measurement is rare in the LTI. Based on data from the AE-C, AE-D, AE-E and DE-2 satellites of the 1970s and 1980s, a large number of events where neutrals are hotter than ions are identified and statistically analyzed. Potential mechanisms that could trigger these events are proposed.

We dealt with the most intense magnetic storm of the 20th century, which took place on 13–15 May 1921. It was also observed at Stará Ďala (present-day Hurbanovo). However, the record was not complete. We estimated the missing sensitivity scale values and presented the resulting digitized Stará Ďala’s data for 13–15 May 1921. The data were compared with the records from other observatories. The analysis suggests that the auroral oval got close to Stará Ďala in the morning hours on 15 May 1921.

Transverse electric fields transmitted from the magnetosphere and those generated by the neutral winds yield a local breakdown of the charge neutrality at the boundaries between the thermosphere and mesosphere. The breakdown may create parallel electric fields in the thermosphere to produce spiral auroras and outflows. This explanation supposes an auroral generator located not in a distant space, but rather in our much nearer upper atmosphere.

We improve a method for modeling the interaction between solar wind and Mars that uses a hybrid model to fit the observed bow shock location to determine a corresponding exobase ion upflux. We applied the method to one Mars Atmosphere and Volatile Evolution orbit to study the effects on ion escape estimates of heavy-ion composition in the ionosphere, alpha particles in the solar wind, solar-wind velocity aberration, and electron temperature. We also studied the morphology of the escaping ions.