Single event upset investigations on the “Flying Laptop” satellite mission

The radiation effects in electronic parts are called single-event effects, which are deemed to be critical for space missions. This paper presents the Single Event Upsets that were observed in an onboard memory device of the Low Earth Orbit “Flying Laptop” satellite mission during its in-orbit operation. The Single Event Upsets were carefully mapped on the satellite orbital space itself and their root causes were investigated together with their rates of occurrence. Subsequently, the events were traced to show several root cause sources such as (i) trapped energetic protons leaking to low altitudes within the South Atlantic Anomaly, (ii) Solar Energetic Particles emitted by an impulsive event on 10 September 2017, and (iii) Galactic Cosmic Rays. A profound analysis was carried out on the observed flight data, and its corresponding results are actually in agreement with the standard energetic particle models. The presented results provide another important insight on the Single Event Upsets for future Low Earth Orbit satellite missions.     

The Geophysics of Mercury: Current Status and Anticipated Insights from the MESSENGER Mission

Current geophysical knowledge of the planet Mercury is based upon observations from ground-based astronomy and flybys of the Mariner 10 spacecraft, along with theoretical and computational studies. Mercury has the highest uncompressed density of the terrestrial planets and by implication has a metallic core with a radius approximately 75% of the planetary radius. Mercury’s spin rate is stably locked at 1.5 times the orbital mean motion. Capture into this state is the natural result of tidal evolution if this is the only dissipative process affecting the spin, but the capture probability is enhanced if Mercury’s core were molten at the time of capture. The discovery of Mercury’s magnetic field by Mariner 10 suggests the possibility that the core is partially molten to the present, a result that is surprising given the planet’s size and a surface crater density indicative of early cessation of significant volcanic activity. A present-day liquid outer core within Mercury would require either a core sulfur content of at least several weight percent or an unusual history of heat loss from the planet’s core and silicate fraction. A crustal remanent contribution to Mercury’s observed magnetic field cannot be ruled out on the basis of current knowledge. Measurements from the MESSENGER orbiter, in combination with continued ground-based observations, hold the promise of setting on a firmer basis our understanding of the structure and evolution of Mercury’s interior and the relationship of that evolution to the planet’s geological history.     

Dynamo Models for Planets Other Than Earth

Observations from planetary spacecraft missions have demonstrated a spectrum of dynamo behaviour in planets. From currently active dynamos, to remanent crustal fields from past dynamo action, to no observed magnetization, the planets and moons in our solar system offer magnetic clues to their interior structure and evolution. Here we review numerical dynamo simulations for planets other than Earth. For the terrestrial planets and satellites, we discuss specific magnetic field oddities that dynamo models attempt to explain. For the giant planets, we discuss both non-magnetic and magnetic convection models and their ability to reproduce observations of surface zonal flows and magnetic field morphology. Future improvements to numerical models and new missions to collect planetary magnetic data will continue to improve our understanding of the magnetic field generation process inside planets.     

Paleomagnetic Records of Meteorites and Early Planetesimal Differentiation

The large-scale compositional structures of planets are primarily established during early global differentiation. Advances in analytical geochemistry, the increasing diversity of extraterrestrial samples, and new paleomagnetic data are driving major changes in our understanding of the nature and timing of these early melting processes. In particular, paleomagnetic studies of chondritic and small-body achondritic meteorites have revealed a diversity of magnetic field records. New, more sensitive and highly automated paleomagnetic instrumentation and an improved understanding of meteorite magnetic properties and the effects of shock, weathering, and other secondary processes are permitting primary and secondary magnetization components to be distinguished with increasing confidence. New constraints on the post-accretional histories of meteorite parent bodies now suggest that, contrary to early expectations, few if any meteorites have been definitively shown to retain records of early solar and protoplanetary nebula magnetic fields. However, recent studies of pristine samples coupled with new theoretical insights into the possibility of dynamo generation on small bodies indicate that some meteorites retain records of internally generated fields. These results indicate that some planetesimals formed metallic cores and early dynamos within just a few million years of solar system formation.     

Ωm – Different Ways to Determine the Matter Density of the Universe

A summary of various measurements of the mean matter density in the universe, _m, is presented. Results from very different kinds of methods using various astronomical objects – from supernovae to large-scale structure – are shown. There is a remarkable preference for _m values around 0.3, but there are also some measurements that favour a higher or a smaller value.