No abstract

We present simultaneous measurements at high temporal resolution of flux transfer events (FTEs) earthward of the magnetopause using four instruments on the Active Magnetospheric Particle Tracer Explorers (AMPTE) UKS spacecraft. The seven events in our study are distributed in local time from early dawn to midafternoon over a GSM latitude range of ∼40°, from 24°N to 17°S. A multilayered structure is revealed with systematic behavior in fields and charged particle populations. The plasma pressure varies in anticorrelation with the field pressure, the total pressure in general exceeding that of the surrounding medium. While it is not the prime concern of this paper to discuss the validity of models proposed for FTEs, the new, detailed experimental results it contains make it clear that the Russell‐Elphic [1978] model needs, at the very least, more detailed development.

Entry of heated solar wind plasma into the magnetosphere is examined using electron distributions measured by AMPTE UKS and HEOS 2. In particular, the angular structure of the electron distributions is studied within the transition region separating the magnetosheath from the inner magnetosphere. The measurements suggest that electrons in the outer part of the transition region originate in the magnetosheath, whilst the population closer to the Earth consists of electrons from the magnetosphere combined with an energized magnetosheath component. This energized component contains “counterstreaming” electrons, which are confined to directions closely parallel and antiparallel to the magnetic field direction. The possibilities, that the energization of the counterstreaming electrons is cumulatively gained from either waves, electric fields perpendicular to the magnetic field, or quasi‐Fermi acceleration, are discussed. It is not possible to identify the topology of the magnetic fields of the outer part of the region, but there is strong evidence that the inner part is on closed magnetic field lines, which map to the day side auroral zone. The outer part of the transition region is a plasma depletion/magnetic field compression layer. The structure of the transition region is similar to that surrounding flux transfer events, which leads to the deduction that the plasma and field signatures of flux transfer events may be the result of displacement of the transition region earthward. Cases where the displacement is such that the field maximum of the depletion/compression region is encountered may well explain “crater” flux transfer event signatures.

The "Ice Giants" Uranus and Neptune are a different class of planet compared to Jupiter and Saturn. Studying these objects is important for furthering our understanding of the formation and evolution of the planets, and unravelling the fundamental physical and chemical processes in the Solar System. The importance of filling these gaps in our knowledge of the Solar System is particularly acute when trying to apply our understanding to the numerous planetary systems that have been discovered around other stars. The Uranus Pathfinder (UP) mission thus represents the quintessential aspects of the objectives of the European planetary community as expressed in ESA's Cosmic Vision 2015-2025. UP was proposed to the European Space Agency's M3 call for medium-class missions in 2010 and proposed to be the first orbiter of an Ice Giant planet. As the most accessible Ice Giant within the M-class mission envelope Uranus was identified as the mission target. Although not selected for this call the UP mission concept provides a baseline framework for the exploration of Uranus with existing low-cost platforms and underlines

No abstract