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Future remote sensing of exoplanets will be enhanced by a thorough investigation of our solar system Ice Giants (Neptune-size planets). What can the configuration of the magnetic field tell us (remotely) about the interior, and what implications does that field have for the structure of the magnetosphere; energy input into the atmosphere, and surface geophysics (for example surface weathering of satellites that might harbour sub-surface oceans). How can monitoring of auroral emission help inform future remote observations of emission from exoplanets? Our Solar System provides the only laboratory in which we can perform in-situ experiments to understand exoplanet formation, dynamos, systems and magnetospheres., Comment: Exoplanet Science Strategy White Paper, submitted to the National Academies of Sciences, Engineering and Medicine, Space Studies Board, 9 March 2018

Formation-flying studies to date have required continuous and minute corrections of the orbital elements and attitudes of the spacecraft.This increases the complexity, and associated risk, of controlling the formation, which often makes formation-flying studies infeasible for technological and economic reasons. Passive formation-flying is a novel space-flight concept, which offers a remedy to those problems. Spacecraft in a passive formation are allowed to drift and rotate slowly, but by using advanced metrology and statistical modelling methods, their relative positions, velocities, and orientations are determined with very high accuracy. The metrology data is used directly by the payloads to compensate for spacecraft motions in software. The normally very stringent spacecraft control requirements are thereby relaxed, which significantly reduces mission complexity and cost. Space-borne low-frequency radio astronomy has been identified as a key science application for a conceptual pathfinder mission using this novel approach. The mission, called FIRST (Formation-flying sub-Ionospheric Radio astronomy Science and Technology) Explorer, is currently under study by the European Space Agency (ESA). Its objective is to demonstrate passive formation-flying and at the same time perform unique world class science with a very high serendipity factor, by opening a new frequency window to astronomy., Comment: Presented at CEAS 2009 European Air & Space Conference - proceedings available for purchase from RAeS http://www.raes.org.uk . 14 pages, 10 figures

We present a new characterization of partially coherent electric and magnetic wave vector fields.This characterization is based on the 36 auto/cross correlations of the 3+3 complex Cartesian components of the electric and magnetic wave fields and is particularly suited for analyzing electromagnetic wave data on board spacecraft. Data from spacecraft based electromagnetic wave instruments are usually processed as data arrays. These data arrays however do not have a physical interpretation in themselves; they are simply a convenient storage format. In contrast, the characterization proposed here contains exactly the same information but are in the form of manifestly covariant space-time tensors. We call this data format the Canonical Electromagnetic Observables (CEO) since they correspond to unique physical observables. Some of them are already known, such as energy density, Poynting flux, stress tensor, etc, while others should be relevant in future space research. As an example we use this formalism to analyze data from a chorus emission in the mid-latitude magnetosphere, as recorded by the STAFF-SA instrument on board the Cluster-II spacecraft., Comment: 8 pages, 1 figure. Submitted to Annales Geophysicae

Starting from positive and negative helicity Maxwell equations expressed in Riemann-Silberstein vectors, we derive the ten usual and ten additional Poincar{\'e} invariants, the latter being related to the electromagnetic spin, i.e., the intrinsic rotation, or state of polarization, of the electromagnetic fields. Some of these invariants have apparently not been discussed in the literature before., Comment: 3 pages, 1 figure. Major revision

We present a systematic and physically motivated characterization of incoherent or coherent electric and magnetic fields, as measured for instance by the low frequency receiver on-board the Solar Orbiter spacecraft. The characterization utilizes the 36 auto/cross correlations of the 3+3 complex Cartesian components of the electric and magnetic fields; hence, they are second order in the field strengths and so have physical dimension energy density. Although such 6x6 correlation matrices have been successfully employed on previous space missions, they are not physical quantities; because they are not manifestly space-time tensors. In this paper we propose a systematic representation of the 36 degrees-of-freedom of partially coherent electromagnetic fields as a set of manifestly covariant space-time tensors, which we call the Canonical Electromagnetic Observables (CEO). As an example, we apply this formalism to analyze real data from a chorus emission in the mid-latitude magnetosphere, as registered by the STAFF-SA instrument on board the Cluster-II spacecraft. We find that the CEO analysis increases the amount of information that can be extracted from the STAFF-SA dataset; for instance, the reactive energy flux density, which is one of the CEO parameters, identifies the source region of electromagnetic emissions more directly than the active energy (Poynting) flux density alone.

Neutrinos interact with matter only through weak processes with low cross-section. To detect cosmic neutrinos most efforts have relied on the detection of visible Vavilov-Cerenkov light in detectors embedded in the target volumes. To access the decreasing flux of ultra-high energy neutrinos, far above 1 PeV, ideas on how to increase the detection volume by observing coherent radio frequency emission caused by the Askaryan effect have been put forward. Here we describe how a satellite in lunar orbit equipped with an electromagnetic vector sensor could detect Askaryan pulses induced by neutrinos interacting with the moon. The threshold neutrino energy is found to be 50 EeV for this setup, and the sensitivity is determined from simulations. A model dependent event rate of 2.2 events per year is calculated., Comment: 8 pages, 2 figures, to appear in the Proc. of the DGLR Int. Symp. "To Moon and Beyond", Bremen, Germany, (2005). v2: Fixed author affiliations, v3: Corrected typos, references