Direct evidence of substorm-related impulsive injections of electrons at Mercury.

Mercury's magnetosphere is known to involve fundamental processes releasing particles and energy like at Earth due to the solar wind interaction. The resulting cycle is however much faster and involves acceleration, transport, loss, and recycling of plasma. Direct experimental evidence for the roles of electrons during this cycle is however missing.

A source of very energetic oxygen located in Jupiter's inner radiation belts.

Jupiter hosts the most hazardous radiation belts of our solar system that, besides electrons and protons, trap an undetermined mix of heavy ions. The details of this mix are critical to resolve because they can reveal the role of Jupiter’s moons relative to other less explored energetic ion sources. Here, we show that with increasing energy and in the vicinity of Jupiter’s moon Amalthea, the belts’ ion composition transitions from sulfur- to oxygen-dominated due to a local source of ≳50 MeV/nucleon oxygen.

Titan's exosphere and its interaction with Saturn's magnetosphere.

Titan's nitrogen-rich atmosphere is directly bombarded by energetic ions, due to its lack of a significant intrinsic magnetic field. Singly charged energetic ions from Saturn's magnetosphere undergo charge-exchange collisions with neutral atoms in Titan's upper atmosphere, or exosphere, being transformed into energetic neutral atoms (ENAs). The ion and neutral camera, one of the three sensors that comprise the magnetosphere imaging instrument (MIMI) on the Cassini/Huygens mission to Saturn and Titan, images these ENAs like photons, and measures their fluxes and energies.

New surprises in the largest magnetosphere of our solar system.

En route to its ultimate rendezvous with Pluto, the New Horizons spacecraft passed through the magnetic and plasma environment of Jupiter in February 2007. Onboard instruments collected high-resolution images, spectroscopic data, and information about charged particles. The results have revealed unusual structure and variation in Jupiter's plasma and large plasmoids that travel down the magnetotail.

The source of Saturn's G ring.

The origin of Saturn's narrow G ring has been unclear. We show that it contains a bright arc located 167,495.6 +/- 1.

A nebula of gases from Io surrounding Jupiter.

Several planetary missions have reported the presence of substantial numbers of energetic ions and electrons surrounding Jupiter; relativistic electrons are observable up to several astronomical units (au) from the planet. A population of energetic (>30[?]keV) neutral particles also has been reported, but the instrumentation was not able to determine the mass or charge state of the particles, which were subsequently labelled energetic neutral atoms. Although images showing the presence of the trace element sodium were obtained, the source and identity of the neutral atoms---and their overall significance relative to the loss of charged particles from Jupiter's magnetosphere---were unknown.