Jovian Energetic Neutrals and Ions (JENI) instrument and the Jovian Energetic Electrons (JoEE) detectors
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Seeing the Hot Cloud Around Jupiter

Building on instrument designs used on missions such as NASA’s Cassini, the Jovian Energetic Neutrals and Ions (JENI) instrument and the Jovian Energetic Electrons (JoEE) detectors will reveal the rich, superheated cloud of particles around Jupiter and help deduce what makes this planet the solar system’s largest particle accelerator.

About the Instrument

Instrument Type
Particle

The space environment around Jupiter is unlike any other in the solar system: It has the fastest rotation, the strongest magnetic field, and the most powerful aurora and radiation belts. Embedded within this space environment are peculiar moons, including Ganymede — the solar system’s largest moon and the only one that has a magnetic field — and the volcanic moon Io, which, with its sibling ocean moon Europa, is the source of oxygen and sulfur ions found in Jupiter’s magnetosphere — the largest cohesive structure in the solar system.

A detailed, 3D rendering of the JoEE instrument and JENI instrument
A detailed, 3D rendering of the JoEE instrument (left) and JENI instrument (right) that will ride on the European Space Agency's JUICE mission to Jupiter and its moons.

APL built two state-of-the-art instruments for the European Space Agency’s Jupiter Icy Moons Explorer, or JUICE, mission to explore this exciting system: the JENI and JoEE instruments. JENI will use a technique pioneered at APL to image neutral atoms that form from interactions between the plasma and neutral gases from the moons with Jupiter’s intense radiation environment. JoEE is an innovative electron particle spectrometer that will use 3D-printed collimators to map the processes responsible for making Jupiter the solar system’s largest particle accelerator.

JoEE’s high-resolution measurements of electrons moving at near lightspeed around Jupiter (depicted in thermal colors)
JoEE’s high-resolution measurements of electrons moving at near lightspeed around Jupiter (depicted in thermal colors above) are possible because of nine collimators (center, in hand) of unprecedented precision. These precise collimators are made by a 3D-printing process on metal pioneered at APL. This innovative process enables new designs that require extreme tolerances and is projected to revolutionize what is mechanically possible in space.

Jupiter's magnetosphere propels electrons to nearly the speed of light and creates a fierce radiation environment around the planet. By simultaneously measuring the electron energy spectra over many directions around the moon Ganymede, JoEE will uncover the missing link needed to understand how Jupiter accelerates electrons to such speeds. JoEE will also help with understanding the interior structure of Ganymede’s subsurface ocean by pinpointing the latitudinal location of Ganymede’s auroras and how they rock back and forth in the Jovian magnetic field.

JoEE’s high-resolution measurements are enabled by nine collimators of unprecedented precision, which is made possible by a 3D-printing process on metal pioneered at APL. This innovative process enables new designs that require extreme tolerances and is projected to revolutionize what is mechanically possible in space.

Europa and Io leave behind a trail of gas and plasma in their orbits around Jupiter
Europa and Io leave behind a trail of gas and plasma in their orbits around Jupiter, depicted here as colors (warmer colors being higher concentrations of energetic neutral atoms or ENAs). No one has been able to image these trails in detail or in their entirety, but the JENI instrument (image on left) will be the first dedicated instrument to reveal and take images of the fast-moving atoms in this trail. It will fly through and measure the energetic ions responsible for the ENA emissions, which in turn will also allow researchers to learn how plasma that’s rushed in from Jupiter’s magnetotail is heated to tens of millions of degrees.

 

Mission

JUICE 

Launched from French Guiana on April 14, 2023, the Jupiter Icy Moons Explorer (JUICE) mission will be the European Space Agency’s first large-class mission in the Cosmic Vision 2015-2025 program, spending at least three years making detailed observations of the giant planet Jupiter and three of its largest moons: Ganymede, Callisto, and Europa.

 

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