Juice images the cloud of charged particles around Earth
As ESA’s Jupiter Icy Moons Explorer (Juice) sailed past the Moon and Earth in August 2024, the mission team took the opportunity to try out the many scientific instruments aboard the spacecraft. The centre of this infographic shows the sharpest-ever image of the cloud of charged particles trapped in Earth’s magnetic field, while the insets show measurements of high-energy ions and electrons detected along the flyby route.
The image and in situ measurements were taken by two sensors provided by NASA for Juice’s Particle Environment Package (PEP).
The Jovian Energetic Neutrals and Ions (JENI) sensor took the image as Juice soared away from Earth. What it captured is invisible to the human eye – unlike traditional cameras, JENI doesn't rely on light. Instead, it can capture energetic atoms emitted by charged particles that interact with hydrogen gas coming from Earth's atmosphere. This reveals the shape of the charged particle cloud surrounding Earth.
Click here to see a video compilation of images taken by JENI following the lunar-Earth flyby.
The JENI sensor is the newest generation of this type of camera, building on the success of a similar instrument used in the NASA/ESA/ASI Cassini-Huygens mission that revealed the magnetospheres of Saturn and Jupiter.
On 20 August 2024, as Juice hurled into Earth’s magnetosphere and passed some 60 000 km above the Pacific Ocean, JENI and its companion sensor Jovian Energetic Electrons (JoEE) got their first taste of the harsh environment that awaits at Jupiter.
They encountered the dense, lower-energy plasma (ions and electrons) characteristic of this region before flying through the heart of Earth’s radiation belts. There, the instruments measured the million-degree plasma encircling Earth to investigate the secrets of plasma heating that are known to fuel dramatic phenomena in planetary magnetospheres.
More about Juice's lunar-Earth flyby
More about Juice's instruments
The Jovian Energetic Neutrals and Ions (JENI) and Jovian Energetic Electrons (JoEE) sensors are built and managed by the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland, USA, on behalf of NASA. They make up the high-energy particle detectors of Juice’s Particle Environment Package (PEP).
[Image description: On a starry background, the Moon is on the top right, Earth in the centre and the Juice spacecraft on the lower left. A curved dotted line shows the Juice’s trajectory, from right to left. Two white ovals surround Earth, indicating Earth’s radiation belts. Behind Earth, a roughly oval-shaped colourful image shows the density of charged particles imaged by Juice’s JENI sensor, with dark red, particle-dense regions visible at 1, 6 and 11 o’clock directions around Earth. The lower right shows the energies of particles measured by Juice’s JENI and JoEE sensors as Juice flew through the radiation belts.]
