In astronomy and planetary science, a magnetosphere is a region of space surrounding an astronomical object in which charged particles are affected by that object's magnetic field. It is created by a celestial body with an active interior dynamo.
Europa, or Jupiter II, is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet of all the 95 known moons of Jupiter. It is also the sixth-largest moon in the Solar System. Europa was discovered independently by Simon Marius and Galileo Galilei and was named after Europa, the Phoenician mother of King Minos of Crete and lover of Zeus.
Ganymede, or Jupiter III, is the largest and most massive natural satellite of Jupiter as well as in the Solar System, being a planetary-mass moon. It is the largest Solar System object without an atmosphere, despite being the only moon in the Solar System with a magnetic field. Like Titan, it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io or the Moon.
A whistler is a very low frequency (VLF) electromagnetic (radio) wave generated by lightning. Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with maximum frequencies usually at 3 kHz to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes where the impulse travels along the Earth's magnetic field lines from one hemisphere to the other. They undergo dispersion of several kHz due to the slower velocity of the lower frequencies through the plasma environments of the ionosphere and magnetosphere. Thus they are perceived as a descending tone which can last for a few seconds. The study of whistlers categorizes them into Pure Note, Diffuse, 2-Hop, and Echo Train types.
Io, or Jupiter I, is the innermost and third-largest of the four Galilean moons of the planet Jupiter. Slightly larger than Earth’s moon, Io is the fourth-largest moon in the Solar System, has the highest density of any moon, the strongest surface gravity of any moon, and the lowest amount of water of any known astronomical object in the Solar System. It was discovered in 1610 by Galileo Galilei and was named after the mythological character Io, a priestess of Hera who became one of Zeus's lovers.
The magnetosphere of Saturn is the cavity created in the flow of the solar wind by the planet's internally generated magnetic field. Discovered in 1979 by the Pioneer 11 spacecraft, Saturn's magnetosphere is the second largest of any planet in the Solar System after Jupiter. The magnetopause, the boundary between Saturn's magnetosphere and the solar wind, is located at a distance of about 20 Saturn radii from the planet's center, while its magnetotail stretches hundreds of Saturn radii behind it.
The magnetosphere of Jupiter is the cavity created in the solar wind by Jupiter's magnetic field. Extending up to seven million kilometers in the Sun's direction and almost to the orbit of Saturn in the opposite direction, Jupiter's magnetosphere is the largest and most powerful of any planetary magnetosphere in the Solar System, and by volume the largest known continuous structure in the Solar System after the heliosphere. Wider and flatter than the Earth's magnetosphere, Jupiter's is stronger by an order of magnitude, while its magnetic moment is roughly 18,000 times larger. The existence of Jupiter's magnetic field was first inferred from observations of radio emissions at the end of the 1950s and was directly observed by the Pioneer 10 spacecraft in 1973.
The exploration of Jupiter has been conducted via close observations by automated spacecraft. It began with the arrival of Pioneer 10 into the Jovian system in 1973, and, as of 2023, has continued with eight further spacecraft missions in the vicinity of Jupiter. All of these missions were undertaken by the National Aeronautics and Space Administration (NASA), and all but two were flybys taking detailed observations without landing or entering orbit. These probes make Jupiter the most visited of the Solar System's outer planets as all missions to the outer Solar System have used Jupiter flybys. On 5 July 2016, spacecraft Juno arrived and entered the planet's orbit—the second craft ever to do so. Sending a craft to Jupiter is difficult, mostly due to large fuel requirements and the effects of the planet's harsh radiation environment.
Energetic Neutral Atom (ENA) imaging, often described as "seeing with atoms", is a technology used to create global images of otherwise invisible phenomena in the magnetospheres of planets and throughout the heliosphere.
Io Volcano Observer (IVO) is a proposed low-cost, outer-planet mission to explore Jupiter's moon Io to understand tidal heating as a fundamental planetary process. The main science goals are to understand (A) how and where tidal heat is generated inside Io, (B) how tidal heat is transported to the surface, and (C) how Io is evolving. These results are expected to have direct implications for the thermal history of Europa and Ganymede as well as provide insights into other tidally heated worlds such as Titan and Enceladus. The IVO data may also improve our understanding of magma oceans and thus the early evolution of the Earth and Moon.
The Jupiter Icy Moons Explorer is an interplanetary spacecraft that was launched on 14 April 2023 from Guiana Space Centre in the French Guiana by the European Space Agency (ESA) with Airbus Defence and Space as the main contractor. The mission is planned to study Ganymede, Callisto, and Europa, three of Jupiter's Galilean moons. They are thought to have significant bodies of liquid water beneath their icy surfaces which would make them potentially habitable environments.
Europa Clipper is an interplanetary mission in development by NASA comprising an orbiter. Planned for launch in October 2024, the spacecraft is being developed to study the Galilean moon Europa through a series of flybys while in orbit around Jupiter.
Waves is an experiment on the Juno spacecraft to study radio and plasma waves. It is part of collection of various types of instruments and experiments on the spacecraft; Waves is oriented towards understanding fields and particles in Jupiter's magnetosphere. Waves is on board the uncrewed Juno spacecraft, which was launched in 2011 and arrived at Jupiter in the summer of 2016. The major focus of study for Waves is Jupiter's magnetosphere, which if could be seen from Earth would be about twice the size of a full moon. It has a tear drop shape, and that tail extends away from the Sun by at least 5 AU. The Waves instrument is designed to help understand the interaction between Jupiter's atmosphere, its magnetic field, its magnetosphere, and to understand Jupiter's auroras. It is designed to detect radio frequencies from 50 Hz up to 40,000,000 Hz (40 MHz), and magnetic fields from 50 Hz to 20,000 Hz (20 kHz). It has two main sensors a dipole antenna and a magnetic search coil. The dipole antenna has two whip antenna's that extend 2.8 meters and they are attached to the main body of the spacecraft. This sensor has been compared to a rabbit ears set-top TV antenna. The search coil is overall a mu metal rod 15 cm (6 in) length with a fine copper wire wound 10,000 times around it. There are also two frequency receivers that each cover certain bands. Data handling is done by two radiation hardened systems on a chip. The data handling units are located inside the Juno Radiation Vault. Waves was allocated 410 Mbits of data per science orbit.
The interchange instability, also known as the Kruskal–Schwarzchild instability or flute instability, is a type of plasma instability seen in magnetic fusion energy that is driven by the gradients in the magnetic pressure in areas where the confining magnetic field is curved.
The Mapping Imaging Spectrometer for Europa (MISE) is an imaging near infrared spectrometer on board the Europa Clipper mission to Jupiter's moon Europa. MISE will examine Europa's surface composition and relate it to the habitability of its internal water ocean.
The Interior Characterization of Europa using Magnetometry (ICEMAG) is a multi-frequency magnetometer that was proposed to be flown on board the Europa Clipper mission to Jupiter's moon Europa, but its inclusion was cancelled in March 2019. Magnetic induction is a powerful tool for probing the subsurface and determine Europa's ocean depth, salinity, and ice shell thickness, as well as detecting erupting plume activity.
The Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON) is a multi-frequency, multi-channel ice penetrating radar system that will be flown on board the Europa Clipper mission to Jupiter's moon Europa. REASON investigation will provide the first direct measurements of Europa's ice shell surface character and subsurface structure.
Tianwen-4 Chinese: 天问四号, formerly known as Gan De, is a planned interplanetary mission by China to study the Jovian system and its environs, sharing a launch with a spacecraft which will make a flyby of Uranus.
Dynamics Explorer 1 was a NASA high-altitude mission, launched on 3 August 1981, and terminated on 28 February 1991. It consisted of two satellites, DE-1 and DE-2, whose purpose was to investigate the interactions between plasmas in the magnetosphere and those in the ionosphere. The two satellites were launched together into polar coplanar orbits, which allowed them to simultaneously observe the upper and lower parts of the atmosphere.
The Europa Clipper Magnetometer (ECM) is a spacecraft magnetometer aboard the planned Europa Clipper mission. It will be used to precisely measure Europa's magnetic field during consecutive fly-bys, allowing scientists to potentially confirm the existence of Europa's hypothesised subsurface ocean. If this ocean exists, the instrument will be able to determine its depth and salinity, as well as the thickness of the moon's icy shell.
