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 the largest in the Solar System, being a planetary-mass moon. It is the largest Solar System object without a substantial atmosphere, despite being the only moon in the Solar System with a substantial magnetic field. Like Titan, Saturn's largest moon, it is larger than the planet Mercury, but has somewhat less surface gravity than Mercury, Io, or the Moon due to its lower density compared to the three.
Ultraviolet astronomy is the observation of electromagnetic radiation at ultraviolet wavelengths between approximately 10 and 320 nanometres; shorter wavelengths—higher energy photons—are studied by X-ray astronomy and gamma-ray astronomy. Ultraviolet light is not visible to the human eye. Most of the light at these wavelengths is absorbed by the Earth's atmosphere, so observations at these wavelengths must be performed from the upper atmosphere or from space.
The Goddard High Resolution Spectrograph was an ultraviolet spectrograph installed on the Hubble Space Telescope during its original construction, and it was launched into space as part of that space telescope aboard the Space Shuttle Discovery on April 24, 1990 (STS-31). The instrument is named after 20th century rocket pioneer Robert H. Goddard.
Io, or Jupiter I, is the innermost and second-smallest 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 by atomic ratio 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.
Juno is a NASA space probe orbiting the planet Jupiter. It was built by Lockheed Martin and is operated by NASA's Jet Propulsion Laboratory. The spacecraft was launched from Cape Canaveral Air Force Station on August 5, 2011 UTC, as part of the New Frontiers program. Juno entered a polar orbit of Jupiter on July 5, 2016, UTC, to begin a scientific investigation of the planet. After completing its mission, Juno will be intentionally deorbited into Jupiter's atmosphere.
An imaging spectrometer is an instrument used in hyperspectral imaging and imaging spectroscopy to acquire a spectrally-resolved image of an object or scene, usually to support analysis of the composition the object being imaged. The spectral data produced for a pixel is often referred to as a datacube due to the three-dimensional representation of the data. Two axes of the image correspond to vertical and horizontal distance and the third to wavelength. The principle of operation is the same as that of the simple spectrometer, but special care is taken to avoid optical aberrations for better image quality.
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.
The exploration of Io, Jupiter's innermost Galilean and third-largest moon, began with its discovery in 1610 and continues today with Earth-based observations and visits by spacecraft to the Jupiter system. Italian astronomer Galileo Galilei was the first to record an observation of Io on January 8, 1610, though Simon Marius may have also observed Io at around the same time. During the 17th century, observations of Io and the other Galilean satellites helped with the measurement of longitude by map makers and surveyors, with validation of Kepler's Third Law of planetary motion, and with measurement of the speed of light. Based on ephemerides produced by astronomer Giovanni Cassini and others, Pierre-Simon Laplace created a mathematical theory to explain the resonant orbits of three of Jupiter's moons, Io, Europa, and Ganymede. This resonance was later found to have a profound effect on the geologies of these moons. Improved telescope technology in the late 19th and 20th centuries allowed astronomers to resolve large-scale surface features on Io as well as to estimate its diameter and mass.
The Jupiter Icy Moons Explorer is an interplanetary spacecraft that was launched on 14 April 2023 from Guiana Space Centre in 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 a space probe in development by NASA. 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.
Journey to Enceladus and Titan (JET) is an astrobiology mission concept to assess the habitability potential of Enceladus and Titan, moons of Saturn.
UVS, known as the Ultraviolet Spectrograph or Ultraviolet Imaging Spectrometer is the name of an instrument on the Juno orbiter for Jupiter. The instrument is an imaging spectrometer that observes the ultraviolet range of light wavelengths, which is shorter wavelengths than visible light but longer than X-rays. Specifically, it is focused on making remote observations of the aurora, detecting the emissions of gases such as hydrogen in the far-ultraviolet. UVS will observes light from as short a wavelength as 70 nm up to 200 nm, which is in the extreme and far ultraviolet range of light. The source of aurora emissions of Jupiter is one of the goals of the instrument. UVS is one of many instruments on Juno, but it is in particular designed to operate in conjunction with JADE, which observes high-energy particles. With both instruments operating together, both the UV emissions and high-energy particles at the same place and time can be synthesized. This supports the Goal of determining the source of the Jovian magnetic field. There has been a problem understanding the Jovian aurora, ever since Chandra determined X-rays were coming not from, as it was thought Io's orbit but from the polar regions. Every 45 minutes an X-ray hot-spot pulsates, corroborated by a similar previous detection in radio emissions by Galileo and Cassini spacecraft. One theory is that its related to the solar wind. The mystery is not that there are X-rays coming Jupiter, which has been known for decades, as detected by previous X-ray observatories, but rather why with the Chandra observation, that pulse was coming from the north polar region.
The Europa Lander is a proposed astrobiology mission concept by NASA to send a lander to Europa, an icy moon of Jupiter. If funded and developed as a large strategic science mission, it would be launched in 2027 to complement the studies by the Europa Clipper orbiter mission and perform analyses on site.
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 SUrface Dust Analyser (SUDA) is a time-of-flight mass spectrometer of reflectron-type that employs impact ionization and is optimised for a high mass resolution. The instrument was selected in May 2015 to fly on board the Europa Clipper mission, that is planned for 2025 to Jupiter's moon Europa.
The Europa Thermal Emission Imaging System (E-THEMIS) instrument is designed to scan the surface of Europa and identify areas of geologically recent resurfacing through the detection of subtle thermal anomalies. This 'heat detector' will provide high spatial resolution, multi-spectral thermal imaging of Europa to help detect active sites such as outflows and plumes. E-THEMIS will be launched on board the planned Europa Clipper astrobiology mission to Jupiter's moon Europa in 2024.
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.
Ralph is a science instrument aboard the robotic New Horizons spacecraft, which was launched in 2006. Ralph is a visible and infrared imager and spectrometer to provide maps of relevant astronomical targets based on data from that hardware. Ralph has two major subinstruments, LEISA and MVIC. MVIC stands for Multispectral Visible Imaging Camera and is a color imaging device, while LEISA originally stood for Linear Etalon Imaging Spectral Array and is an infrared imaging spectrometer for spaceflight. LEISA observes 250 discrete wavelengths of infrared light from 1.25 to 2.5 micrometers. MVIC is a pushbroom scanner type of design with seven channels, including red, blue, near-infrared (NIR), and methane.
Alice is an ultraviolet imaging spectrometer, with one used on the New Horizons spacecraft, and another on the Rosetta spacecraft. Alice is a small telescope with a spectrograph and a special detector with 32 pixels each with 1024 spectral channels detecting ultraviolet light. The instrument has a mass of 4.4 kg and draws 4.4 watts of power. Its primary role is to determine the relative concentrations of various elements and isotopes in Pluto's atmosphere.
