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A computer simulation gives an idea of how Europa's magnetic field interacted with an erupting plume. Magnetic field lines (blue) show how the plume interacts with the ambient flow of Jovian plasma. Red colors on the lines show more dense areas of plasma.

Comparison of Europa observed with Gemini Planet Imager in K1 band on the right and visible albedo visualization based on a composite map made from Galileo SSI and Voyager 1 and 2 data (from USGS) on the left.

Artist's concept of Galileo passing near Jupiter's small inner moon Amalthea.

A NASA spacecraft sees a volcanic explosion on Jupiter’s third-largest moon.

About Image

Artist’s illustration of Jupiter and Europa (in the foreground) with the Galileo spacecraft after its pass through a plume erupting from Europa’s surface. A new computer simulation gives us an idea of how the magnetic field interacted with a plume. The magnetic field lines (depicted in blue) show how the plume interacts with the ambient flow of Jovian plasma. The red colors on the lines show more dense areas of plasma.NASA/JPL-Caltech/Univ. of Michigan

Comparison of Europa observed with Gemini Planet Imager in K1 band on the right and visible albedo visualization based on a composite map made from Galileo SSI and Voyager 1 and 2 data (from USGS) on the left. While GPI is not designed for ‘extended’ objects like this, its observations could help in following surface alterations on icy satellites of Jupiter or atmospheric phenomena (e.g. clouds, haze) on Saturn’s moon Titan. The GPI near-infrared color image is a combination of 3 wavelength channels.Processing by Marshall Perrin, Space Telescope Science Institute and Franck Marchis SETI Institute

Artist's concept of Galileo passing near Jupiter's small inner moon Amalthea.Michael Carroll

A NASA spacecraft sees a volcanic explosion on Jupiter’s third-largest moon.NASA/JPL/University of Arizona

Mission name: Galileo

Galileo mission

Mission to Jupiter and its mysterious moons

Launch Date October 18, 1989
Arrival Date December 07, 1995
End DateSeptember 21, 2003
Mission TypeOrbiter
TargetJupiter System

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Mission Overview
The primary aim of NASA’s Galileo mission was to study the giant planet Jupiter and its many moons. The mission also made many valuable discoveries on route to Jupiter. Galileo was the first spacecraft to visit an asteroid, and visited two during its journey – Gaspra and Ida. Galileo also captured infrared images of clouds at Venus. Galileo also carried a small probe that it deployed and sent deep into the atmosphere of Jupiter, taking readings for almost an hour before the probe was crushed by overwhelming pressure.

After discoveries including evidence for the existence of a saltwater ocean beneath the Jovian moon Europa’s icy surface, extensive volcanic processes on the moon Io and a magnetic field generated by the moon Ganymede, Galileo plunged into Jupiter’s atmosphere on September 21, 2003 to prevent an unwanted impact with Europa.

Relevance to Astrobiology
NASA’s Galileo mission returned data that continues to shape astrobiology science. It was Galileo’s observations in the Jupiter system that led to the discovery that moons of the giant planet – particularly Europa – had evidence of hidden oceans beneath their surfaces. Because of Galileo, Europa is one of the most important astrobiology targets in the Solar System. These findings also expanded the search for habitable environments outside of the traditional ‘habitable zone’ of a system, the distance from a star at which liquid water can persist on the surface of a planet.

NASA Astrobiology Involvement
Researchers supported by elements of the Astrobiology Program continue to use data gathered by the Galileo mission to better understand the potential habitability of jovian moons, such as Europa. The Astrobiology program devotes resources toward determining life’s potential on moons like Europa. Studies supported by the program include Earth-based research in laboratories and in the field that are used to interpret data from Galileo. The Astrobiology Program also supports the development of instruments that will be used on future missions to the Jupiter system. Data from Galileo’s journey to Jupiter, and within the Jupiter system, has also greatly informed our understanding of how and where potentially habitable worlds could form beyond our own solar system.

Mission news and discoveries

Phosphorus in the Oceans of Icy MoonsJune 12, 2023

Hyperhydrated Salt on Icy MoonsMarch 30, 2023

Study Finds Ocean Currents May Affect Rotation of Europa’s Icy Crust (NASA)March 17, 2023

All News

Major mission findings

October 22, 1998Europa's Ocean

Galileo provided data that was instrumental in the discovery of a global ocean of liquid water that exists under the icy surface of Jupiter’s moon Europa. Galileo showed that Jupiter’s magnetic field was disrupted in the space around Europa, implying that a special type of magnetic field is being created within Europa by a deep layer of electrically conductive fluid beneath the surface. (Khurana et al., 1998)

Galileo image of the trailing hemisphere of Jupiter's moon Ganymede. The north and south polar areas can be distinguished by their light purple shade in this image.

December 12, 1996Magnetic Ganymede

Galileo provided data that identified Jupiter’s moon Ganymede as the first moon known to possess a magnetic field. (Kivelson et al. 1996)

June 10, 2002Subsurface Water: Ganymede and Callisto

Magnetic data from Galileo also provided evidence that the moons Ganymede and Callisto are also likely to have layers of liquid saltwater beneath their surfaces.

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Mission Facts

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Artist impression of the Galileo mission.

Galileo features in Issue #4 of the Astrobiology Graphic Histories, <em>Astrobiology: The History of Our Search for Life in the Universe</em>.

Science InstrumentsGalileo carried nine instruments

Solid-state imaging camera; Near-infrared mapping spectrometer; Ultraviolet spectrometer; Photopolarimeter radiometer; Magnetometer; Energetic particles detector; Plasma wave spectrometer; Dust detector; Heavy ion counter

Astrobiology Graphic History SeriesAstrobiology: The History of Our Search for Life in the Universe

Galileo features in Issue #4 of the Astrobiology Graphic History Series, availabe at: https://astrobiology.nasa.gov/resources/graphic-histories/

Explore other missions

In this illustration, NASA's Perseverance Mars rover uses the Planetary Instrument for X-ray Lithochemistry (PIXL). The X-ray spectrometer will help search for signs of ancient microbial life in rocks.

ExploreMars 2020

This illustration shows NASA's Europa mission spacecraft, which is being developed for a launch sometime in the 2020s.

ExploreEuropa Clipper