Distribution of Water in Jupiter's Stratosphere

This map shows the distribution of water in the stratosphere of Jupiter as measured with ESA's Herschel space observatory. White and cyan indicate highest concentration of water, and blue indicates lesser amounts. The map has been superimposed over an image of Jupiter taken at visible wavelengths with the NASA/ESA Hubble Space Telescope.

The distribution of water clearly shows an asymmetric distribution across the planet's disc: water is more abundant in the southern hemisphere. Based on this and other clues collected with Herschel, astronomers have established that at least 95 per cent of the water currently present in Jupiter's stratosphere has been supplied by comet Shoemaker-Levy 9, which famously impacted the planet at intermediate southern latitudes in 1994.

The map is based on spectrometric data collected with the PACS instrument on board Herschel around 66.4 microns, a wavelength that corresponds to one of water's many spectral signatures.

Image credit: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

Note: For more information, see Herschel Links Water in Stratosphere to 1994 Comet Impact and Herschel Links Water Around Jupiter to Comet Impact.

Energy From Above Affecting Surface of Europa

This graphic of Jupiter's moon Europa maps a relationship between the amount of energy deposited onto the moon from charged-particle bombardment and the chemical contents of ice deposits on the surface in five areas of the moon (labeled A through E).

Energetic ions and electrons tied to Jupiter's powerful magnetic field smack into Europa as the field sweeps around Jupiter. The magnetic field travels around Jupiter even faster than Europa orbits the planet. Most of the energetic particles hitting Europa strike the moon's "trailing hemisphere," the half facing away from the direction Europa travels in its orbit. The "leading hemisphere," facing in the direction of travel, receives fewer of the charged particles.

Researchers assessed the amount of sulfate hydrates -- compared with relatively pristine water -- in the surface ice in five widely distributed areas of Europa. They used data from observations made by the near infrared spectrometer (NIMS) instrument on NASA's Galileo spacecraft, which orbited Jupiter from 1995 to 2003. They found that the concentration of frozen sulfuric acid on the surface varies greatly. It ranges from undetectable levels near the center of Europa's leading hemisphere, to more than half of the surface material near the center of the trailing hemisphere. The concentration is closely related to the amount of energy received from electrons and sulfur ions striking the surface, with a distribution controlled by interactions between Jupiter and Europa's magnetic fields.

This pattern could provide direction for the best places to study the surface of Europa for learning about material churned up from the moon's subsurface, which includes a deep saltwater ocean beneath an icy shell. The portions of the surface least affected by the bombardment of charged particles from above are most likely to preserve the original chemical compounds that erupted from the interior. Understanding the chemical ingredients of Europa's subsurface ocean could help scientists determine whether, as many suspect, the ocean could have supported life in the past or even now.

The images of Europa used for the base maps of this figure were taken by the solid state imager on Galileo. The areas labeled A through E are the areas covered by five sets of NIMS observations, and color-coded with darker, bluer portions having more sulfate hydrates and brighter, pinker portions having more water ice. The mapped patterns for energy input are derived from models for the flux of electrons and ions delivered by Jupiter's magnetic field. The color-code key at the right is labeled in units of mega electron volts per square centimeter per second.

Image Credit: NASA/JPL-Caltech/University of Arizona/JHUAPL/University of Colorado

Note: For more information, see Where are the Best Windows Into Europa's Interior?

Europa in Natural and Enhanced Colors

This color composite view combines violet, green, and infrared images of Jupiter's intriguing moon, Europa, for a view of the moon in natural color (left) and in enhanced color designed to bring out subtle color differences in the surface (right). The bright white and bluish part of Europa's surface is composed mostly of water ice, with very few non-ice materials. In contrast, the brownish mottled regions on the right side of the image may be covered by hydrated salts and an unknown red component. The yellowish mottled terrain on the left side of the image is caused by some other unknown component. Long, dark lines are fractures in the crust, some of which are more than 3,000 kilometers (1,850 miles) long.

North is to the top of the picture and the sun fully illuminates the surface. Europa is about 3,160 kilometers (1,950 miles) in diameter, or about the size of Earth's moon. The finest details that can be discerned are 25 kilometers across. The images in this global view were taken in June 1997 at a range of 1.25 million kilometers by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft, during its ninth orbit of Jupiter.

Image credit: NASA/JPL/University of Arizona

Note: For more information, see Mapping the Chemistry Needed for Life at Europa.

Io Predicted Heat Flow Map

This map shows predicted heat flow at the surface of Jupiter's moon Io from two tidal-heating models. Red indicates areas where more heat is expected; blue where less heat is expected.

Figure A predicts surface heat concentration at the poles if tidal heating occurs primarily within Io's deep mantle.

Figure B shows surface heat concentrations at the equator if heating occurs primarily within Io's shallower asthenosphere.

Map credit: NASA/Christopher Hamilton

Io's Tvashtar Volcano

This five-frame sequence of New Horizons images captures the giant plume from Io's Tvashtar volcano. Snapped by the probe's Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year [2007], this first-ever "movie" of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon's surface. Only the upper part of the plume is visible from this vantage point -- the plume's source is 130 kilometers (80 miles) below the edge of Io's disk, on the far side of the moon.

The appearance and motion of the plume is remarkably similar to an ornamental fountain on Earth, replicated on a gigantic scale. The knots and filaments that allow us to track the plume's motion are still mysterious, but this movie is likely to help scientists understand their origin, as well as provide unique information on the plume dynamics.

Io's hyperactive nature is emphasized by the fact that two other volcanic plumes are also visible off the edge of Io's disk: Masubi at the 7 o'clock position, and a very faint plume, possibly from the volcano Zal, at the 10 o'clock position. Jupiter illuminates the night side of Io, and the most prominent feature visible on the disk is the dark horseshoe shape of the volcano Loki, likely an enormous lava lake. Boosaule Mons, which at 18 kilometers (11 miles) is the highest mountain on Io and one of the highest mountains in the solar system, pokes above the edge of the disk on the right side.

The five images were obtained over an 8-minute span, with two minutes between frames, from 23:50 to 23:58 Universal Time on March 1, 2007. Io was 3.8 million kilometers (2.4 million miles) from New Horizons; the image is centered at Io coordinates 0 degrees north, 342 degrees west.

The pictures were part of a sequence designed to look at Jupiter's rings, but planners included Io in the sequence because the moon was passing behind Jupiter's rings at the time.

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute

Note: For more information, see Scientists to Io: Volcanoes are in the Wrong Spot.