Jupiter's Icy Moon Europa

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Observations by the Hubble Space Telescope recently revealed water vapour in the atmosphere of Ganymede, one of Jupiter's moons. A new analysis of archival images and spectra has now revealed that water vapour is also present in the atmosphere of Jupiter's icy moon Europa. The analysis found that a water vapour atmosphere is present only on one hemisphere of the moon. This result advances our understanding of the atmospheric structure of icy moons, and helps lay the groundwork for upcoming science missions which will explore Jupiter's icy moons.

Europa – one of Jupiter's 79 moons – is both the sixth closest moon to Jupiter and the sixth largest moon in the Solar System. It is an icy orb larger than the dwarf planet Pluto with a smooth, icy surface scarred by cracks and fissures. The surface of the moon is a bleak environment with an average temperature of −170 °C and only a tenuous atmosphere. However, astronomers suspect that Europa harbours a vast ocean underneath its icy surface, which some scientists speculate could host extraterrestrial life. Now, for the first time, an astronomer has discovered evidence for persistent water vapour in the atmosphere of Europa.

Using a technique that recently resulted in the discovery of water vapour in the atmosphere of Jupiter's moon Ganymede, an astronomer has found evidence of water in Europa's trailing hemisphere – the portion of the moon that is always opposite to its direction of motion. The asymmetric distribution of water vapour was predicted by previous studies based on computer simulations, but had not previously been detected observationally.

“The observation of water vapour on Ganymede and on the trailing side of Europa advances our understanding of the atmospheres of icy moons,” commented Lorenz Roth of the KTH Royal Institute of Technology in Stockholm, Sweden, the author of this study. “The detection of a stable H2O abundance on Europa is surprising because the surface temperatures are so low.”

To make this discovery, Roth delved into archival Hubble datasets, selecting ultraviolet observations of Europa from 1999, 2012, 2014 and 2015 while the moon was at various orbital positions. These observations were all taken with one of Hubble's most versatile instruments – the Space Telescope Imaging Spectrograph (STIS). These ultraviolet STIS observations allowed Roth to determine the abundance of oxygen – one of the constituents of water – in Europa's atmosphere, and by interpreting the strength of emission at different wavelengths he was able to infer the presence of water vapour.

Previous observations of water vapour on Europa have been associated with transient plumes erupting through the ice, analogous to geysers here on Earth but more than 100 kilometers high. The phenomena seen in these plume studies were apparently transient inhomogeneities or blobs in the atmosphere. The new results, however, show similar amounts of water vapour to be present spread over a larger area in observations spanning from 1999 to 2015. This suggests the long-term presence of a water vapour atmosphere on Europa's trailing hemisphere. Despite the presence of water vapour on Europa's trailing hemisphere there is no indication of H2O on the leading hemisphere of Europa.

This reprocessed colour view of Jupiter's moon Europa was made from images taken by NASA's Galileo spacecraft in the late 1990s.

Image Credit: NASA/JPL-Caltech/SETI Institute

Image enhancement: Jean-Baptiste Faure

Jupiter's Magnificent Swirling Clouds

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A multitude of magnificent, swirling clouds in Jupiter's dynamic North North Temperate Belt is captured in this image from NASA's Juno spacecraft. Appearing in the scene are several bright-white "pop-up" clouds as well as an anticyclonic storm, known as a white oval. This color-enhanced image was taken at 4:58 p.m. EDT on Oct. 29, 2018 as the spacecraft performed its 16th close flyby of Jupiter. At the time, Juno was about 4,400 miles from the planet's cloud tops, at a latitude of approximately 40 degrees north.

Citizen scientists Gerald Eichstädt and Seán Doran created this image using data from the spacecraft's JunoCam imager. JunoCam's raw images are available at www.missionjuno.swri.edu/junocam for the public to peruse and process into image products.

Image Credit: Enhanced Image by Gerald Eichstädt and Sean Doran (CC BY-NC-SA)/NASA/JPL-Caltech/SwRI/MSSS

Mars 2020 Perseverance Rover

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The Mars 2020 mission with its Perseverance rover is part of NASA's Mars Exploration Program, a long-term effort of robotic exploration of the Red Planet. The Mars 2020 mission addresses high-priority science goals for Mars exploration, including key Astrobiology questions about the potential for life on Mars.

The Mars 2020 Perseverance rover will investigate a region of Mars where the ancient environment may have been favorable for microbial life, probing the Martian rocks for evidence of past life. Throughout its investigation, it will collect samples of soil and rock, and cache them on the surface for potential return to Earth by a future mission.

Perseverance will carry an entirely new subsystem to collect and prepare Martian rocks and soil samples that includes a coring drill on its arm and a rack of sample tubes. About 30 of these sample tubes will be deposited at select locations for return on a potential future sample-retrieval mission. In laboratories on Earth, specimens from Mars could be analyzed for evidence of past life on Mars and possible health hazards for future human missions.

Two science instruments mounted on the rover's robotic arm will be used to search for signs of past life and determine where to collect samples by analyzing the chemical, mineral, physical and organic characteristics of Martian rocks. On the rover's mast, two science instruments will provide high-resolution imaging and three types of spectroscopy for characterizing rocks and soil from a distance, also helping to determine which rock targets to explore up close.

The Perseverance rover will use the same sky crane landing system as Curiosity, but will have the ability to land in more challenging terrain with two enhancements, making more rugged sites eligible as safe landing candidates.

Image Credit: NASA/JPL

Curiosity rover on Mars

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NASA's Curiosity rover took this selfie on the 2,553rd Martian day, or sol, of its mission. The rover drilled twice in this location, nicknamed "Glen Etive" (pronounced "glen EH-tiv"). About 300 meters (984 feet) behind the rover, Vera Rubin Ridge rises up. Behind it lies the floor of Gale Crater, which Curiosity is exploring, and the northern rim of the crater.

Just left of the rover are the two drill holes, called "Glen Etive 1" (right) and "Glen Etive 2" (left). Curiosity performed its first wet-chemistry experiment on a drilled sample at this location. The rover can analyze the chemical composition of rock samples by powderizing them with the drill, then dropping the samples into a portable lab in its belly called Sample Analysis at Mars (SAM).

This panorama is made up of 57 individual images taken by the Mars Hand Lens Imager (MAHLI), a camera on the end of the rover's robotic arm. The images are stitched together into a panorama; the robotic arm isn't visible in the parts of the images used in the composite.

MAHLI was built by Malin Space Science Systems in San Diego. The SAM instrument suite was built at Goddard Space Flight Center with significant elements provided by industry, university, and national and international NASA partners. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate in Washington. JPL designed and built the project's Curiosity rover.

Image Credit: NASA/JPL-Caltech/MSSS

Jupiter's Northern Hemisphere

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This stunning image of Jupiter's stormy northern hemisphere was captured by NASA's Juno spacecraft as it performed a close pass of the gas giant planet. Some bright-white clouds can be seen popping up to high altitudes on the right side of Jupiter's disk.

Juno took the four images used to produce this color-enhanced view on May 29, 2019, between 3:52 a.m. EDT and 4:03 a.m. EDT, as the spacecraft performed its 20th science pass of Jupiter. At the time the images were taken, the spacecraft was between 18,600 kilometers (11,600 miles) and 8,600 kilometers (5,400 miles) above Jupiter's cloud tops, above a northern latitude spanning from about 59 to 34 degrees.

Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

Io's shadow on Jupiter

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Jupiter's volcanically active moon Io casts its shadow on the planet in this dramatic image from NASA's Juno spacecraft. As with solar eclipses on the Earth, within the dark circle racing across Jupiter's cloud tops one would witness a full solar eclipse as Io passes in front of the Sun.

Such events occur frequently on Jupiter because it is a large planet with many moons. In addition, unlike most other planets in our solar system, Jupiter's axis is not highly tilted relative to its orbit, so the Sun never strays far from Jupiter's equatorial plane (+/- 3 degrees). This means Jupiter's moons regularly cast their shadows on the planet throughout its year.

Juno's close proximity to Jupiter provides an exceptional fish-eye view, showing a small fraction near the planet's equator. The shadow is about 3,600 kilometers (2,200 miles) wide, approximately the same width as Io, but appears much larger relative to Jupiter. A little larger than Earth's Moon, Io is perhaps most famous for its many active volcanoes, often caught lofting fountains of ejecta well above its thin atmosphere.

Image Credit: NASA/JPL-Caltech/SwRI/MSSS

Pluto's Close-up in Color

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This enhanced color mosaic combines some of the sharpest views of Pluto that NASA's New Horizons spacecraft obtained during its July 14 flyby. The pictures are part of a sequence taken near New Horizons' closest approach to Pluto, with resolutions of about 77-85 meters per pixel – revealing features smaller than half a city block on Pluto’s surface. Lower resolution color data (at about 630 meters, per pixel) were added to create this new image. The images form a strip 80 kilometers wide, trending (top to bottom) from the edge of "badlands" northwest of the informally named Sputnik Planum, across the al-Idrisi mountains, onto the shoreline of Pluto's "heart" feature, and just into its icy plains. They combine pictures from the telescopic Long Range Reconnaissance Imager (LORRI) taken approximately 15 minutes before New Horizons' closest approach to Pluto, with – from a range of only 17,000 kilometers – with color data (in near-infrared, red and blue) gathered by the Ralph/Multispectral Visible Imaging Camera (MVIC) 25 minutes before the LORRI pictures. The wide variety of cratered, mountainous and glacial terrains seen here gives scientists and the public alike a breathtaking, super-high-resolution color window into Pluto's geology.

Image Credit: NASA/JHUAPL/SwRI

Dione and Enceladus as seen by Cassini

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Although Dione (near) and Enceladus (far) are composed of nearly the same materials, Enceladus has a considerably higher reflectivity than Dione. As a result, it appears brighter against the dark night sky. The surface of Enceladus (504 kilometers across) endures a constant rain of ice grains from its south polar jets. As a result, its surface is more like fresh, bright, snow than Dione's (1123 kilometers across) older, weathered surface. As clean, fresh surfaces are left exposed in space, they slowly gather dust and radiation damage and darken in a process known as "space weathering". This view looks toward the leading hemisphere of Enceladus. North on Enceladus is up and rotated 1 degree to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Sept. 8, 2015. The view was acquired at a distance of approximately 83,000 kilometers from Dione. Image scale is 500 meters per pixel. The distance from Enceladus was 364,000 kilometers for an image scale of 2.2 kilometers per pixel. The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

Image Credit: NASA/JPL-Caltech/Space Science Institute

Image enhancement: Jean-Baptiste Faure

Io as seen by the Galileo spacecraft

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Two sulfurous eruptions are visible on Jupiter's volcanic moon Io in this color composite image from the robotic Galileo spacecraft that orbited Jupiter from 1995 to 2003. At the image top, over Io's limb, a bluish plume rises about 140 kilometers above the surface of a volcanic caldera known as Pillan Patera. In the image middle, near the night/day shadow line, the ring shaped Prometheus plume is seen rising about 75 kilometers above Io while casting a shadow below the volcanic vent. Named for the Greek god who gave mortals fire, the Prometheus plume is visible in every image ever made of the region dating back to the Voyager flybys of 1979 - presenting the possibility that this plume has been continuously active for at least 18 years. This digitally sharpened image of Io was originally recorded in 1997 from a distance of about 600,000 kilometers. Recent analyses of Galileo data has uncovered evidence of a magma ocean beneath Io's surface.
Image Credit: Galileo Project, JPL, NASA
Image enhancement: Jean-Baptiste Faure

Mercury's horizon seen by MESSENGER spacecraft

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Another day, another beautiful view of Mercury's horizon. In this scene, which was acquired looking from the shadows toward the sunlit side of the planet, a 120-km (75 mi.) impact crater stands out near the center. Emanating from this unnamed crater are striking chains of secondary craters, which gouged linear tracks radially away from the crater. While this crater is not especially fresh (its rays have faded into the background), it does appear to have more prominent secondary crater chains than many of its peers. This image was acquired on Oct. 2, 2013 by the Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) aboard NASA's MESSENGER spacecraft, as part of the MDIS's limb imaging campaign. Once per week, MDIS captures images of Mercury's limb, with an emphasis on imaging the southern hemisphere limb. These limb images provide information about Mercury's shape and complement measurements of topography made by the Mercury Laser Altimeter (MLA) of Mercury's northern hemisphere. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the solar system's innermost planet. During the first two years of orbital operations, MESSENGER acquired over 150,000 images and extensive other data sets. MESSENGER is capable of continuing orbital operations until early 2015.
Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

A view of Saturn and its Rings, Enceladus and Epimetheus!

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A pair of Saturn's moons appear insignificant compared to the immensity of the planet in this Cassini spacecraft view along the terminator where day transitions to night. The larger moon Enceladus (504 kilometers, or 313 miles across) is also on the left, just a bit closer to the center of the image. Epimetheus (113 kilometers, or 70 miles across) appears as a tiny black speck on the far left of the image, left of Enceladus, just below the thin line of the rings. The rings cast wide shadows on the southern hemisphere of the planet. This view looks toward the northern, sunlit side of the rings from just above the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Nov. 4, 2011 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 1.2 million kilometers (746,000 miles) from Saturn and roughly 1 million kilometers (600,000 miles) from Enceladus and Epimetheus. Image scale is about 75 kilometers (47 miles) per pixel on Saturn, 60 kilometers (37 miles) per pixel on Enceladus and 66 kilometers (41 miles) per pixel on Epimetheus.
Credit: NASA/JPL-Caltech/Space Science Institute

Dramatic Voyager 1 view of Jupiter's Great Red Spot

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This dramatic view of Jupiter's Great Red Spot and its surroundings was obtained by Voyager 1 on Feb. 25, 1979, when the spacecraft was 9.2 million kilometers (5.7 million miles) from Jupiter. Cloud details as small as 160 kilometers (100 miles) across can be seen here. The colorful, wavy cloud pattern to the left of the Red Spot is a region of extraordinarily complex end variable wave motion. The Jet Propulsion Laboratory manages the Voyager mission for NASA's Office of Space Science.
Credit: NASA/JPL

Saturn's geyser moon Enceladus as seen by NASA's Cassini

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NASA's Cassini spacecraft successfully completed its Oct. 1 flyby of Saturn's moon Enceladus and its jets of water vapor and ice. At its closest approach, the spacecraft flew approximately 62 miles (100 kilometers) above the moon's surface. The close approach was designed to give some of Cassini's instruments, including the ion and neutral mass spectrometer, the chance to "taste" the jets themselves. At a higher vantage point during the encounter, Cassini's high-resolution camera captured pictures of the jets emanating from the moon's south polar region. The images of the surface include previously seen leading-hemisphere terrain. However, during this encounter, multi-spectral imaging of these terrains extended farther into the ultraviolet region of the electromagnetic spectrum than had previously been achieved at this resolution. By looking at the surface at ultraviolet wavelengths, scientists can better detect the difference between surface materials and shadows than they can at visible wavelengths, where icy materials are highly reflective and shadows are washed out. With both ultraviolet and visible images of the same terrain available to them, scientists will better understand how the surface coverage of icy particles coming from the vents and plumes changes with terrain type and age. Cassini's next pass of this fascinating moon will be Oct. 19, when the spacecraft flies by at an altitude of approximately 765 miles (1231 kilometers).
Credit: NASA/JPL-Caltech/Space Science Institute

Asteroid Vesta full-frame image taken by Dawn spacecraft!

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NASA's Dawn spacecraft obtained this image of the giant asteroid Vesta with its framing camera on July 24, 2011. It was taken from a distance of about 5,200 kilometers (3,200 miles). Dawn entered orbit around Vesta on July 15, and will spend a year orbiting the body. After that, the next stop on its itinerary will be an encounter with the dwarf planet Ceres. The framing camera project is funded by NASA, the Max Planck Society and DLR.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Close-up view of "Snowman" Craters on Asteroid Vesta

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In this image, obtained by the framing camera on NASA's Dawn spacecraft, a set of three craters, informally nicknamed "Snowman" by the camera's team members, is located in the northern hemisphere of Vesta. The image was taken on July 24, 2011, from a distance of about 5,200 kilometers (3,200 miles). The Dawn mission to Vesta and Ceres is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington, D.C. It is a project of the Discovery Program, managed by NASA's Marshall Space Flight Center, Huntsville, Ala. UCLA is responsible for overall Dawn mission science. Orbital Sciences Corporation of Dulles, Va., designed and built the Dawn spacecraft.
Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Stunning color image of Asteroids Ida and Dactyl

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This color picture is made from images taken by the imaging system on the Galileo spacecraft about 14 minutes before its closest approach to asteroid 243 Ida on August 28, 1993. The range from the spacecraft was about 10,500 kilometers (6,500 miles). The images used are from the sequence in which Ida's moon was originally discovered; the moon is visible to the right of the asteroid. This picture is made from images through the 4100-angstrom (violet), 7560 A (infrared) and 9680 A (infrared) filters. The color is 'enhanced' in the sense that the CCD camera is sensitive to near infrared wavelengths of light beyond human vision; a 'natural' color picture of this asteroid would appear mostly gray. Shadings in the image indicate changes in illumination angle on the many steep slopes of this irregular body as well as subtle color variations due to differences in the physical state and composition of the soil (regolith). There are brighter areas, appearing bluish in the picture, around craters on the upper left end of Ida, around the small bright crater near the center of the asteroid, and near the upper right-hand edge (the limb). This is a combination of more reflected blue light and greater absorption of near infrared light, suggesting a difference in the abundance or composition of iron-bearing minerals in these areas. Ida's moon also has a deeper near-infrared absorption and a different color in the violet than any area on this side of Ida. The moon is not identical in spectral properties to any area of Ida in view here, though its overall similarity in reflectance and general spectral type suggests that it is made of the same rock types basically. These data, combined with study of further imaging data and more detailed spectra from the Near Infrared Mapping Spectrometer, may allow scientists to determine whether the larger parent body of which Ida, its moon, and some other asteroids are fragments was a heated, differentiated object or made of relatively unaltered primitive chondritic material. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science by the Jet Propulsion Laboratory.
Credit: NASA/JPL

A view of the Asteroid Lutetia from the ESA Rosetta probe

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This image of the unusual asteroid Lutetia was taken by ESA's Rosetta probe during its closest approach in July 2010. Lutetia, which is about 100 kilometres across, seems to be a leftover fragment of the same original material that formed the Earth, Venus and Mercury. It is now part of the main asteroid belt, between the orbits of Mars and Jupiter, but its composition suggests that it was originally much closer to the Sun.
Credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA

Victoria Crater on Mars as seen by the MRO spacecraft

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This image from the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter shows Victoria Crater, an impact crater at Meridiani Planum, near the equator of Mars. The crater is approximately 800 meters (half a mile) in diameter. It has a distinctive scalloped shape to its rim, caused by erosion and downhill movement of crater wall material. Layered sedimentary rocks are exposed along the inner wall of the crater, and boulders that have fallen from the crater wall are visible on the crater floor. The floor of the crater is occupied by a striking field of sand dunes. Since January 2004, the Mars Exploration Rover Opportunity has been operating at Meridiani Planum. Five days before this image was taken, Opportunity arrived at the rim of Victoria crater, after a drive of more than 9 kilometers (over 5 miles). The rover can be seen in this image, at roughly the "ten o'clock" position along the rim of the crater.
This view is a portion of an image taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on Oct. 3, 2006. The complete image is centered at minus7.8 degrees latitude, 279.5 degrees East longitude. The range to the target site was 297 kilometers (185.6 miles). At this distance the image scale is 29.7 centimeters (12 inches) per pixel (with 1 x 1 binning) so objects about 89 centimeters (35 inches) across are resolved. The image shown here has been map-projected to 25 centimeters (10 inches) per pixel and north is up. The image was taken at a local Mars time of 3:30 PM and the scene is illuminated from the west with a solar incidence angle of 59.7 degrees, thus the sun was about 30.3 degrees above the horizon. At a solar longitude of 113.6 degrees, the season on Mars is northern summer. This is an enhanced-color view generated from images acquired by theHiRISE camera using its red filter and blue-green filter.

Image Credit: NASA/JPL-Caltech/University of Arizona/Cornell/Ohio State University

A crescent Saturn nestled within encircling Rings!

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A crescent Saturn appears nestled within encircling rings in this Cassini spacecraft image. Clouds swirl through the atmosphere of the planet. Prometheus (86 kilometers, or 53 miles across) orbits between the main rings and the thin F ring, and this moon appears as a speck above the rings near the middle of the image. This view looks toward the southern, unilluminated side of the rings from about 3 degrees below the ringplane. The image was taken with the Cassini spacecraft wide-angle camera on Sept. 14, 2010 using a spectral filter sensitive to wavelengths of near-infrared light centered at 890 nanometers. The view was obtained at a distance of approximately 2.6 million kilometers (1.6 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 100 degrees. Image scale on Saturn is 151 kilometers (94 miles) per pixel.
Credit: NASA/JPL/Space Science Institute

Water vapor and ice erupt from Saturn's moon Enceladus!

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Water vapor and ice erupt from Saturn's moon Enceladus, the source of a newly discovered donut-shaped cloud around Saturn. The small, dynamic moon spews out dramatic plumes of water vapor and ice - first seen by NASA's Cassini spacecraft in 2005. It possesses simple organic particles and may house liquid water beneath its surface. Its geyser-like jets create a gigantic halo of ice, dust and gas around Enceladus that helps feed Saturn's E ring. Now, thanks again to those icy jets, Enceladus is the only moon in our solar system known to influence substantially the chemical composition of its parent planet. In June, the European Space Agency announced that its Herschel Space Observatory, which has important NASA contributions, had found a huge donut-shaped cloud, or torus, of water vapor created by Enceladus encircling Saturn. The torus is more than 373,000 miles (600,000 kilometers) across and about 37,000 miles (60,000 kilometers) thick. It appears to be the source of water in Saturn's upper atmosphere.
Credit: NASA/JPL-Caltech/Space Science Institute