Category: Saturn

The two moons Tethys and tiny Atlas. Image credit: NASA/JPL/SSI Click to enlarge
This view from Cassini contains not one, but two moons. Tethys is slightly overexposed so that the real target of this image, tiny Atlas, can be seen. Atlas is at image center, just outside the A ring.

A couple of faint ringlets are visible in the Encke Gap, right of center. Tethys is 1,071 kilometers (665 miles) wide; Atlas is a mere 32 kilometers (20 miles) wide.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 21, 2005, at a distance of approximately 2 million kilometers (1.2 million miles) from Tethys and 1.7 million kilometers (1.1 million miles) from Atlas. The image scale is 12 kilometers (7 miles) per pixel on Tethys.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

The Saturnian moons Prometheus and Dione. Image credit: NASA/JPL/SSI Click to enlarge
The ring moon Prometheus continues its work shaping the delicate F ring as Dione looks on. It is easy to see how Prometheus has an irregular, oblong shape, while Dione is quite round.

The rings are partly cut off by Saturn’s shadow at right. Prometheus is 102 kilometers (63 miles) wide; Dione is 1,123 kilometers (700 miles) wide.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 20, 2005, at a distance of approximately 2.5 million kilometers (1.6 million miles) from Dione and 2.2 million kilometers (1.4 million miles) from Prometheus. The image scale is 15 kilometers (9 miles) per pixel on Dione and 13 kilometers (8 miles) per pixel on Prometheus.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

NASA/JPL/SSI News Release

Icy Epimetheus behind Saturn’s rings. Image credit: NASA/JPL/SSI Click to enlarge
The Cassini spacecraft captured this glimpse of icy Epimetheus just before the small moon disappeared behind the bulk of Saturn’s atmosphere.

See Looking Down on Epimetheus for a closer view of Epimetheus (116 kilometers, or 72 miles across).

The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 20, 2005, at a distance of approximately 2.3 million kilometers (1.4 million miles) from Epimetheus and 2.2 million kilometers (1.4 million miles) from Saturn. The image scale is 14 kilometers (9 miles) per pixel on Epimetheus and 13 kilometers (8 miles) per pixel on Saturn.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

False-colour images of Titan obtained by Cassini-Huygens Visual Infrared Mapping Spectrometer. Image credit: Click to enlarge
Using recent Cassini, Huygens and Earth-based observations, scientists have been able to create a computer model which explains the formation of several types of ethane and methane clouds on Titan.

Clouds have been observed recently on Titan, Saturn’s largest moon, through the thick haze, using near-infrared spectroscopy and images of the south pole and temperate regions near 40? South. Recent observations from Earth-based telescopes and the NASA/ESA/ASI Cassini spacecraft are now providing an insight into cloud climatology.

A European team, led by Pascal Rannou of the Service d?Aeronomie, IPSL Universite de Versailles-St-Quentin, France, has developed a general circulation model which couples dynamics, haze and cloud physics to study Titan climate and enables us to understand how the major cloud features which are observed, are produced.

This climate model also allows scientists to predict the cloud distribution for the complete Titan year (30 terrestrial years), and especially in the next years of Cassini observations.

The Voyager missions of the early 1980s gave the first indications of condensate clouds on Titan. Because of the cold temperatures in the moon?s atmosphere (tropopause), it was assumed that most of the organic chemicals formed in the upper atmosphere by photochemistry would condense into clouds while sinking. Methane would also condense at high altitudes, it was believed, having been transported from the surface.

Since then, several one-dimensional models of Titan’s atmosphere including sophisticated microphysics models were created to predict the formation of drops of ethane and methane. Similarly, the methane cycle had been studied separately in a circulation model, but without cloud microphysics.

These studies generally found that methane clouds could be triggered when air parcels cooled while moving upward or from equator to pole. However, these models hardly captured the fine details of the methane and ethane cloud cycles.

What Rannou’s team has done is to combine a cloud microphysical model into a general circulation model. The team can now identify and explain the formation of several types of ethane and methane clouds, including the south polar and sporadic clouds in the temperate regions, especially at 40? S in the summer hemisphere.

The scientists found that the predicted physical properties of the clouds in their model matched well with recent observations. Methane clouds that have been observed to date appear in locations where ascending air motions are predicted in their model.

The observed south polar cloud appears at the top of a particular ‘Hadley cell’, or mass of vertically circulating air, exactly where predicted at the south pole at an altitude of around 20-30 kilometres.

The recurrent large zonal (longitudinal direction) clouds at 40? S and the linear and discrete clouds that appear in the lower latitudes are also correlated with the ascending part of similar circulation cell in the troposphere, whereas smaller clouds at low latitudes, similar to the linear and discrete clouds already observed by Cassini are rather produced by mixing processes.

“Clouds in our circulation model are necessarily simplified relative to the real clouds, however the main cloud features predicted find a counterpart in reality.

“Consistently, our model produces clouds at places where clouds are actually observed, but it also predicts clouds that have not, or not yet, been observed,” said Pascal Rannou.

Titan’s cloud pattern appears to be similar to that of the main cloud patterns on Earth and Mars. The puzzling clouds at 40? S are produced by the ascending branch of a Hadley cell, exactly like tropical clouds are in the Intertropical Convergence Zone (ITCZ), as on Earth and Mars.

Polar clouds – produced by ‘polar cells’ – are similar to those produced at mid-latitudes on Earth. On other hand, clouds only appears at some longitudes. This is a specific feature of Titan clouds, and may be due to a Saturn tidal effect. The dynamical origin of cloud distribution on Titan is easy to test.

Cloudiness prediction for the coming years will be compared to observations made by Cassini and ground-based telescopes. Specific events will definitely prove the role of the circulation on the cloud distribution.

Original Source: ESA Portal

Saturnian storms swirling in the region “storm alley”. Image credit: NASA/JPL/SSI Click to enlarge
Two Saturnian storms swirl in the region informally dubbed “storm alley” by scientists. This mid-latitude region has been active with storms since Cassini scientists began monitoring Saturn in early 2004.

The large storm at left is at least 2,500 kilometers (1,600 miles) across from north to south. This is bigger than typical storms in the region, which are the size of large Earth hurricanes, or about 1,000 kilometers (600 miles) across. To the left, the smaller storm is about 700 kilometers (400 miles) across.

The two storms are interacting. Their threadlike arms are intertwined, and they might have merged a few days after this image was taken. See PIA06082 and PIA06083 for movies of storm activity in this region.

The image was taken with the Cassini spacecraft narrow-angle camera on Dec. 9, 2005, at a distance of approximately 3.2 million kilometers (2 million miles) from Saturn. The image was obtained using a filter sensitive to wavelengths of infrared light centered at 727 nanometers. The image scale is 38 kilometers (23 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

An artist’s impression of Huygens at its landing site on Titan. Image credit: ESA Click to enlarge
One year ago this week, on January 14, 2005, the European Space Agency’s (ESA) Huygens probe reached the upper layer of Titan’s atmosphere and landed on the surface after a parachute descent 2 hours and 28 minutes later.

As part of the joint NASA/ESA/ASI mission to Saturn and its moons, the Huygens probe was sent from the Cassini spacecraft to explore Titan, Saturn’s largest moon. Titan’s organic chemistry may be like that of the primitive Earth around 4000 million years ago, and it may hold clues about how life began on our planet.

The Huygens mission has been an outstanding engineering and scientific success, one of the most complex and scientifically rewarding space missions to date.

The touchdown on the surface of Titan marked the farthest a man-made spacecraft has successfully landed away from Earth.

Clear images of the surface of Titan were obtained below an altitude of 40 kilometers (25 miles) — revealing an extraordinary world that resembled Earth in many respects, especially in meteorology, geomorphology and fluvial activity, but with different ingredients. The images show strong evidence for erosion due to liquid flows, possibly methane.

Huygens enabled studies of the atmosphere and surface, including the first in-situ sampling of the organic chemistry and the aerosols below 150 kilometers (93 miles). These confirmed the presence of a complex organic chemistry, which reinforces the idea that Titan is a promising place to observe the molecules that may have been the precursors of the building blocks of life on Earth.

Around 260 scientists and up to 10,000 engineers and other professionals from 19 countries overcame cross-cultural and multi-disciplinary differences to achieve an astonishing co-operation. ESA’s Huygens project scientist, Jean-Pierre Lebreton said, “This mission took two decades to accomplish and pushed the limits of our capabilities, whether scientific, technological or organisational. But the scientists and engineers used their skills and intelligence to overcome technical, political and celestial barriers to their goals.

“In the end, they triumphed spectacularly and, apart from the amazing scientific return, the mission should be an inspiration and a lesson for organisations of all kinds, in all sectors, of how people can work together.”

The Cassini-Huygens mission is a cooperative project of NASA, 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 Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The Descent Imager/Spectral team is based at the University of Arizona, Tucson, Ariz.

Original Source: NASA/JPL/SSI News Release

Haze layers in the atmosphere encircling Saturn. Image credit: NASA/JPL/SSI Click to enlarge
In this magnificent view, delicate haze layers high in the atmosphere encircle the oblate figure of Saturn. A special combination of spectral filters used for this image makes the high haze become visible. A methane-sensitive filter (centered at 889 nanometers) makes high altitude features stand out, while a polarizing filter makes small haze particles appear bright.

Methane in the atmosphere absorbs light with wavelengths around 889 nanometers as it travels deeper into the gas planet, thus bright areas in this image must represent reflective material at higher altitudes. Small particles or individual molecules scatter light quite effectively to a polarization of 90 degrees, which this polarizing filter is sensitive to. Thus, high altitude haze layers appear bright in this view.

The small blob of light at far right is Dione (1,126 kilometers, or 700 miles across).

The image was taken with the Cassini spacecraft wide-angle camera on Dec. 5, 2005, at a distance of approximately 2.9 million kilometers (1.8 million miles) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 100 degrees. The image scale is 169 kilometers (105 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Tethys floating past the massive golden globe of Saturn. Image credit: NASA/JPL/SSI Click to enlarge
Tethys floats before the massive, golden-hued globe of Saturn in this natural color view. The thin, dark line of the rings curves around the horizon at top.

Visible on Tethys (1,071 kilometers, or 665 miles across) are the craters Odysseus (top) and Melanthius (bottom). The view looks toward the anti-Saturn side of Tethys.

Images taken using red, green and blue spectral filters were combined to create this color view. Tethys is apparently darker than Saturn at these wavelengths. The edge of the planet appears fuzzy, which may indicate that we are seeing haze layers that are separated from the main cloud deck.

The images were acquired by the Cassini spacecraft narrow-angle camera on Dec. 3, 2005, at a distance of approximately 2.5 million kilometers (1.6 million miles) from Saturn. The image scale is 15 kilometers (9 miles) per pixel on Saturn and 13 kilometers (8 miles) per pixel on Tethys.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release.

Tethys shows off its great scar. Image credit: NASA/JPL/SSI Click to enlarge
A crescent Tethys shows off its great scar, Ithaca Chasma, for which the moon is renowned. The chasm is 100 kilometers (60 miles) across on average, and is 4 kilometers (2 miles) deep in places.

See Steep Scarps for a much closer view of the chasm taken during a Cassini flyby.

Ithaca Chasma is the most prominent sign of ancient geologic activity on Tethys (1,071 kilometers, or 665 miles across), whose surface is characterized principally by heavy cratering.

The lit surface visible here is on the moon’s Saturn-facing hemisphere. North on Tethys is straight up.

The image was taken with the Cassini spacecraft narrow-angle camera on Nov. 28, 2005 using a filter sensitive to wavelengths of infrared light centered at 930 nanometers. The view was acquired at a distance of approximately 1.1 million kilometers (700,000 miles) from Tethys and at a Sun-Tethys-spacecraft, or phase, angle of 123 degrees. Resolution in the original image was 6 kilometers (4 miles) per pixel. The image has been magnified by a factor of two and contrast-enhanced to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release

Titan’s orange globe surrounded with a soft purple haze. Image credit: NASA/JPL/SSI Click to enlarge
With its thick, distended atmosphere, Titan’s orange globe shines softly, encircled by a thin halo of purple light-scattering haze.

Images taken using blue, green and red spectral filters were used to create this enhanced-color view; the color images were combined with an ultraviolet view that makes the high-altitude, detached layer of haze visible. The ultraviolet part of the composite image was given a purplish hue to match the bluish-purple color of the upper atmospheric haze seen in visible light.

Small particles that populate high hazes in Titan’s atmosphere scatter short wavelengths more efficiently than longer visible or infrared wavelengths, so the best possible observations of the detached layer are made in ultraviolet light.

The images in this view were taken by the Cassini narrow-angle camera on May 5, 2005, at a distance of approximately 1.4 million kilometers (900,000 miles) from Titan and at a sun-Titan-spacecraft, or phase, angle of 137 degrees. Image scale is 8 kilometers (5 miles) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, 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, D.C. 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, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL/SSI News Release.