OrbitalHub

NASA dixit:

“October 23, 2016. Dione’s lit hemisphere faces away from Cassini’s camera, yet the moon’s darkened surface features are dimly illuminated in this image, due to Saturnshine. Although direct sunlight provides the best illumination for imaging, light reflected off of Saturn can do the job as well. In this image, Dione (698 miles or 1,123 kilometers across) is above Saturn’s day side, and the moon’s night side is faintly illuminated by sunlight reflected off the planet’s disk.

This view looks toward the Saturn-facing side of Dione. North on Dione is up and rotated 8 degrees to the right. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 313,000 miles (504,000 kilometers) from Dione. Image scale is 1.8 miles (3 kilometers) per pixel.”

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

NASA dixit:

“April 2, 2016. Saturn’s main rings, along with its and moons, are much brighter than most stars. As a result, much shorter exposure times (10 milliseconds, in this case) are required to produce an image and not saturate the detectors of the imaging cameras on NASA’s Cassini spacecraft. A longer exposure would be required to capture the stars as well. Cassini has captured stars on many occasions, especially when a target moon is in eclipse, and thus darker than normal. Dione (698 miles, 1123 kilometers across) and Epimetheus (70 miles, 113 kilometers across) are seen in this view, above the rings at left and right respectively.

This image looks toward the sunlit side of the rings from about 3 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera. The view was obtained at a distance of approximately 257,000 miles (413,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 34 degrees. Image scale is 15 miles (25 kilometers) per pixel.”

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

NASA dixit:

“April 11, 2015. Unusual arc-shaped, reddish streaks cut across the surface of Saturn’s ice-rich moon Tethys in this enhanced-color mosaic. The red streaks are narrow, curved lines on the moon’s surface, only a few miles (or kilometers) wide but several hundred miles (or kilometers) long. The red streaks are among the most unusual color features on Saturn’s moons to be revealed by Cassini’s cameras.

A few of the red arcs can be faintly seen in Cassini imaging observations made earlier in the mission, but the color images for this observation, which were obtained in April 2015, were the first to show large northern areas of Tethys under the illumination and viewing conditions necessary to see the features clearly. As the Saturn system moved into its northern hemisphere summer over the past few years, northern latitudes have become increasingly well illuminated. As a result, the red arc features have become clearly visible for the first time.

The origin of the features and their reddish color is currently a mystery to Cassini scientists. Possibilities being studied include ideas that the reddish material is exposed ice with chemical impurities, or the result of outgassing from inside Tethys. The streaks could also be associated with features like fractures that are below the resolution of the available images.

Except for a few small craters on Dione, reddish tinted features are rare on other moons of Saturn. However, many reddish features are observed on the geologically young surface of Jupiter’s moon Europa.

Images taken using clear, green, infrared and ultraviolet spectral filters were combined to create the view, which highlights subtle color differences across Tethys’ surface at wavelengths not visible to human eyes. The moon’s surface is fairly uniform in natural color. The yellowish tones on the left side of the view are a result of alteration of the moon’s surface by high-energy particles from Saturn’s magnetosphere. This particle radiation slams into the moon’s trailing hemisphere, modifying it chemically and changing its appearance in enhanced-color views like this one.

The area of Tethys shown here is centered on 30 degrees north latitude, 187 degrees west longitude, and measures 305 by 258 miles (490 by 415 kilometers) across. The original color images were obtained at a resolution of about 2,300 feet (700 meters) per pixel. This is a mosaic of images that have been photometrically calibrated and map-projected.”

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

NASA dixit:

“December 23, 2012. The famed wispy terrain on Saturn’s moon Dione is front and center in this recent Cassini spacecraft image. The ”wisps” are fresh fractures on the trailing hemisphere of the moon’s icy surface. This view is centered on 55 degrees north latitude and 85 degrees west longitude on Dione (698 miles, or 1,123 kilometers across). North is up and rotated 39 degrees to the left.

The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was obtained at a distance of approximately 153,000 miles (246,000 kilometers) from Dione. Image scale is 0.9 miles (1.5 kilometers) per pixel.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

NASA dixit:

“March 28, 2012. This raw image from NASA’s Cassini spacecraft was taken with the camera pointing toward Saturn’s moon Dione at approximately 27,668 miles (44,528 kilometers) away.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA

NASA dixit:

“March 4, 2010. Saturn’s moon Dione dwarfs the moon Telesto in this Cassini spacecraft image. Dione (1123 kilometers, 698 miles across) is the fourth largest of Saturn’s moons, and it dominates this view. Tiny Telesto (25 kilometers, or 16 miles across) can be seen below and to the left of Dione. This view looks toward the anti-Saturn side of Dione. North on Dione is up. The image was taken in visible light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 477,000 kilometers (296,000 miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 72 degrees. Scale on Dione is 3 kilometers (2 miles) per pixel.”

“After almost 20 years in space, NASA’s Cassini spacecraft begins the final chapter of its remarkable story of exploration: its Grand Finale. Between April and September 2017, Cassini will undertake a daring set of orbits that is, in many ways, like a whole new mission. Following a final close flyby of Saturn’s moon Titan, Cassini will leap over the planet’s icy rings and begin a series of 22 weekly dives between the planet and the rings.

No other mission has ever explored this unique region. What we learn from these final orbits will help to improve our understanding of how giant planets – and planetary systems everywhere – form and evolve.

On the final orbit, Cassini will plunge into Saturn’s atmosphere, sending back new and unique science to the very end. After losing contact with Earth, the spacecraft will burn up like a meteor, becoming part of the planet itself.

Cassini’s Grand Finale is about so much more than the spacecraft’s final dive into Saturn. That dramatic event is the capstone of six months of daring exploration and scientific discovery. And those six months are the thrilling final chapter in a historic 20-year journey.”

Image credit: NASA