Tag: Saturn

Link here. The article does a nice job of outlining, with videos, what will happen as the spacecraft makes multiple dives inside rings.

Cassini’s final acts, which will play out over the next year. That pass placed Cassini in a high-inclination orbit tilted 60° relative to the ring plane. Cassini will perform 20 passes just 620 miles (1000 kilometers) outside the F ring of Saturn in a phase known as the Ring-Grazing Orbits, which runs from late November 2016 through April 2017.

Cassini already reached apoapse, or its farthest point from Saturn, on Wednesday, November 30th. The first ring crossing is coming right up this weekend on Sunday, December 4th, at 7:09 a.m. EST / 13:09 UT. During the first periapse pass on Sunday, Cassini will also burn its main engine for the 183rd and final time for the mission. All later fine course corrections will be made using thrusters only.

Things get even more interesting after April, when the series of Grand Finale Orbits will begin, taking the spacecraft through the 1240-mile-wide (2000-kilometer-wide) gap between the planet’s cloud tops and rings for 22 final orbits. The Grand Finale Orbits start with the spacecraft’s 126th and final pass near Titan, which will set the spacecraft up for much tighter final orbits.

Cool image time! The image on the right, reduced in resolution to show here, shows Saturn from above as Cassini began re-positioning itself into a higher inclination orbit for its last year of orbit dives near and inside the planet’s rings.

The view looks toward the sunlit side of the rings from about 41 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on July 16, 2016 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 1 million miles (2 million kilometers) from Saturn. Image scale is 68 miles (110 kilometers) per pixel.

A comparison of images taken by Cassini in 2012 and then in 2016 of Saturn’s north polar region shows a significant change in color.

Scientists are investigating potential causes for the change in color of the region inside the north-polar hexagon on Saturn. The color change is thought to be an effect of Saturn’s seasons. In particular, the change from a bluish color to a more golden hue may be due to the increased production of photochemical hazes in the atmosphere as the north pole approaches summer solstice in May 2017.

Cool image time! The image on the right, reduced to fit here, is a recent Cassini image, taken July 2, 2016, that shows the rings as well as the moon Pan nestled within the ring’s narrow gap

Pan (17 miles or 28 kilometers across, left of center) holds open the Encke gap and shapes the ever-changing ringlets within the gap (some of which can be seen here). In addition to raising waves in the A and B rings, other moons help shape the F ring, the outer edge of the A ring and open the Keeler gap. This view looks toward the sunlit side of the rings from about 8 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on July 2, 2016.

The image also highlights the incredible and quite magical beauty of Saturn’s rings, which remain to me one of the solar system’s most amazing wonders.

Cool image time. The Cassini science team have released a beautiful full-color image of Saturn, shown cropped on the right, as well as a movie, both produced from images taken in April.

This view shows Saturn’s northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Saturn’s year is nearly 30 Earth years long, and during its long time there, Cassini has observed winter and spring in the north, and summer and fall in the south. The spacecraft will complete its mission just after northern summer solstice, having observed long-term changes in the planet’s winds, temperatures, clouds and chemistry.

Cassini scanned across the planet and its rings on April 25, 2016, capturing three sets of red, green and blue images to cover this entire scene showing the planet and the main rings. The images were obtained using Cassini’s wide-angle camera at a distance of approximately 1.9 million miles (3 million kilometers) from Saturn and at an elevation of about 30 degrees above the ring plane. The view looks toward the sunlit side of the rings from a sun-Saturn-spacecraft angle, or phase angle, of 55 degrees. Image scale on Saturn is about 111 miles (178 kilometers) per pixel.

The exposures used to make this mosaic were obtained just prior to the beginning of a 44-hour movie sequence.

The only real tragedy here is that the Cassini mission is ending soon. When it does, it will be decades, at a minimum, before we have another spacecraft in orbit around Saturn and capable of giving us this view.

Update: NASA today issued a press release detailing what will happen during Cassini’s final year at Saturn, including 22 plunges between Saturn and its rings!

Cool image time! The image to the right (reduced in resolution to show here) was posted today on the Cassini gallery page. The release focused on the bright spot in the widest ring just above the center of the image.

An ethereal, glowing spot appears on Saturn’s B ring in this view from NASA’s Cassini spacecraft. There is nothing particular about that place in the rings that produces the glowing effect — instead, it is an example of an “opposition surge” making that area on the rings appear extra bright. An opposition surge occurs when the Sun is directly behind the observer looking toward the rings. The particular geometry of this observation makes the point in the rings appear much, much brighter than would otherwise be expected.

I however am more interested in the black outline at Saturn’s limb that visually separates the planet from the rings. Is that natural or introduced intentionally in data processing to make the image more pleasing? If it is natural than I wonder how Saturn’s top cloud layer could produce such an opaque and sharply defined region able to so successfully block the light coming from the rings. If introduced intentionally I question the wisdom, as I can’t see any reason to do it and therefore am worried that they might have done some other unnecessary manipulation that makes it difficult to draw any honest conclusions from the image.

Either way, from an aesthetic perspective the image still remains breath-taking. It also underlines once again the amazing engineering that made it possible. All things remain possible, if we maintain our ability to build this kind of engineering.

Cool image time! The picture on right, cropped by me to show here, was taken by Cassini on April 2, 2016. You can see the moons Dione (on left) and Epimetheus (on right) above the rings. The full image can be seen here.

I am sure there is a lot of important science contained within this image. I post it here however not because of any scientific reason but entirely because it is simply damn spectacular. More than a decade after Cassini arrived at Saturn, every new picture of the planet’s giant ring system still seems incredibly unbelievable.

The universe is an amazing place, isn’t it?

Cool image time! The image on the right, reduced in resolution to post here, shows how, because of the seasonal tilt of Saturn, the shadow of its rings is now cover much of the gas giant’s southern hemisphere.

When NASA’s Cassini spacecraft arrived at Saturn 12 years ago, the shadows of the rings lay far to the north on the planet. As the mission progressed and seasons turned on the slow-orbiting giant, equinox arrived and the shadows of the rings became a thin line at the equator. This view looks toward the sunlit side of the rings from about 16 degrees above the ring plane. The image was taken in red light with the Cassini spacecraft wide-angle camera on March 19, 2016.

We will continue to get from Cassini increasingly beautiful images of Saturn and its rings as the spacecraft positions itself better for its final flight down into the planet’s atmosphere.

Cool image time! The picture below, taken by Cassini in April, looks down at Saturn’s vast rings and shows a disruption in Saturn’s outermost F ring, likely caused by an interaction of objects within the ring.

Cool image time! Be sure to click on this link to see the full resolution Cassini version of the image on the right. Its resolution is 10 miles per pixel, and even so the giant planet cannot be fit in the frame.

One moon, Tethys, is visible, though to make it so required its brightness to be increased by 2. Also, if you look close at the bands at the north pole you can see their strange still-not-understood pentagon shape.