Tag: asteroids

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Cool image time! The Dawn science team has released new images of Ceres, including one of a single mountain they have dubbed the Lonely Mountain.

The mountain, located in the southern hemisphere, stands 4 miles (6 kilometers) high. Its perimeter is sharply defined, with almost no accumulated debris at the base of the brightly streaked slope with bright streaks. The image was taken on August 19, 2015. The resolution of the image is 450 feet (140 meters) per pixel.

I have cropped the image and posted it on the right. Be sure to look at the full resolution version. Not only does the mountain have no debris at its base, it truly is lonely. There are no similar features anywhere near it. It almost looks like someone took a shovel of material out of the ground to create the crater immediately to the south and then dumped that material to create the mountain.

Note that the mountain is more like a mesa, with a flat top, which suggests it is the remains of a higher elevation surface that eroded away in the distant past. The geological processes that could have done this however remain quite puzzling at this point.

Dawn, in orbit around Ceres, has detected a haze above the dwarf planet’s double bright spot, suggesting that the tiny asteroid/planet is still geologically active.

Haze on Ceres would be the first ever observed directly in the asteroid belt. In 2014, researchers using the European Space Agency’s Herschel Space Observatory reported seeing water vapour spraying off Ceres, which suggested that it was geologically active1. At least one-quarter of Ceres’s mass is water, a much greater proportion than seen in most asteroids.

Bright spots pepper Ceres’s surface, but the haze has so far been seen in only one location — a crater named Occator, which has a large bright area at its centre and several smaller spots nearby. Mission scientists have been trying to work out whether the bright spots are made of ice, evaporated salts or other minerals, or something else entirely.

Some team members had been leaning towards the salt explanation, but the discovery of haze suggests the presence of sublimating ice. “At noontime, if you look at a glancing angle, you can see what seems to be haze,” Russell says. “It comes back in a regular pattern.” The haze covers about half of the crater and stops at the rim.

Cool image time! Using images that Dawn has accumulated since it entered orbit around Ceres, scientists have created an animation showing the dwarf planet as it rotates.

Video below the fold. Note that this is an animation. They have filled in the gaps between images to make the rotation smooth, exaggerated the scale two times to bring out details, and added a background of stars that is not visible in the original images. Even so, this video is scientifically useful, as it shows Ceres in its entirety. It is also very spectacular.
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Cool image time! Dawn has now swooped down to 3,200 miles, and provided a very nice image of the cratered surface of Ceres. Though it does appear to resemble the Moon, there are some differences that come to mind if you take a close look at the full resolution image. The surface appears smoother. All of the craters appear worn or eroded or less rugged. Also, there are no mountains. The terrain resembles the Moon’s lowlands or maria, but more so.

Note that the region in this picture is tantalizingly close to the double bright spot, but does not include it. Because Dawn is still easing its way into its first survey orbit of 2,700 miles elevation, it only takes pictures when it stops firing its ion engine, which it is doing almost all the time to get where it wants to be. Thus, they apparently only had time for this image.

The spacecraft enters its mapping orbit on June 3. Expect some cool images, including the first good images of the double bright spots, shortly thereafter.

Cool image time! Dawn’s science team has released a much closer image of the double bright spots on Ceres.

The spots can now be resolved into a half-dozen spots of varying size, all of which suggest material with a high reflectivity, likely ice. They look so bright because the rest of the dwarf planet’s surface is so dark.

Cool image time! Dawn has released a new animation made from images taken in early May, showing more details of the dwarf planet’s double bright spot.

As they note at the link, the double spot is now “revealed to be composed of many smaller spots.” As they also add, “Their exact nature remains unknown.”

Dawn’s engineers are now beginning to ease the spacecraft down to its survey orbit, about 2,700 miles above the surface.

Cool image time! The Dawn science team has released its first new images as the spacecraft begins its slow journey from Ceres’ night to day sides.

The images are looking down on the giant asteroid’s north pole. They have also released a short animation where they stitch together the images, allow us to see Ceres rotate under the spacecraft.

Data collected by Dawn since it entered orbit around Ceres on March 6 now strongly suggests that the bright spots on the surface are produced by venting water,

Andreas Nathues, principal investigator for Dawn’s framing camera, says the feature has spectral characteristics that are consistent with ice. Intriguingly, the brightness can be seen even when the spacecraft is looking on edge at the crater rim, suggesting that the feature may be outgassing water vapor above the rim and into space. “Ceres seems to be indeed active,” he says. The feature brightens through the course of the day, and then shuts down at night. Nathues says the behavior is similar to that of comets.

More here. By mid-April Dawn should finally settle this with high resolution images.

Get ready for cool images! Dawn was successfully captured by the gravitational field of Ceres early this morning, and is now in orbit around the planet/asteroid.

Because of the orbital mechanics of its arrival, however, Dawn will observing Ceres’s night side until mid-April, which means we will not see many new images until then.

Cool images! Dawn’s newest images have revealed that the brightest spot on Ceres, shown on the right in a cropped version of the full image, has a dimmer companion.

“Ceres’ bright spot can now be seen to have a companion of lesser brightness, but apparently in the same basin. This may be pointing to a volcano-like origin of the spots, but we will have to wait for better resolution before we can make such geologic interpretations,” said Chris Russell, principal investigator for the Dawn mission, based at the University of California, Los Angeles.

The spots are still too small for Dawn’s camera to resolve. That they are inside what looks like a crater is very puzzling. If they are water-ice, why are they so bright and distinct? One one think the ice would pile up along the crater wall, but then, that’s what we think based on our experience here on Earth with wind, rain, and our heavy gravity. Ceres is cold, has no atmosphere, and a tiny gravitational field. Every geological process will proceed in a different manner.