The mound in the center of this image appears to have blocked the path of the dunes as they marched south (north is to the left in this image) across the scene. Many of these transverse dunes have slipfaces that face south, although in some cases, it’s hard to tell for certain. Smaller dunes run perpendicular to some of the larger-scale dunes, probably indicating a shift in wind directions in this area.
Although it might be hard to tell, this group of dunes is very near the central pit of a 35-kilometer-wide impact crater. Data from other instruments indicate the presence of clay-like materials in the rock exposed in the central pit.
Sand dunes are scattered across Mars and one of the larger populations exists in the Southern hemisphere, just west of the Hellas impact basin. The Hellespontus region features numerous collections of dark, dune formations that collect both within depressions such as craters, and among “extra-crater” plains areas.
This image displays the middle portion of a large dune field composed primarily of crescent-shaped “barchan” dunes. Here, the steep, sunlit side of the dune, called a slip face, indicates the down-wind side of the dune and direction of its migration. Other long, narrow linear dunes known as “seif” dunes are also here and in other locales to the east.
NB: “Seif” comes from the Arabic word meaning “sword.”
Much of Mars’ surface is covered by fine-grained materials that hide the bedrock, but elsewhere, such as in this scene, the bedrock is well exposed (except where covered by sand dunes).
The bright spots in the center of Occator Crater on Ceres are shown in enhanced color in this view from NASA’s Dawn spacecraft. Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA/PSI/LPI › Full image and caption
The bright central area of Ceres’ Occator Crater, known as Cerealia Facula, is approximately 30 million years younger than the crater in which it lies, according to a new study in the Astronomical Journal. Scientists used data from NASA’s Dawn spacecraft to analyze Occator’s central dome in detail, concluding that this intriguing bright feature on the dwarf planet is only about 4 million years old — quite recent in terms of geological history.
Researchers led by Andreas Nathues at the Max Planck Institute for Solar System Research (MPS) in Gottingen, Germany, analyzed data from two instruments on board NASA’s Dawn spacecraft: the framing camera, and the visible and infrared mapping spectrometer.
The new study supports earlier interpretations from the Dawn team that this reflective material — comprising the brightest area on all of Ceres — is made of carbonate salts, although it did not confirm a particular type of carbonate previously identified. The secondary, smaller bright areas of Occator, called Vinalia Faculae, are comprised of a mixture of carbonates and dark material, the study authors wrote.
New evidence also suggests that Occator’s bright dome likely rose in a process that took place over a long period of time, rather than forming in a single event. They believe the initial trigger was the impact that dug out the crater itself, causing briny liquid to rise closer to the surface. Water and dissolved gases, such as carbon dioxide and methane, came up and created a vent system. These rising gases also could have forced carbonate-rich materials to ascend toward the surface. During this period, the bright material would have erupted through fractures, eventually forming the dome that we see today.
The spacecraft is currently on its way to a high-altitude orbit of 12,400 miles (20,000 kilometers), and to a different orbital plane. In late spring, Dawn will view Ceres in “opposition,” with the sun directly behind the spacecraft. By measuring details of the brightness of the salt deposits in this new geometry, scientists may gain even more insights into these captivating bright areas.
The Dawn mission is managed by JPL for NASA’s Science Mission Directorate in Washington. Dawn is a project of the directorate’s Discovery Program, managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://dawn.jpl.nasa.gov/mission
More information about Dawn is available at the following sites:
Cassini Reveals Strange Shape of Saturn’s Moon Pan . This raw, unprocessed image of Saturn’s moon Pan was taken on March 7, 2017 by NASA’s Cassini spacecraft. Larger view
These raw, unprocessed images of Saturn’s tiny moon, Pan, were taken on March 7, 2017, by NASA’s Cassini spacecraft. The flyby had a close-approach distance of 24,572 kilometers (15,268 miles).
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA’s Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency’s Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado. Caltech in Pasadena manages JPL for NASA.
NASA’s Cassini spacecraft captured these remarkable views of a propeller feature in Saturn’s A ring on Feb. 21, 2017. These are the sharpest images taken of a propeller so far, and show an unprecedented level of detail. The propeller is nicknamed “Santos-Dumont,” after the pioneering Brazilian-French aviator.
This observation was Cassini’s first targeted flyby of a propeller. The views show the object from vantage points on opposite sides of the rings. The top image looks toward the rings’ sunlit side, while the bottom image shows the unilluminated side, where sunlight filters through the backlit ring.
The two images presented as figure A are reprojected at the same scale (0.13 mile or 207 meters per pixel) in order to facilitate comparison. The original images, which have slightly different scales, are also provided here, without reprojection, as figure B; the sunlit-side image is at left, while the unlit-side image is at right.
The original images, which have slightly different scales, are seen here without reproduction; the sunlit-side image is at left, while the unlit-side image is at right. › Full image
Cassini scientists have been tracking the orbit of this object for the past decade, tracing the effect that the ring has upon it. Now, as Cassini has moved in close to the ring as part of its ring-grazing orbits, it was able to obtain this extreme close-up view of the propeller, enabling researchers to examine its effects on the ring. These views, and others like them, will inform models and studies in new ways going forward.
Like a frosted window, Saturn’s rings look different depending on whether they are seen fully sunlit or backlit. On the lit side, the rings look darker where there is less material to reflect sunlight. On the unlit side, some regions look darker because there is less material, but other regions look dark because there is so much material that the ring becomes opaque.
Observing the same propeller on both the lit and unlit sides allows scientists to gather richer information about how the moonlet affects the ring. For example, in the unlit-side view, the broad, dark band through the middle of the propeller seems to be a combination of both empty and opaque regions.
The propeller’s central moonlet would only be a couple of pixels across in these images, and may not actually be resolved here. The lit-side image shows that a bright, narrow band of material connects the moonlet directly to the larger ring, in agreement with dynamical models. That same thin band of material may also be obscuring the moonlet from view.
Lengthwise along the propeller is a gap in the ring that the moonlet has pried open. The gap appears dark on both the lit and unlit sides. Flanking the gap near the moonlet are regions of enhanced density, which appear bright on the lit side and more mottled on the unlit side.
One benefit of the high resolution of these images is that, for the first time, wavy edges are clearly visible in the gap. These waves are also expected from dynamical models, and they emphasize that the gap must be sharp-edged. Furthermore, the distance between the wave crests tells scientists the width of the gap (1.2 miles or 2 kilometers), which in turn reveals the mass of the central moonlet. From these measurements, Cassini imaging scientists deduce that the moonlet’s mass is comparable to that of a snowball about 0.6 mile (1 kilometer) wide.
For the original images (figure B), the lit-side image has a scale of 0.33 mile (530 meters) per pixel in the radial (or outward from Saturn) direction and 0.44 mile (710 meters) per pixel in the azimuthal (or around Saturn) direction. The different scales are the result of Cassini’s vantage point being off to the side of the propeller, rather than directly above it. The unlit-side image has a scale of 0.25 (410 meters) per pixel in both directions.
In order to preserve its original level of detail, the image has not been cleaned of bright blemishes due to cosmic rays and to charged particle radiation from Saturn.
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.
The north pole of Saturn sits at the center of its own domain. Around it swirl the clouds, driven by the fast winds of Saturn. Beyond that orbits Saturn’s retinue of moons and the countless small particles that form the ring.
Although the poles of Saturn are at the center of all of this motion, not everything travels around them in circles. Some of the jet-stream patterns, such as the hexagon-shaped pattern seen here, have wavy, uneven shapes. The moons as well have orbits that are elliptical, some quite far from circular.
This view looks toward the sunlit side of the rings from about 26 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Dec. 2, 2016 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 890 nanometers.
The view was acquired at a distance of approximately 619,000 miles (996,000 kilometers) from Saturn. Image scale is 37 miles (60 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.
On recent summer afternoons on Mars, navigation cameras aboard NASA’s Curiosity Mars rover observed several whirlwinds carrying Martian dust across Gale Crater. Dust devils result from sunshine warming the ground, prompting convective rising of air. All the dust devils were seen in a southward direction from the rover. Timing is accelerated and contrast has been modified to make frame-to-frame changes easier to see.
but they can certainly pick up dust and move it across the ground as seen in these video clips of Dust Devils: