Blog Archives

A Craterful of Cracks

The northwest quadrant of a frost-filled crater on Mars. Original image ESP_042895_2495; credit: NASA/JPL/University of Arizona.

The northwest quadrant of a frost-filled crater on Mars. Original image ESP_042895_2495; credit: NASA/JPL/University of Arizona.

Here’s a view of a section of a crater on Mars filled with a lacework of bright spidery fractures, acquired on Sept. 20, 2015 with the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter. The crater is approximately 3 miles (5 km) wide and located in Mars’ north polar region, and its old, infilled interior has undergone countless millennia of freeze/thaw cycles that have broken the surface into polygons of all sizes, outlined by frost-filled cracks.

The fractured segments get increasingly more compressed closer to the crater rim, which contains the outward freeze expansion.

According to the image description from the HiRISE team:
The crater rim constrains the polygon formation within the crater close to the rim, creating a spoke and ring pattern of cracks. This leads to more rectangular polygons than those near the center of the crater. The polygons close to the center of the crater display a more typical pattern. A closer look shows some of these central polygons, which have smaller polygons within them, and smaller polygons within those smaller polygons, which makes for a natural fractal! 

See a wider view of the imaged region here.

Source: HiRISE/University of Arizona

Icy Enceladus Shines in the Latest Images from Cassini

A view of the Saturn-lit night side of Enceladus from Oct. 14, 2015.

A view of the Saturn-lit night side of Enceladus from Oct. 14, 2015.

On Wednesday, Oct. 14 2015, Cassini performed its scheduled “E-20” close pass of Enceladus, a 320-mile-wide moon of Saturn that is now famous for the organics-laden ice geysers that fire from cracks in its southern crust. E-20 is the first of a series of three flybys to be performed before the end of 2015, specifically timed to give the spacecraft a good view of Enceladus’ north polar region now that Saturn is moving into its summer season.

The raw image data from E-20 has just arrived on Earth today (which, by the way, is the 18th anniversary of Cassini’s launch!) and I particularly liked the one above. Crescent-lit by the Sun, Enceladus’ night side is seen bathed in the dimmer glow of reflected light off Saturn and its rings. Dead-center is the 6.5-mile-wide crater Bahman, surrounded by a wrinkly field of cracks and troughs in the moon’s highly-reflective icy surface.

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Oh What a Relief! Cool 3D Views of the Moon via LROC

Red/cyan anaglyph of Hell Q crater on the Moon's near side  (NASA/GSFC/Arizona State University)

Red/blue anaglyph of Hell Q crater on the Moon’s near side (NASA/GSFC/Arizona State University)

Do you have any of those paper 3D viewers around? You know, with the red and blue lenses? If so, pop ’em on and check out the image above from NASA’s Lunar Reconnaissance Orbiter Camera (LROC) showing the crater “Hell Q,” located on the Moon’s southern near side near the brightly-rayed Tycho. You might think a crater was just carved into your screen!

The 3.75-km-wide Hell Q is one of a cluster of 19 craters located around the main 32.5-km Hell crater. (And no, it wasn’t named after a realm of the afterworld but rather for Hungarian astronomer Maximillian Hell.)

The image was acquired on April 11, 2014. You can see a larger 3D view of the region around Hell Q below.

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Mars Gets a Brand New Crater

HiRISE image of a bright rayed crater on Mars (NASA/JPL-Caltech/Univ. of Arizona)

HiRISE image of a bright rayed crater on Mars (NASA/JPL-Caltech/Univ. of Arizona)

If you count at least slightly over two years old as “brand new” then yes, this one is certainly that!

Seen above in an image taken by the HiRISE camera aboard NASA’s Mars Reconnaissance Orbiter on Nov. 19, 2013, a 100-foot-wide (30-meter) crater is surrounded by bright rays of ejected material and blown-clear surface. Since HiRISE calibrates color to surface textures, the less-dusty cleared surface at the crater site appears blue. (See a true-color calibrated scan here.)

By narrowing down when this particular spot was last seen to be crater-free, scientists have determined that the impact event that caused this occurred between July 2010 and May 2012.

Ejected material from this cratering event was thrown outward over 9 miles (15 km). It’s estimated that impacts producing craters at least 12.8 feet (3.9 meters) in diameter occur on Mars at a rate of over 200 per year.

Source: NASA/JPL (And download this on a HiFlyer here!)

Highlighting Rhea’s Subtle Colors – New Cassini Images of Saturn’s Moon

Color-composite of Rhea (NASA/JPL/SSI/J. Major)

Color-composite of Rhea (NASA/JPL/SSI/J. Major)

This is a color composite image of Rhea (pronounced REE-ah) I made from raw images acquired by the Cassini spacecraft on March 9, 2013, during its most recent — and final — close pass of the moon. The visible-light colors of Rhea’s frozen surface have been oversaturated to make them more apparent… even so, it’s still a very monochromatic place.

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Rhapsody on an Impact Event: Mercury’s Rachmaninoff Crater

The peak-ringed interior of Mercury’s Rachmaninoff crater

Rachmaninoff is a spectacular double-ring basin on Mercury, and this color view is one of the highest resolution color image sets acquired of the basin’s floor. Visible around the edges of the frame is a circle of mountains that make up Rachmaninoff’s peak ring structure. The color of the basin’s floor inside the peak-ring differs from the darker material outside of it, and contains concentric troughs formed by extension (pulling apart) of the surface, likely as the molten surface solidified and cooled in the wake of the initial impact event.

This image was acquired as a high-resolution targeted color observation by MESSENGER on July 31, 2012. See a wider-angle view of the 140-km-wide Rachmaninoff crater here.

Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington


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