HRSC: Crashing into martian mud

water-rich-impact-craterAn impactor smashing into an ice-rich surface gave rise to the complex flow features around this ancient crater on Mars.

Impacts of comets and asteroids have shaped the surfaces of rocky planets and moons over the Solar System’s 4.6 billion year history, and can reveal environmental conditions at the time of their formation.

During an impact, the energy transferred to the ground goes into melting and vapourising the impactor and parts of the surface, as well as excavating vast amounts of material from the ground, throwing it out onto the surrounding terrain as a blanket of debris.

The characteristics of the ejected material can provide clues as to the conditions of the planet’s surface and its general environment.

The 32 km-wide crater seen centre-stage in this image clearly formed at a time when water or ice was present near the surface. The energy of the impact heated up the water-rich sub-surface, allowing it to flow more easily, leading to the ‘fluidised’ nature of the ejecta blanket…. [More at link]

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HiRISE: An isolated secondary crater cluster from Resen Crater in Hesperia Planum

tumblr_ou2ebait4R1rlz4gso1_1280An isolated secondary crater cluster from Resen Crater in Hesperia Planum. Beautiful Mars series.

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Curiosity: Ridge-top rock, broken and layered

1814-mastcam34Sol 1814, September 13, 2017. Curiosity’s Mastcam turned its gaze downward to image the rock surface next to the rover. Seen close-up (click the image), the rocks are finely layered, but heavily broken and eroded, with pebbles and sand collecting in low spots.

Below is Curiosity’s location on the ridge; note the many large cracks in the rock. (See the panorama here also.) In addition, while the ridge-top is broadly flat, several eroded layers appear to rise successively toward the south (image bottom). Click either image to enlarge it.

Sol 1814 raw images (from all cameras), and Curiosity’s latest location.


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MARCI weather report, September 4-10, 2017

MARCI-September-7-2017During the past week, the seasonal north polar cap edge had retreated to about 67 degrees north latitude. Water vapor released from the north polar cap was transported southward by the general circulation to the northern tropics, where it formed into clouds as part of the devloping aphelion (equatorial) cloud belt. Water ice clouds were also observed over the major shield volcanoes and in the southern mid-latitudes. Hellas and Argyre remained rather hazy due to these clouds. A number of local dust storms were observed west of Argyre basin and more sporadically throughout the rest of the southern mid-latitudes. Arculate shaped storms were along the north polar cap edge… [More at link, including video]

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Curiosity update: Stopping to smell the rocks

NLB_558533366EDR_F0660054NCAM00385M_-br2Sol 1815-16, September 14, 2017, update by MSL scientist Abigail Fraeman: Planning for Curiosity this morning was a bit like reading a great mystery novel. There were several twists and turns along the way, but we eventually reached an exciting ending that will reveal “Whodunnit?” – or more accurately — what geologic forces had done to shape this landscape billions of years ago.

The drive yestersol was successful, and placed us in front of one of many meter-scale factures that criss-cross this area. These fractures are visible in high-resolution orbital images, and on the ground are surrounded by raised broken rocks that appear to be slightly more resistant to erosion than their surroundings. We are interested in understanding how these fractures formed, if they were conduits for ancient water, and why the rocks on their edges are raised. We made a quick decision early in the planning day that these rocks were interesting enough to warrant staying here another couple of days to collect good contact science targets, rather than the single touch-and-go we had originally planned… [More at link]

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New gravity map suggests Mars crust is porous

mars_crust_cover_imageNASA scientists have found evidence that Mars’ crust is not as dense as previously thought, a clue that could help researchers better understand the Red Planet’s interior structure and evolution.

A lower density likely means that at least part of Mars’ crust is relatively porous. At this point, however, the team cannot rule out the possibility of a different mineral composition or perhaps a thinner crust.

“The crust is the end-result of everything that happened during a planet’s history, so a lower density could have important implications about Mars’ formation and evolution,” said Sander Goossens of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Goossens is the lead author of a Geophysical Research Letters paper describing the work.

The researchers mapped the density of the Martian crust, estimating the average density is 2,582 kilograms per meter cubed (about 161 pounds per cubic foot). That’s comparable to the average density of the lunar crust. Typically, Mars’ crust has been considered at least as dense as Earth’s oceanic crust, which is about 2,900 kilograms per meter cubed (about 181 pounds per cubic foot)… [More at links]

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Curiosity’s views on approach to Vera Rubin Ridge

pia21850-16-640x350NASA’s Mars rover Curiosity has begun the steep ascent of an iron-oxide-bearing ridge that’s grabbed scientists’ attention since before the car-sized rover’s 2012 landing.

“We’re on the climb now, driving up a route where we can access the layers we’ve studied from below,” said Abigail Fraeman, a Curiosity science-team member at NASA’s Jet Propulsion Laboratory in Pasadena, California.

“Vera Rubin Ridge” stands prominently on the northwestern flank of Mount Sharp, resisting erosion better than the less-steep portions of the mountain below and above it. The ridge, also called “Hematite Ridge,” was informally named earlier this year in honor of pioneering astrophysicist Vera Rubin.

“As we skirted around the base of the ridge this summer, we had the opportunity to observe the large vertical exposure of rock layers that make up the bottom part of the ridge,” said Fraeman, who organized the rover’s ridge campaign. “But even though steep cliffs are great for exposing the stratifications, they’re not so good for driving up.”

The ascent to the top of the ridge from a transition in rock-layer appearance at the bottom of it will gain about 213 feet (65 meters) of elevation — about 20 stories. The climb requires a series of drives totaling a little more than a third of a mile (570 meters). Before starting this ascent in early September, Curiosity had gained a total of about 980 feet (about 300 meters) in elevation in drives totaling 10.76 miles (17.32 kilometers) from its landing site to the base of the ridge.

Curiosity’s telephoto observations of the ridge from just beneath it show finer layering, with extensive bright veins of varying widths cutting through the layers.

“Now we’ll have a chance to examine the layers up close as the rover climbs,” Fraeman said. [More at link]

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THEMIS: Merging dunes in Siton Undae

Merging dunes in Siton Undae (THEMIS_IOTD_20170914)THEMIS Image of the Day, September 14, 2017. Siton Undae is a large dune field located in the northern plains near Escorial Crater. Siton Undae is west of the crater and is one of three dune fields near the crater. The nearby north polar cap is dissected by Chasma Boreale, which exposes an ice free surface. This image shows part of the center of the dune field. In this image the crescent nature of the individual dunes can be see in the lower left portion of the image. As the dunes coalesce the crescent form is lost.

NASA’s Mars Odyssey spacecraft has spent over 15 years in orbit around Mars, circling the planet more than 69,000 times. It holds the record for longest working spacecraft at Mars. THEMIS, the IR/VIS camera system, has collected data for the entire mission and provides images covering all seasons and lighting conditions.

Over the years many features of interest have received repeated imaging, building up a suite of images covering the entire feature. From the deepest chasma to the tallest volcano, individual dunes inside craters and dune fields that encircle the north pole, channels carved by water and lava, and a variety of other feature, THEMIS has imaged them all.

For the next several months the Image of the Day will focus on the Tharsis volcanoes, the various chasmata of Valles Marineris, and the major dunes fields. We hope you enjoy these images!

More THEMIS Images of the Day by geological topic.

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Curiosity: Up on the ridge-top…

1814-navcamNSol 1814, September 13, 2017. The Navcam shoots a composite looking north over the view — Curiosity is now up on top of Vera Rubin Ridge. Click image to enlarge it.

Sol 1814 raw images (from all cameras), and Curiosity’s latest location.

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HiRISE: Pits and cracks along a crater wall

tumblr_ou2e2eux3c1rlz4gso2_1280Pits and cracks along a crater wall — February 2017, approximately 303 km above the surface. Beautiful Mars series.

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