HiRISE: Gullies in winter shadow

ESP_049058_2360This is an odd-looking image. It shows gullies during the winter while entirely in the shadow of the crater wall. Illumination comes only from the winter skylight.

We acquire such images because gullies on Mars actively form in the winter when there is carbon dioxide frost on the ground, so we image them in the winter, even though not well illuminated, to look for signs of activity. The dark streaks might be signs of current activity, removing the frost, but further analysis is needed. [More at link]

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THEMIS: Arabia Terra crater in false color

Arabia Terra crater in false color (THEMIS_IOTD_20170321)THEMIS Image of the Day, March 21, 2017. Today’s false color image shows the floor of an unnamed crater in Arabia Terra.

The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image.

More THEMIS Images of the Day by geological topic.

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Curiosity update: First half of long-baseline stereo

NLB_543263205EDR_F0612740NCAM00312M_Sol 1643, March 20, 2017, update by USGS scientist Ken Herkenhoff: MSL drove about 28 meters toward the south on Sol 1642 and again is in an area with Murray Formation bedrock blocks surrounded by dark sand.  I helped plan ChemCam observations today, and we settled on a target called “Vinalhaven” at the left side of the layered bedrock exposure seen at upper left in this image.  Right Mastcam will image Vinalhaven and coarse material to the right of that bedrock block, at targets named “Rindgemere” and “Hurd Mountain.”  Then Right Mastcam will image more distant targets, with a 3×1 mosaic of a layered rock about 11 meters away dubbed “Saint Daniel” and a 28×1 mosaic of the hematite-bearing “Vera Rubin Ridge”… [More at link]

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Arsia Mons turned off its volcanic activity about 50 million years ago

PIA00177-16New NASA research reveals that the giant Martian volcano Arsia Mons produced one new lava flow at its summit every 1 to 3 million years during the final peak of activity. The last volcanic activity there ceased about 50 million years ago…

Located just south of Mars’ equator, Arsia Mons is the southernmost member of a trio of broad, gently sloping shield volcanoes collectively known as Tharsis Montes. Arsia Mons was built up over billions of years, though the details of its lifecycle are still being worked out. The most recent volcanic activity is thought to have taken place in the caldera-the bowl-shaped depression at the top — where 29 volcanic vents have been identified. Until now, it’s been difficult to make a precise estimate of when this volcanic field was active.

“We estimate that the peak activity for the volcanic field at the summit of Arsia Mons probably occurred approximately 150 million years ago — the late Jurassic period on Earth — and then died out around the same time as Earth’s dinosaurs,” said Jacob Richardson, a postdoctoral researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s possible, though, that the last volcanic vent or two might have been active in the past 50 million years, which is very recent in geological terms.”

Richardson is presenting the findings on March 20, 2017, at the Lunar and Planetary Science Conference in The Woodlands, Texas. The study also is published in Earth and Planetary Science Letters. (…)

“Think of it like a slow, leaky faucet of magma,” said Richardson. “Arsia Mons was creating about one volcanic vent every 1 to 3 million years at the peak, compared to one every 10,000 years or so in similar regions on Earth.” [More at links]

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HiRISE: The hills are colorful in Juventae Chasma

ESP_049045_1760There are many hills about 1 kilometer high in Juventae Chasma, which is located north of the main Valles Marineris canyon system. The floor of the canyon is covered by a sea of sand, but the hills rise above the sand.

A few adventuresome sand dunes have slowly climbed up on the hills, like that near the upper left of the enhanced-color cutout. The color diversity here is exceptional, due to varying mineral compositions and good exposures. [More at link]

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Curiosity: Threading between the sand traps

1642Sol 1642, March 20, 2017. Four Navcam frames capture Mt. Sharp rising above the rocky path leading south towards it, threading between the sand traps along the way. Click image to enlarge it.

Sol 1642 raw images (from all cameras), and Curiosity’s latest location.

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ExoMars 2020 landing sites will narrow to two

WhereOnMars_screenshot_565(1)On Monday 27 March, the 4th ExoMars Landing Site Selection Workshop will take place at the European Space Research and Technology Centre (ESTEC), The Netherlands. At the conclusion of the two-day meeting the Landing Site Selection Working Group will make their recommendation for which two landing sites should continue to be studied for the ExoMars 2020 mission.

The ExoMars rover and surface platform will launch in 2020. The primary objective is to land at a site with high potential for finding well-preserved organic material, particularly from the very early history of the planet.

While the surface platform will remain stationary at the landing site, the rover is expected to travel several kilometres during its time on Mars, and to drill down to two metres below the surface to collect samples for analysis in the rover’s onboard laboratory. Underground samples are more likely to include possible chemical biosignatures in a good state of conservation, since the tenuous martian atmosphere offers little protection from radiation to complex molecules at the surface.

At the previous landing site selection workshop, which took place in October 2015, the Landing Site Selection Working Group (LSSWG) chose three landing sites for detailed study. At the time, the ExoMars rover was scheduled for launch in 2018 and Oxia Planum was identified as the primary choice. (…)

The final decision about where to land the rover is expected to take place no later than mid-2019. [More at links]

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Opportunity: Pancam snaps the sourroundings

4672-navcamS4674-pancam-225Sols 4672 & 4674, March 16 & 18, 2017. Opportunity has halted on a low ridge to shoot Pancam color frames on the outcrops nearby. Above, a Navcam composite from Sol 4672 looks south, with yellow outlining the general area for a Pancam color composite (Holger Isenberg) at right.

1P543130496EFFCWSBP2552L5M1_L2L5L5L7L7Below is a Sol 4674 Navcam view back along the rover’s track, with yellow marking another Pancam composite (right). Click any image to enlarge it.

Opportunity raw images, its latest mission status, a location map, and atmospheric opacity, known as tau.


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Mars rings: Not now, but maybe someday

PIA17089-16As children, we learned about our solar system’s planets by certain characteristics — Jupiter is the largest, Saturn has rings, Mercury is closest to the sun. Mars is red, but it’s possible that one of our closest neighbors also had rings at one point and may have them again someday.

That’s the theory put forth by NASA-funded scientists at Purdue University, Lafayette, Indiana, whose findings were published in the journal Nature Geoscience. David Minton and Andrew Hesselbrock developed a model that suggests that debris that was pushed into space from an asteroid or other body slamming into Mars around 4.3 billion years ago alternates between becoming a planetary ring and clumping together to form a moon.

One theory suggests that Mars’ large North Polar Basin or Borealis Basin — which covers about 40 percent of the planet in its northern hemisphere — was created by that impact, sending debris into space.

“That large impact would have blasted enough material off the surface of Mars to form a ring,” Hesselbrock said.

Hesselbrock and Minton’s model suggests that as the ring formed, and the debris slowly moved away from the Red Planet and spread out, it began to clump and eventually formed a moon. Over time, Mars’ gravitational pull would have pulled that moon toward the planet until it reached the Roche limit, the distance within which a planet’s tidal forces will break apart a celestial body that is held together only by gravity.

Phobos, one of Mars’ moons, is getting closer to the planet. According to the model, Phobos will break apart upon reaching the Roche limit, and become a set of rings in roughly 70 million years. Depending on where the Roche limit is, Minton and Hesselbrock believe this cycle may have repeated between three and seven times over billions of years. Each time a moon broke apart and reformed from the resulting ring, its successor moon would be five times smaller than the last, according to the model, and debris would have rained down on the planet, possibly explaining enigmatic sedimentary deposits found near Mars’ equator. [More at links]

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THEMIS: Sand sea in Rabe Crater

Sea of dunes in Rabe Crater (THEMIS_IOTD_20170320)THEMIS Image of the Day, March 20, 2017. Today’s false color image shows part of the floor of Rabe Crater, which is covered mostly with a wind-shaped sea of sand.

The THEMIS VIS camera contains 5 filters. The data from different filters can be combined in multiple ways to create a false color image. These false color images may reveal subtle variations of the surface not easily identified in a single band image.

More THEMIS Images of the Day by geological topic.

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