Triggered! A possible new impact site (formed at most between February 2004 and December 2011) is the likely cause of these slope streaks.
Dark blast zones not seen in other images with lower resolution than HiRISE can often trigger a request for us to take a closer look.
HiRISE Picture of the Day archive. [More at links]
THEMIS Image of the Day, July 8, 2019. The two linear depressions at the bottom of today’s VIS image are part of Cerberus Fossae.
The features are termed graben and are formed by crustal extension that allows material to subside between paired tectonic faults. The straight sides and uniform depths are indications that these are tectonic features rather than channels caused by fluid erosion.
Explore more THEMIS Images of the Day by geological subject.
A ridge in Hesperia Planum. Our objective is to look for fault offsets to see if these thrusts are surface breaking or not. Hesperia Planum is a broad lava plain in the southern highlands of Mars. The plain is notable for its moderate number of impact craters and abundant wrinkle ridges.
HiRISE Picture of the Day archive. [More at links]
THEMIS Image of the Day, July 5, 2019. Today’s VIS image shows a complex block of material located on the floor of an unnamed crater in Arabia Terra. The feature is offset from the center of the circular depression and is approximately the same height of the surrounding surface.
It is unlikely to be a peak created during the cratering event. Perhaps the crater is not an impact formed feature and was created by some other process. It is often difficult to interpret the geologic processes that created landforms from data collected far above the surface.
Explore more THEMIS Images of the Day by geological subject.
ESA’s Mars Express has been keeping an eye on local and regional dust storms brewing at the north pole of the Red Planet over the last month, watching as they disperse towards the equator.
Local and regional storms lasting for a few days or weeks and confined to a small area are common place on Mars, but at their most severe can engulf the entire planet, as experienced last year in a global storm that circled the planet for many months.
It is currently spring in the northern hemisphere of Mars, and water-ice clouds and small dust-lifting events are frequently observed along the edge of the seasonally retreating ice cap.
Many of the spacecraft at Mars return daily weather reports from orbit or from the surface, providing global and local impressions of the changing atmospheric conditions. ESA’s Mars Express observed at least eight different storms at the edge of the ice cap between 22 May and 10 June, which formed and dissipated very quickly, between one and three days… [More at link]
Channels and ripples in Schoner Crater. A HiWish public suggestion: “We would like a HiRISE image of the selected area to look for evidence of both fluvial and aeolian processes on the crater wall. Specifically, we are looking for channels that would be evident of erosion. It would be useful to know how widespread fluvial processes are across the surface of Mars and the timescale on which these processes take place.”
HiRISE Picture of the Day archive. [More at links]
There was a slight uptick in frequency of dust-lifting events over the southern hemisphere of Mars this past week. Dust storms north of Argyre were once again advected equatorwards — this time extending past eastern Valles Marineris to Xanthe Terra. Local storm activity was observed all along the edge of the south polar hood. Moving our attention to the northern hemisphere, dust activity continued to be at a minimum, apart from another arcuate-shaped dust storm over Acidalia. While afternoon diffuse water ice clouds remained scattered and sporadic across… [More at link, including video]
THEMIS Image of the Day, July 4, 2019. The linear depressions in this VIS image are graben called Labeatis Fossae.
Graben are formed when extension between paired faults causes the material to move downward. These are part of a general series of faults cutting across Tempe Terra.
Explore more THEMIS Images of the Day by geological subject.
[Editor’s note: From a paper by Daniel Lalich and two co-authors recently published in the Journal of Geophysical Research.]
• Radar reflections can be used to constrain the dust content of individual layers in the north polar layered deposits of Mars
• Layer dust contents are higher than predicted by models, indicating a gap in our understanding of how the global dust cycle varies with time
• Dust content and completeness of the climate record vary strongly by location and with depth
The north polar cap of Mars is very similar to ice sheets on Earth. On Earth, scientists use the layers of ice to learn about how the climate has changed over time. It should be possible to do something similar on Mars, but we cannot drill ice cores on Mars, and so far, scientists have had difficulty pulling useful information out of the layers.
In this paper, we show that it is possible to use radar reflections in the ice to get a rough idea of how much dust is in a certain type of layer. The brightness of a reflection is related to the composition of the layer that caused it, so after making a few assumptions, we can first measure that brightness and then use a model to estimate how much dust would have to be present in the ice to get a matching reflection.
After doing this for many reflections at 10 different study sites, we found that some layers are a lot dustier than we previously believed, meaning our previous understanding of the Mars ice and dust cycles is incomplete. We also found that the composition of layers was very different from place to place, which means local conditions are playing a large role in ice and dust accumulation. [More at link]
