THE COSMIC DIARY NETWORK

Westward moving
Published 7/17/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: No great scientific insights today, just a really lovely view of bright TARs and some very dark sand in this 0.875x0.5 km (0.54x0.31 mi) scene. Only one major wind acts in this region, moving sediment toward the west. Jezero crater, a prime landing site candidate for the Mars 2020 rover, lies 50 km to the west, so some of the sand blown into that crater passed through this area at some point in the past. (HiRISE, ESP_050899_1985, NASA/JPL/Univ. of Arizona) read more ❯

Experimenting with 3D views
Published 7/13/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: I often use JMARS to visualize Mars data sets, especially images. They've recently updated their 3D layer, allowing folks to make lovely vistas by overlaying DTMs with images. I'm new at this, but I'll experiment and see what I can do to make nice views. Here's a series of barchan dunes marching away from a tall stack of layers in Becquerel crater, with no vertical exaggeration. (HiRISE, DTEEC_045140_2015_044784_2015, NASA/JPL/Univ. of Arizona) read more ❯

Reversing slip faces
Published 7/10/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: This 523x750 m (0.32x0.47 mi) scene shows a large dune. It's quite colorful for some reason, although it's partially false-color. What caught my eye is that the slip face on this dune has reversed direction, which is somewhat rare on Mars (but common on Earth). The main sand-moving wind blows from the right, forming a long avalanching slope (you can see long bright lines of grain fall slips at the lower center). But at some point a wind blew from the left, forming a small slip face in the opposite direction. Although many other wind directions have also help to build this dune, those two are the main winds apparent here. (HiRISE ESP_050887_2225, NASA/JPL/Univ. of Arizona) read more ❯

The real tetrahedrons of Mars
Published 6/19/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: The real tetrahedrons of Mars are dunes, built by winds blowing sand from more than one direction. This 0.5x0.5 km (0.31x0.31 mi) area shows a dune formed from two winds that are about 90 degrees apart: one blowing from the bottom and one blowing from the right. This makes the dune have two slip faces, which is a rare occurrence on Earth dunes. (Earth dunes are complicated by superposed secondary dunes that interfere with and obscure this pattern. Or if they're small enough to not have those secondary dunes, then they are changing fast enough that one slip face will quickly erase the other. I've only ever seen two slip faces at once for very short periods in Earth dunes - they don't last.) Here, the two winds have worked together to form a little spit of sand off to the upper left. The result is... read more ❯

The thinnest landslides
Published 6/15/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: In the dustiest regions of Mars, steep slopes occasionally produce very thin avalanches of dust, revealing a darker surface under the top layer of dust. This shows one that is 610 m (0.38 mi) long, running from its tiny point of initiation near the top of the slope down to the bottom of the slope where accumulated landslides have slowly buried old windblown dunes (or TARs). These landslides occur every spring, and may be triggered by sublimation of small accumulations of winter ice, or perhaps by the wind. This one formed some time between May 7, 2012 and May 22, 2013, as it appeared between two successive images of this spot. It's still there today, most recently imaged on May 5, 2017, slowly accumulating dust until it fades into the background with the rest of the slope. (HiRISE ESP_035307_2115, NASA/JPL/Univ. of Arizona) read more ❯

Dunes fighting for survival
Published 6/5/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Having a bad day? You're in good company with these dunes in this 0.96x0.48 km (0.6x0.3 mi) scene. The gray barchanoid dunes are covered in ripples, as the wind valiantly tries to push the sand to the dune crests. But they are besieged by other processes at work. Dark scribbles show how dust devils have swept by, removing dust and probably scattering a little bit of the sand. The steep slip faces are not covered in dry avalanches typical of active dunes, but rather they appear eroded, as if some force locked the dune in place and started eroding the surface wherever ripples couldn't rescue it. Splotches on the tan ground between the dunes, and narrow furrows attest to seasonal ice reworking the surface. And in this great battle, what I wonder is: can those dunes have formed like this amidst such turmoil, or are they... read more ❯

Weird and wild southern polar dunes
Published 5/29/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: This 0.96x0.48 km (0.6x0.3 mi) scene shows a bit of a south polar dune field. The more recently-active dark sand is rippled, but there are bright splotches where something else has happened. Presumably it's ground ice that sublimated away explosively, as happens at many high latitude locations on Mars, only here the dunes are stabilized enough that those spots aren't eroded away by wind activity every summer. Because the dunes aren't active, their crests have diminished to subtle bumps on the landscape (would you even know they were dunes if I hadn't told you? Look at the whole HiRISE image to be sure!) (HiRISE ESP_013224_1080, NASA/JPL/Univ. of Arizona) read more ❯

Is it an old fossil barchan dune?
Published 5/22/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: There are many barchans on Mars, those lovely isolated crescent-shaped dunes. In a few places there are what looks like ancient preserved barchans, now lithified. The mound in the center of this 0.96x0.54 km (0.6x0.33 mi) scene shows what may be an example of a fossil barchan. If so, then this is quite unusual. On Earth, dunes are very rarely preserved in their full form, usually having been at least partially eroded away before being preserved. I love how much geology is visible from orbit on Mars! (HiRISE ESP_049955_1665, NASA/JPL/Univ. of Arizona) read more ❯

Sand tails
Published 5/8/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Up on the tallest volcanoes, the wind screams downhill at night. This 500x500m (0.31x0.31 mi) scene shows how dust is carried downhill, but only that which is trapped behind boulders and crater rims sticks around. The big hole may be a window into a lava tube. Formation of the window itself is one of the younger events to have formed this landscape, as the screaming dust hasn't fully filled in the hole (although it has begun the process and formed a tailing wind streak). (HiRISE ESP_050089_1660, NASA/JPL/Univ. of Arizona) read more ❯

SETI Alumni: Portrait of Sarah Blunt
Published 5/5/2017 in Franck Marchis Blog Author Franck Marchis
Sarah Blunt, REU student class of 2015, is today a full member of the Gemini Planet Imager Exoplanet Survey. Together with SETI researcher Eric Nielsen and Franck Marchis, she has developed an innovative method to fit the orbits of directly imaged exoplanets. She has published her work in Astronomical Journal and is a recipient of an NSF Graduate Research Fellowship that will fund her graduate school. Here her story. Every year the SETI Institute hosts several interns who work with our researchers through a Research Experience for Undergraduates (or REU) program funded by the National Science Foundation. We often wonder what happened to those students, several years after they come to work with us in our HQ here in California. Sarah Blunt is one of these interns who joined the Institute in 2015. Her application was one of the 200 we received every year for 12-15 internships. Sarah was a bachelor student... read more ❯

Curiosity, recovering from the Bagnold dunes campaign
Published 5/1/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: You'll probably want to click on this image to see the whole thing, it's pretty big, and it's worth seeing. This 850x550 m (0.53x0.34 mi) scene shows the barchanoid dunes of the Bagnold dune field, imperceptibly crawling southwestward (to the lower left). This is the site where the Curiosity rover first encountered an active dune in its trek through Gale crater. This image was taken after the rover's intensive field campaign of the two dunes in the upper middle of the frame - the rover is in fact in this frame (extra credit if you can find it!), but it's backed off a bit from the dunes, and it's sitting on some old sandstone (that we now know was also once a dune field, long ago, much like some of the sandstones we find on Earth). This image was taken in March 2016; the rover has... read more ❯

The bowl of windstuff
Published 4/24/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Get out your red and cyan glasses to see an old crater, which fills this 0.775x0.7 km (0.48x0.43 mi) scene. The crater punched through many thin layers when it formed, some of which you can still see in around the rim. The crater is filled with many small dunes called transverse aeolian ridges (TARs), given this laborious and generic name because they aren't quite like dunes we find on Earth and we don't yet understand what they are. The TARs are common in this area, but there are even more here, where sand is swept into and then trapped inside this deep bowl. (HiRISE PSP_008735_1700_PSP_007878_1700, NASA/JPL/Univ. of Arizona) read more ❯

A change of fluids
Published 4/17/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Water carved this ~800 m (0.5 mi) wide channel billions of years ago. The water dried up, and since then it's been sand that flows through here (from the right), building up lovely dunes. A single crater on one of the dunes indicates that they're not very active (dunes of this type on Mars all seem to be inactive, unlike their bigger, darker cousins). Look closely between the dunes and you might see a few little dots - these are boulders that have fallen, weathered out from the channel walls. (HiRISE ESP_022693_1530, NASA/JPL/Univ. of Arizona) read more ❯

Another smoking gun in the search for life in Enceladus’ ocean
Published 4/13/2017 in Franck Marchis Blog Author Franck Marchis
Today, NASA-funded scientists announced a major new step in the search for life on Enceladus, Saturn’s sixth-largest moon, thanks to new data collected by the NASA/ESA Cassini mission. Enceladus has attracted a lot of interest because it has an active pole that spews jets of material into outer space. During its last flyby over that pole, an instrument on board the Cassini spacecraft detected the presence of a biomarker—molecular hydrogen. This suggests that the ocean we know lies beneath the moon’s surface could indeed contain an ecosystem similar to the ones we find in deep-sea hydrothermal vents on Earth. Hunter Waite, a researcher at the Southwestern Research Institute in San Antonio, Texas, is the lead author of a paper... read more ❯

Two directions
Published 4/10/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Sometimes I just want to show the interior of a dune field, because it's full of waves: ripples and dune crests, slip faces, all of which signs of movement. The dunes in this 0.67x0.47 km (0.41x0.29 mi) view have been made by two winds: one blowing from the top of the frame, and a more-recently-active one blowing from the right. Together, these two winds (and gravity) push this sand between a series of hills and down into Coprates Chasma, one of the longest canyons on Mars. (HiRISE ESP_035278_1655, NASA/JPL/Univ. of Arizona) read more ❯

Where on Mars is this dune?
Published 4/3/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: This 0.48x0.27 km (0.3x0.17 mi) scene shows a rotund barchan dune. Can you tell from looking at it where on Mars it might be? To me the most obvious feature are the bumpy piles at the bottom of the slip face (at the foot of the dune on the right). They're probably the remains of avalanches that occurred when there was still winter frost on the dunes. This is a summertime image, so the frost is long gone and the wind is reworking the dune, trying to erase signs of the cold season avalanches. This sort of pattern is best seen in dunes near the north pole. (HiRISE ESP_027674_2650, NASA/JPL/Univ. of Arizona) read more ❯

A big rock in a big air stream
Published 3/27/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Sand pours in from the top of this 1.95x1.95 km (1.21x1.21 mi) scene. The sand piles up and up (here ~115 m or 377 ft high), but ahead (at the bottom) is a mountain poking up. Like water diverting around a rock in a stream, the mountain affects the air flow just upwind of it, causing the sand to move around it. The steep dune slope is a slip face, caused by oversteepened sand avalanching. If you look closely, you'll see some of those narrow avalanches near the bottom of the slip face (those at the top have been covered by ripples and falling sand). (HiRISE ESP_049045_1760, NASA/JPL/Univ. of Arizona) read more ❯

More Earth-like views of Mars
Published 3/20/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: In a recent post (Dunes in a Colorful Hole), I showed some dunes crawling over layered terrain, with a view that looked a lot like some desert regions of Earth. Here's another spot on Mars (0.95x1.1 km, 0.59x0.68 mi) showing yet more beautiful layers with dunes filling up the valleys. Part of what makes it seem Earth-like is the lack of craters, although if you go looking you'll see there are some there. It's hard to tell from here, but this whole scene is inside an old fluvial channel. The layers are thought to be lake deposits from when the river dammed up, ages ago. Since then the wind has taken over, taking apart the layers one grain at a time, and then building up dunes with some of those grains. (HiRISE PSP_010329_1525, NASA/JPL/Univ. of Arizona) read more ❯

Windblown or not? Probably...
Published 3/14/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: This 0.95x0.95 km (0.59x0.59 mi) scene shows an eroding surface punctured by some old craters. Long, thin lines seem to form in the wake of many brighter knobs. Are those thin lines windblown in origin? They look like erosional features - things that are left behind when other stuff erodes away around it (not like sand dunes, which are things that pile up over time). If so, they don't look like typical yardangs, which are streamlined bedrock, formed as sand wears down the rock. But this isn't typical bedrock - it is easily erodible material. The bright knobs and crater rims are what's left of a once-higher surface. The darker material may be a lag deposit that has built up as that brighter layer eroded down, leaving behind coarser grains that the wind has a harder time transporting (a similar process has occurred in Meridiani Planum,... read more ❯

The Three Discoveries of Pan
Published 3/9/2017 in Mark Showalter's Blog Author Mark Showalter
This morning, NASA's Cassini spacecraft obtained the first closeup images of Saturn's innermost moon, Pan. The images show a peculiar body shaped like a "flying saucer". Pan occupies a unique position in the rings, at the center of the 300-km wide Encke Gap. As best we can tell, Pan probably started its life as a more spherical moon, but it subsequently swept up a thick equatorial belt of ring-dust. A smattering of crevasses and craters across the surface add to our view of a moon that has endured a long and dynamic history. Yesterday, Pan was just a "tiny ring-moon"; today, it has been revealed as a world in its own right. Seeing these images has brought back vivid memories of the day way back in June, 1990 when I became the first person to see Pan. That story... read more ❯