THE COSMIC DIARY NETWORK

Dunes with comet tails
Published 1/8/2018 in Lori Fenton's Blog Author lfenton
A Piece of Mars: The north polar dunes in this 575x325 m (0.36x0.2 mi) scene are made of dark sand covered by bright winter frost (which will soon sublimate away, as this image was taken in late spring). To the right of the dunes extend pale yellow bumpy hills, making the dunes look like they have little "comet tails". What's going on here? These dunes are migrating towards the left, so the tails are what they leave behind. The dunes are located very far north, where the ground is always frozen. Ice freezes the lowest parts of the dunes, so that as the upper sections can be pushed downwind, the lower sections remain locked in place behind. This can happen on Earth too, but here it's usually the water table stabilizing the lower portions of the dunes (and many of the thick continental sandstones, like the Navajo sandstone, were built... read more ❯

Fuzzy dunes
Published 1/2/2018 in Lori Fenton's Blog Author lfenton
A Piece of Mars: The dunes (or maybe they're ripples) in this valley appear to be fuzzy (the view is 625x775 m, 0.39x0.48 mi). They're not really fuzzy, but it's not actually clear what's going on. They seem to have smaller ripples superposed on them, and maybe bright dust has settled into the troughs between ripple peaks, so that they take on a striped, feathered look. It's unlike anything I've seen on Earth. (HiRISE ESP_052776_1785, NASA/JPL/Univ. of Arizona) read more ❯

Buried by ejecta
Published 12/26/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: To see this one well you'll have to click on the image. At the lower right, a 240 m (787 ft) diameter crater formed when a bolide hit the surface, throwing out ejecta on the surrounding terrain. Zooming in, you can see that the ejecta has a distinctive rough surface. Farther from the crater there are smooth patches where ejecta didn't fall. What I like about this is the many small bedforms (ripples), some of which are covered by ejecta and some of which aren't. Closer to the crater, you don't see so many of these bedforms because the ejecta is thick enough to have buried them. The crater itself is fairly "young" for a geologic feature on Mars, but enough time has passed to allow small bedforms to accumulate inside it (ripples like these don't form overnight). (HiRISE ESP_052794_1545, NASA/JPL/Univ. of Arizona) read more ❯

The mysterious bright streaks
Published 12/18/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Some things just go unexplained (so far, anyway). Here's a mysterious bright streak (scene is 1.2x1.8 km, 0.75x1.12 mi) concentrated between two sets of ripple-like bedforms. It looks sort of like a river, but it's on flat terrain and it's not water. It's part of a larger set of bright streaks that you can see throughout the top of this broader CTX image (the bright streak shown in detail here is visible as a distinct white stripe on the floor of a crater). My guess is that at some point, probably at least several million years ago, a bunch of fine bright silt was blown towards the north-northwest, settling in a few places. I'm guessing it's silt (finer-grained than sand) because it didn't form dunes, and it's not as fine as the clay-sized dust that blows into dust storms because this stuff wasn't completely blown away... read more ❯

Dunes in a row
Published 12/11/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: Look at the alignment of the ~100 m dunes in this 713x750 m (0.44x0.47 mi) scene. How do dunes form in such straight lines? And why don't they always do that? It's likely that these dunes were once long ridges stretching from the lower right to upper left. The shape of the slip faces suggests they're formed from two winds that blow from similar directions, both of which push sand toward the upper left. To stay stable, this sort of dune needs a constant influx of sand from upwind (from the lower right), but if that flow of incoming sand lessened, then a long dune would be forced to break up into a series of smaller dunes. That may be what's happened here. Check out the whole image, and you'll see other long ridges that haven't yet broke up into smaller dunes. (HiRISE ESP_052798_2565, NASA/JPL/Univ. of... read more ❯

Ripples of rock
Published 12/4/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: To the upper right of this 0.85x0.6 km (0.53x0.37 mi) scene is a flat-lying plain strewn with large ripples. To the lower left is a rugged hill with gray rock laced with white veins (this might be part of an impact megabreccia identified nearby in Holden crater). Notice that some of the ripples on the rugged hill are also veined - this is evidence that they are actually eroded into the bedrock, rather than fine-grained deposits like their counterparts on the plain. It's not yet clear how these "Periodic Bedrock Ridges" form, and they may be unique to Mars. (HiRISE ESP_052789_1520, NASA/JPL/Univ. of Arizona) read more ❯

Athena Coustenis, Full Curriculum Vitae
Published 11/27/2017 in Athena Coustenis Author Athena Coustenis
www.coustenisplanetologist.com/#FullCV read more ❯

The corpse of a dune
Published 11/27/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: The rippled darker patch in this 600x600 m (0.37x0.37 mi) scene is the former site of a sand dune. This is one of a few "dune corpses" found just upwind of a dune field in Holden crater. The dunes are migrating to the south and east - you can see that the arc of this former dune opens to the south, the way a barchan slip face would. This dune is what's left behind after most of its sand has migrated downwind. (HiRISE ESP_052367_1540, NASA/JPL/Univ. of Arizona) read more ❯

List of publications
Published 11/26/2017 in Athena Coustenis Author Athena Coustenis
www.coustenisplanetologist.com/ScienceNotes.html#PublicationsFullList read more ❯

Intriguing pair of satellites caught with the eVscope
Published 11/23/2017 in Franck Marchis Blog Author Franck Marchis
If you often look at the evening dark sky in a clear area far away from the city, you have probably seen a speck of light which moves with respect to the star, that's probably a distant satellite that shines because it reflects the light of the sun at high altitude. According to NASA's Orbital Debris Program office, there are an  about 21,000 large debris (>10 cm) and satellites orbiting around Earth right now, so much more than you can see with your naked eye. The eVscope is designed to pinpoint and image Deep Sky Objects (nebulae, galaxies), but we have already shown its potential to observe dwarf planet like Pluto, as well as asteroid like Florence. Because the telescope can image targets as faint as those astronomical bodies, we thought that it will also be able to image small satellites and debris as well passing serendipitously in the field of view. This is what... read more ❯

1,500th telescope on our Kickstarter. Thank you!
Published 11/21/2017 in Franck Marchis Blog Author Franck Marchis
We have just passed the pledge of our 1,500th telescope on our Kickstarter campaign. With such an amazing number of eVscopes soon to be in operation around the planet, our Campaign Mode and Citizen Science applications will be extraordinary exciting and revolutionary! Your support has brought us to this truly amazing moment, and all we can say is thank you. After so many questions about planets and requests for additional photos, we felt the need to conduct new observations—and despite bad weather in parts of the Northern Hemisphere, we managed to do it! As you check out these pictures, please keep in mind that what you see through the eVscope’s eyepiece is far more beautiful and mind blowing. The image quality and observing experience there are definitely superior to what you see in these photos. The eVscope provides truly amazing astronomical views when pointed at nebulae and galaxies. As you can imagine,... read more ❯

Is it windblown or not (#2)?
Published 11/20/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: This 0.93x1.25 km (0.57x0.78 mi) scene shows what I'm starting to think are windblown features. I posted something similar to this once before, from a location not that far from here. In this one region of Mars there are parallel lines cut into the tops of hills. A geologist would first presume they were exposed, tilted layers. But the regularity of their spacing (especially when you zoom in) is a bit unusual, and suggests some sort of self-organization (like windblown ripples). And then the questions begin: why just in this spot on Mars? what's unusual about the rocks (or the wind) here? I still have no good answers. (HiRISE ESP_052386_1565 NASA/JPL/Univ. of Arizona) read more ❯

Overhang
Published 11/15/2017 in Lori Fenton's Blog Author lfenton
A Piece of Mars: There's a fabric of erosion in this 1x1 km (0.62x0.62 mi) scene, with the main wind blowing from lower right to upper left (and if you look carefully you'll see there's a second, subtler fabric a bit clockwise from that one). The result is a landscape strewn with streamlined rock called yardangs. The darkest areas are shadows from rock faces scoured by the wind so deeply that they've been undermined until there's overhang. Normally this would lead to collapse features, like rock piles, but you don't see those here. That's an indication that the rock here is easily eroded and fine-grained, so that as it's eroded, it's simply carried off by the wind. (HiRISE ESP_052384_1800, NASA/JPL/Univ. of Arizona) read more ❯