THE COSMIC DIARY NETWORK

The martian wind is a geologist
Published 10/18/2018 in Lori Fenton's Blog Author lfenton
Right now, the Fourth Landing Site Workshop for the Mars 2020 rover mission is happening. It's the last one, and in a few hours the scientists attending the workshop will vote on which of four sites they think the rover should land. I love the geology, but mostly I love one little corner of geology: where the rocks meet the atmosphere. I like how studying the rocks can teach us about how the atmosphere, and therefore the climate, has changed over time on Mars. There are signs of windblown things pretty much anywhere you look on Mars, and since none of the landing sites is within range of an actual dune field, I'm not really partial to any of the proposed sites. One of the proposed sites is in Gusev crater, taking us back to where the Mars Exploration Rover Spirit went. That would be great - they obtained a lot of... read more ❯

Pretty little dune field in Noachis Terra
Published 10/8/2018 in Lori Fenton's Blog Author lfenton
Noachis Terra is an ancient terrain on Mars, located in the mid southern highlands. It's the home of many dune fields, big and small. Here's a fairly small one. You can't see it, but this is the floor of an unnamed crater. If you follow the link to the CTX image, you'll see that there's a much larger dune field to the south, trapped in a pit eroded into the floor of the same crater. If you look carefully, you'll see that the dunes on the east side look a bit like barchans that are migrating southwestward, and on the west side the dunes look a bit like barchans that are migrating southeastward. This dune field is here because those two winds converge at... read more ❯

Lyot crater, Mars
Published 9/28/2018 in Lori Fenton's Blog Author lfenton
It's a rough day. A tsunami in Indonesia has killed many people, and the pain is so fresh that there's not even a death count yet. A couple of my good friends are going through various personal crises that will affect them for the rest of their lives. And if you're in the US, then one way or another you're probably upset about what's going on with the Supreme Court nomination. I should be working on any number of other things. There are projects to complete, and new projects that need to get sorted out before they begin. But for the moment I need to clear my head, and I'm going to do that by talking about Lyot crater. (BTW, I made most of these screenshots using JMARS, which anybody can download for free and use. All funded by US tax dollars, making NASA's hard-won Mars images available to the world. Take... read more ❯

Complexity
Published 9/24/2018 in Lori Fenton's Blog Author lfenton
Being a geomorphologist and reading a landscape is a little bit like being one of the forensic scientists on CSI (or choose your own favorite investigative show). A Mars geomorphologist usually has to do this entirely by remote sensing. So now imagine that forensic scientist trying to piece together a crime scene by peering at images taken by a drone. On Earth, at least, a geologist can head out to the actual field site and take samples and do some honest labwork to figure out how ancient landscapes formed. Planetary scientists aren't often so lucky (although we do use analog sites on Earth to try to learn something about other worlds). Take this scene for example. I've purposefully left it at full resolution (25 cm/pixel, click on it to see), but it's not the whole image. Be sure to follow the link to the HiRISE website if you want to see... read more ❯

The End of Kepler – It’s not over yet but it will happen soon.
Published 9/20/2018 in Franck Marchis Blog Author Franck Marchis
The Kepler space telescope, which was launched in March 2009, is the tenth NASA Discovery mission and the first dedicated to searching for and studying exoplanets. It was scheduled to operate for about four years, but is still active almost a decade later and after its scientific objectives changed when it was renamed the K2 mission. Despite these tremendous successes, scientists are now concerned about the health of the spacecraft, and a team of engineers and astronomers are working together in hopes of extending the spacecraft’s data-gathering capabilities for as long as possible. In May 2013, loss of a second reaction wheel should have ended the mission, but Kepler was rebooted, renamed the K2 mission, and given a new goal: use the telescope’s high-photometric precision to observe stars and solar system objects located along the ecliptic. Each cycle of observation, which is known technically as a campaign, lasts about eighty days... read more ❯

Ever shifting
Published 9/13/2018 in Lori Fenton's Blog Author lfenton
Dunes are just so amazingly beautiful. I'll never get over how nature can sculpt such regular patterns into endlessly overlapping structures. Here's a small bit of a dune field trapped up high between mountains in the middle of Coprates Chasma. Here I'm not focusing on their setting, but rather the intricate structures of the dunes themselves. The dunes are formed by wind funneling down a narrow valley, headed towards the floor of the much bigger chasma (to the left, far offstage). Here we are in the midst of a dune field, looking at a rippled sandy surface that piles into dunes. The dunes avalanche downwind, slowly advancing forward (mainly toward the left here), as successive avalanches carry more sand down the slip faces. Ripples cover every surface they can - the wind seems to like to make them. They'll even form on slip faces, only to be erased later by avalanches... read more ❯

The end of winter
Published 8/28/2018 in Lori Fenton's Blog Author lfenton
Richardson crater is located at 72ºS, about 1000 km (~621 miles) from the south pole of Mars. It's a moderately large crater, about 90 km (56) miles across, and it's mostly filled by one of the biggest dune fields in the southern hemisphere. The dune field has been targeted repeatedly by HiRISE, with a recent count of 83 images. I've probably included images in my blog in the past, but a quick search shows I didn't label them (and I'm far too lazy to go searching). But no matter, since there are plenty of brand new images of the place to keep us happy. Like this one:   If you're confused by which way is up: the sun is shining from the left toward the right. The curvy bright... read more ❯

Different sands
Published 8/21/2018 in Lori Fenton's Blog Author lfenton
There's a lot we don't understand about the sediment on Mars. Water, wind, ice, changing temperatures, and volcanic eruptions can all break rocks into grains small enough for the wind to transport. The smallest grains are lofted by the wind, contributing to dust storms, and settling out as fine layers of dust. Slightly larger grains hop (saltate) along the ground and self-organize into beautiful ripples and dunes. Even larger grains (more than a few millimeters in diameter) might be moved by the wind on occasion - these grains are too big to saltate (unless the wind is really strong), but repeated impacts from smaller saltating grains can slowly make them move (Aeolian scientists call this sort of movement creep. Yep.). Those bigger grains can also self-organize, along with the smaller grains, into a different type of ripple. That could be what's happening in the image below. Two... read more ❯

Capturing a Snapshot of Pluto’s Atmosphere. The Story of an Occultation
Published 8/19/2018 in Franck Marchis Blog Author Franck Marchis
Last Tuesday night, a large number of amateur and professional astronomers located across Mexico, the US, and Canada took advantage of a rare and exciting opportunity: observe a blinking star while Pluto occulted it. In Southern California, the SETI Institute, the Observatoire de Paris, Unistellar, and Oceanside Photo and Telescope (OPT), one of the largest telescope retailers in the world, collaborated to observe this rare event and gather the precious data we need to understand Pluto’s atmosphere and climate. Here is our story.   Like most events in the world of modern astronomy, this one started with an email. In February 2018, I sent my colleagues at the Observatoire de Paris a message letting them know that the eVscope was ready and able to observe occultations. We had by then already observed our first occultation, by main-belt asteroid 175 Andromache, from the south of France and I wanted to get input from Bruno... read more ❯

Where dunes once trod
Published 8/13/2018 in Lori Fenton's Blog Author lfenton
Mars has been dusty, and that's affecting the quality of HiRISE images (just look at the recent images in the catalog and you'll see they're not that great). That's made it hard for me to choose a good one for my blog. I suppose I could go with a grainy image and talk about things like the "cost of real data" and "one person's noise is another person's data" (because surely someone will make use of those poor-quality images to track dust clouds, or something). I'm waiting to see where the bright dust falls out on the surface, because I want to show you dust-covered dunes, and then watch how the wind slowly clears them off. It will be a bit like watching snow melt in the spring, if you live in a place that gets snow in the winter. But first I found a really neat image of missing dunes. No... read more ❯

Oh, Mars!
Published 8/2/2018 in Lori Fenton's Blog Author lfenton
The HiRISE camera has a website called HiWish that lets anybody (yes, even you!) make image requests. That's right, you can choose any spot on Mars that HiRISE can see, pick any season (or let them pick for you if you don't care), and one day the Mars Reconnaissance Orbiter's path will fly over your spot and, if it isn't scheduled for other observations, HiRISE will take your image! I've made several requests that way. Sometimes I want to get repeat coverage of an area to see if dunes and ripples have migrated - that requires both a "before" and an "after" image. Sometimes I want a closer look at something that isn't easy to figure out using other images - HiRISE is still the highest resolution camera sent to orbit Mars, so it's sort of like whipping out a magnifying glass to have a closer look at something you could... read more ❯

Spring is a messy time
Published 7/16/2018 in Lori Fenton's Blog Author lfenton
In many areas on Earth that get winter snow, spring thaw is a messy time. Frozen ground turns to mud, and there may be runoff everywhere from melting snow and spring rain. Or if you live in a place that gets winter rains, spring might be the time when mudslides are most common. Spring can be messy on Mars too, although in this case the ice isn't H2O, but CO2. Also, it's not melting, but rather sublimating. But that can still make a big mess. Here's part of a dune field in early spring, located in the high southern latitudes. Normally dunes on Mars are dark because they're made of dark sand, but here they're still mostly covered by bright wintertime frost. If you didn't already know there were dunes here, you might never guess that's what's there. Zoom in (click on the image) and you'll see the ice is draped... read more ❯

Field of barchans
Published 7/8/2018 in Lori Fenton's Blog Author lfenton
It's July, and I've had a busy summer so far. This is my first post in a few weeks - I've been out at various meetings, and last week I spent with my family on vacation. The one week of normal work I had was spent furiously working to help a colleague put together a paper. That left me no time to share pretty pictures with the world. So finally I'm back and able to make another blog post. I decided to make it simple: just a field of pretty barchans. Barchans are one of the simplest types of dunes - they're just piles of sand blown by wind coming from only one direction. The barchans here in Lyot crater are some of the smallest dunes (the smallest one here is ~60 m, or ~200 ft across, which... read more ❯

Seeing the Sombrero Galaxy Seen From Cities
Published 5/31/2018 in Franck Marchis Blog Author Franck Marchis
I am happy to share with you an update from Unistellar. Our team has recently collected a pair of images of the glorious Sombrero Galaxy (M104 in the Messier Catalog) taken during one of the most recent observing runs. Both images were taken in heavily light-polluted environments, the first near Marseille, in the south of France, on May 17 and the second from San Francisco, California on May 14. As usual, these are unedited images, and they clearly show what you can see with our eVscope prototype after just a few hundreds of seconds of observing.     Located in the constellation of Virgo, the Sombrero Galaxy is too faint to be seen with naked eye (V~8). It was discovered in 1781 by French astronomer and comet hunter Pierre Méchain, a colleague of Charles Messier, and reported independently by... read more ❯

The Mars Global Digital Dune Database
Published 5/30/2018 in Lori Fenton's Blog Author lfenton
There are a lot of dune fields on Mars. Over the last ten years I've been part of a group that's mapped out the big dark dunes on the planet to see where they form, and to understand the sedimentary and meteorological processes that control their formation. We compiled a database showing their locations and various physical characteristics. Wait, why do piles of sand form in the first place? On Earth, it's because: 1. There's a lot of sand (not a surprise). 2. There's a lot of strong wind (also not a surprise). 3. The sand is free to be moved by the wind. That is, it's not held down by vegetation, or covered by a lake, or paved over. That mostly amounts to dune fields piling up in arid places, where there's not a lot of vegetation or rainfall to stop the wind from moving sand around. And even then, you don't see piles... read more ❯

Entourage
Published 5/9/2018 in Lori Fenton's Blog Author lfenton
Here's a grand dune, making its stately way northward under winds blowing mainly from the south-southeast (bottom to top), with a secondary wind blowing from the southwest (lower left to upper right). There are two rippled and sharp-crested slip faces on this dune -- can you identify both of them (hint: each wind creates one slip face on the downwind side)?   The dune is ~750 m (2,460 ft) long. It's made of dark sand the wind blows along the ground until it piles up into these big mobile hills we call dunes. But the dune isn't alone. Trailing behind the dune, like a veil, is an entourage of smaller, paler ripples. These are coarse-grained ripples, made partly of larger grains that are too heavy to move as quickly as the finer dark sand that makes up the bulk... read more ❯

Wild & dark lacy dunes on twisty bright layers
Published 4/30/2018 in Lori Fenton's Blog Author lfenton
Some windblown dunes on Mars are just beyond words. Take these beasts in this 0.95x0.95 km (0.59x0.59 mi) scene: These are a peculiar type of bedform called a transverse aeolian ridge, or TAR for short, with a spacing of about 50 m (164 ft). Nobody really understands these things: are they dunes or ripples or something totally different? They're common on Mars but unusual (maybe even nonexistent) on Earth. They're also pretty dark-toned here, whereas on most of Mars they tend to be lighter than the surrounding rocks. The TARs mostly cover the surface, but you can see bright bits poking through in places. You can see layers sweeping around - this is a place where stuff (either sediment or volcanic rock) was deposited in successive layers. It may then have been tilted or deformed, and then it was eroded away to expose the... read more ❯

Reusing old canvases
Published 4/23/2018 in Lori Fenton's Blog Author lfenton
The wind on Mars is an artist, or at least it tries really hard to be one. It flutters up and down mountains, winding along valleys, dragging its wings in the sand and building up really amazing structures that could win any sand sculpture award. Well okay maybe I'm a little biased. Like this 0.92x1.325 km (0.57x0.82 mi) view (click to see the detail, it's worth it): HiRISE ESP_054171_1605, NASA/JPL/Univ. of Arizona A while back (maybe a million years or so), the wind blew sediment from the lower right to upper left, leaving behind some long, thin ripple-like things we call TARs. It even managed to pile up some little ones on the hilltops, which is pretty wild. But the wind kept blowing, pushing the TARs downwind towards the left. At some point, the area ran out of new sand to pile up into new TARs (the loose stuff exited stage right),... read more ❯

An Update on the Potential Habitability of TRAPPIST-1. No Aliens yet, but We’ve Learned a lot.
Published 4/20/2018 in Franck Marchis Blog Author Franck Marchis
One year ago, I wrote an article about the remarkable discovery of the TRAPPIST-1 planetary system, a system of seven temperate terrestrial planets orbiting an ultra-cool red dwarf star. This was an enormous astronomical discovery because these low-mass stars are the most numerous ones in our galaxy, and the discovery of potentially habitable planets around one of them led many people to speculate about the existence of life there and elsewhere in our galaxy around similar stars. This announcement also inspired a lot of additional studies by astronomers worldwide, who have used additional instruments and run complex models to better understand this planetary system and its potential for hosting life. One year later, it seems to me that the time is right to give you an update on what we’ve learned about this planetary system, which is located only 41 light-years from Earth. Better Understanding of the Planetary System Between December 2016 and March... read more ❯

Squish! ????
Published 4/20/2018 in Lori Fenton's Blog Author lfenton
This isn't a full blog post. Just something I saw while looking around for other things on Mars. And for once it's (probably) not related to the wind. But it's cool enough to share. I saw something that went "squish" ???? . This is a ~1.2 km (0.75 mi) wide crater in the northern mid-latitudes of Mars. I don't know much about this region geologically (haven't done my homework, as this is just a quick look). This crater has a set of layers in it that have partially eroded away. And underneath those layers on the crater floor are what look like the remnants of something that got 'sploded from underneath those layers. Judging from the direction of the 'sploded rays, it came from under that beak-shaped part of the layers. And I can sort of convince myself that maybe the squishing event happened once the layers got to the shape they're in now... read more ❯

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