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Dust devils and wind scours on ripples on dunes

ESP_040885_1295_1.0xA piece of Mars: So much wind. There are dark swirly tracks of dust devils that have passed by, ripples covering dunes, wind scours around rocks, and of course dunes. Dune crests have a different color than other regions: are they less covered in dust? made of a more grayish sand that is more easily blown up the dune by the wind? or both? (HiRISE ESP_040885_1295, NASA/JPL/Univ. of Arizona)

Abscicon 2015 in Chicago: Finding Habitable Worlds and Life Beyond the Solar System

What could the near future hold for detecting habitable, and eventually inhabited, extrasolar planets?

That’s the question we asked together with my colleagues Victoria Meadows, A. Mandell and Margaret Turnbull. To this purpose we organized a session for the Astrobiology Science Conference 2015 (#abscicon2015) held at Chicago on June 15-19 entitled “Finding Habitable Worlds and Life Beyond the Solar System”. The goal of our session was to provide a venue to discuss the prospective in the near future to detect habitable extrasolar planets.

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Frosty dunes

ESP_041433_2650_1.0xA piece of Mars: In this image (0.96×0.54 km or 0.6×0.33 mi), it’s late winter and the sun is barely above the horizon here near the north pole. The dunes are covered in winter frost, most of which is CO2 ice (also known as dry ice). The dark regions are those facing the sun, where the ice has started to sublimate, revealing the dark sand below. (HiRISE ESP_041433_2650, NASA/JPL/Univ. of Arizona)

Telling Pluto’s Story, One Fragment at a Time

The Pluto System

Pluto and Charon are in the middle, orbiting around their common center of mass. The four smaller moons orbit around them.

When you begin a new research project, you usually have expectations about where it will lead. Most projects take you or less to the expected destination. Some go nowhere. However, every now and then a project picks you up and makes you feel like you’re just coming along for the ride.

Today, in the journal Nature, we have published the results of a research project that fits solidly into the third category.

Our original plan was straightforward. We had recently discovered two small moons of Pluto, now known as Kerberos and Styx. We wanted to publish a short discovery paper that would just cover the basics: How did we find the moons? What are their orbits? How big are they? What are the implications of the discovery?

The Pluto system had other ideas. (more…)

Small dunes on Mars

ESP_041089_1980_0.75xA piece of Mars: These dunes are some of the smallest on Mars. The smallest in this frame is ~150 m long (492 ft). But the smallest Earth dunes are ~20 m across. Why are they so much bigger on Mars? The air is thinner, so the wind has to blow stronger to lift sand grains. So once the sand is moving, it goes fast – and therefore goes farther before it lands. This makes for a bigger dune. (HiRISE ESP_41809_1890, NASA/JPL/Univ. of Arizona)

The looming dune

ESP_027432_1350_1.0xA piece of Mars: this 0.96×0.54 km (0.6×0.33 mi) scene shows a large, rippled dune that is slowly marching towards the upper right. The smooth striped band running from upper left to lower right is the slip face, where sand pushed by the wind eventually avalanches. Smaller scars show where slope failures (little landslides) have formed. (HiRISE ESP_027432_1350, NASA/JPL/Univ. of Arizona)

Windblown or not?

A piece of Mars: The surface in this 960×540 m (0.6×0.34 mi) scene has a distinct fabric to it that runs from the upper left to lower right. Are these old lithified dunes? And what makes the tiny filamentary lines that run from upper right to lower left, are those ripples? I’m not convinced either way, but I suspect the wind has had a hand in shaping them, one way or another. (HiRISE ESP_040297_1605, NASA/JPL/Univ. of Arizona)

Wind stripes

ESP_039581_1520_1.0xA piece of Mars: Yes, I post a lot of pictures of martian dunes with striped patterns. They’re all distinct and beautiful. So here’s another one, 480×270 m (0.3×0.17 mi) in size. These beasts moved from right to left across the scene, some of them leaving behind some stripey deposits in their wake. (HiRISE ESP_039581_1520, NASA/JPL/Univ. of Arizona)

Martian lace

ESP_040776_2115_1.0xA piece of Mars: This 300×300 m (984×984 ft) scene shows bright windblown dunes or ripples arrayed in a lacy pattern (the biggest ones are about 5 m, or 16 ft, across). This is near the landing site of Ares 3, a science fiction book called “The Martian”, by Andy Weir that’s being made into a movie. I’m betting these beauties won’t make an appearance in the movie, though… (HiRISE ESP_040776_2115, NASA/JPL/Univ. of Arizona)

Flow

ESP_039902_1965_0.724xA piece of Mars: Below this ~550 m (0.3 mi) wide crater lies a ~1.3 km (0.8 mi) long “beard”, the wake of an ancient flow around the crater. Based on its location on Mars, I’m guessing the fluid flowing was lava. Inside the (interestingly dual) crater are bedforms, the remnants of more recent fluid flow – but in this case, the fluid is air. (HiRISE ESP_039902_1965, NASA/JPL/Univ. of Arizona)