barchan

May 22, 2017

Is it an old fossil barchan dune?

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 0.96×0.54 km (0.6×0.33 mi) […]
May 1, 2017

Curiosity, recovering from the Bagnold dunes campaign

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 850×550 m (0.53×0.34 mi) scene shows the barchanoid dunes of the Bagnold dune field, imperceptibly […]
April 3, 2017

Where on Mars is this dune?

A Piece of Mars: This 0.48×0.27 km (0.3×0.17 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 […]
September 5, 2016

Eroded dune

A Piece of Mars: Barchan dunes on Mars have a characteristic crescent shape, with a steep slope (“slip face”) on the inside of the sharpest curve (see examples like this, this, these, or this). This image (873×491 m, or 0.54×0.31 […]
June 6, 2016

Itty bitty changes: places where the wind barely moves sand

A Piece of Mars: Not all dunes on Mars are moving at a measurable pace. This 0.96×0.45 km (0.6×0.28 mi) scene looks a lot like one I posted 3 years ago called Martian Sports. This image shows the same dunes […]
October 5, 2015

Dune trails

A Piece of Mars: The dark dunes in this 0.96×0.54 km (0.60×0.34 mi) scene are slowly migrating towards the lower left. Look closer and you’ll see brighter ripples between the dunes – the biggest ones are ~8m (26 ft) apart. […]
July 27, 2015

Dust devils and wind scours on ripples on dunes

A 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 […]
June 1, 2015

Small dunes on Mars

A 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 […]
July 22, 2014

Summery dune

A piece of Mars: Last December I blogged about a picture of a sand dune taken in early northern spring. This is the same dune, without frost, now that summer has come to the northern hemisphere and all the frost […]