aeolian

February 21, 2017

Who wins in the fight of wind vs. ice?

A Piece of Mars: This is the crest of one of the largest dunes on Mars (0.5×0.5 km or 0.31×0.31 mi). The wind mostly blows from the right, slowly pushing sand up the windward slope. But frost accumulates on (and […]
February 13, 2017

Mars’ yin-yangs

A Piece of Mars: Is this 480×270 m (0.3×0.17 mi) scene showing a 150 m (492 ft) wide yin-yang symbol on Mars? Sort of, maybe, if you blur your eyes and lend me artistic license, but it’s not doing so […]
December 19, 2016

The trail of a dune

A Piece of Mars: A low, broad dune occupies the center of this 800×450 m (0.5×0.28 mi) scene, blown by a dominant wind towards the lower left. The slip face on the lee side has several small avalanches, formed as […]
December 12, 2016

Them that make ripples and them that don’t

A Piece of Mars: Higher ground is to the left. You’re seeing a tan layer sandwiched between two gray layers in this 0.96×0.54 km (0.6×0.34 mi) scene. Large ripples have accumulated in the lowest area to the right, which is […]
November 21, 2016

Bedforms on crater rims

A Piece of Mars: Dunes and ripples most commonly form in topographic lows. But not in this 0.96×0.54 km (0.6×0.34 mi) scene. Here, and in other places on Mars, these bedforms (called TARs) form on plains, and sometimes appear to […]
November 7, 2016

Dunes and rock hurdles in Gale crater (3D)

A Piece of Mars: Wind from the upper left is blowing dark dunes toward the lower right in this 1.92×1.08 km (1.19×0.67 mi) anaglyph (if you don’t have your red/blue 3D glasses handy, you can also check out the black […]
October 31, 2016

On Mars the wind carves stream channels

A Piece of Mars: This 1.6×2 km (1×1.24 mi) scene mostly shows what wind will do to fine-grained, weakly-consolidated surfaces. It has created topography that further strengthens wind scour in the hollows, which even leave kilometers-long grooves reminiscent of water-carved […]
October 3, 2016

Windblown: ancient and recent

A Piece of Mars: HiRISE is celebrating 10 years of success by showcasing its first high resolution image, taken back in 2006. Here is a portion of it, shown at 1/4 the full resolution (the scene is 2.5×2.5 km across). […]
September 19, 2016

Light and dark

A Piece of Mars: This 0.96×0.54 km (0.6×0.34 mi) late winter scene is a study in contrast. The dark top half is uniformly rippled. This is the shady surface of the main windward side of one of Mars’ biggest dunes, […]