When
3:30 p.m., March 3, 2011
Where
Kuiper Space Sciences 308
Nathan Bridges (Applied Physics Laboratory, JHU) is the scheduled speaker.
"The Blowing Sands of Mars"
Abstract:
Previous images of Mars showed that bedform migration was limited or non-existent, consistent with predictions that winds of sufficient intensity to mobilize sand were rare in the low density atmosphere. A new compilation of HiRISE images shows that virtually all dark sand patches and dunes on Mars exhibit movement of a few meters per year in the form of migration of small ripples and edges of dunes and patches.
The data can be divided into three classes: 1) Bedforms that exhibit no motion, most of which are large sand ridges, 2) dune and sand patch ripples that move at rates 2-3 orders of magnitude less than ripples of comparable size on Earth, and 3) dunes which have migration rates comparable to some terrestrial dunes. These results demonstrate that Martian sand migrates under current conditions in most areas of the planet. Winds occur at greater speeds above threshold, or do so at a higher frequency, than predicted by global circulation models.
"The Blowing Sands of Mars"
Abstract:
Previous images of Mars showed that bedform migration was limited or non-existent, consistent with predictions that winds of sufficient intensity to mobilize sand were rare in the low density atmosphere. A new compilation of HiRISE images shows that virtually all dark sand patches and dunes on Mars exhibit movement of a few meters per year in the form of migration of small ripples and edges of dunes and patches.
The data can be divided into three classes: 1) Bedforms that exhibit no motion, most of which are large sand ridges, 2) dune and sand patch ripples that move at rates 2-3 orders of magnitude less than ripples of comparable size on Earth, and 3) dunes which have migration rates comparable to some terrestrial dunes. These results demonstrate that Martian sand migrates under current conditions in most areas of the planet. Winds occur at greater speeds above threshold, or do so at a higher frequency, than predicted by global circulation models.