<p>Dunes in Northern Summer – Repeated observations by HiRISE of dunes like these show measurable changes in some locations. 
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NASA/JPL/University of Arizona (<a rel="nofollow" class="external text" href="http://www.uahirise.org/PSP_009840_2745">www.uahirise.org/PSP_009840_2745</a>)
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/71688597@N05">UAHiRISE (NASA)</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/uahirise-mars/32532778201/">PSP_009840_2745</a>