Space Forum / Space Science / April 2005

I was thinking that the hole might be from a piece of debris thrown up
from the 'Viking' Crater that Opportunity looked on sol 421 -- two
weeks previously.  However, I suspect the crater is much older than
the dune hole.  The dune hole was likely formed in the last couple of
years otherwise dust would have drifted in and filled it.

http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20050408a/site_B52_B5_c
yl-B424R1_br2.jpg
http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20050408a.html

Without a thick atmosphere, there will be more meteorites reaching the
surface than here on Earth.  My guess it is a recent mini-meteorite
crater but I like the gas eruption idea as well.

There is another smaller hole just across the dune from it, just a low
gravity bunny-hop away as it were.  This smaller hole looks more
filled in than the larger close-by one.  See
http://www.lyle.org/mars/imagery/1N166636311EFF5400P0703R0M1.JPG.html
Also the dust down-hill below the close-by hole is subtlely disturbed.

That's a beautiful colour reconstruction.  Thanks for posting it.

Michael