Recent impact event on Mars

Pat,

besides impact there is another explanation: Some type of water eruption.
Look at the site "Evidence for Liquid Surface Water on Mars":
http://scireview.de/mars/
specially at
1.1 Unusual albedo situations perhaps related to black streaks
There is a pair of very similar craters like the above but in much
better resolution.



Those are very interesting photos, and some of them do look like water
eruption events (or liquid CO2 eruption events for that matter) but I
still think that this particular one looks more like an impact feature,
particularly given its fairly fast fading, and long detached rays.

Malins interpretation is at
http://www.msss.com/mars_images/moc/...lysses_crater/

His crater has a convincing bowl/ejecta size relation to interpret it
as impact crater. Wheras my two craters under 1.1-4 have to large a
bowl for such a small ejecta radius. That 1.1-4 is eruption related
does not prove Malins one is of the same type too. There had to be
fresh impact craters on Mars. But that the crater was not visible in
the Viking image of 1976 does not mean it was not present. Maybe only
his ejecta was fadded away again. The VO image had not the resolution
to show the bowl.

I only want to note two further things. At
http://www.msss.com/moc_gallery/m07_.../M0801170.html
we see black streaks in the area. Thats slight support for my interpretation.

The MGS second higher resolution image at
http://www.msss.com/moc_gallery/r22_.../S0200470.html
shows at full resolution (the msss release of 09/20 is size adjusted to
the smaller M0801170 image) a dark area around the bowl. Because the
fadding is by dust setteling all of the crater suroundings should be
fadded the same way. But on my interpretation the ejecta could be caused
by several eruptions, the last perhaps smaller than the big one. That would
better explain the dark area around the bowl.

Btw, I should be more carefully to call it eruption. On my interpretation
of darkening by a water/soil reaction such ejecta could be created in
a none eruptive way too. By hot vapour clouds rising from the crater,
drifting by the wind and setteling nearby to shape the "ejecta".


Btw, the elsewhere mentioned meteorite near the Opportunity heat shield
is a clear proof that the whole landscape there was or is in a
process of vanishing. The "blue berries" all around perhaps were
before all inside those light toned sediments.



Are you suggesting large scale sublimation of ice or solid CO2
containing soil, leaving its solids exposed on the surface?

No, no. I`m no fan of any solid or liquid CO2 surface activities
outside polar latitudes. I see the blue berries and the light toned
stuff as sediments or evaporites. It was created by salty water from
underground. The water vaporized and left back this material. That
happend at a time when more water was vaporizing here or when the
water was more salty than today. Perhaps this material (at least the
light toned one) is not chemical stable in a CO2 atmosphere and its
reaction product gaseous.

I saw a lot of evidence in MER images that both sites had sometimes
liquid water at the surface. Specially Opportunity showed surface
features suggesting very recent (hours, days) flow of water up to
quantities in the 1 kg range per event. This water could be a factor
in the chemical process at Meridiani too. Unfortunately no MER has
any instrument to detect water. Dont ask me why.



## CrossPoint v3.12d R ##