Victoria Annulus, Discusions about Victoria's Apron Options

[RNeuhaus]

From today, Oppy will start to head toward the Victoria Crater which is about 500 meters away. The drive would take about one month (that is 15 soles of driven with an average of 33 meters/sol, the other 15 soles would be for other purposes or restrictive soles).

The surface around Victoria Annulus, I seems it won't be as smooth as the way between Eagle and Endurance craters but the surface would have no uniform or parallel wave of sand and dust in small size of ripple. See Phil's Victoria Annulus partial map, Tesheiner's one Victoria Crater picture

Otherwise, the surface might have ripples smaller and alike to the ones of El Dorado, on the skirt south side of Columbia Hill. Besides, the Anuulus has no outcrops except to around of few small mini-craters.

This is a change of morphology of surface around the Victoria Annulus. What does it explain about this developing kind of surface of sand? Its extension is just around the inside of Victoria's ray of ejection. That is coincidence. Around that has no bigger ripples as the outside of Annulus.

The explanation would be that around annulus has smoother rock or outcrop surface, no blocks which had not helped to build ripples by the winds. Other factor, I am not sure, is that the slope from the border of Annulus to crater is positive (going up by few meters), then this might be another factor not to build ripples. I have seen that anywhere in the desert that have a slopes does not have any ripples but only flat surface.

Any debate about why the Victoria Annulus does not look like ripples as the outside of Annulus.

Rodolfo

[Bill Harris]

I'm thinking that one sub-cycle of the Martian hydrologic cycle involves frost formation at night and when the frost is heated in the early morning it already in contact with a sulfate salt and briefly makes a saturated "brine" with a low freezing point which soaks the underlying sand and dust. The water quickly evaporates and the dissolved salts cement the sand. The quantity of water is very very small, but this can happen millions of times, daily, over thousands of years and build up to appreciable thickness. We've seen the duricrust almost universally on Mars.

There may be more to it, but this is the quick explanation of what appears to be happening.

--Bill

[Aldebaran]

I'm thinking that one sub-cycle of the Martian hydrologic cycle involves frost formation at night and when the frost is heated in the early morning it already in contact with a sulfate salt and briefly makes a saturated "brine" with a low freezing point which soaks the underlying sand and dust. The water quickly evaporates and the dissolved salts cement the sand. The quantity of water is very very small, but this can happen millions of times, daily, over thousands of years and build up to appreciable thickness. We've seen the duricrust almost universally on Mars.

There may be more to it, but this is the quick explanation of what appears to be happening.

--Bill

Bill,

I may have said this before either here or on another forum, but the Martian regolith contains a high proportion of salts such as magnesium and calcium sulfates and chlorides. These are either anhydrous or monohydrates, such as Kieserite, MgSO4.H2O. My understanding is that the hydration state can change depending on the temperature, and it's a very complex multiphase system. I don't think it can get to the saturated brine stage, simply because there is too much 'dessicant'. I think of Mars in terms of a planet sized vacuum desicator. I've worked with vacuum dessicators in a lab environment, and strange effects can result from phase changes, without involving any free water being produced. These include the production of filament-like crystals among other things. The constant diurnal and season variation over a long timescale can produce such duricrust either without any free water, or at the very least, extremely thin films several molecules thick, due to non equilibrium effects.