[X] My Assistant

[rogelio]

http://www.latimes.com/news/science/la-sci...=la-home-center

[nprev]

I think that a nice, deep hit dead square on Meridiani is on all our Christmas lists, a few kilometers from Oppy (who would, in this perfect scenario, be well sheltered from any ill effects inside Victoria...)

[dburt]

I think that a nice, deep hit dead square on Meridiani is on all our Christmas lists, a few kilometers from Oppy (who would, in this perfect scenario, be well sheltered from any ill effects inside Victoria...)

Careful what you wish for... A few kilometers might not be enough to protect Oppy, even in Victoria. If you look at images (MOC and HiRISE) of very recent Mars impact craters detected from orbit, visible scouring effects extend for at least 10 crater diameters, and ground-hugging impact surge clouds composed mainly of dust could therefore reach at least that far, bowling Oppy over, or at the very least, coating its solar cells with dust and sand. Surge deposit accumulations should be thicker than usual inside a crater, although the surge cloud might have enough internal energy to climb the far side and keep going (original dip - deposition as inclined beds - is common in surge deposits, such as those at Home Plate, that may have overridden an old impact crater or other small bowl shaped depression).

But what I wouldn't give for some nice pancam and orbital images of the dust storm-like impact surge cloud rapidly advancing across Meridiani Planum towards Oppy! Of course, that still wouldn't convince the doubters...

-- HDP Don

[ElkGroveDan]

Of course, that still wouldn't convince the doubters...

Not until we witnessed freshly created hematite spheres raining from your impact surge cloud.

[dburt]

Not until we witnessed freshly created hematite spheres raining from your impact surge cloud.

Sorry, I haven't been monitoring this speculative thread over the weekend. But hey, EGD, the blue-gray hematitic spherules are the Meridiani exception, not the martian rule - you don't find them everywhere on Mars, even though Mars was virtually saturated with impact craters. To form the hematitic spherules via impact, there must have been something unusual about the target, or something unusual about the impactor, or both. So you can't very well expect hematitic spherules from every martian impact. Also, keep in mind that Mars at the time of the Meridiani-forming impacts (if that's what formed Meridiani's uppermost layers and blueberries) presumably had a somewhat thicker atmosphere (although by then, about 3.8 billion years ago, Mars may have already lost 99 per cent of its atmosphere owing to erosion by the Late Heavy Bombardment). And, if not formed by impact (or other high temperature process), why are the spherules apparently the blue-gray or high temperature (specular) form of hematite (i.e., why aren't they the same color as the rest of Mars)? And if they're indeed sedimentary concretions, why do the blueberries so little resemble actual sedimentary concretions in terms of their distribution, size, shape, degree of aggegation (clumping), and host rocks?

BTW, I much enjoyed the two competing artistic impressions of distant meteorite impacts as seen from Victoria. One, the nuclear bomb-type "mushroom cloud" looks like what I would expect of a small impact on any planet with an atmosphere (i.e., Earth or Mars). The other looks like virtually all textbook illustrations of impacts, and shows the early-formed ballistic ejecta curtain only. It is what I might expect for impacts on the Moon or other planet with no atmosphere (although even there the rocks themselves are vaporized, at least ephemerally). Keep in mind that, AFAIK, there are absolutely no photos of actual large impacts to use as a basis for comparison (and that any such photos might well be the photographer's last ever). All the more reason to wish for Oppy to supply such an actual impact image, and survive.

-- HDP Don