Updated Mars History video

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Larry Burford</i>
<br />Shouldn't that be three or more captured moons? At least one of which has de-orbited and impacted at/created the Valles Marineris area?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Gravitational screen capture (see "Dark Matter...") works this way. Mars captures a large number of small satellites from the explosion that pass through its atmosphere and lose enough momentum to remain in temporary orbits. Then when the larger explosion debris arrives, it can collide with the small stuff and drop into a more stable, long-term orbit. Continued collisions tend to drive the orbit toward the plane of the equator and to circularize it.

The video was not ambitious enough to attempt to show that additional feature of probable Mars history. But our graphics artist needs a break for now.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Or, might this feature be even older, dating from a moon or moons that originated with the Planet V event?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Not if Planet V really was a helium-class gas giant.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Is there any observational evidence that one of those volcano high spots was hit by anything? Erosion would probably obliterate a minor hit, but there might still be signs of a major hit.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">There are some peculiar lineations that might be scrape marks across the top. I've not looked for them in MRO imagery, nor even attempted to see if they line up properly with VM. But that would make a nice research project for someone. -|Tom|-

Tom,
I might add that balsaltic subterrannean magma flows from east to west. An impact to the east of the Tharsis volcanoes can provide heat the would travel to hot spots west of the impact zone. Shield volcanism could result from low silica basalt flowing as a result of the energy. Pre-existing volcanic activity could steepen from nearby impact. This is supported by continuing Yucatan and Western Caribean vulcanism arising from the asteroid impact of 65 myo. Do you see any connections with this line of thinking?

Mark Vitrone

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by MarkVitrone</i>
<br />This is supported by continuing Yucatan and Western Caribean vulcanism arising from the asteroid impact of 65 myo. Do you see any connections with this line of thinking?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">As it stands now, the model suggests that Tharsis volcanism resulted from spin-axis change by ~90 degrees. Then rotational squeezing at the new poles and bulging at the new equator would occur, and would be most intense in the region near the new equator that was formerly near the old pole. Presumably, these internal pressures combined with strong tidal forces from Body C ("Bellona"), which creates an Io-like tidal pumping.

The bottom line is that Mars volcanism was probably induced by centrifugal and tidal forces rather than by impacts. -|Tom|-