Martian Cartography |
Martian Cartography |
May 15 2006, 04:16 PM
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Member Group: Members Posts: 147 Joined: 14-April 06 From: Berlin Member No.: 744 |
I have recently freaked out a little bit about Martian maps of all sorts. And finally I was astonished with those highly detailed beauties that I list below. Nonetheless. some of them have huge inconsistencies (crater names) easily noticed when we compare the surroundings of Gusev crater. Enjoy:
http://www.ralphaeschliman.com/ http://planetologia.elte.hu/1cikkeke.phtml...arsmapinte.html http://pubs.usgs.gov/imap/i2782/ -------------------- |
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Jan 10 2009, 05:22 AM
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
Great comparison presentation, Phil. Very easy to compare the albedo features mapped by each team.
I do want to point out that the Mariner 9 map was prepared with far greater contrast than the other two maps, which attempt to present realistic-to-the-eye contrast levels. So it's easier to compare features between the Viking and MGS maps. Variations between the Mariner 9 map and the other two maps seem just as likely to be artifacts of the preparation as they are actual changes over time. Also, I think it bears mentioning that Viking and MGS overflew the terrain at different times of day nadir LST. IIRC, MGS flew over terrain which, at nadir, was at roughly 2pm LST, and I believe Viking had a couple of different windows (with the two different orbiters) but saw nadir at generally lower sun angles (I want to say between 3 and 4 pm LST, but I just can't remember with confidence... *sigh*... ). We all know albedo features can vary somewhat by sun angle, so at least some of the variations between the Viking and MGS maps may be due to different sun angles. However, all of that said, there are obviously places where large gross changes (and also small, subtle changes) have occurred in the times between the three eras. And that is very definitely fascinating. Plus, I seem to recall that some people already have done analyses of albedo variations in telescopic images/drawings from oppositions since, oh, probably 1840.... In fact, I remember reading a book when I was a kid that presented Mars images from several successive oppositions, comparing the albedo features and noting observed changes. It might make a good thesis for some astrogeology postgrad out there to pull up all those old telescopic analyses and plug them into the patterns of changes we've seen from our orbiters from 1971 to present... -the other Doug -------------------- “The trouble ain't that there is too many fools, but that the lightning ain't distributed right.” -Mark Twain
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