More Wet Gullies |
More Wet Gullies |
Apr 12 2010, 09:12 PM
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#1
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Member Group: Members Posts: 447 Joined: 1-July 05 From: New York City Member No.: 424 |
A new paper argues that HiRISE photos show evidence for recent short-lived surface water flows. Neat pictures on Phil Plait's site (my source for the news).
It would be interesting to learn if there was any MGS coverage of the same area. TTT |
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Apr 13 2010, 09:49 AM
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#2
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Junior Member Group: Members Posts: 55 Joined: 6-March 10 From: Cincinnati, OH Member No.: 5246 |
These gully-like features in Russell crater were described by Nicholas Mangold and others in 2003 using MGS MOC and MOLA images:
Mangold, N.; Costard, F.; Forget, F. (2003). Debris Flows over Sand Dunes on Mars: Evidence for Liquid Water. J. Geophys. Res., 108(E4), 5027, doi:10.1029/2002JE001958. Michael Carr also discusses them briefly in his book The Surface of Mars, 2006. Tom FULL INLINE QUOTE REMOVED - Admin |
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Apr 14 2010, 12:46 AM
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#3
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Member Group: Members Posts: 447 Joined: 1-July 05 From: New York City Member No.: 424 |
Thanks!
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Apr 23 2010, 02:20 AM
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#4
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Junior Member Group: Members Posts: 46 Joined: 6-January 10 From: Toronto, ON Member No.: 5163 |
It would be interesting to learn if there was any MGS coverage of the same area. There are a number of MOC narrow-angle images of the Russel dune gullies as the area was monitored for change. MSSS put out a few captioned image releases of them: http://www.msss.com/mars_images/moc/2003/04/27/index.html http://www.msss.com/mars_images/moc/2005/05/08/index.html http://www.msss.com/mars_images/moc/2005/11/05/ -------------------- Twitter: @tanyaofmars
Web: http://www.tanyaofmars.com |
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Apr 23 2010, 02:37 AM
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#5
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Member Group: Members Posts: 753 Joined: 23-October 04 From: Greensboro, NC USA Member No.: 103 |
Say, were you guys the victims of those pranks in high school, too?
Oh, sorry. I thought this topic was More Wet Willies. -------------------- Jonathan Ward
Manning the LCC at http://www.apollolaunchcontrol.com |
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May 3 2010, 05:15 PM
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#6
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Senior Member Group: Members Posts: 1729 Joined: 3-August 06 From: 43° 35' 53" N 1° 26' 35" E Member No.: 1004 |
on arXiv today: Martian gullies: Produced by fluidization of dry material
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May 4 2010, 11:34 PM
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#7
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Junior Member Group: Members Posts: 46 Joined: 6-January 10 From: Toronto, ON Member No.: 5163 |
on arXiv today: Martian gullies: Produced by fluidization of dry material Someone has started a separate thread about this paper: http://www.unmannedspaceflight.com/index.p...ic=6584&hl= -------------------- Twitter: @tanyaofmars
Web: http://www.tanyaofmars.com |
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Dec 11 2013, 02:38 PM
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#8
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Newbie Group: Members Posts: 10 Joined: 27-August 12 Member No.: 6618 |
A new paper showing recurring dark streaks.
Nature comments : "Water seems to flow freely on Mars" McEwen, A. S. et al. Nature Geosci. http://dx.doi.org/10.1038/ngeo2014 (2013). QUOTE River-like valleys attest to the flow of water on ancient Mars, but today the planet is dry and has an atmosphere that is too thin to support liquid water on the surface for long. However, intriguing clues suggest that water may still run across the surface from time to time. In 2011, for example, researchers who analysed images from NASA's Mars Reconnaissance Orbiter (MRO) spacecraft observed dark streaks a few metres wide that appeared and lengthened at the warmest time of the year, then faded in cooler seasons, reappearing in subsequent years2. "This behaviour is easy to understand if these are seeps of water," says planetary scientist Alfred McEwen of the University of Arizona in Tucson, who led that study. "Water will darken most soils." The streaks, known as recurring slope lineae, initially were found at seven sites in Mars's southern mid-latitudes. The water may have come from ice trapped about a metre below the surface; indeed, the MRO has spotted such ice in fresh impact craters at those latitudes. McEwen and his colleagues have now found the reappearing streaks near the equator, including in the gargantuan Valles Marineris canyon that lies just south of it. The MRO has turned up 12 new sites — each of which has hundreds or thousands of streaks — within 25 degrees of the equator. The temperatures there are relatively warm throughout the year, says McEwen, and without a mechanism for replenishment, any subsurface ice would probably already have sublimated. He says that this suggests that water may come from groundwater deep in the crust (...) But even though McEwen says that water is the most likely explanation for the streaks, he is not sure of the sources. Some of the streaks seem to begin at the tops of ridges, too close to the surface to easily be explained by subsurface aquifers. So the water may come instead from atmospheric water vapour that is pulled into salts in the soil and later released. "It is quite difficult to understand how [the streaks] can occur with the current understanding of Mars," says Gerhard Kminek, vice-chair of COSPAR's planetary protection panel and planetary protection officer at the European Space Agency. "And that makes it more interesting of course." source : Nature news -------------------- |
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Dec 12 2013, 03:43 PM
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#9
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Interesting idea, but still a long way from proof.
I often wish for an orbiter capable of capturing events in real-time, not only for this phenomenon but also for the landslides in the polar regions, dust devils, etc. What seem to be dynamic processes are much easier to understand if you catch them in the act. -------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Dec 12 2013, 10:42 PM
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#10
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Junior Member Group: Members Posts: 78 Joined: 16-October 12 From: Pennsylvania Member No.: 6711 |
Maybe NASA should land the next rover near a gully to clear it up.
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Dec 12 2013, 11:07 PM
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#11
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Senior Member Group: Members Posts: 3516 Joined: 4-November 05 From: North Wales Member No.: 542 |
Well, we already have a rover sniffing for organics in retreating scarps. Maybe it will also find ice subliming there and not just minerals with a lot of water of crystallisation. On the other hand the water in the gullies could come from the breakdown of hydrated minerals rather than melting ice.
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Dec 13 2013, 12:49 AM
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#12
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Senior Member Group: Members Posts: 1057 Joined: 17-February 09 Member No.: 4605 |
Breakdown of hydrated minerals on the polar side of dark, probably basaltic dunes at temperatures no higher that say 20 celcius for a brief period? What hydrated minerals are you proposing or are you thinking minerals in frozen brines?
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Dec 13 2013, 12:59 AM
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#13
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Solar System Cartographer Group: Members Posts: 10229 Joined: 5-April 05 From: Canada Member No.: 227 |
I can't yet see these features as anything but dry granular flows. I'm willing to be shown I am wrong...
Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PDF: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Dec 13 2013, 01:15 AM
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#14
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
Breakdown of hydrated minerals on the polar side of dark, probably basaltic dunes at temperatures no higher that say 20 celcius for a brief period? What hydrated minerals are you proposing or are you thinking minerals in frozen brines? The only hydrated mineral with that property I know of is meridianiite decomposing in epsomite and water. This should be possible to distinguish from basalt, i.e. confirmed or discarded. |
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Dec 13 2013, 01:36 AM
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#15
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Merciless Robot Group: Admin Posts: 8785 Joined: 8-December 05 From: Los Angeles Member No.: 602 |
Again, speed of propagation is a critical parameter which we are currently not well equipped to measure.
-------------------- A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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