Author Topic: Previous Evidence of Water on Mars Now Identified as Grainflows  (Read 4903 times)

Online Chris Bergin

Hmmmm.

USGS Presser:

Planet appears to have water-restricted environment

Dark features previously proposed as evidence for significant liquid water flowing on Mars have now been identified as granular flows, where sand and dust move rather than liquid water, according to a new article published in Nature Geoscience by the U.S. Geological Survey.

These new findings indicate that present-day Mars may not have a significant volume of liquid water. The water-restricted conditions that exist on Mars would make it difficult for Earth-like life to exist near the surface of the planet.

Scientists from the USGS, the University of Arizona, Durham University (England) and the Planetary Science Institute analyzed narrow, down-slope trending surface features on Mars that are darker than their surroundings, called Recurring Slope Lineae, or RSL. These RSL features grow incrementally, fade when inactive and recur annually during the warmest time of year on Mars. RSL are mostly found on steep rocky slopes in dark regions of Mars, such as the southern mid-latitudes, Valles Marineris near the equator, and in Acidalia Planitia on the northern plains. The appearance and growth of these features resemble seeping liquid water, but how they form remains unclear, and this research demonstrated that the RSL flows seen by HiRISE are likely moving granular material like sand and dust.

ďWeíve thought of RSL as possible liquid water flows, but the slopes are more like what we expect for dry sand,Ē said USGS scientist and lead author Colin Dundas. ďThis new understanding of RSL supports other evidence that shows that Mars today is very dry.Ē

The terminal end of the RSL slopes, said Dundas, are identical to the slopes of sand dunes where movement is caused by dry granular flows. Water almost certainly is not responsible for this behavior, which would require the volume of liquid to correspond to the length of slope available, producing more liquid on longer slopes. Instead, the 151 RSL examined by the study authors all end on similar slopes despite very different lengths. Additionally, said the scientists, water is unlikely to be produced only near the tops of slopes at these angles and if it were, it should be able to flow onto lower slopes.

This new research finds that these RSL features are flows of granular material and thus, align with the long-standing hypothesis that the surface of Mars lacks flowing water. Small amounts of water could still be involved in their initiation in some fashion, as hydrated minerals have been detected at some RSL locations. The authors conclude that liquid on present-day Mars may be limited to traces of dissolved moisture from the atmosphere and thin films of water.

This study was done in cooperation with the NASA Mars Reconnaissance Orbiter project.

(Paper: https://www.nature.com/articles/s41561-017-0012-5)
« Last Edit: 11/20/2017 03:38 PM by Chris Bergin »

Offline mike robel

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 2168
  • Merritt Island, FL
  • Liked: 229
  • Likes Given: 41
Hmmm, is right.

What we need to do is figure out a way to blanket Mars with softball - basketball sized sensors with a spike to allow surface penetration to about 6 feet to pave the way to get a geologist to the best sights.


Offline Rocket Science

  • Senior Member
  • *****
  • Posts: 8615
  • NASA Educator Astronaut Candidate Applicant 2002
  • Liked: 2666
  • Likes Given: 6833
Didn't know whether to like or unlike this news but facts are facts in science...
« Last Edit: 11/20/2017 04:14 PM by Rocket Science »
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator, Vintage auto racer

Online guckyfan

  • Senior Member
  • *****
  • Posts: 6675
  • Germany
  • Liked: 1732
  • Likes Given: 1694
This is relevant for search for life on Mars. Not relevant for water supply. It means that a lot of places that had to be avoided as potential sites for life would now be cleared for access.


Online saliva_sweet

  • Full Member
  • ****
  • Posts: 552
  • Liked: 423
  • Likes Given: 1330
This is relevant for search for life on Mars. Not relevant for water supply.

I disagree. These streams were one of the very few pieces of evidence pointing to abundant water ice on mars (at least in equatorial regions). All plans involving ISRU fueling (and Musks plan specifically) require copious amounts of easily accessible water. From what I've read on these forums the plan would be to land on mars and then - mine the glacier. Where's that glacier? It's not showing up on Mars Odyssey neutron or gamma ray data. AFAIK, it's not showing up in any data. That's a big problem in my opinion.

Offline whitelancer64

This is relevant for search for life on Mars. Not relevant for water supply.

I disagree. These streams were one of the very few pieces of evidence pointing to abundant water ice on mars (at least in equatorial regions). All plans involving ISRU fueling (and Musks plan specifically) require copious amounts of easily accessible water. From what I've read on these forums the plan would be to land on mars and then - mine the glacier. Where's that glacier? It's not showing up on Mars Odyssey neutron or gamma ray data. AFAIK, it's not showing up in any data. That's a big problem in my opinion.

The existence of Martian glaciers isn't in question, even with this new information. Odyssey's gamma ray spectrometer did detect large amounts of water on widespread areas of Mars.

What this information says may not exist on Mars is liquid water causing these recurring slope linae.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Online saliva_sweet

  • Full Member
  • ****
  • Posts: 552
  • Liked: 423
  • Likes Given: 1330
large amounts of water on widespread areas of Mars.

Poles :(


Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2167
  • Liked: 301
  • Likes Given: 368
This is relevant for search for life on Mars. Not relevant for water supply.

I disagree. These streams were one of the very few pieces of evidence pointing to abundant water ice on mars (at least in equatorial regions). All plans involving ISRU fueling (and Musks plan specifically) require copious amounts of easily accessible water. From what I've read on these forums the plan would be to land on mars and then - mine the glacier. Where's that glacier? It's not showing up on Mars Odyssey neutron or gamma ray data. AFAIK, it's not showing up in any data. That's a big problem in my opinion.

The RSLs were never supposed to have any connection to water ice.  They were supposed to be formed by deliquescent salts during seasons of high humidity.  the new hypothesis has no impact on our understanding of the distribution of water ice.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2167
  • Liked: 301
  • Likes Given: 368
large amounts of water on widespread areas of Mars.

Poles :(

Very widespread (and 300 km resolution) within 1 m of the surface down to latitudes of about 50 degrees N and S. Probably common at deeper depths closer to the equator.  Possibly closer to the surface close to the wquator as well, in sheltered regions less than 300 km across.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Online saliva_sweet

  • Full Member
  • ****
  • Posts: 552
  • Liked: 423
  • Likes Given: 1330
See http://forum.nasaspaceflight.com/index.php?topic=41680.msg1612647#msg1612647 or the article that started that thread: https://www.space.com/34811-mars-ice-more-water-than-lake-superior.html

Thanks. Interesting. Is there a link to the original paper? I'd like to know how they resolve the huge discrepancy with the Mars Odyssey data. The "lake superior" is located in one of the driest places on the planet according to odyssey. Also their argument seems to be that they see surface features that kind of suggest ice underneath so they interpret the radar data assuming there's ice underneath. Interpreting ground penetrating radar data is tricky on earth where we have all sorts of additional data to calibrate against. I suspect there may be many pitfalls for mars data. But I think I kind of see what they see on the radar data, so I'm hopeful.

The RSLs were never supposed to have any connection to water ice.  They were supposed to be formed by deliquescent salts during seasons of high humidity.  the new hypothesis has no impact on our understanding of the distribution of water ice.

It's all connected. I mean, how were these seasons of high humidity supposed to come about? Now it looks like there are no seasons of sufficient humidity to cause such flows - Mars became a drier place.

Very widespread (and 300 km resolution) within 1 m of the surface down to latitudes of about 50 degrees N and S.

Are you talking about the Mars Odyssey data?

Due to the funky scale what looks blue like the ocean at 50 degrees is actually dry as bone :(

Probably common at deeper depths closer to the equator.  Possibly closer to the surface close to the wquator as well, in sheltered regions less than 300 km across.

Can't fill your tank with theories.

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2167
  • Liked: 301
  • Likes Given: 368
See http://forum.nasaspaceflight.com/index.php?topic=41680.msg1612647#msg1612647 or the article that started that thread: https://www.space.com/34811-mars-ice-more-water-than-lake-superior.html

Thanks. Interesting. Is there a link to the original paper? I'd like to know how they resolve the huge discrepancy with the Mars Odyssey data. The "lake superior" is located in one of the driest places on the planet according to odyssey. Also their argument seems to be that they see surface features that kind of suggest ice underneath so they interpret the radar data assuming there's ice underneath. Interpreting ground penetrating radar data is tricky on earth where we have all sorts of additional data to calibrate against. I suspect there may be many pitfalls for mars data. But I think I kind of see what they see on the radar data, so I'm hopeful.

The RSLs were never supposed to have any connection to water ice.  They were supposed to be formed by deliquescent salts during seasons of high humidity.  the new hypothesis has no impact on our understanding of the distribution of water ice.

It's all connected. I mean, how were these seasons of high humidity supposed to come about? Now it looks like there are no seasons of sufficient humidity to cause such flows - Mars became a drier place.

Very widespread (and 300 km resolution) within 1 m of the surface down to latitudes of about 50 degrees N and S.

Are you talking about the Mars Odyssey data?

Due to the funky scale what looks blue like the ocean at 50 degrees is actually dry as bone :(

Probably common at deeper depths closer to the equator.  Possibly closer to the surface close to the wquator as well, in sheltered regions less than 300 km across.

Can't fill your tank with theories.

No, but you can use them to scope out resource exploration requirements.  Orbital data must always be validated by ground truth, which we have in only a few places.  But the probability and possibility I mentioned are very high.
We
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Bob Shaw

  • Full Member
  • ****
  • Posts: 1049
  • Liked: 423
  • Likes Given: 371
Why argue that water isnít present close to the surface? Ice was photographed in-situ by the Phoenix lander and ice has been observed scattered around fresh impact sites from orbit. This isnít just some arcane form of  remote-sensing!

Offline KelvinZero

  • Senior Member
  • *****
  • Posts: 3611
  • Liked: 513
  • Likes Given: 130
Why argue that water isnít present close to the surface? Ice was photographed in-situ by the Phoenix lander and ice has been observed scattered around fresh impact sites from orbit. This isnít just some arcane form of  remote-sensing!
I think the phoenix mission landed at about the same latitude as the Louth crater ~70į North, which has permanent white ice frost visible from space.

https://www.uahirise.org/PSP_007805_2505
https://www.nasa.gov/mission_pages/phoenix/images/polar_AGU.html
« Last Edit: 11/23/2017 09:14 AM by KelvinZero »

Online saliva_sweet

  • Full Member
  • ****
  • Posts: 552
  • Liked: 423
  • Likes Given: 1330
Why argue that water isnít present close to the surface?

Look, I want to believe, but I need to be aware of my own cognitive biases as well. So I want to separate the evidence from conjecture and wishful thinking.

Ice was photographed in-situ by the Phoenix lander

Phoenix lander is consistent with Odyssey data. I attached a map with approximate locations. It landed at the polar ice cap and perished in the winter buried under CO2 ice. Not an appealing prospect for a colony.
 
and ice has been observed scattered around fresh impact sites from orbit.

Any sources for that?
« Last Edit: 11/23/2017 02:55 PM by saliva_sweet »

Offline KelvinZero

  • Senior Member
  • *****
  • Posts: 3611
  • Liked: 513
  • Likes Given: 130
and ice has been observed scattered around fresh impact sites from orbit.

Any sources for that?
Just google it. Eg try "mars" in front of Bob Shaw's statement:
"Mars ice has been observed scattered around fresh impact sites from orbit."

The top three hits looked spot on to me, eg:

https://science.nasa.gov/science-news/science-at-nasa/2009/24sep_martianice
So far, the camera team has found bright ice exposed at five Martian sites with new craters that range in depth from approximately half a meter to 2.5 meters

The finds indicate water-ice occurs beneath Mars' surface halfway between the north pole and the equator, a lower latitude than expected in the dry Martian climate.

Offline Bob Shaw

  • Full Member
  • ****
  • Posts: 1049
  • Liked: 423
  • Likes Given: 371
Iíve always thought that a prime target for an early manned ISRU demo should be a new crater with ice lying around on the surface and pulverised sub-surface ice ready to be harvested for hydrogen and oxygen.

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2167
  • Liked: 301
  • Likes Given: 368
Why argue that water isnít present close to the surface?

Look, I want to believe, but I need to be aware of my own cognitive biases as well. So I want to separate the evidence from conjecture and wishful thinking.

It's not a question of wanting to believe, but following the evidence.  There are multiple lines of evidence for ice on Mars.  GRO neutron data.  HEND neutron data. Phoenix observations. HiRISE observations of ice surrounding high latitude craters.  Viking observations of seasonal water frosts.  Spectral and radiometer evidence of the composition of polar caps.

More indirect but still convincing in my opinion is the geomorphic evidence consistant will subsurface ice-rich material. 

Possible evidence also comes from thermal inertia data.

Ice was photographed in-situ by the Phoenix lander

Phoenix lander is consistent with Odyssey data. I attached a map with approximate locations. It landed at the polar ice cap and perished in the winter buried under CO2 ice. Not an appealing prospect for a colony.[/quote]

Not everything is about colonisation.  Nor is the performance of a lander with a short design life evidence of unsuitability.
 
and ice has been observed scattered around fresh impact sites from orbit.

Any sources for that?
[/quote]
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Offline Dalhousie

  • Senior Member
  • *****
  • Posts: 2167
  • Liked: 301
  • Likes Given: 368
The Gamma Ray Observatory data was always conclusive proof to me that there is water flowing thru Valles Marineris. Inferring hydrogen content of minerals as absolute proof of water always seemed like a pretty honky-dory logical inference to me.

However, this news from USGS really makes me wonder why there hasn't been much news (or for that matter) interest with water on Mars.  If you plot Google searches over time, there has been some transient interest with water on Mars.  As a comparison, I plotted the interest with the Oort Cloud. 

So, if water on Mars doesn't exist... I'd conclude that the Oort cloud doesn't exist as well. 

For whatever reason there is no interest with water on Mars, or the Oort Cloud, in Wyoming.

You are using the wrong bibliometric indices.

It would be better to use Google scholar

Water and Mars google scholar hits

1995-1996 8,480
1996-1997 9,800
1997-1998 11,000
1998-1999 12,300
1999-2000 14,000
2000-2001 15,300
2001-2002 16,100
2002-2003 19,200
2004-2005 26,400
2005-2006 17,100
2006-2007 13,300
2007-2008 19,700
2008-2009 35,600
2009-2010 19,600
2010-2011 39,900
2011-2012 21,800
2012-2013 41,900
2013-2014 21,900
2014-2015 38,800
2015-2016 17,600

These data show a steady increase from 8,480 hits in 1995-1996 to 26,400 in 2004-2005.  This covers the revolutionary discoveries of MGS,MO2001, and the MER landings. Since then interest has varied but never fallen below 13,300 (2006-2007) and peaking in 2012-2013 with 41,900 hits (iitial MSL period).

Scientific nterest is not transient and is increasing over time.
"There is nobody who is a bigger fan of sending robots to Mars than me... But I believe firmly that the best, the most comprehensive, the most successful exploration will be done by humans" Steve Squyres

Tags: