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List of evidence for water on Mars
brellis
post Sep 28 2015, 10:36 PM
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One of the blurbs alluded to the possibility of an airborne source/process. The vineyards of Lanzarote (Canary Islands) are collections of pits that trap condensation from passing clouds and funnel it down to the vines at the bottoms. Could a similar process of condensation be in play here with prevailing winds?
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JRehling
post Sep 28 2015, 11:43 PM
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My sense is:

The subsurface ice layer (as seen under the Phoenix lander) has a ragged boundary where it ends around 40° North/South. Where it abuts steep slopes (often craters), it verges into soil that undergoes significant seasonal heating/cooling cycles. Where it does not do that, it remains at fairly constant temperatures year-round. When local conditions achieve maximum heating and cross a threshold that has not been reached before (either slightly warmer than previous summers), a bit of the edge melts and runs downslope. This partially exhausts the local supply of ice ("local" may mean meters, or even centimeters), so that the same precise spot may not undergo this activity again for a very, very long time, if ever.

If this is an accurate model of the phenomenon, then exploring it will be hard because:

1) It will be easy to list candidate locations to watch but very hard to list candidates that will actually have flows in any given year.
2) Once a location shows the phenomenon while we are watching, that may make the location very unlikely to exhibit the phenomenon again anytime soon.

By rough analogy, imagine trying to send a lander to Earth and place it where a tornado will later happen. The odds are very slim. (In fact, even with people on the ground, few successes of this kind have been achieved.)

We would have better luck if we tried to observe a place where it happened and then explore it relatively soon thereafter.
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serpens
post Sep 29 2015, 02:45 AM
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I have to admit to being a touch underwhelmed by this announcement.
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pac56
post Sep 29 2015, 06:17 AM
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I think the news is they did spectral analysis of it.
Edit: see Emily's blog http://www.planetary.org/blogs/emily-lakda...nouncement.html
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marsbug
post Sep 29 2015, 08:59 AM
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I'd point towards Emily's blog as well. WRT supporting life, I doubt the RSL hang about for long enough. For my two penny worth the significance of this is more as a proof of principle: We now know that the perchlorate salts on Mars can and do produce liquid water, which has been long suggested before but not shown to be actually happening. Finding evidence that it is happening boosts the chances of larger amounts of water being present in the relatively near subsurface.

As for habitability of the water... on Earth, if there's water there's microbial life (almost) without exception, even if the water is acidic or alkaline enough to be deadly to people. If there is any life on Mars I'd expect it to have adapted to use any resource, especially one as precious and scarce there as liquid water, just as it would on Earth.


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dvandorn
post Sep 29 2015, 03:15 PM
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It seems to me that the confirmation of liquid water mostly impacts landing site selection for future missions, in that the planetary protection protocols specifically prohibit any landings near liquid water with any lander at a sterilization level less stringent than that defined for the Viking landers (i.e., less than 30 spores per vehicle). Otherwise very attractive sites may end up on the verboten list if there are close-by RSL's.

Any idea if this might affect the landing site selection for the 2020 rover? Especially considering the fact that the 2020 rover will be caching samples for potential return -- if you land near RSL's, you have to postulate not only sterilizing the rover to the Viking standards, but also whatever follow-on vehicle collects the samples and returns them to Martian orbit...

-the other Doug


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surbiton
post Sep 29 2015, 04:11 PM
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QUOTE (dvandorn @ Sep 29 2015, 04:15 PM) *
It seems to me that the confirmation of liquid water mostly impacts landing site selection for future missions, in that the planetary protection protocols specifically prohibit any landings near liquid water with any lander at a sterilization level less stringent than that defined for the Viking landers (i.e., less than 30 spores per vehicle). Otherwise very attractive sites may end up on the verboten list if there are close-by RSL's.

Any idea if this might affect the landing site selection for the 2020 rover? Especially considering the fact that the 2020 rover will be caching samples for potential return -- if you land near RSL's, you have to postulate not only sterilizing the rover to the Viking standards, but also whatever follow-on vehicle collects the samples and returns them to Martian orbit...

-the other Doug


If we are so scared of contaminating Mars, why do we send anything there ?

If we really want to keep all the planets pristine, then we should leave them alone.

In fact, we should be more careful that we accidentally do not bring any "new" microbes back to earth !
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JRehling
post Sep 29 2015, 04:36 PM
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QUOTE (dvandorn @ Sep 29 2015, 08:15 AM) *
Any idea if this might affect the landing site selection for the 2020 rover?


I would suspect not. The two kinds of environments seem probably distinct, although I recall Spirit finding that "magic carpet" surface and wonder if it was actually on top of some briny liquid or slush.

The elephant in the room is that there are two distinct exploration pathways – Past Water vs. Current Water – and surface missions typical of ones we've seen that pursue one pathway aren't pursuing the other, so there needs to be some strategy. If only one of these pathways existed, we'd be pursuing it. Given that two pathways exist, do we "finish" one before starting the other, interleave them with separate mission architectures, or find a way to combine them?

One possibility for combining them would be to have a single craft for Mars-orbit-to-Earth sample return, and have sample returns from both kinds of environment travel from Mars surface up to that return craft. With craft weighing many tens of kg and samples weighing and 10 g, that would provide a lot of savings if we acknowledge that both kinds of sample return are desirable. Further savings would be achieved in sharing clean ground facilities on Earth for examining samples.
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marsophile
post Sep 30 2015, 02:51 AM
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http://www.hou.usra.edu/meetings/lpsc2015/pdf/2327.pdf

Figure 1 in the above LPSC abstract shows some candidate RSLs in Gale Crater. These were mentioned during the press conference in conjunction with the possibility of a visit by Curiosity. During the question period one of the reporters raised the issue of planetary protection. The reply suggested that they could be observed from a distance at times different from the fixed MRO flyover time, which would be useful. The panelists also suggested that Mars 2020 could have a role and it was stated that the budget included some money for sterilization.

The PC recording can be seen here:

http://www.ustream.tv/recorded/74355422

It is worth listening to the Q&A on the topic of planetary protection.
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Explorer1
post Sep 30 2015, 03:50 AM
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The fact that these features are spread out over so many different regions of Mars separated by thousands of km seems to imply that its false positives that would be the main concern for a future mission, not somehow contaminating the entire planet with one mission. Though like others have said, since their occurrence is almost by definition on steep slopes that can't be easily reached in any case, it's likely to remain an academic question for a good while yet....
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JRehling
post Sep 30 2015, 05:00 PM
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I think there are lots of ways to study/sample these areas if we want to. Of course, there are engineering challenges and a chance of failure, but it's not impossible.

A stationary lander could be paired with an aerobot with cameras on the lander and the aerobot helping the aerobot land precisely on an RSL, sample the soil there and bring it to the lander for analysis or even sample return. That would completely neutralize problems related to the steepness of the slope.
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serpens
post Oct 1 2015, 04:45 AM
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JRehling's post #47 proposing the water source makes good sense. In the main the popular press has reported the finding as salt water flowing on the surface of Mars giving the impression of a bubbling stream. The reality is that the RSL where hydrated perchlorates were identified are a flow in the geological sense of a land slip with ephemeral brine as the fluidizing agent.
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Explorer1
post Oct 1 2015, 04:51 AM
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'Fluidizing agent found on Mars' doesn't have quite the same ring to it in the headlines though....
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serpens
post May 20 2016, 08:14 AM
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This makes for rather interesting reading.

http://www.nature.com/articles/srep25106

Accumulating evidence of ocean and lakes, groundwater, streams and deltas, river valley networks seemingly traceable to precipitation, It is beginning to become clear that early Mars had an interesting hydrological cycle.
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marsbug
post Aug 24 2016, 11:38 AM
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The question marks around the RSL's are growing again: http://www.jpl.nasa.gov/news/news.php?release=2016-215


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