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Water on Mars?


LordFerret
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Perchlorate removal is a very involved process.

Maybe they will repurpose the Mars 2020 mission? But it is more likely that "brown patch" exploration will be the focus of the mission after that one, which would postpone the sample return mission. In any case, there is going to be some reshuffling of exploration cards in the near future.

I think they said in the stream that the Mars 2020 rover, which is based on curiosity, is not fit to explore the area. They will need to design a new robotic craft that can travel the steep area and remain easy to be sterilized for planetary protection purpose (apparently that is a design concern that KSP players never have to care for).

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Phoenix wasn't in Hellas. Phoenix was in the arctic, in Green Valley. If the pressure wasn't high enough for water there, the ice that the droplets were supposedly from would have directly sublimed to gas. And then there wouldn't have been droplets. As long as the water temperature is within the melting and boiling temperature at that pressure, the water is stable AFAIK.

Did you intentionally leave off the rest of my post, in particular this part:

... but that is for pure water...

Its always been assumed that if these gullies are do to "water", that the water is a very salty brine. Water saturated with salt has a lower melting point and a lower vapor pressure.

Pure water cannot exist on the vast majority of Mars' surface.

The surface is loaded with salts (including nasty perchlorate) so that is what they've found

- - - Updated - - -

As to the announcement, if you read wikipedia right now, it still hasn't been updated.

This was the state of the science before today's announcement:

Researchers surveyed flow-marked slopes with the Mars Reconnaissance Orbiter's CRISM and no spectrographic evidence of water was apparent.[13] If water is present, it may quickly evaporate. A flow initiated by salty water (brine) could rearrange grains or change surface roughness in a way that darkens the appearance. How the features brighten again when temperatures drop is harder to explain.[10][16]

...

The seasonality, latitude distribution and brightness changes strongly indicate a volatile material â€â€such as water is involved, but there is no direct detection of one. Some hypotheses on the formation of these features have been proposed. One hypothesis is that RSL could form by rapid heating of nocturnal frost.[12] Another one proposes flows of carbon dioxide, but the settings in which the flows occur are too warm for carbon-dioxide frost (CO

2), and at some sites is too cold for pure water.[12] Other hypotheses include dry granular flows, but no entirely dry process can explain seasonal flows that progressively grow over weeks and months.[15] Seasonal melting of shallow ice would explain the RSL observations, but it would be difficult to replenish such ice annually.[15]

Brines

The leading hypothesis involves the flow of brines â€â€very salty water.[17][13][18][14][19][20] Salt deposits over much of Mars indicate that brine was abundant in Mars's past.[10][16] Salinity lowers the freezing point of water to sustain a liquid flow. Less saline water would freeze at the observed temperatures.[10] Thermal infrared data from the Thermal Emission Imaging System (THEMIS) onboard the 2001 Mars Odyssey orbiter, have allowed the temperature conditions under which RSL form to be constrained. While a small number of RSL are visible at temperatures above the freezing point of water, most are not, and many appear at temperatures as low as −43 °C (230 K). Some scientists think that under these cold conditions, a brine of iron sulphate (Fe2(SO4)3) or calcium chloride (CaCl

2) is the most likely mode of RSL formation.[21] Another team of scientists reported that the evidence for hydrated salts is most consistent with the spectral absorption features of magnesium perchlorate (Mg(ClO4)2), magnesium chloride (MgCl2(H2O)x) and sodium perchlorate (NaClO

4).[17][20]

These observations are the closest scientists have come to finding evidence of liquid water on the planet's surface today.[10][16] Frozen water, however, has been detected near the surface in many middle to high-latitude regions. Purported droplets of brine also appeared on struts of the Phoenix Mars Lander in 2008.[22]

They thought it was water, but couldn't detect any... it seems they did detect some now

Edited by KerikBalm
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I think they said in the stream that the Mars 2020 rover, which is based on curiosity, is not fit to explore the area.

I wonder if the Exomars 2018 rover might be diverted to this area. Being smaller and lighter, it might be more capable of climbing the slopes, and it is planned to carry an exobiology package. Its funding isn't very secure, but this might cause a strong incentive to get it properly funded.

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I wonder if the Exomars 2018 rover might be diverted to this area. Being smaller and lighter, it might be more capable of climbing the slopes, and it is planned to carry an exobiology package. Its funding isn't very secure, but this might cause a strong incentive to get it properly funded.

It might be even less capable than curiosity in climbing these slopes.

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So they found water

I wonder if this means they will be landing the next rover someplace different, will it have the appropriate instruments and performance for directly analyzing water on the slopes of a crater?

Edited by RuBisCO
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By water do they mean liquid water or just water ice that sublimates and refreezes or what?

They mean brine, as in salt water.

Just read that there are 2 candidate recurring slope lineae in Gale crater within range of Curiosity, they could be their if they so choose to approach.

"That prohibition may continue even though two candidate streaks have been identified on the mountain in Gale Crater that NASA’s Curiosity rover is now exploring, a mile or two from its planned path.

NASA and the Curiosity team could decide to approach the streaks without driving onto them, or to simply observe from a distance. The rover is still probably a couple of years away.

NASA officials did not reject the possibility of a detour, although they said it would require analysis and debate.

In an interview after the news conference, Dr. Green of NASA said that if the streaks in Gale Crater turned out to be recurring slope lineae, the space agency would consider how great a contamination threat Curiosity, irradiated by ultraviolet light for several years, might pose to a potential Martian habitat.

“If we can go within 20 meters, we can zap it with a laser,†Dr. Green said, referring to an instrument that identifies material inside a rock by the colors of light it emits as it is vaporized. “Then we can learn much more about the details what’s in those R.S.L.s. If we can get closer and actually scoop it up, that would be even better.â€Â

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They mean brine, as in salt water.

Just read that there are 2 candidate recurring slope lineae in Gale crater within range of Curiosity, they could be their if they so choose to approach.

Actually, they just found hydrated salt... but they assume that is due to liquid water.

Its probably right, but there is still a distinction.

I can show you hydrated salts here on Earth, with no brine - just solid salts complexed with water molecules.

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Actually, they just found hydrated salt... but they assume that is due to liquid water.

Its probably right, but there is still a distinction.

I can show you hydrated salts here on Earth, with no brine - just solid salts complexed with water molecules.

No, they found the evidence of a high salinity brine (where salinity has much to do with perchlorate salts of alkali and earth alkali metals) occuring seasonally as wet streaks on some slopes.

It's basically a very saturated solution, surface phase, coupled to hydrated minerals.

mars-screen-grab_3455894b.jpg

No evidence of surface running water or aqueous solutions exist. Not even mud burps, as I like to call them, although these might exist seasonally in the lowest regions.

I'd describe these as taking some calcium chloride powder and sprinkling it on a rocky desert slope. It will absorb moisture and that highly saturated solution is gonna wet the dry dirt and make it optically darker.

And this is not news. This is a PR stunt of an organization struggling with rednecks in the Congress that decide how much money it gets.

Cull, S. C. et al. Concentrated perchlorate at the Mars Phoenix landing site: Evidence for thin film liquid water on Mars. Geophys. Res. Lett. 37, L22203 (2010).

We knew about these liquid films and voila - there will be a streak if you do it on an inclined plane. :)

Edited by lajoswinkler
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No, they found the evidence of a high salinity brine (where salinity has much to do with perchlorate salts of alkali and earth alkali metals) occuring seasonally as wet streaks on some slopes.

It's basically a very saturated solution, surface phase, coupled to hydrated minerals.

I don't think that's right. Brine is a solution of water saturated with dissolved salts. They didn't detect a solution consisting of water with dissolved salts.

You said "It's basically a very saturated solution ... coupled to hydrated minerals"

They detected the hydrated minerals, not the very saturated solution. They infer the saturated solution from the presence of hydrated minerals.

They detected hydrates in the dark slopes:

https://en.wikipedia.org/wiki/Hydrate

Something like Cobalt(II) chloride hexahydrate CoCl2•6H2O

(yes, I know it wasn't cobalt chloride... I mean just the H2O salt complex like that).

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2546.html

We find evidence for hydrated salts at all four locations in the seasons when recurring slope lineae are most extensive, which suggests that the source of hydration is recurring slope lineae activity.

Hydrated Salt is not the same thing as salty water.

That is my main point.

They continue:

The hydrated salts most consistent with the spectral absorption features we detect are magnesium perchlorate, magnesium chlorate and sodium perchlorate. Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars.

In the introduction they say:

Confirmation of this wet origin hypothesis for RSL would require either detection of liquid water absorptions on the surface, or detection of hydrated salts precipitated from that water.

The part in bold still has not been detected.

The 2nd part is what they detected, but I don't buy their assertion that that detection of hydrated salts is sufficient to conclude liquid water. Salts can become hydrated just from contact with humid air.

We already know that there is enough humidity on mars to cause water ice to form... so... those salts could become hydrated without any liquid water.

The part that makes me think there might be (very salty)liquid water is that water ice can form, the association with the stuff that looks like a flow, and that it occurs when the temperature increases... when ice might start melting.

Maybe its just ice sublimating, and the vapor hydrates the salt, and the loss of ice and expansion of the now hydrated salts disturbs the loos gravel, and its a gravel flow, like you may have seen as a kid digging holes in a sandbox.

I'm going to say its *probably* brine, but its still not conclusive.

- - - Updated - - -

Followup, more relevant statements from the paper:

The absorptions observed in CRISM images of Palikir are too narrow to be explained by liquid water. Instead, they may be consistent with hydrated salts (Fig. 1). The rapid change in hydration state of the minerals imply that at the times and places where RSL form, either the hydration state of the minerals is being increased by the presence of RSL, or hydrated minerals are deposited by RSL and later desiccated.
The origin of water forming the RSL is not understood1, 2, 3. Water could form by the surface/subsurface melting of ice, but the presence of near-surface ice at equatorial latitudes is highly unlikely24. RSL could form alternatively through deliquescence, but it is unclear whether the Martian atmosphere can supply sufficient water vapour every year to create RSL (ref. 2). Another hypothesis is seasonal discharge of a local aquifer, but lineae extending to the tops of local peaks2 are difficult to explain. It is conceivable that RSL are forming in different parts of Mars through different formation mechanisms.

In short... there's no good explanation for how there could be water there... so if there's no way for water to get there, are we really to believe that water is flowing there?

Terrestrially, in the hyperarid core of the Atacama Desert, deliquescence of hygroscopic salts offers the only known refuge for active microbial communities25, 26 and halophylic prokaryotes27. If RSL are indeed formed as a result of deliquescence of perchlorate salts, they might provide transiently wet conditions near surface on Mars, although the water activity in perchlorate solutions may be too low to support known terrestrial life

Or perhaps there is no deliquescence of perchlorate salts at all in the RSL

Edited by KerikBalm
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Can you grow a plant of some sort in perchlorate brine?

No, and the main reason is not because there are perchlorate anions inside (they're sluggish at low temperatures, unlike when heated, for example in a solid rocket booster), but because it's brine. Osmotic tension inside is enormous. That's why NaCl brine is a preservative agent for many foods, and also the reason honey won't spoil if hermetically sealed. Not because honey is special, but because sugars inside are so concentrated.

Also, if you want to extract water for drinking, you'd need some serious processing because perchlorate anion is an endocrine disruptor.

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I don't think that's right. Brine is a solution of water saturated with dissolved salts. They didn't detect a solution consisting of water with dissolved salts.

You said "It's basically a very saturated solution ... coupled to hydrated minerals"

They detected the hydrated minerals, not the very saturated solution. They infer the saturated solution from the presence of hydrated minerals.

They detected hydrates in the dark slopes:

https://en.wikipedia.org/wiki/Hydrate

Something like Cobalt(II) chloride hexahydrate CoCl2•6H2O

(yes, I know it wasn't cobalt chloride... I mean just the H2O salt complex like that).

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2546.html

Hydrated Salt is not the same thing as salty water.

That is my main point.

They continue:

In the introduction they say:

The part in bold still has not been detected.

The 2nd part is what they detected, but I don't buy their assertion that that detection of hydrated salts is sufficient to conclude liquid water. Salts can become hydrated just from contact with humid air.

We already know that there is enough humidity on mars to cause water ice to form... so... those salts could become hydrated without any liquid water.

The part that makes me think there might be (very salty)liquid water is that water ice can form, the association with the stuff that looks like a flow, and that it occurs when the temperature increases... when ice might start melting.

Maybe its just ice sublimating, and the vapor hydrates the salt, and the loss of ice and expansion of the now hydrated salts disturbs the loos gravel, and its a gravel flow, like you may have seen as a kid digging holes in a sandbox.

I'm going to say its *probably* brine, but its still not conclusive.

- - - Updated - - -

Followup, more relevant statements from the paper:

But wasn't liquid surface bound layer found years ago? There's a paper on it, I've linked the title.

By all means, don't think I'm one of those "yay, rivers!" people. I'm well aware of how hydration occurs and what happens, and I'm inclined to think what NASA said yesterday is really a PR stunt.

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You linked it, but it was again inferred.

They looked at the distribution of perchlorates, and inferred that the distribution was due to dissolution and perciptatation from a thin layer of water.

To date, the closest thing we have to direct detection of liquid water on mars, are those blobs on the struts of the phoenix lander.

* They didn't see water in that paper.

"we use spectral data from Phoenix’s Surface Stereo Imager to map the distribution of perchlorate salts at the Phoenix landing site, and find that perchlorate salt has been locally concentrated into subsurface patches, similar to salt patches that result from aqueous dissolution and redistribution on Earth. We propose that thin films of liquid water are responsible for translocating perchlorate from the surface to the subsurface, and for concentrating it in patches."

* They didn't see water with the orbiter.

"MRO’s mid-afternoon (~3 p.m.) observations occur at the time of the day with lowest relative humidity19, which minimizes the probability of detecting liquid brines that emplaced hydrated salts, and may even facilitate dehydration of salts."

"The absorptions observed in CRISM images of Palikir are too narrow to be explained by liquid water. Instead, they may be consistent with hydrated salts (Fig. 1)."

* They did directly see *something* on the struts of Phoenix... that looked like water, but was not 100% convincing.

What we have are indirect inferences, or direct but unclear observations.

I think it is *probably* a brine there, and that was probably liquid brine on the struts of the Phoenix lander.

I'm also not "one of those 'yay, rivers!' people."

Just like when I recently corrected that guy about the Arsenic life stuff, even though his main point was good - I'm just pointing out that this was not a detection of liquid water. This was a detection of hydrated salt. Liquid water is still inferred.

Even if there is liquid water there... its hard to get a water activity any lower than that... physics is physics, and there's pretty much no way that life could pull water from that.

Drink salt water... get dehydrated... drink fresh water, get hydrated.

Land/fresh water animals have lower internal salt concentration than sea animals... but higher than fresh water

Sea animals have higher internal salt concentrations than the ocean (some exceptions like whales, which excrete salt to allow them to drink sea water)

Bacteria that live in salty conditions have very salty interiors.

But on mars...a bacteria like think can't really get any saltier than that brine, to get the water to flow into the cell rather than out of the cell into the hydrates... because ...physics...

Not only that... but that close to the surface... the radiation is quite intense.

I don't think that is a habitable environment.

Maybe deeper underground, but mars doesn't have much geothermal heat left... and I don't think you're going to find less salty water conditions underground...

That is a dead planet methinks...

Edited by KerikBalm
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You linked it, but it was again inferred.

They looked at the distribution of perchlorates, and inferred that the distribution was due to dissolution and perciptatation from a thin layer of water.

No, they saw that this distribution changed over time, seasonally. They didn't just see hydrated salts, they saw salts becoming hydrated and drying out over relatively short periods of time, and they're pretty sure the quantities involved are much too high to be due to absorption from the atmosphere. If you're going to try and criticise their work, at least read the abstract first.

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*** Are you confusing my comments on the 2010 Phoenix paper and and this most recent paper? ***

I did read it, I even quoted it:

http://repository.brynmawr.edu/cgi/viewcontent.cgi?article=1011&context=geo_pubs

NASA's Phoenix mission, which landed on the northern plains of Mars in 2008, returned evidence of the perchlorate anion distributed evenly throughout the soil column at the landing site. Here, we use spectral data from Phoenix's Surface Stereo Imager to map the distribution of perchlorate salts at the Phoenix landing site, and find that perchlorate salt has been locally concentrated into subsurface patches, similar to salt patches that result from aqueous dissolution and redistribution on Earth. We propose that thin films of liquid water are responsible for translocating perchlorate from the surface to the subsurface, and for concentrating it in patches. The thin films are interpreted to result from melting of minor ice covers related to seasonal and long-term obliquity cycles.

Nowehere in the abstract does it mention: "they saw salts becoming hydrated and drying out over relatively short periods of time"

"Spectra of soils with the 0.967µm feature did not change through time. Each patch was uncovered during an RA excavation, exposed for two or more sols, and in some cases reâ€Âburied by new trenching. One patch was left undisturbed for 113 sols, during which no changes were observed to the shape of its spectrum, its overall albedo, or the depth of the 0.967 µm feature. In addition, the size and shape of the clods did not change. Thus, the patches are stable on the surface on timescales of hundreds of sols"

Edited by KerikBalm
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No, they saw that this distribution changed over time, seasonally. They didn't just see hydrated salts, they saw salts becoming hydrated and drying out over relatively short periods of time, and they're pretty sure the quantities involved are much too high to be due to absorption from the atmosphere. If you're going to try and criticise their work, at least read the abstract first.

I doubt he'd be satisfied by anything short of Buzz Lightyear going out there, drinking a pint of it on camera, and it being streamed life on Twitch.

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I've already said multiple times that there is probably water there.

I'm just trying to balance out the hype, and get people to adopt the appropriate level of caution in their statements.

You should not say that they detected flowing liquid water, when they detected hydrated salts along lines on a slope, and failed to detect actual liquid water.

I'm sorry if I'd rather be precise than jump on a hype bandwagon... wait... nope... not sorry.

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Yay, rivers!

sorry XD

I think we already basically knew that the RSLs were water-based materials or made by water-based materials 'cause there's nothing else on Mars capable of making dark streaks on hills when it gets warm.

Edited by Findthepin1
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Anyone think this might be enough to NASA a little extra political leverage? They now have a chance to answer the "Are we alone?" question with facts instead of mere statistics. I think it's definitely time for a raise.

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Any life on Mars or Venus would be very, very likely to have a common origin with the life on Earth. It says nothing about how common life is in the universe. I think if we find life that we know doesn't share a common origin with Terran life, it'll be on Titan. Any water-based life in the solar system is probably related to us, and if it wasn't I doubt we'd be able to tell. In another star system, if there's life, then we can say with near certainty that it arose independently.

Edited by Findthepin1
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