> 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.

So, this article says there's no water on the surface of Mars, rather than underneath it.

Though it looks like this suggests that water beneath the surface is unlikely to be there as well?

Liquid water anyway. We know there is a lot of water ice locked into glaciers on mountain slopes etc.

What was it that made them think it was water rather than grain flows in the first place, on this dry grainy planet?

See section 4.1 [page 909] of this report: https://www.researchgate.net/profile/David_Beaty/publication...

The main driver is that the flows seem to be associated with seasonally higher temperatures, and therefore the flows ("RSL") may be caused by a melting brine. RSLs have been controversial and they have gotten a lot of attention from planetary scientists.

wishful thinking

also an isotope in the sand would have allowed water to stay flowing at the below freezing temperatures that mars has, so if you were grasping for straws at why there would be water, this would support it, but if you weren't wishing there was water there as the presupposition then this new answer would have been more immediately obvious

Did they simply went with the visual look of it? Probably did some simulations on a computer and compared and decided its water. I would be shocked by such low quality of Science behind it if that was the case. Extra ordinary claims require extra ordinary evidence.

Please don't post obvious dismissals of other people's work unless you have some specific knowledge about it.

There's nothing more lowering of discussion quality otherwise; it's like a snake in snakes and ladders.

Problem is if they actually suspect it's water they aren't allowed to bring their rovers or probes anywhere near as they don't want to risk contaminating it with Earth microorganisms.

And yet Elon Musk is going to build a colony?

I don't believe he is bound by this, or maybe wouldn't care if he was. https://planetaryprotection.nasa.gov/about

https://planetaryprotection.nasa.gov/intpolicy/

Yeah, I've been intrigued by this cognitive dissonance for a while. Are we going to visit, or would contaminating the planet be a disaster for science and our understanding of the nature of life?

god bless anyone dumb enough to believe him

What would it mean for us if Mars were without water or life?

This isn't saying Mars has no water. They've found that one particular instance of what they thought was liquid water turns out to not be, but there is tons of evidence for water ice and possibly deep sub-surface briny water.

Mars likely does not have life at the surface. Too much cosmic radiation. It may not have life at all but if it does it would be beneath the surface or in deep caves.

If there is no subsurface ice anywhere, I think the SpaceX colonizing team might have a challenge. It seems their current plan is to dig tunnels in suspected ice areas, processing the soil to extract water to electrolyze for fuel and air, then using the tunnels and castings for housing. Bringing all the fuel, air, and water from Earth is probably a no-go.

Wait- SpaceX is planning to tunnel on Mars? That means the Boring Company... Is everything Musk does part of his not-secret secret plan to retire on Mars?

Yes.

It's not like there are fossil fuels on the Red Planet, so we're going to need solar cells and batteries to power our electric rovers.

Yep, (ding!) and solar cells, batteries, compressed gasses, vehicles... all important colonization core tech.

Underground structures will also be well-shielded from radiation that Mars' lack of a strong magnetic field fails to deflect.

We're more likely to become an advanced civilization [1].

[1] https://en.wikipedia.org/wiki/Great_Filter

We'll bring both.

How do you propose we relocate any significant volume of water?

Science fiction has proposed a number of possible-if-difficult ways.

Comets, to start, are mostly water. If you're patient, you can redirect some very sightly while they're in the far end of the system and have them impact Mars. Takes a while though. Also, big boom when they arrive.

Really though, there's plenty of carbon <edit>oxygen, in the form of carbon dioxide</edit> on Mars- you just need hydrogen. Jupiter is mostly that. With a very large fleet of ships, you might be able to bring some to Mars. Solar sails might help keep costs low, and ideally they're fully autonomous. Heck, if that works, you'd probably want to start doing the same trick and pouring hydrogen into Venus while taking away CO2.

I'm sure there's other ways too. Plus, we know there is some water on Mars already. If we can use it carefully, reuse exhaustively, it could sustain a large population.

>Plus, we know there is some water on Mars already

do we know that?

what i'm reading with regards to this article and comments is that now we're back to not having any concrete evidence of this

We are fairly certainly that the ice caps are mostly water ice with a much smaller and more seasonal dry ice layer; what this article means is that the indication of liquid water on the surface seems to have been wrong.

You need oxygen, not carbon, to make water.

Ah, teaches me for trying to write before my morning caffeine.

Oxygen. Oxygen is what Mars already has, in the form of CO2, carbon dioxide.

I’m guessing he meant carbon dioxide, rather than just carbon.

Without a decent atmosphere water will just boil / sublimate off and get blown away; Mars would need a magnetosphere to retain anything.

A sufficiently large radio system built on Mars or at its solar LaGrange point could provide the shielding effect that is normally the responsibility of the magnetosphere. It was studied for feasibility by NASA and found possible with current technology. Of course, possible doesn't imply practical and the natural formation of Martian atmosphere if we did that would be on geologic timescales.

Water would get blown away over a period of millions of years though. I think that's not much of a problem.

Even if you could increase the atmospheric density, the lack of magnetosphere is still a problem when it comes to human habitation, however. Any long-term habitats would need to be built underground, or at least heavily shielded against solar radiation.

Could people go out at night?

I've previously seem ideas such as nuking the poles. It implied there were enough gases stored in the ice to created a sufficient atmosphere. The loss of the atmosphere due to lack of a magnetosphere would take millions of years.

We shall no longer call our race mankind, but Galactus, the planet eaters!

Shai-Hulud

Isn't there significant amounts of ice at the poles?

A long hose?

A portal from Earth, maybe.

https://what-if.xkcd.com/54/

With copious amounts of thrust

'How' is not interesting, the real question is 'why'.

There's nothing there on Mars that would ever make human habitation profitable or self-sustaining.

Is it like the Sailing Stones we have observed in the desert but with grains of sand?

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

Those rocks move because they're carried by thin ice sheets every once in a while:

> rocks move when large ice sheets a few millimeters thick floating in an ephemeral winter pond start to break up during sunny days. These thin floating ice panels, frozen during cold winter nights, are driven by wind and shove rocks at up to 5 m/min.

It's interesting that the release doesn't address the seasonality of the effect unless it falls under the possible initiation handwave. Is there some other temperature dependent effect on such flows?

Actually the seasonality is addressed:

"The preference for warm seasons and the detection of hydrated salts are consistent with some role for water in their initiation. However, liquid water volumes may be small or zero, .."

I think it's funny they say it's a new theory that mars didnt have water.