[headdie]

Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons. They appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit (minus 23 Celsius), and disappear at colder times.

So flowing water on Mars.... Discuss away

[watsisname]

Very exciting, but not very surprising.   The modern Martian surface is extremely inhospitable to liquid-phase water, but it does sometimes and someplaces get warm enough to exist temporarily, especially if it is briny.  I think a lot of the planetary scientists were pretty confident that the streaks were associated with water, but it's nice to now have very strong evidence to show it.  And of course the implications for life on Mars, past or present, is obvious.

I just really hope the media doesn't present this as to make people think of it like a stream on Earth.   The flow is essentially entirely subsurface, more like a percolation.

[NGTM-1R]

NASA: accidentally ensuring The Martian is a big hit.

[Dragon]

Ironically, it's something The Martian had gotten wrong. Not Weir's fault, though, we actually thought Mars to be bone dry at the time the novel was written.

Anyway, this is interesting. I wonder where the -23 degrees figure comes from. As any driver in the higher latitudes can tell you, surface temperature and air temperature can differ, sometimes by a fair margin. With atmosphere this thin, convection rates would be lower and this difference would be even more pronounced. I wonder what the actual ground temperatures are.

[watsisname]

Still pretty bone dry though.

And funny enough, even Earth is drier than bone, if you consider by percent of total mass.

[Dragon]

Not to an extent Weir specified, though. Also not to an extent that you couldn't get water from the soil. That said, I don't think distribution of water in the soil is uniform. While I do have a feeling that a dry riverbed should be fairly "wet", there's a lot of stuff about Mars we don't understand yet. So it doesn't seem that implausible for the particular landing area to actually be this dry (as for why he had to be stranded in a place this dry, when the Mars is full of water? Well, that's well within realms of ordinary rotten luck. Wouldn't be the first case like that).