

Scientists have found more evidence for liquid water on Mars - ikeboy
https://www.vox.com/2015/4/13/8384337/mars-water-liquid-curiosity

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stephengillie
The crux of the problem with Mars is that its magnetic field is smaller than
its atmosphere. All water gets blown away by the solar wind. Venus has a
similar situation, and it's reacting somewhat similarly, having lightweight
particles blown away by solar wind. Indeed, the Earth is the only one of the 3
with a larger magnetic field than its atmosphere. We look like a small gas
giant by comparison - our magnetic field reaches far out into space, more than
half as big as Neptune or Uranis' magnetic fields. This protects our water and
other environmental factors.

Sadly, this means that seeding the planet with water, perhaps by towing an
ice-asteroid into orbit and knocking it to the planet, would be a temporary
fix at best. Eventually all of that water would just evaporate away and join
the Heliopause.

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aetherson
My understanding is that "temporary" in this case means, like, "one million
years or more."

While I appreciate that that's a very short span of time by both geological
and evolutionary standards, I don't think it's meaningfully "temporary" by
human standards.

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acconrad
> However, many scientists believe Mars was much warmer and wetter billions of
> years ago, when it may have had a thicker atmosphere to help trap heat.

This is both fascinating and horrifying. Given the timeline of the solar
system thus far, it would seem plausible that an entire evolution of species,
including the rise and demise of intelligent life, could have already started
and finished on Mars.

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cryptoz
Taking this one step further, it is also possible that life has been exchanged
between our two worlds. Large meteor collisions in the past have moved parts
of Mars to Earth, and possibly also Earth to Mars. And some small life can
exist clung to rocks in space (we know of such creatures here on Earth)! So
perhaps, Mars was once wet and warm and full of life. Perhaps it suffered a
large impact of some kind billions of years ago, and perhaps that impact flung
Mars rocks with little tiny Martians on them towards Earth. In fact, this
could have happened thousands of times.

It's possible, anyway. You know, while we're speculating.

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inigoesdr
Yep, it's called Panspermia:
[http://en.wikipedia.org/wiki/Panspermia](http://en.wikipedia.org/wiki/Panspermia)

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deeviant
Why do I feel that this is the 5th time scientists have found the first
evidence for liquid water on Mars?

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goodcanadian
Because this is far from the first evidence. There is plenty of evidence for
liquid water on Mars both past and present. In fairness, the article mentions
this. In spite of the headline, it only claims the first direct evidence.
Personally, I think even that is a bit of an overstatement. To me, this is
simply one more bit of evidence that supports the current scientific
consensus.

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altrus
From the Nature Abstract[1]: Indirect evidence for water on Mars was found by
detecting the presence of salts that absorb atmospheric water vapour, and
suggest that transient brines form in the upper 15cm of the martian
subsurface.

It's fairly exciting news.

[http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo24...](http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2412.html)

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iwwr
A little less than half the surface of Mars has pressures above the triple
point of water, so wherever the temperatures dip above 0C, maybe a few hours a
day in the equatorial regions, liquid water can exist. Deeper craters closer
to the equator or seasonally in the northern lowlands or the southern Hellas
or Argyre region.

