Mars Gullies Show Water Once Flowed 59
NewYorkCountryLawyer writes "A new analysis of puzzling gullylike features on Mars offers further evidence that water flowed on the Red Planet's surface, perhaps as recently as several hundred thousand years ago. The findings bolster the case that melting snow from a departed Martian ice age carved these gullies, rather than shifting sands or other 'dry' phenomena."
Where did it go? (Score:4, Interesting)
That is the real question. Is the atmosphere too thin to keep the water there or did it all freeze or go underground. Do we (earth) lose water as well?
Re:Where did it go? (Score:5, Informative)
Our combination of gravity, temperature and magnetic field strength means there is negligible loss to the atmosphere even over massive time-scales.
Thankfully.
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Whoops,
loss to = loss from.
Large semantic difference there.
Re:Where did it go? (Score:4, Informative)
Mars's biggest problem is gravity.
The molecules in a gas move at rather high velocities (you can calculate this with a Maxwell-Boltzmann distribution [wikipedia.org]). If some of those molecules are moving faster than escape velocity, they may simply fly off into space. Over time, unless the atmosphere is constantly being renewed (from volcanic eruptions, etc.), the planet will become a bare rock.
Not all gases disperse at the same rate, mind you. A mixture of gases tends to exist at a common temperature. And temperature is a measure of kinetic energy, a product of both mass and velocity. In other words, light atoms and molecules move more quickly, and massive atoms and molecules move more slowly. Planets with low escape velocity can only retain heavy, slow moving molecules. Planets with high escape velocity can retain lighter, faster atoms and molecules. This is why large planets can have atmospheres composed of the lightest elements (hydrogen, helium), while small planets and moons have no atmosphere or are limited to heavier molecules (like hydrocarbons).
Fortunately, the Earth is massive enough that it loses its primary atmospheric gases (nitrogen and oxygen) very slowly, and any small losses can be replaced by outgassing from the surface. However, smaller, faster atoms and molecules like hydrogen and helium still escape.
Mars, on the other hand, is far lighter than the earth and cannot retain an atmosphere nearly as well. Mars also has no magnetic field or ozone layer, so the atmosphere is subject to high-energy solar radiation. This radiation both adds heat and breaks molecules apart, speeding them up and "helping" them escape the gravity well. Over time, it's likely that whatever atmosphere Mars had created during its volcanic period simply dispersed.
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Mars's biggest problem is gravity.
earth:mars != venus:earth
Okay Earth has ~ 100 times as much atmosphere as mars and loses less to space because of a higher escape velocity.
But Venus has a lower escape velocity than Earth, higher atmospheric temperatures and ~ 100 times as much atmosphere.
Venus must be outgassing massive quantities of CO2 to keep the atmosphere it has. Maybe we should look at restarting some Martian volcanoes.
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Nowadays liquid water cannot exist on Mars surface, and the bigger mistery is why Mars lost it's magnetic field.
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This hapenned supposedly when Mars had an active nucleus that generated a magnetic field, protecting the atmosphere from solar winds.
Nowadays liquid water cannot exist on Mars surface, and the bigger mistery is why Mars lost it's magnetic field.
It lost its magnetic field as the core cooled. The fluid movement of a metallic core is what generates Earth's magnetic field.
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Several reasons:
Size - Mars is just smaller than Earth, and even the Earth's core is cooling down.
No large moon - Earth's moon causes tidal forces in both bodies. This causes heat, although the moon's small size allowed its core to cool like Mars. Mars' small moons don't have the same effect and have not always been there (they are likely captured asteroids).
Farther from the Sun - the same tidal forces that a moon would impart, the Sun does as well. But less of it, as Mars is farther away.
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According to this [nasa.gov] article:
Earth's global magnetic field comes from an active dynamo -- that is, circulating currents at the planet's liquid metallic core. A similar dynamo once churned inside Mars, but for reasons unknown it stopped working four billion years ago.
Given that the Solar System has an estimated age of 4.6 billion years, Mars dynamo stopped very early, thus the reasons you listed aren't en
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IANA Rocket Scientist, but the Earth-Moon system also has a large angular momentum, presumably because of the large-body impact that formed the moon in the first place. This imparted a lot of spin and an infusion of core material to the young Earth that may have kept the dynamo going longer.
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Liquid water can be metastable at close to current orbital parameters (Mars' obliquity - the tilt of its orbital axis, varies significantly).
This was investigated by Hecht (2002): doi:10.1006/icar.2001.6794.
Abstract:
A simple model of local heat transport on Mars demonstrates that transient melting of ice may occur in depressions and gullies nearly anywhere on the planet where thin ice is illuminated by normal-incidence insolation. An experiment has been performed to confirm the model of evaporation rate at
Re:Where did it go? (Score:4, Interesting)
Ok, I'll bite.
Someone else pointed out this site, I'll post the link and pull some references from it:
http://science.nasa.gov/headlines/y2001/ast31jan_1.htm [nasa.gov]
Where did it go?
"New evidence from NASA's Mars Global Surveyor (MGS) spacecraft supports a long-held suspicion that much of the Red Planet's atmosphere was simply blown away -- by the solar wind."
So... according to NASA, Mars has been screwed for about 4 billion years:
"How do scientists know when the dynamo turned off? "Mars has been kind to us," explains Mitchell. "There are two large impact basins, Hellas and Argyre, about four billion years old that are demagnetized. If the dynamo was still operating when those impact features formed, the crust would have re-magnetized as they cooled. The dynamo must have stopped before then.""
According to the following link, life started on earth 3.8 billion years ago:
http://en.wikipedia.org/wiki/Timeline_of_evolution [wikipedia.org]
According to the following link our solar system is about 4.6 billion years old:
http://www.universetoday.com/guide-to-space/the-solar-system/how-old-is-the-solar-system/ [universetoday.com]
So... this gives Mars approximately 600 million years to come up with "some" form of life before its magnetosphere stopped working (because after that, the environment probably became very inhospitable). Considering it took earth 2.2 billion years to create life... we are gambling that Mars had life sooner than Earth?
Would it even be possible for a planet to have life on it within 500 million years of its creation? From what I understand, Earth was awfully uninhabitable to life in its first billion years (fire and brimstone kinda stuff, Venus like). Why would Mars be any different?
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According to the following link, life started on earth 3.8 billion years ago:
http://en.wikipedia.org/wiki/Timeline_of_evolution [wikipedia.org]
According to the following link our solar system is about 4.6 billion years old:
http://www.universetoday.com/guide-to-space/the-solar-system/how-old-is-the-solar-system/ [universetoday.com]
So... this gives Mars approximately 600 million years to come up with "some" form of life before its magnetosphere stopped working (because after that, the environment probably became very inhospitable). Considering it took earth 2.2 billion years to create life...
By my math, 4.6e9 - 3.2e9 = 0.8 billion years for life to appear on Earth.
we are gambling that Mars had life sooner than Earth?
Would it even be possible for a planet to have life on it within 500 million years of its creation? From what I understand, Earth was awfully uninhabitable to life in its first billion years (fire and brimstone kinda stuff, Venus like). Why would Mars be any different?
First, the Moon was formed 4.5e9 years ago; that event presumably reheated the Earth's crust, so it's more accurate to say that life took 0.7e9 years to appear. Also, since Mars is much smaller than the Earth, it would cool more quickly, reaching temperature conducive to life faster than the Earth. Combining those two fact, 600 million years seems quite reasonable.
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World: Really? Cool.
NASA: We have found ice on Mars! There is water on Mars!
World: Alright cool, thanks for the info.
NASA: We have found gullylike features on Mars that really proves the past existance of water!
World: Alright, we fucking get it, there was once water on Mars. Jeez, what do you want? Acknowledgement? Everybody, these guys found out that there was once water on Mars. Now either let us know when you've found th
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Since they get modded into oblivion hardly anyone is going to read it. But if you take the time to make a decent post instead, you'll probably get modded up for it. For an attention whore that should be fairly appealing.
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It is like Sharpe's Rifles (Score:2)
wohoo! (Score:3, Funny)
didn't know global warming's reach had extended to Mars.
Re: Mars Gullies Show Water Once Flowed (Score:2, Interesting)
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Would be excited to hear if underground water is found. The ice caps probably don't have the volume to fill what potentially could have been an Earth-ish looking planet.
They wouldn't need to. Mars has only about a third of the surface area of Earth. Which makes for a nice coincidence as we both have roughly the same available landmass!
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Uh, no, not if the ice caps melted and created anything resembling an ocean on Mars. If water flowed on Mars again they would no longer have roughly the same available landmass.
Hence "have" and not "will have if *".
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What about extremely large debris-covered glaciers? Would that do the trick for you?
The SHARAD instrument (really cool, 15Mhz radar) has shown conclusive evidence of ice cores in features called lobate debris aprons. These debris-covered features have probably been stable for ~100 Ma.
http://www.sciencemag.org/cgi/content/abstract/322/5905/1235 [sciencemag.org]
abstract: Lobate features abutting massifs and escarpments in the middle latitudes of Mars have been recognized in images for decades, but their true nature has been c
Re:Yawn (Score:5, Insightful)
Haven't they reported this a dozen times over the last decade? ...
For some reason, every time there's an incremental advance in understanding the environment of Mars, in the process of turning the results from science into news reports, the actual science gets simplified and simplified until the net result seems to be a headline of "Water found on Mars."
There's a lot more to the real science, of course.
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I am waiting for the discovery of intelligent life on Earth. (There is some intelligent life on Slashdot, but I'm convinced that is from aliens breaking into the Intertubes via SETI@Home.)
Search for intelligence... [Re:Yawn] (Score:2)
I am waiting for the discovery of intelligent life on Earth.
Ah, but the search for intelligent life relies on searching radio and television signals!
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The main point of the Schon et al. article is on the timing of gully activity, not simply the presence of liquid water. We know from numerous morphological and mineralogical lines of evidence that Mars once had a more temperate climate, but that was > 3 billion years ago....
This study points to flowing water (however transient) during the last period of higher obliquity, about a million years ago. -- the blink of an eye in geologic time.
http://geology.gsapubs.org/cgi/content/full/37/3/207 [gsapubs.org]
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What the heck does water on Mars have to do with Battling the Evil RIAA??? Get back to work, Ray!!! ;-)
What, are you kidding? We need some place to house these guys when the law catches up to them. Our existing prison infrastructure doesn't have that much room.
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I shudder at the thought of a new society being founded by those folks. We'd be handing them an entire planet.
At least they'd be doing less damage to ours from that distance.
NYCL (Score:5, Funny)
Hi NYCL,
the summary (TFS) should have been written as:
"Lest there be any doubt that Brown University's Planetary Geosciences Group graduates Samuel C. Schon, James W. Head, and Caleb I. Fassett, study authors, NASA Martian crater dating, really do 'get it' about the presence of water in recent Mars history, all such doubt should be removed by the paper his team just released (http://geology.gsapubs.org - March 2009, either slashdotted or slow). It shows the Martian gully system is craterless, possibly as young as 1.25 million years old (see bottom right of photo). In the paper lead study author Schon spells out, in the clearest possible terms so that there can be no misunderstanding, that at the extraordinary HiRISE (High Resolution Imaging Science Experiment) image taken by the Mars Reconnaissance Orbiter ...
Re:NYCL (Score:4, Informative)
Hi NYCL, the summary (TFS) should have been written as: "Lest there be any doubt that Brown University's Planetary Geosciences Group graduates Samuel C. Schon, James W. Head, and Caleb I. Fassett, study authors, NASA Martian crater dating, really do 'get it' about the presence of water in recent Mars history, all such doubt should be removed by the paper his team just released (http://geology.gsapubs.org - March 2009, either slashdotted or slow). It shows the Martian gully system is craterless, possibly as young as 1.25 million years old (see bottom right of photo). In the paper lead study author Schon spells out, in the clearest possible terms so that there can be no misunderstanding, that at the extraordinary HiRISE (High Resolution Imaging Science Experiment) image taken by the Mars Reconnaissance Orbiter ...
:)
(For those of you who don't know what Troll8901 is getting at... he's mocking me, referring to this [slashdot.org])
Re: (Score:1)
Credit goes to wwwillem (253720) for the idea in his comment [slashdot.org] (March 03, 2009):
"Lest there be any doubt ... the toxic effect [...] have had on the judicial process ... the decision-making process ... in the clearest possible terms ... can be no misunderstanding ... the extraordinary 2-day settlement ... who has corporate, decision-making, power ... with any limits or range attached to it", etc.
We can put these words into a template!
Several Hundred Thousand Years? (Score:2)
More like 70 to 80 thousand. The surviving Hain probably would have traveled to our world to escape the cataclysm there on the fourth planet.
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I was going to say, "damn, we *just* missed it!"
Now I Have Seen It All (Score:2)
I guess NewYorkCountryLawyer has finally fallen completely under Slashdot's influence. He is now discussing water on Mars. This lawyer has become a certifiable geek.
I, for one, welcome you to our ranks.
And once again, I must also thank you for helping Free People everywhere battle the wickedness of the recording industry.
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NYCL, to my mind, qualifies as as a proto-Geek or semi-Geek at this point. Full Geekdom is not conferred until he finds a way to tie the alleged presence of water on Mars to his particular area of expertise.
For instance, some of us slashdotters are concerned about Martian water rights issues. NYCL could do us a marvelously geeky service by explaining the implications that Martian water rights will have for further NASA explorations and possible settlements. For instance, in what jurisdiction will conflict
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What about "Biologically Reversible Exploration"???
"The international Committee on Space Research (COSPAR) has established a "planetary protection" policy that involves not contaminating other worlds in a way that would jeopardize the conduct of future scientific investigations. As a signatory to the 1967 Outer Space Treaty, the United States is required by article IX to avoid "harmful contamination" of the other worlds of the Solar System. However, further revisions to the policy are needed...
The spacecraf
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True enough, and we should all expect that shortly, I suppose:
NYCL announces "No Copyrights on Mars"
In an effort to keep our solar system free of the excesses of the *AAs, Slashdot's own NYCL has recently lobbied Congress to pass its controversial "No Copyrights on Mars" (hereafter known as NCoM) bill. The president is expected to sign it into law within the next week. The NCoM provides protection for extraplanetary missions from lawsuits over digital materials while the astronauts are in space --
Cat in the roof (Score:2)
Sure it was not just the MAFIAA digging a hole...? (Score:2)
After all, the gullies were probably caused by "sue-one's-own-customers", cease&desist letters, subpoenas and other dry phenomena.
And the planet's red color is presumably from gigatons of decaying hardware generations rendered obsolete by ever-changing DRMs that brought down the Martian culture and civilization...
Water once flowed on mars... (Score:1)
wait a second, don't we already know that water was there. if it was there don't you think it was moving!!
Mars cooled (Score:2)