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 Post subject: Ancient streambed located...on FUCKING MARS PostPosted: 2012-09-28 09:13am
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NASA wrote:
PASADENA, Calif. -- NASA's Curiosity rover mission has found evidence a stream once ran vigorously across the area on Mars where the rover is driving. There is earlier evidence for the presence of water on Mars, but this evidence -- images of rocks containing ancient streambed gravels -- is the first of its kind.

Scientists are studying the images of stones cemented into a layer of conglomerate rock. The sizes and shapes of stones offer clues to the speed and distance of a long-ago stream's flow.

"From the size of gravels it carried, we can interpret the water was moving about 3 feet per second, with a depth somewhere between ankle and hip deep," said Curiosity science co-investigator William Dietrich of the University of California, Berkeley. "Plenty of papers have been written about channels on Mars with many different hypotheses about the flows in them. This is the first time we're actually seeing water-transported gravel on Mars. This is a transition from speculation about the size of streambed material to direct observation of it."

The finding site lies between the north rim of Gale Crater and the base of Mount Sharp, a mountain inside the crater. Earlier imaging of the region from Mars orbit allows for additional interpretation of the gravel-bearing conglomerate. The imagery shows an alluvial fan of material washed down from the rim, streaked by many apparent channels, sitting uphill of the new finds.

The rounded shape of some stones in the conglomerate indicates long-distance transport from above the rim, where a channel named Peace Vallis feeds into the alluvial fan. The abundance of channels in the fan between the rim and conglomerate suggests flows continued or repeated over a long time, not just once or for a few years.

The discovery comes from examining two outcrops, called "Hottah" and "Link," with the telephoto capability of Curiosity's mast camera during the first 40 days after landing. Those observations followed up on earlier hints from another outcrop, which was exposed by thruster exhaust as Curiosity, the Mars Science Laboratory Project's rover, touched down.

"Hottah looks like someone jack-hammered up a slab of city sidewalk, but it's really a tilted block of an ancient streambed," said Mars Science Laboratory Project Scientist John Grotzinger of the California Institute of Technology in Pasadena.

The gravels in conglomerates at both outcrops range in size from a grain of sand to a golf ball. Some are angular, but many are rounded.

"The shapes tell you they were transported and the sizes tell you they couldn't be transported by wind. They were transported by water flow," said Curiosity science co-investigator Rebecca Williams of the Planetary Science Institute in Tucson, Ariz.

The science team may use Curiosity to learn the elemental composition of the material, which holds the conglomerate together, revealing more characteristics of the wet environment that formed these deposits. The stones in the conglomerate provide a sampling from above the crater rim, so the team may also examine several of them to learn about broader regional geology.

The slope of Mount Sharp in Gale Crater remains the rover's main destination. Clay and sulfate minerals detected there from orbit can be good preservers of carbon-based organic chemicals that are potential ingredients for life.

"A long-flowing stream can be a habitable environment," said Grotzinger. "It is not our top choice as an environment for preservation of organics, though. We're still going to Mount Sharp, but this is insurance that we have already found our first potentially habitable environment."

During the two-year prime mission of the Mars Science Laboratory, researchers will use Curiosity's 10 instruments to investigate whether areas in Gale Crater have ever offered environmental conditions favorable for microbial life.

NASA's Jet Propulsion Laboratory, a division of Caltech, built Curiosity and manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington.

For more about Curiosity, visit: http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl .

You can follow the mission on Facebook and Twitter at: http://www.facebook.com/marscuriosity and http://www.twitter.com/marscuriosity .


Guy Webster / D.C. Agle 818-354-5011
Jet Propulsion Laboratory, Pasadena,Calif.
guy.webster@jpl.nasa.gov / agle@jpl.nasa.gov

Dwayne Brown 202-358-1726
NASA Headquarters, Washington
dwayne.c.brown@nasa.gov


Really,the title says it all. There once was flowing water on Mars.

Can I get a fuck yeah for science? Is anybody else excited about this find?



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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-09-28 10:44am
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Isn't it generally accepted that Mars had a life sustaining atmosphere sometime between 2-4 billion years ago?



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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-09-28 10:52am
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Well, the point is that now we have evidence...



The Greeks are somewhat undependable allies when it comes to keeping promises. I am sure the fleet of 300 galleys they promised will turn out to be 3 guys in an oversized cooking pot. (Thanas, revealing the plans for German world domination)

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-09-28 11:54am
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Fuck yeah! I caught this on the radio at the pub an hour ago. THe rest of us astronomers all stopped, listened, then started high-fiving each other.



"I could be bounded in a nutshell and count myself a king of infinite space, were it not that I have bad dreams" - Hamlet

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-09-28 04:02pm
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So, for almost a century, science fiction writers have been waxing poetic about how discovering alien life would be a social game changer on Earth. But of course, it's likely that the first alien "life" we run into is going to be something like Pre-Cambrian bacteria. So, what sort of social effect, if any, would it have if Curiosity discovers definitive evidence of extinct microbial life on Mars? My guess is not much - but it would significantly add, along with the recent explosion of exo-planet discoveries, to the case that the Universe is teeming with life.

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-09-28 04:13pm
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Channel72 wrote:
So, for almost a century, science fiction writers have been waxing poetic about how discovering alien life would be a social game changer on Earth. But of course, it's likely that the first alien "life" we run into is going to be something like Pre-Cambrian bacteria. So, what sort of social effect, if any, would it have if Curiosity discovers definitive evidence of extinct microbial life on Mars? My guess is not much - but it would significantly add, along with the recent explosion of exo-planet discoveries, to the case that the Universe is teeming with life.


Most people think that our first contact with aliens will be a ship full of guys with bowl haircuts and pointed ears, or a deliberate radio transmission aimed straight at the Earth. Truthfully it'll probably be bacteria or radio leakage. It won't be nearly as dramatic as people are hoping for. Honestly I think that's fine, because too much drama would lead to panic. It'll be us intellectuals who would be going apeshit when that happens.



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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-11 12:00pm
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Yeah - truthfully, I think it's very, very likely that microbial extraterrestrial life will be discovered within our lifetime, probably on Mars. The conditions on Earth and Mars are similar enough that water existed on both planets, and bacteria has existed on Earth since the Archaen eon (~3 billion years ago). It's likely that similar prokaryotic life existed on Mars, especially given the (admittedly contraversial) evidence found on the ALH84001 meteorite. Given the abundance of bacteria that has existed on Earth for most of it's existence, I'd be surprised if something similar didn't happen on Mars.

The interesting thing will be coming up with a geological timeline for Mars, and trying to identify why Mars never experienced the transition to multi-cellular organisms. There was obviously never a Martian "Cambrian explosion", and it will be nice to finally have another planet with a history of life to use as a comparison to Earth.

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-11 12:21pm
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Mars was too small. It had a smaller magnetic field which meant more of it's air could be blown away by solar winds. It just wasn't massive enough to hang on to enough air for advanced life to form.



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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-11 09:11pm
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Borgholio wrote:
Mars was too small. It had a smaller magnetic field which meant more of it's air could be blown away by solar winds. It just wasn't massive enough to hang on to enough air for advanced life to form.


The "not massive enough" part is the important factor with respect to retaining an atmosphere. Unless someone has found one in the last six months or so, Mars doesn't have a magnetic field. It being smaller also meant less radioactive rocks inside to keep it warm over billion of years.



"I could be bounded in a nutshell and count myself a king of infinite space, were it not that I have bad dreams" - Hamlet

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-12 01:10am
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Eternal_Freedom wrote:
Borgholio wrote:
Mars was too small. It had a smaller magnetic field which meant more of it's air could be blown away by solar winds. It just wasn't massive enough to hang on to enough air for advanced life to form.


The "not massive enough" part is the important factor with respect to retaining an atmosphere. Unless someone has found one in the last six months or so, Mars doesn't have a magnetic field. It being smaller also meant less radioactive rocks inside to keep it warm over billion of years.


I thought it was a combination of the mass and the magnetic field?

Space.com wrote:
One caveat is the loss of neutral atoms, which go largely undetected by current space instruments. Mars is likely losing many more neutral atoms than its counterparts. This is because Mars is smaller and thus has a weaker gravitational hold on its atmosphere. Certain chemical interactions can give neutral oxygen atoms enough speed to escape Mars' gravity.

<snip>

We don't have a direct record of the sun's history, but astronomers can study other stars that are similar to our sun at an earlier age. These young sun-like stars appear to be more active, with possibly stronger winds and more ultraviolet light emission. Therefore, it's likely that our sun was stripping planets of their atmospheres at a faster rate in the past.

Luhmann argues that the Earth's magnetic field may have been a better shield against a more active sun. In comparison, the loss rates on defenseless Venus and Mars could have gone up by a factor of a thousand or more, relative to Earth.

Strangeway isn't convinced.

"I'm very cautious," he said. "I don't know enough to say how the young Sun would interact with a planetary magnetic field."



Are you accusing me of not having a viable magnetic field? - Masaq' Hub, Look to Windward

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-12 10:28am
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It's the gravity more than anything else that keeps an atmosphere. For instance, look at Venus, that has no magnetic field and yet it retains a much thicker atmosphere than Earth does.



"I could be bounded in a nutshell and count myself a king of infinite space, were it not that I have bad dreams" - Hamlet

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-12 07:03pm
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Channel72 wrote:
Yeah - truthfully, I think it's very, very likely that microbial extraterrestrial life will be discovered within our lifetime, probably on Mars. The conditions on Earth and Mars are similar enough that water existed on both planets, and bacteria has existed on Earth since the Archaen eon (~3 billion years ago). It's likely that similar prokaryotic life existed on Mars, especially given the (admittedly contraversial) evidence found on the ALH84001 meteorite. Given the abundance of bacteria that has existed on Earth for most of it's existence, I'd be surprised if something similar didn't happen on Mars.

The interesting thing will be coming up with a geological timeline for Mars, and trying to identify why Mars never experienced the transition to multi-cellular organisms. There was obviously never a Martian "Cambrian explosion", and it will be nice to finally have another planet with a history of life to use as a comparison to Earth.


I'd settle for just seeing Humans land on Mars in my lifetime. Discovering Life would be a nice bonus though!

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-13 12:11am
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Eternal_Freedom wrote:
It's the gravity more than anything else that keeps an atmosphere. For instance, look at Venus, that has no magnetic field and yet it retains a much thicker atmosphere than Earth does.


But isn't that thought to be the result of the oceans of Venus boiling off plus massive volcanic eruptions in the past? I'm pretty sure it is loosing its atmosphere, just very slowly. If Mars started with less it might have simply lost it sooner. Certainly you need to have a minimal amount of gravity to even think about holding an atmosphere, but it takes a magnetic field to avoid the worst of losses to solar wind. Lighter gases are always going to want to float to the top of an atmosphere and they'll be vulnerable to loss.



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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-13 11:24am
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Sea Skimmer wrote:
Eternal_Freedom wrote:
It's the gravity more than anything else that keeps an atmosphere. For instance, look at Venus, that has no magnetic field and yet it retains a much thicker atmosphere than Earth does.


But isn't that thought to be the result of the oceans of Venus boiling off plus massive volcanic eruptions in the past? I'm pretty sure it is loosing its atmosphere, just very slowly. If Mars started with less it might have simply lost it sooner. Certainly you need to have a minimal amount of gravity to even think about holding an atmosphere, but it takes a magnetic field to avoid the worst of losses to solar wind. Lighter gases are always going to want to float to the top of an atmosphere and they'll be vulnerable to loss.


Yeah, Venus is losing it's atmosphere, so is Earth, just very slowly. yes, a magnetic field helps, but if there isn't enough gravity it won't be enough to hold an atmosphere on its own.



"I could be bounded in a nutshell and count myself a king of infinite space, were it not that I have bad dreams" - Hamlet

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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-13 01:25pm
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Look at it from an air molecule's point of view.

At room temperature, air molecules travel at an average speed of about 500 m/s. Doubling the temperature increases this by a factor of 1.4, halving it drops it to about 70% of its former value. I could explain the physics, but you can look it up too: google the words 'rms velocity air molecule.'

That's an average speed. Some molecules are, at any given moment, moving much slower. Others are moving much much faster, a few at something like double the 'root mean square' average speed. So the fastest, zippiest percentage of the air molecules might be moving at something like 1000 m/s at room temperature. On Venus it might be more like 1200 or 1300 m/s (heavier molecules are slower, and carbon dioxide is heavier than air, but Venus is about three times hotter).

Now, for air molecules to escape the atmosphere, they have to reach escape velocity, just like anything else. Escape velocity on Earth is about 11200 m/s. On Venus it's 10300 m/s.

You see the problem. Even though these molecules are ricocheting around like drunk-driving bullets, they're nowhere near fast enough to get away. It would take a ridiculously unlikely combination of events to give any air molecule in the Earth's atmosphere enough kinetic energy to get away. Even solar wind won't do it much, not to speak of.


Now try the same calculation on Mars- escape velocity 5000 m/s. This makes things easier for escaping molecules; there's a lot less kinetic energy to gain. Both Mars and Venus lack a magnetic field to shield them from solar wind and cosmic ray particles, sure- but Venus's gravity means that even an air molecule that gets kicked by a proton flying out of the sun probably isn't getting away. On Mars, the escape is a lot easier, so it proceeds at a higher rate.



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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-13 02:33pm
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Simon_Jester wrote:
Look at it from an air molecule's point of view.

At room temperature, air molecules travel at an average speed of about 500 m/s. Doubling the temperature increases this by a factor of 1.4, halving it drops it to about 70% of its former value. I could explain the physics, but you can look it up too: google the words 'rms velocity air molecule.'

That's an average speed. Some molecules are, at any given moment, moving much slower. Others are moving much much faster, a few at something like double the 'root mean square' average speed. So the fastest, zippiest percentage of the air molecules might be moving at something like 1000 m/s at room temperature. On Venus it might be more like 1200 or 1300 m/s (heavier molecules are slower, and carbon dioxide is heavier than air, but Venus is about three times hotter).

Now, for air molecules to escape the atmosphere, they have to reach escape velocity, just like anything else. Escape velocity on Earth is about 11200 m/s. On Venus it's 10300 m/s.

You see the problem. Even though these molecules are ricocheting around like drunk-driving bullets, they're nowhere near fast enough to get away. It would take a ridiculously unlikely combination of events to give any air molecule in the Earth's atmosphere enough kinetic energy to get away. Even solar wind won't do it much, not to speak of.


Now try the same calculation on Mars- escape velocity 5000 m/s. This makes things easier for escaping molecules; there's a lot less kinetic energy to gain. Both Mars and Venus lack a magnetic field to shield them from solar wind and cosmic ray particles, sure- but Venus's gravity means that even an air molecule that gets kicked by a proton flying out of the sun probably isn't getting away. On Mars, the escape is a lot easier, so it proceeds at a higher rate.

Indeed. Mars is about 10% the mass of Earth (which means it only has twice the mass of Mercury, and a mere ten times the mass of the Moon.) So the gas molecules have a much harder time being knocked off the top of the atmosphere. On top of that, Earth and Venus are both geologically active worlds, where enough volatiles are being outgassed from their interiors that losses from various processes don't matter so much.

Quite unlike Mars, which is geologically dead (okay, not totally dead. There are lava flows on the great shield volcanoes that are only a few tens of millions of years old, and some that may have even possibly occurred within the last ten. And it does outgas enough to replenish what little methane is present, and it may have tectonically-driven quakes . . . however, the interior was only liquid enough to support an Earth-like magnetic field for only the first half-billion years of Mars' existence, and the vast majority of the planet's geological activity was over and done with between one to two billion years ago.) Mars doesn't have enough free volatiles left to replenish atmosphere lost through solar wind erosion and chemical weathering of the surface.




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 Post subject: Re: Ancient streambed located...on FUCKING MARS PostPosted: 2012-10-17 06:25am
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Sea Skimmer wrote:
If Mars started with less it might have simply lost it sooner. Certainly you need to have a minimal amount of gravity to even think about holding an atmosphere, but it takes a magnetic field to avoid the worst of losses to solar wind. Lighter gases are always going to want to float to the top of an atmosphere and they'll be vulnerable to loss.

Nope. Or at least if you need minimal amount of gravity, it's much smaller than Mars' - even our own Moon is capable of holding an atmosphere. Heck, Titan, moon of Saturn, holds atmosphere with surface pressure 1.5 of Earth's, not to mention Mars, while having gravity considerable smaller than either :wink:

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