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Hellish Vision of Mars Unveiled
mvladivostok writes "Yahoo has an interesting little article in which it is suggested that Mars may not have once been a warm, wet and hospitable planet that somehow lost its atmosphere; instead, it is suggested that the dead planet was occasionally bombarded by melting meteorites that carved out its distinctive craters and valleys. An interesting read."
I am reading the 3rd volume of the excellent Mars trilogy of Kim Stanley Robinson: Red Mars, Green Mars and Blue Mars. In the story, those that are for the terraforming of Mars are the Greens and those against are the Reds.
I'll do it for cheesy poofs.
Nope! One theory goes that this is the same way that Earth got its water. (Orginal water was boiled away in early hot days when there was no atmosphere). The only problem with such theories is the isotope ratios of the water found in comets versus Earth. Search around a bit, you'll find more. One Two Three
Discover ran a story about someone who thinks Earth is still being bombarded by smaller bodies like this -- it was a couple of years ago I think. He's regarded as a flake, but he's at least on the edges of the real scientific community.
Regardless of maturity, in order for deep riverbeds such as appear on Mars to form you need a lot of water flowing for a fairly long time (years, not days).
Ever hear of the Lake Missoula ice-age floods? Water from a penned-in glacial lake burst through ice dams several times, ripping up the northwestern US in colossal floods. The entire surface of eastern Washington state was formed through quite sudden flooding:
Imagine ripples like in a streambed, only on the scale of hillsides. It doesn't necessarily take years.
Not that I'm buying this idea, but it's not as outrageous as all that.
"Fundamentalism" isn't about divine morality. It's about human authority.
This article is not quite clear in its interpretation of the research- the main source of the water would be ice on the planet, not on the meteorites.
For a better article head to the bbc website http://news.bbc.co.uk/1/hi/sci/tech/2546923.stm
The gist is that large impacts by asteroids or other bodies would heat water in subsurface ice, leading to massive flash flooding. They are speculating that very large impacts would have planet wide effects for short periods of time. This isn't that contrived, as there is evidence around small martian craters that suggest that ice has been melted leading to mud flows around the crater rim.
However, this doesn't explain why the northern hemisphere of mars looks like a dessicated ocean floor, which suggests a relatively long period of warm conditions.
BBC version
:).
a little nicer one the eyes in my opinion and has a picture too
"Wait a minute, isn't that the same as earth and the rest of the planets? I mean, mercury doesn't get this kind of attention."
No, what they're saying is this: Earth has two basic kinds of geo-physical features, those caused by extraterrestrial effects such as meteor impacts, and those caused by terrestrial effects such as techtonic plate shifting or magma bursts as lava through volcanos.
The point here is that mainstream thought suggests that the craters/valleys were caused by water pooling/travel akin to that of earth, whereas this new model suggests that the craters/valleys were exclusively caused by the impacts. In such a system, you explain why the tributaries that are normally associated with water bodies aren't present on mars, along with several other problems.
"Stumble before you crawl"
Um... check your facts. The atmospheric pressure on Mars (a direct effect of the density of the atmosphere) is approximately 1/100th of the pressure on Earth. So actually, Earth has a FAR thicker atmosphere.
"Mars has a denser atmosphere than Earth. While spaceborne objects would be a nice explanation for these formations- if a bit uncreative- it forgets the element of the atmosphere, which is the only reason Earth doesn't get pounded into rubble every meteor shower."
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Interesting. There's only one problem. You're incorrect. Mars' surface density is pretty close to the Earth's at 35000 meters. Roughly 0.015 kg/m3. Earth's at the surface (sea level) is approximately 1.2 kg/m3.
The martian figure is from Nasa (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat
and the Earth figure is from any standard atmosphere chart available on the web. I don't have my texts with me so I just grabbed the one off USA Today's site. (http://www.usatoday.com/weather/wstdatmo.htm)
Even if it were, Mars' atmosphere is much thinner and has a much lower pressure than Earth's. Meteors entering Mars' atmosphere stand a much better chance at reaching the surface than they would on Earth. Combined with the ambient atmospheric temperature of the planet's atmosphere, even the density wouldn't prevent this.
The equation of state for an ideal gas shows this relationship. (http://www.grc.nasa.gov/WWW/K-12/airplane/eqstat
"Admittedly, it's possible that the atmosphere was carried in a solid-frozen format on said bombardial objects, but that's even more of a stretch."
I have one word: "Comets" They are believed to be responsible for a large amount of the atmospheres of Venus, Earth, and Mars.
Anyway, just my $.02..
Daniel
Aerospace Engineering major
University of Central Florida - Orlando
Planetes
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Gravity per se has nothing to do with precipitation. However, if it affects the small dust particles then it can also affect the precipitation.
For instance on Earth the formation of water droplets would be practically impossible without small dust and ice particles in the atmosphere.
The owls are not what they seem