| Topic: |
Religions > Atheism |
| User: |
"johac" |
| Date: |
22 Feb 2007 12:50:50 AM |
| Object: |
Titan Sheds Light on Earth's Hazy Past |
Titan gives clues as to how early life may have sread on Earth.
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Titan Sheds Light on Earth's Hazy Past
Saturn's moon Titan is notorious for its shroud of organic haze. Recent
experiments suggest that early Earth may have been covered by a similar
haze. The discovery could shed light on how life spread around the globe.
NASA - Saturn's giant moon Titan is enveloped by a thick layer of
organic haze. Although Titan's haze layer is unique in the present-day
solar system, a recent experiment by researchers at the University of
Colorado at Boulder suggests that, billions of years ago, Earth was also
covered by organic haze. The finding not only sheds light on our
planet's early atmosphere, but could also help explain how life spread
around the globe.
Titan's haze is the result of methane in the moon's atmosphere. Hundreds
of miles above its surface, ultraviolet sunlight bombards methane gas
molecules with high-energy photons, breaking them apart. This
destructive process, known as photolysis, leaves behind free hydrogen
and small hydrocarbon fragments (CH2). The fragments are like building
blocks: they can combine with each other to form larger, chain-like
molecules, such as ethane, propane and acetylene.
Methane in Titan's atmosphere is a transparent gas, but the larger
molecules condense into aerosol particles, which form the haze. Computer
modeling studies by Alex Pavlov, currently a professor of planetary
science at the University of Arizona at Tucson, predicted that if early
Earth also produced methane, then perhaps it too was covered in haze.
But early Earth's atmosphere also had a component that Titan's
atmosphere lacks: carbon dioxide (CO2). Margaret Tolbert, a professor of
chemistry at the University of Colorado in Boulder, and her graduate
student Melissa Trainer set up a lab experiment to test Pavlov's model,
to see if they could produce haze in an "atmosphere" simulating early
Earth's.
Initially, they were skeptical. We thought "you would get these oxygen
atoms coming off of the CO2," which would react with the CH2 fragments
from the methane and prevent longer hydrocarbon chains from forming,
says Trainer. "And so you wouldn't get big enough molecules to condense
into particles." No particles, no haze. But "that's not what we found,"
says Tolbert. "Quite the contrary."
Their initial experiment replicated what takes place in Titan's
atmosphere. They put methane gas in a sealed container (along with
nitrogen, a major component of Titan's atmosphere, as it was of early
Earth's), and irradiated the contents with very-short-wavelength,
high-energy UV radiation. The researchers chose a radiation source that
included a wavelength of 121 nm, which is powerful enough to crack apart
methane molecules. "The sun's spectrum has a peak emission right at that
wavelength," Tolbert explains. Under these conditions, a haze did form,
just as it does on Titan.
They used a novel instrument known as an aerosol mass spectrometer (AMS)
to catalogue the microscopic haze particles. Using the AMS allowed them
to obtain results for particles "on the fly." Past experiments had to be
run for hours, days, or even weeks, long enough for the particles to
form a coating on the inside of the container, which was then scraped
off and analyzed. But the AMS let Trainer and Tolbert assess the aerosol
particles while they were still airborne in the container. "If we turn
on our UV lamp, and there are gases flowing, within minutes we can get
an aerosol mass spectrum telling us what the particles are made of,"
Tolbert says.
Then they ran the experiment again, adding increasing ratio of CO2 to
the methane, to simulate early Earth. And they still got haze. In fact,
says Tolbert, "when you have CO2 and methane in roughly equal amounts,
you actually get even more haze than if you just had methane alone." As
they increased the amount of CO2 further, the haze formation tapered
off, "but we always saw some level of haze produced," Tolbert says.
They're still trying to understand what happened. "We can't fully
explain it," Tolbert admits.
But they have a hypothesis. When only methane is present, some of the
hydrogen atoms that get split off from methane recombine with the CH2
fragments to reform methane. That limits the number of CH2 fragments
available to bind together into longer-chain molecules. But when carbon
dioxide is also present, it is split into carbon monoxide and oxygen
atoms. The researchers suspect that this oxygen combines with hydrogen
from the methane to make water. That leaves less hydrogen available to
re-attach to the CH2 molecules, so more of the CH2 molecules bond to
each other. The result: more long-chain molecules, and more haze.
If they're right, their findings could have important implications for
the spread of life on Earth. When life first emerged, it most likely was
restricted to isolated enclaves, because it was dependent on nutrients
that were highly localized. But some of these early organisms were
methanogens, which were belching out methane that eventually drifted up
to the upper atmosphere. There this methane, along with CO2, was
bombarded by high-energy UV radiation from the sun. Long hydrocarbon
chains started to form, and the longer the chains got, the more readily
they condensed into aerosol particles. Eventually, the Earth was covered
by a haze of these particles, which rained down onto the surface.
In this process, CO2 was important for a second reason. Although much of
the oxygen liberated from the carbon dioxide combined with hydrogen to
form water - that's the process that let the haze form - some of it
attached to the growing hydrocarbon chains. Oxygenated hydrocarbon
chains are an energy-rich food source, and when these molecules began to
rain down onto Earth, that food source became available planet-wide.
"Life could be sustained in every little puddle on Earth," says Tolbert.
If they're right. Being right, however, requires that the atmosphere of
early Earth was not brimming with oxygen, as it is today. Most
researchers believe that the rise of oxygen in Earth's atmosphere didn't
come until some 2 billion years after the origin of life. But if early
Earth had an oxygen-rich atmosphere, haze formation could not have taken
place.
On the other hand, it's possible that some purely chemical process on
early Earth produced methane even before there were methanogens. There
clearly is an abiotic source for atmospheric methane on Titan, and
possibly on Mars as well. If that were the case, then haze chemistry,
and a nutrient-rich rain, could have been in place before life got
started, and the biosphere could have become a global phenomenon almost
as soon as it began. Indeed, haze particles could have played a role in
life's beginnings.
One way to sort this all out is to consult the rock record. Ancient
rocks contain evidence of chemical reactions that were taking place in
the atmosphere when the rocks formed. But this is tricky work. There are
only a handful of places on Earth where rocks can be found that date
back to life's earliest days. Over time these rocks have been
extensively altered by heat and pressure, so their chemical signatures
are degraded.
What's more, says Alex Pavlov, scientists have yet to establish what to
look for. "The systematic analysis of what signature to expect hasn't
been done so far." The first step, he says, is "to redo the experiment
which Maggie did and analyze the bulk composition of these aerosols,"
the relative proportions of carbon, hydrogen, oxygen and nitrogen. That
would give geologists a clearer idea of what type of chemical signature
they were seeking.
Meanwhile, another of Tolbert's graduate students, Langley DeWitt, is
conducting a follow-up experiment to test Tolbert and Trainer's
hypothesis about why haze forms in the presence of CO2. "If that model
is correct," Tolbert says, "adding hydrogen to the system should lead to
less haze." The jury is still out.
--
http://tinyurl.com/2lkmy6
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "stoney" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
07 Mar 2007 06:26:19 PM |
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On Wed, 21 Feb 2007 22:50:50 -0800, johac <jhachmann@sbcglobal.com>
wrote in alt.atheism
Titan gives clues as to how early life may have sread on Earth.
---
Titan Sheds Light on Earth's Hazy Past
Saturn's moon Titan is notorious for its shroud of organic haze. Recent
experiments suggest that early Earth may have been covered by a similar
haze. The discovery could shed light on how life spread around the globe.
Wild.
[]
--
Fundies and trolls are cordially invited to
shove a wooden cross up their arses and rotate
at a high rate of speed. I trust you'll
be 'blessed' with a plethora of splinters.
.
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| User: "johac" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
08 Mar 2007 12:28:54 AM |
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In article <o0muu25r11eiqdehtm2vaagpm543cggeq8@4ax.com>,
stoney <stoney@the.net> wrote:
On Wed, 21 Feb 2007 22:50:50 -0800, johac <jhachmann@sbcglobal.com>
wrote in alt.atheism
Titan gives clues as to how early life may have sread on Earth.
---
Titan Sheds Light on Earth's Hazy Past
Saturn's moon Titan is notorious for its shroud of organic haze. Recent
experiments suggest that early Earth may have been covered by a similar
haze. The discovery could shed light on how life spread around the globe.
Wild.
Science is much more interesting and useful than sitting around with a
two thousand year old book saying goddidit.
[]
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "stoney" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
12 Mar 2007 09:10:59 PM |
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On Wed, 07 Mar 2007 22:28:54 -0800, johac <jhachmann@sbcglobal.com>
wrote in alt.atheism
In article <o0muu25r11eiqdehtm2vaagpm543cggeq8@4ax.com>,
stoney <stoney@the.net> wrote:
On Wed, 21 Feb 2007 22:50:50 -0800, johac <jhachmann@sbcglobal.com>
wrote in alt.atheism
Titan gives clues as to how early life may have sread on Earth.
---
Titan Sheds Light on Earth's Hazy Past
Saturn's moon Titan is notorious for its shroud of organic haze. Recent
experiments suggest that early Earth may have been covered by a similar
haze. The discovery could shed light on how life spread around the globe.
Wild.
Science is much more interesting and useful than sitting around with a
two thousand year old book saying goddidit.
The former takes work, honest work. The latter simply drools copiously.
--
Fundies and trolls are cordially invited to
shove a wooden cross up their arses and rotate
at a high rate of speed. I trust you'll
be 'blessed' with a plethora of splinters.
.
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| User: "Uncle Clover" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
12 Mar 2007 10:20:04 PM |
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On Mon, 12 Mar 2007 18:10:59 -0800, stoney <stoney@the.net> wrote:
On Wed, 07 Mar 2007 22:28:54 -0800, johac <jhachmann@sbcglobal.com>
wrote in alt.atheism
In article <o0muu25r11eiqdehtm2vaagpm543cggeq8@4ax.com>,
stoney <stoney@the.net> wrote:
On Wed, 21 Feb 2007 22:50:50 -0800, johac <jhachmann@sbcglobal.com>
wrote in alt.atheism
Titan gives clues as to how early life may have sread on Earth.
---
Titan Sheds Light on Earth's Hazy Past
Saturn's moon Titan is notorious for its shroud of organic haze. Recent
experiments suggest that early Earth may have been covered by a similar
haze. The discovery could shed light on how life spread around the globe.
Wild.
Science is much more interesting and useful than sitting around with a
two thousand year old book saying goddidit.
The former takes work, honest work. The latter simply drools copiously.
Or in the case of plagiaristic monstrosities like Christianity,
copyously.
.
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| User: "Uncle Vic" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
22 Feb 2007 01:07:33 AM |
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One fine day in alt.atheism, johac <jhachmann@sbcglobal.com> bloodied us up
with this:
ASA - Saturn's giant moon Titan is enveloped by a thick layer of
organic haze. Although Titan's haze layer is unique in the present-day
solar system, a recent experiment by researchers at the University of
Colorado at Boulder suggests that, billions of years ago, Earth was also
covered by organic haze. The finding not only sheds light on our
planet's early atmosphere, but could also help explain how life spread
around the globe.
Duke will now claim this is how his fuzzygod initiated evolution. Arm
yourselves.
--
Uncle Vic
aa Atheist #2011
Supervisor, EAC Department of little adhesive-backed "L" shaped
chrome-plastic doo-dads to add feet to Jesus fish department.
Convicted by Earthquack. Plonked by Fester.
Member Duke Spanking Club.
.
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| User: "johac" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
22 Feb 2007 06:13:46 PM |
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In article <Xns98DEEB4D06562vicman@66.250.146.128>,
Uncle Vic <address@withheld.com> wrote:
One fine day in alt.atheism, johac <jhachmann@sbcglobal.com> bloodied us up
with this:
ASA - Saturn's giant moon Titan is enveloped by a thick layer of
organic haze. Although Titan's haze layer is unique in the present-day
solar system, a recent experiment by researchers at the University of
Colorado at Boulder suggests that, billions of years ago, Earth was also
covered by organic haze. The finding not only sheds light on our
planet's early atmosphere, but could also help explain how life spread
around the globe.
Duke will now claim this is how his fuzzygod initiated evolution. Arm
yourselves.
Of that I'm sure.
--
John Hachmann aa #1782
"Those who can make you believe absurdities can make you commit atrocities"
-Voltaire
Contact - Throw a .net over the .com
.
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| User: "Father Haskell" |
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| Title: Re: Titan Sheds Light on Earth's Hazy Past |
12 Mar 2007 10:33:11 PM |
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On Feb 22, 3:07 am, Uncle Vic <addr...@withheld.com> wrote:
One fine day in alt.atheism, johac <jhachm...@sbcglobal.com> bloodied us up
with this:
ASA - Saturn's giant moon Titan is enveloped by a thick layer of
organic haze. Although Titan's haze layer is unique in the present-day
solar system, a recent experiment by researchers at the University of
Colorado at Boulder suggests that, billions of years ago, Earth was also
covered by organic haze. The finding not only sheds light on our
planet's early atmosphere, but could also help explain how life spread
around the globe.
Duke will now claim this is how his fuzzygod initiated evolution. Arm
yourselves.
Divert and toy with him. Ask him why gawd made Titan look like
Northern Wisconsin. The resemblance is impossible to miss.
.
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