Whatever the name of the moon is ... it has an atmosphere of Methane - along with "seas" of Methane.

Why doesn't the moon go BOOM when a foreign object penetrates the atmosphere? I trust that massive amounts of heat are generated when the probe enters the atmosphere ...

Any thoughts or links?

Such ignorance!! The name is Titan!

Anyways in my rush I forgot to tell that 80-90% of Titan's atmosphere is Nitrogen not Methan, though it has Methan in it too, Methan rain and liquid Methan on surface is possible, but the new data from the ESA's Huygens probe should tell that in detail.

Eman,

Here are some links for you, man. BTW: Ignorance is bliss. Stay curious, stay cool.

http://saturn.jpl.nasa.gov/home/index.cfm
http://news.google.com/news?q=Titan&hl=en&lr=&sa=N&tab=nn&oi=newsr
http://abcnews.go.com/International/wireStory?id=414842
http://news.scotsman.com/latest.cfm?id=4004227
http://www.abc.net.au/news/newsitems/200501/s1281784.htm

It wont all go FOOM in a great fireball, because fire requires oxygen, and there is next to no oxygen on Titan.

Here are ESA's prepared video talks on Huygens probe.
It's a good presentation.
http://www.esa.int/SPECIALS/Cassini-Huygens/SEMPXZ2AR2E_0.html

It wont all go FOOM in a great fireball, because fire requires oxygen, and there is next to no oxygen on Titan.

Heh, so if ever there's warfare there, all we gotta do is make some oxygen bombs. Crazy how something that we need so dearly for life can be so lethal. And if a human ever breathed on that planet, I guess that would seriously be some bad breath! :p

- N

On prehistoric early Earth there was next to no oxygen in the atmosphere, our's was very like Titan and most of the early life died out, when plants introduced oxygen. Oxygen was deadly to the most of that time microbes, bacteria, etc.

When oxygen was first introduced to Earth's atmosphere, it was one of the worst poisons known. It may as well have been acid, as even exposed rocks were oxidized and destroyed in very little time. I don't know if humanity will ever live up to the plant kingdom in sheer polluting ability.

I was shocked when I learned that Titan had river channels, lakes, and shorelines. It amazes me that one of the coldest bodies in the solar system is still so active. It even seems to get a fair amount of sunlight. For the first time, I believe we might be able to get some severely engineered life to grow and flourish in Titan... though of a type normal humans would probably never be able to use.

I think much of the credit to Titan's activity has to be given to the enormous gravity of Saturn.

It seems to me that we are speculating that there was no oxygen on Earth at it's origin. How is it speculated that oxygen was introduced to our atmosphere?

Actually it's quite proven and it's the accepted theory. Even NASA says so, when linking Titan's atmsphere to that of early Earth.
The following text is not from NASA

Two models are most favored for the origin of the atmosphere: outgassing or accretion. Outgassing is related to the differentiation of the Earth and the release of gases by volcanoes. Assuming that the gases we presently observe were also released by early volcanoes the atmosphere would be made of water vapor (H2O), carbon monoxide (CO), carbon dioxide (CO2), hydrochloric acid (HCl), methane (CH4), ammonia (NH3), nitrogen (N2), & sulfur gases. The atmosphere was reducing (no free oxygen).

The present-day atmosphere is quite different:

* 78% nitrogen, 21% oxygen, 1% argon, 0.03% carbon dioxide plus small amounts of water vapor

Early in Earth history, water vapor formed clouds, rain, and ultimately all of the surface water (oceans, ground water, lakes, rivers, glaciers). The presence of the ancient oceans and lakes is recorded by different types of sedimentary rocks.

Perhaps the best geologic evidence for the composition of the early atmosphere is the presence and abundance of Banded Iron Formations. These rocks are made of layers of sulfide minerals (evidence for a reducing environment) and chert or fine-grained quartz. These rocks are not present in rocks younger than 1.8 - 2.5 billions of years ago, when oxygen starting becoming more abundant.

The amount of carbon dioxide was reduced by chemical weathering of minerals at the surface:

* CaSiO3 + CO2 <-> CaCO3 + SiO2.

The amount of oxygen increased due to early life forms, like the algae in stromatolites.

The introduction of red beds, sedimentary rocks with ferric oxide (hematite) cement, to the rock record indicates the addition of free oxygen to the atmosphere.
http://volcano.und.nodak.edu/vwdocs/Gases/origin.html

And this
The Early Earth and the Evolution of the Atmosphere.

1. Early Earth probably had an atmosphere dominated by carbon dioxide similar to the atmosphere of Venus today.
2. There are a group of one-celled organisms that can live in an oxygen free environment. These are the bacteria or prokaryotes. They do not have a nucleus and reproduce only by cell division. These creatures are the earliest evidence of life on earth. They were the first organisms to develop photosynthesis. Photosynthesis today is balanced by oxygen using respiration.
1. Hypothesis: Oxygen was nearly absent in the atmosphere of early Earth so photosynthesis would have created a net gain of oxygen first in the ocean and later in the atmosphere. Eventually with sufficient oxygen in the atmosphere respiration would have balanced photosynthesis except when burial removed the organic material from the oxygenated water or air. Before oxygen could build up in the atmosphere it must have oxidized reduced ions in seawater.
1. Evidence to support the above hypothesis:

Iron (Fe) is a very abundant element in the earth's crust so much is released by the chemical disintegration of minerals contained in rocks. Fe++ is slightly soluble in seawater while Fe+++ is insoluble (Figure 6). During the time when the earth had a reducing atmosphere Fe++ should have accumulated as dissolved ions in seawater. However at some point the oxygen build-up in the ocean from prokaryote photosynthesis should have oxidized the Fe++ to Fe+++ resulting in the precipitation of insoluble iron compounds. Are such ancient iron rich compounds preserved? Yes there are, in fact the bulk of the iron ore mined to produce steel comes from iron deposits that are about two billion years old (Figure 7). Such deposits are found on all continents and all look much the same (Figure 8). They are reddish and have clearly visible bands hence they are called Banded Iron Formations. The Messabi range of Minnesota is an example of such a deposit. It was for much of US history the primary source of iron ore for the steel mills of Pittsburg, Pennsylvania and Gary, Indiana. If we know the mass of these banded iron formations and the rate at which we mine them we can calculate their residence time and determine how long they will last, or when we will run out of this kind of iron ore (Figure 9).

A second line of evidence, to suggest that the early earth had a reducing atmosphere like Venus and Mars, is the presence of detrital (formed from the products of erosion of pre-existing rocks) pyrite in sedimentary deposits older than two billion years old. Iron pyrite forms in reducing environment and is quickly chemically decomposed in the presence of oxygen. Today such minerals are only preserved in rocks that formed in reducing environments such as swamps etc. However, in rocks older than two billion years old this mineral (iron pyrite) is found in rocks that were probably formed in streambeds.

http://eesc.columbia.edu/courses/ees/climate/lectures/earth.html

and this too
First Atmosphere

* Composition - Probably H2, He
* These gases are relatively rare on Earth compared to other places in the universe and were probably lost to space early in Earth's history because
o Earth's gravity is not strong enough to hold lighter gases
o Earth still did not have a differentiated core (solid inner/liquid outer core) which creates Earth's magnetic field (magnetosphere = Van Allen Belt) which deflects solar winds.
* Once the core differentiated the heavier gases could be retained

Second Atmosphere
Produced by volcanic out gassing.

* Gases produced were probably similar to those created by modern volcanoes (H2O, CO2, SO2, CO, S2, Cl2, N2, H2) and NH3 (ammonia) and CH4 (methane)
* No free O2 at this time (not found in volcanic gases).

* Ocean Formation - As the Earth cooled, H2O produced by out gassing could exist as liquid in the Early Archean, allowing oceans to form.
o Evidence - pillow basalts, deep marine seds in greenstone belts.

Addition of O2 to the Atmosphere
Today, the atmosphere is ~21% free oxygen. How did oxygen reach these levels in the atmosphere? Revisit the oxygen cycle:

* Oxygen Production
o Photochemical dissociation - breakup of water molecules by ultraviolet
+ Produced O2 levels approx. 1-2% current levels
+ At these levels O3 (Ozone) can form to shield Earth surface from UV
o Photosynthesis - CO2 + H2O + sunlight = organic compounds + O2 - produced by cyanobacteria, and eventually higher plants - supplied the rest of O2 to atmosphere. Thus plant populations
* Oxygen Consumers
o Chemical Weathering - through oxidation of surface materials (early consumer)
o Animal Respiration (much later)
o Burning of Fossil Fuels (much, much later)

Throughout the Archean there was little to no free oxygen in the atmosphere (<1% of presence levels). What little was produced by cyanobacteria, was probably consumed by the weathering process. Once rocks at the surface were sufficiently oxidized, more oxygen could remain free in the atmosphere.

During the Proterozoic the amount of free O2 in the atmosphere rose from 1 - 10 %. Most of this was released by cyanobacteria, which increase in abundance in the fossil record 2.3 Ga. Present levels of O2 were probably not achieved until ~400 Ma.
Evidence from the Rock Record

* Iron (Fe) i s extremely reactive with oxygen. If we look at the oxidation state of Fe in the rock record, we can infer a great deal about atmospheric evolution.
* Archean - Find occurrence of minerals that only form in non-oxidizing environments in Archean sediments: Pyrite (Fools gold; FeS2), Uraninite (UO2). These minerals are easily dissolved out of rocks under present atmospheric conditions.
* Banded Iron Formation (BIF) - Deep water deposits in which layers of iron-rich minerals alternate with iron-poor layers, primarily chert. Iron minerals include iron oxide, iron carbonate, iron silicate, iron sulfide. BIF's are a major source of iron ore, b/c they contain magnetite (Fe3O4) which has a higher iron-to-oxygen ratio than hematite. These are common in rocks 2.0 - 2.8 B.y. old, but do not form today.
* Red beds (continental siliciclastic deposits) are never found in rocks older than 2.3 B. y., but are common during Phanerozoic time. Red beds are red because of the highly oxidized mineral hematite (Fe2O3), that probably forms secondarily by oxidation of other Fe minerals that have accumulated in the sediment.

Conclusion - amount of O2 in the atmosphere has increased with time.
Biological Evidence

* Chemical building blocks of life could not have formed in the presence of atmospheric oxygen. Chemical reactions that yield amino acids are inhibited by presence of very small amounts of oxygen.
* Oxygen prevents growth of the most primitive living bacteria such as photosynthetic bacteria, methane-producing bacteria and bacteria that derive energy from fermentation. Conclustion - Since today's most primitive life forms are anaerobic, the first forms of cellular life probably had similar metabolisms.
* Today these anaerobic life forms are restricted to anoxic (low oxygen) habitats such as swamps, ponds, and lagoons.



Atmospheric oxygen built up in the early history of the Earth as the waste product of photosynthetic organisms and by burial of organic matter away from surficial decay. This history is documented by the geologic preservation of oxygen-sensitive minerals,
deposition banded iron formations, and development of continental "red beds" or BIFs. Figure from the University of Michigan's Introduction to Global Change web site.
from here -> http://www.ux1.eiu.edu/~cfjps/1400/atmos_origin.html