Zapping Titan-like atmosphere with UV rays creates life precursors

Jun 29, 2010
This image taken by the Cassini orbiter on October 15, 2007, shows Saturn's A and F rings, the small moon Epimetheus and smog-enshrouded Titan, Saturn’s largest moon. The image is colorized to approximate the scene as it might appear to human eyes. Credit: NASA/JPL/Space Science Institute

The first experimental evidence showing how atmospheric nitrogen can be incorporated into organic macromolecules is being reported by a University of Arizona team.

The finding indicates what organic molecules might be found on Titan, the moon of Saturn that scientists think is a model for the chemistry of pre-life Earth.

Earth and Titan are the only known planetary-sized bodies that have thick, predominantly nitrogen atmospheres, said Hiroshi Imanaka, who conducted the research while a member of UA's chemistry and biochemistry department.

How complex organic molecules become nitrogenated in settings like early Earth or Titan's atmosphere is a big mystery, Imanaka said.

"Titan is so interesting because its nitrogen-dominated atmosphere and might give us a clue to the on our Earth," said Imanaka, now an assistant research scientist in the UA's Lunar and Planetary Laboratory. "Nitrogen is an essential element of life."

However, not just any nitrogen will do. must be converted to a more chemically active form of nitrogen that can drive the reactions that form the basis of biological systems.

Imanaka and Mark Smith converted a nitrogen-methane similar to Titan's atmosphere into a collection of nitrogen-containing organic molecules by irradiating the gas with high-energy UV rays. The laboratory set-up was designed to mimic how affects Titan's atmosphere.

In an experiment to simulate what happens when sunlight hits Titan's atmosphere, University of Arizona researchers put nitrogen and methane gas into a stainless steel cylinder and zapped it with high-energy UV light. The nitrogen molecules emit blue light when zapped by the UV light. The white in the picture surrounds the pinhole opening that is the source of the UV beam. The experiment was conducted at the Advanced Light Source facility at Lawrence Berkeley National Laboratory in Berkeley, Calif. Credit: Hiroshi Imanaka, University of Arizona.

Most of the nitrogen moved directly into solid compounds, rather than gaseous ones, said Smith, a UA professor and head of chemistry and biochemistry. Previous models predicted the nitrogen would move from gaseous compounds to solid ones in a lengthier stepwise process.

Titan looks orange in color because a smog of organic molecules envelops the planet. The particles in the smog will eventually settle down to the surface and may be exposed to conditions that could create life, said Imanaka, who is also a principal investigator at the SETI Institute in Mountain View, Calif.

However, scientists don't know whether Titan's smog particles contain nitrogen. If some of the particles are the same nitrogen-containing organic molecules the UA team created in the laboratory, conditions conducive to life are more likely, Smith said.

Laboratory observations such as these indicate what the next space missions should look for and what instruments should be developed to help in the search, Smith said.

Imanaka and Smith's paper, "Formation of nitrogenated organic aerosols in the Titan upper atmosphere," is scheduled for publication in the Early Online edition of the Proceedings of the National Academy of Sciences the week of June 28. NASA provided funding for the research.

The UA researchers wanted to simulate conditions in Titan's thin upper atmosphere because results from the Cassini Mission indicated "extreme UV" radiation hitting the atmosphere created .

Therefore, Imanaka and Smith used the Advanced Light Source at Lawrence Berkeley National Laboratory's synchroton in Berkeley, Calif. to shoot high-energy UV light into a stainless steel cylinder containing nitrogen-and-methane gas held at very low pressure.

The researchers used a mass spectrometer to analyze the chemicals that resulted from the radiation.

University of Arizona researcher Hiroshi Imanaka stands next to the experiment he and UA's Mark Smith have set up inside the Advanced Light Source facility at Lawrence Berkeley National Laboratory in Berkeley, Calif. Credit: Doug Archer, University of Arizona.

Simple though it sounds, setting up the experimental equipment is complicated. The UV light itself must pass through a series of vacuum chambers on its way into the gas chamber.

Many researchers want to use the Advanced Light Source, so competition for time on the instrument is fierce. Imanaka and Smith were allocated one or two time slots per year, each of which was for eight hours a day for only five to 10 days.

For each time slot, Imanaka and Smith had to pack all the experimental equipment into a van, drive to Berkeley, set up the delicate equipment and launch into an intense series of experiments. They sometimes worked more than 48 hours straight to get the maximum out of their time on the Advanced Light Source. Completing all the necessary experiments took years.

It was nerve-racking, Imanaka said: "If we miss just one screw, it messes up our beam time."

At the beginning, he only analyzed the gases from the cylinder. But he didn't detect any nitrogen-containing organic compounds.

Imanaka and Smith thought there was something wrong in the experimental set-up, so they tweaked the system. But still no nitrogen.

"It was quite a mystery," said Imanaka, the paper's first author. "Where did the nitrogen go?"

Finally, the two researchers collected the bits of brown gunk that gathered on the cylinder wall and analyzed it with what Imanaka called "the most sophisticated mass spectrometer technique."

Imanaka said, "Then I finally found the nitrogen!"

Imanaka and Smith suspect that such compounds are formed in Titan's and eventually fall to Titan's surface. Once on the surface, they contribute to an environment that is conducive to the evolution of life.

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User comments : 13

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hudres
1.9 / 5 (9) Jun 30, 2010
While an important experiment, this is not the first time this has been done. A nearly identical experiment was done in the late 1800's where Miller used an electric arc inside a glass bulb filled with a similar gas mixture to produce what we now know as amino acids. The experiment reported here merely duplicates the earlier work. Fact checking please!
DamienS
4.5 / 5 (8) Jun 30, 2010
@hundres, I would imagine that the experiments are different in detail, if not in concept. The Miller–Urey experiment (conducted in 1952, by the way) used hypothesized atmospheric conditions thought to have existed on early Earth, while this experiment used the actual conditions on Titan as measured by Cassini.

As a side note, it has been shown since, that the Miller experiment did not in fact reflect the conditions of early Earth as originally thought.
Greeniemax
2.3 / 5 (3) Jun 30, 2010
Experiments can last few hours, days, months or even years, but life didn't emerge in few years, it might have taken billions of years of different kind of conditions for life to come up. Maybe what we're looking at is wrong, maybe the basic molecules where life started from was never amino acids or anything as such. Maybe 2 different types of things were produced and by chance they merged which gave the way to replication.

Secondly original replication has to really fast and furious otherwise it wouldn't work out as that original cell would have died very quickly without food.

Too many issues, seriously, its not so simple.
kevinrtrs
1.4 / 5 (10) Jun 30, 2010
Time for a reality check.
I'll state it again - has anyone EVER recorded that some dead thing came back to life all by itself again? No.
Even though we know for a fact that all the ingredients for life is present when something dies, life doesn't spontaneously enter into those ingredients again. Never. EVER.
So how come scientists who know this basic fact are busy trying to find life somewhere else to have arisen spontaneously from mere chemicals?
This doesn't make sense. Especially when Pasteur has shown conclusively that life only comes from life.
And we know this from ALL our combined billions of lives experience. Dead things do NOT come back to life by themselves [at least not in the secular recorded history].
Yes, I'm repeating it over and over because people insist over and over that the opposite is true which really makes the mind boggle when we consider that they base evolution on uniformatarian, naturalistic principles.

yyz
4.2 / 5 (5) Jun 30, 2010
@kevinrtrs,

This is a SCIENCE site. We don't need to be reminded of your RELIGIOUS views on every post. We KNOW what your views are. Please stay on topic and refrain from spamming. It gets BORING (and repetitive).
Modernmystic
1 / 5 (2) Jun 30, 2010
Wow what non news. This is like saying buying lottery tickets is the precursor to you winning a Billion dollars...how underwhelming.
antialias
4 / 5 (4) Jun 30, 2010
Secondly original replication has to really fast and furious otherwise it wouldn't work out as that original cell would have died very quickly without food.

The original 'replicator' was probably much simpler than a cell. Probably more akin to a prion or some even simpler chemical compound that had just the knack of working as an enzyme for creating more of itself from other, simple, substances.

Mutation can start from there (substituting individual atoms, forming complexes of two such units failing to separate, ... )
Modernmystic
not rated yet Jun 30, 2010
Secondly original replication has to really fast and furious otherwise it wouldn't work out as that original cell would have died very quickly without food.

The original 'replicator' was probably much simpler than a cell. Probably more akin to a prion or some even simpler chemical compound that had just the knack of working as an enzyme for creating more of itself from other, simple, substances.

Mutation can start from there (substituting individual atoms, forming complexes of two such units failing to separate, ... )


Interesting, but it really didn't address his point at all.
antialias
4.5 / 5 (2) Jun 30, 2010
Metabolisation is not a prerequisite for propagation/replication. There are also plenty of bacteria which can work at a very slow rate. Speed is only of the essence if you have competition - and the first replicator didn't have that. Only once it got to the point where it would start to exhaust the precursor molecules would competition set in. From that point onward speed is one beneficial mutational trait (of many)
grimm
1 / 5 (1) Jun 30, 2010
"This is a SCIENCE site. We don't need to be reminded of your RELIGIOUS views on every post. We KNOW what your views are. Please stay on topic and refrain from spamming. It gets BORING (and repetitive)."

Actually it is your comment that is unscientific. All his above statements are factually correct. Every origin-of-life scientist knows this, and also knows that this "news" is not much to write home about, considering the physical challenges involved with creating life using "natural" processes.

One of which is - how to get all your DNA molecules to be right-handed, while your amino acids are only left-handed?

The odds of assembling a 200-chain protein are many orders of magnitude larger than the number of subatomic particles in the universe. To believe in such an occurence is ... unscientific.
hudres
1 / 5 (2) Jun 30, 2010
@damians: OK I got the date wrong, but you knew exactly who and what I was talking about. The current experiment used nitrogen and methane, while Miller used water, methane, ammonia, and hydrogen. We don't know the mix ratio in either experiment, but it is clear that the only difference is a small amount of oxygen. I admit that this does allow for a little more diversity in Miller, but you are going to get a lot of the same compounds formed. The absence of oxygen means that you don't get CO, Co2 or formaldehyde. This means that the current experiment is a simpler version of Miller, as the main reaction products will be Hydrogen Cyanide and Cyanoacetylene and derivatives.

So, do we get excited about a simpler, less exciting experiment and hail it as breakthrough science? Or, do we take it in context and recognize that what the current experiment does is to show that you can get some interesting chemistry on Titan? No chance of life as we know it as there is no oxygen.
DamienS
5 / 5 (1) Jun 30, 2010
hudres, you got more than the date wrong - you got the century wrong. :) But more to the point, your supercilious tone showed that you missed the relevance of the article.
Skeptic_Heretic
5 / 5 (2) Jul 03, 2010
I'll state it again - has anyone EVER recorded that some dead thing came back to life all by itself again? No.
Isn't your entire religion based on this being an occurance?

Here's the problem kev. No one is saying that a dead thing will come back to life. We're saying that the difference between life and unlife is simply the continuance of a chemical reaction. Death occurs when the chemical reaction that is a being ceases to be.

Life occurs when that chemical reaction starts. So no, a self sustaining chemical reaction ceasing to run, then starting up again has been witnessed, it has happened multiple times and been recorded in both simple and complex life. Get a new tag line, or at least understand the one you are spewing.