Genetic Building Blocks Found In Meteorite

FiReaNGeL writes to tell us scientists have confirmed that the components of genetic material could have originated in a place other than Earth. A recently published report explains how uracil and xanthine, two basic biological compounds, were found within a meteorite that landed in Australia. From Imperial College London: "They tested the meteorite material to determine whether the molecules came from the solar system or were a result of contamination when the meteorite landed on Earth. The analysis shows that the nucleobases contain a heavy form of carbon which could only have been formed in space. Materials formed on Earth consist of a lighter variety of carbon."

What does that mean?

[ScrewMaster]

The analysis shows that the nucleobases contain a heavy form of carbon which could only have been formed in space. Materials formed on Earth consist of a lighter variety of carbon.

What are they talking about? Heavy carbon? Is that just a non-technical way of referring to an isotope? No, I didn't RTFA.

Re:Wow.

[Anonymous Coward]

Well, yeah thats what I meant. It would come as a surprise to me to learn that even the building blocks of life came here, rather than being home grown. And thats what this seems new evidence seems to support.

There is no support for that idea at all. Nothing has eliminated the options that the building blocks of life formed here in isolation or that some of the building blocks of life formed here and were supplemented with meteorite material. In fact, I think it is highly likely that the building blocks formed here in isolation just due to the volume comparison problem. The early Earth after the ends of the bombardment phase was more than capable of forming carbohydrates, nucleobases, and amino acids, especially with free water and shitloads of carbon and nitrogen in a very electrically active atmosphere. It also had orders of magnitude more volume to perform these actions and didn't have to worry about atmospheric entry. Compared with the ideal conditions of the early Earth, it is pretty unreasonable to say that this evidence supports extraterrestrial formation of these critical chemicals. For every carbohydrate, nucleobase, or amino acid that survived entry to the atmosphere, there were probably billions formed naturally in Earth's chemical reactor.

Re:Let's go over the line...

[drinkypoo]

I don't think that it's necessarily a given that any life within a rock entering the atmosphere will be baked to a crisp, depending on the ablative properties of the body in question. Given that we've already seen evidence that fungus, mold spores, and bacteria can all survive prolonged exposure to vacuum, it would not be especially surprising if actual life came here... or, for that matter, has already left here. Numerous scenarios have been envisioned for Earth's past which involve a serious encounter with a major impactor.

Re:Statistically more probable life started in Spa

[plasmacutter]

the so called hostile temperatures on earth are nothing compared to the hostility of the environment in space.

massive radiation, shockwaves, coronal mass ejections, MASSIVE extremes of heat and cold, and very importantly, the tendency for water to remain in a vaporous or solid form rather than liquid because of the lack of pressure.

Not to say the first dna fragments, amino acids, or single celled life forms could not have come from space, but they had to develop on some body with enough gravity and atmospheric pressure to host some liquid water water.

This characteristic need for liquid water is too fundamental to have simply arisen after this life came to earth.

Re:Let's go over the line...

[symbolset]

We were talking about a particular rock, not rocks in general. A ELE object would of course throw off objects of sufficient mass for embedded life to survive reentry. Our planet is known to have been hit by these objects several times while life was present. This happens considerably less frequently than the passing meteor scenario - perhaps frequently enough to be a vector within our solar system but not frequently enough for reliable interstellar diaspora.

Quit modding yourself up. It's creepy.

Re:Wow.

[Pvt. Cthulhu]

Whole microbes surviving in an airless, nutrientless, radiation-saturated enviornment is not unprecedented. The Apollo 12 crew found scores of living streptococcus mitus doing just fine on the Surveyor probes on the moon, which had been there for three years. While its doubtful whole cells came here and populated the planet, it also seems unlikely that the Earth alone provided all the ingredients.

A booger...of a booger...of a booger.

[UttBuggly]

An admittedly crude statement I've made on occasion indicating we may someday be surprised to learn our entire Universe is someone else's Petri dish.

And if you considered the Universe as a biological system, it would make sense that genetic material could travel, to us, vast distances on a meteorite.

Life on other worlds could be remotely or closely related to life on Earth.

"Honey....your 9th x 10e47 cousin from Rigel is here! He brought the wives and kids. You know they don't like my cooking, so bring home some KFC."

If this holds up, I am dying to see how folks like my fundamentalist Christian sister deal with the fact we may be bacteria in the actual grand scheme of things.

Are these simple molecules?

[Jugalator]

I wonder how simple molecules these would be treated as by a chemist. That's the big question to me. Are they so simple that it's quite likely they'll both have appeared on Earth and in space? Because, in that case, this isn't really as impressive as it may seem. Just because they're used in DNA/RNA doesn't imply they're complex alone.

Uracil: http://en.wikipedia.org/wiki/Uracil [wikipedia.org]
Xanthine: http://en.wikipedia.org/wiki/Xanthine [wikipedia.org]

As an amateur, they don't look too complex to me, but hey, what do I know... :)

Atmospheric properties

[symbolset]

And anyone know if the atmosphere was so dense back then that would fry an incoming object?

The atmosphere of Venus is considerably more dense than Earth's. As is Saturn's, Jupiter's and Uranus'. The importance of the density of atmosphere is irrelevant. For every atmospheric density there is an insertion vector where a lifeform resident on a meteor could be brushed off and float gently down.

What's important is the hospitality to life and the flexibility of life. We know that life is ridiculously flexible. There are forms of life in volcanic vents on Earth that would find Venus a paradise beyond imagining. In the past most of the planets in our solar system have been hospitable to some form of life found on our planet. It's reasonable to expect that there is some form of life on Earth that might find the crushing pressures of a gas giant inviting. For all we know the Great Red Spots are actually a life form of some kind.

In short, "life finds a way." We can take it as a given that our solar system has been so thoroughly polluted by life that everywhere it could take root it did. It's an open question whether it first took root in our solar system on Earth or elsewhere. I'm for Mars, but that's just an opinion. We're infested with life and with this meteorite we have evidence we're not the only solar system to be so infested. It follows that life is as common elsewhere in our galaxy as it is here. That means that the panspermia theory is at least partly true -- in the one example that we know of it's possible that some form of life will cross the stars. In regards to life if it can be done, it will be done. Therefore all the planets in our galaxy that can support life similar to ours have life. This is a big discovery.

When we get to the planets around distant stars we will find life that we understand. Let's go!

Re:Obsession with outer space

[khallow]

Here's my thinking on the matter. Let's assume some sort of abiogenesis happened. There are several related problems for pan that I don't believe are satifactorily explained. First, Panspermia requires that life originated somewhere. I think it reasonable to assume life whether it originated here or elsewhere started in a liquid water-based environment. Warm planets near stars or large asteroids heated by heat of formation and fission decay are the likely suspects. Rarified clouds of organic material near cosmic background temperature are not. At this point, it's worth noting that even if you ignore the liquid water requirement, chemical reactions are much slower in cold temperates and in lower density material (like the usual gas cloud of a nebula). My feeling is you need something much like Earth to start with.

Then we have to worry about transportation. The viability of spores is exaggerated. Sure we have spores on Earth that can survive thousands of years in a mild radiation environment like Earth. Space is a harsher radiation environment with cosmic rays able to penetrate meters of dense material easily. Sure you could have spore survival for thousands of years, but that doesn't help if the spores came from somewhere else other than the Solar System. There would need to be some sort of regeneration mechanism. On Earth, that mechanism is normal cellular operation. But if the spores are frozen for millions of years and exposed to cosmic radiation, it's going to need a lot of shielding in order to survive.

Also as noted before, Earth is large and most of its surface probably has always been covered with liquid water since near the begining of the Solar System. For panspermia to be worth considering now in the absence of evidence of life elsewhere, we need to consider where else has similar or greater likelihood of generating life. I think it would need to be something large with a considerable volume of ice or water. We can assume further that some currently frozen bodies like Ceres may have been sufficiently liquid in the past. In fact, Ceres would be one of my suspects. It has considerable volume, is likely to have had liquid water early in its history, and a relatively low escape velocity. Mars is next. Followed by the Jovian moons.

Continuing on, then you need to transport alien gently enough that some of it survives. So far, we know that small, solid asteroids can land gently enough to preserve life. Anything that is too small burns up in the upper atmosphere, anything that doesn't have a lot of structural integrity (say a comet or a loose ball of gravel) is going to break up high in the atmosphere and subject the interior to considerable heating. Finally, anything that is too big will hit Earth with considerable speed and expose the interior to a lot of heat and shock. My take is that the only objects that can transport life to the ground relatively safely are also too small to shield that life from the radiation environment above.

That means chaining some unlikely coincidences together on top of the generation of life coincidence.