Friday, 3 September 2010

Panspermia, Red Rain, and Hot Water in Space

The abstract of Growth and replication of red rain cells at 121 oC and their red fluorescence by Gangappa et al
We have shown that the red cells found in the Red Rain (which fell on Kerala, India, in 2001) survive and grow after incubation for periods of up to two hours at 121 oC . Under these conditions daughter cells appear within the original mother cells and the number of cells in the samples increases with length of exposure to 121 oC. No such increase in cells occurs at room temperature, suggesting that the increase in daughter cells is brought about by exposure of the Red Rain cells to high temperatures. This is an independent confirmation of results reported earlier by two of the present authors, claiming that the cells can replicate under high pressure at temperatures up to 300 oC. The flourescence behaviour of the red cells is shown to be in remarkable correspondence with the extended red emission observed in the Red Rectangle planetary nebula and other galactic and extragalactic dust clouds, suggesting, though not proving, an extraterrestrial origin.
From MIT's Technology Review :
In 2001, numerous people observed red rain falling over Kerala in the southern tip of India during a two month period. One of them was Godfrey Louis, a physicist at nearby Cochin University of Science and Technology. Intrigued by this phenomena, Louis collected numerous samples of red rain, determined to find out what was causing the contamination, perhaps sand or dust from some distant desert.

Under a microscope, however, he found no evidence of sand or dust. Instead, the rain water was filled with red cells that look remarkably like conventional bugs on Earth. What was strange was that Louis found no evidence of DNA in these cells which would rule out most kinds of known biological cells (red blood cells are one possibility but ought to be destroyed quickly by rain water).

Louis published his results in the peer-reviewed journal Astrophysics and Space in 2006, along with the tentative suggestion that the cells could be extraterrestrial, perhaps from a comet that had disintegrated in the upper atmosphere and then seeded clouds as the cells floated down to Earth. In fact, Louis says there were reports in the region of a sonic boom-type noise at the time, which could have been caused by the disintegration of an object in the upper atmosphere.

And from Wired Science:
Hot water discovered around a giant carbon star requires a new theory for the chemistry around stars to be explained. The new theory could significantly alter our understanding of what materials exist in interstellar space, and where water and life could exist in the universe.

“It makes us realize that the chemistry in all stars can be much more complex than we thought it was,” said astronomer Leen Decin of the Instituut voor Sterrenkunde in Belgium, lead author of the study published Sept. 2 in Nature. “If we don’t understand what is created from these old stars, we don’t know what the main ingredients of new stars and planets are made from.”

The star the water vapor was found around is much like our star will be in 6 billion years: nearing the end of its life, expanding outward, and with more carbon than oxygen in its atmosphere. Water vapor wasn’t expected around such a star, because it was thought that all the oxygen would be bound up in carbon monoxide, a stable molecule, and not available for making water molecules.

However, water vapor of unknown temperature was first discovered around this star in 2001. Astronomers proposed that the star had icy planets and comets that were vaporized as the star expanded outward. If this theory was right, the water vapor would be far away from the central core of the star, and cold.

With the launch of Herschel satellite in 2009, it was finally possible to test the theory because astronomers could collect information about the temperature of the water around the star. They found water vapor of all different temperatures around the star, which refutes the vaporized comet theory. Water could only get hot if it is closer to the star than where the comets and icy planets would have existed.

The new explanation for the water is that high energy ultraviolet light from nearby hot stars is penetrating the atmosphere of the carbon star and breaking apart the carbon monoxide molecules. Breaking these molecules apart would release oxygen that could react with the abundant hydrogen to form water.
The coincidence of these two papers may be just that - coincidence. Then again, maybe they're no such thing.

Previous posts on Panspermia - which I consider a more likely theory for the origin of life than a planetary one - at these previous posts.

I'll summarise why I believe an extra-planetary origin for pre-biotic and biotic substances is most likely by quoting myself:
Basically, look at the conditions on Earth when Life-as-we-know-it is believed to have formed. Water available, Carbon available, unfiltered sunlight available, and a clay or other substrate (floor) with regularities that would encourage formation of complex compounds.

The take a look at the conditions in the Oort cloud, in insterstellar gas clouds, and in infalling comets. A few quick mathematical calculations will show that theres heaps, piles, zillions more places where conditions like this exist in Space than on a planet's surface. The difference between a few flecks of paint on the surface of some very small marbles, and great vats of paint the size of Jupiter.
We're finding more all the time. I think the case for pre-biotic molecules is very strong, that for biotic material in membranes - cells - less so. But you'll have to Watch This Space.


Zimbel said...

The main problem with life on small bodies (comets, most asteroids) is that chemistry outside of a fluid either is extremely slow (solid chemistry), or that the chemicals loose contact with each other (for gases). Liquid phases really help a lot for complex chemistry.

Then there's the question for how life would make it here... first, it has to survive in space, both with the sun's radiation and the extremely low pressure making for harsh conditions. Then there's the time - getting from nearly any significant body in the modern solar system to another costs significant time, during which food stores can be depleted, and survivors die of starvation. Then, if it makes it to Earth, it needs to survive entry into Earth's atmosphere (perhaps being on an inner surface?)... but still somehow open up to mix with Earth's biosphere.

So, at least at the moment, I'm rather skeptical that anything living has influenced our biosphere. I think that some carbon-based molecules (example: Amino acids) may have, but I'm not certain that it's been significant - after all, the Earth itself formed from smaller rocks with presumably similar properties to the smaller rocks presently in the solar system, so I'd think that they'd be just as likely to have useful molecules as later comets or asteroids. I think that the presence of extraterrestrial amino acids just indicates how easy they are to make.

For example, if extraterrestrial amino acids were significant in Earth's formulation(s) of life (whether that was one event or multiple), I'd expect that the amino acids we note in space to be similar to those used in life on Earth. Take this for example - "Murchison has been found to contain Carbon (as graphite) amd more than 70 extraterrestrial amino acids and several other classes of compounds including carboxylic acids, hydroxy carboxylic acids, sulphonic and phosphonic acids, aliphatic, aromatic and polar hydroCarbons, fullerenes, heterocycles as well as kerogen, Carbonyl compounds, alcohols, amines and amides (in all, about 250 hydrocarbon species). Most of the amino acids do not have terrestrial counterparts but 8 of the 20, principally glycine, that make up proteins were in the group"

In other words, less than half of the amino acids found in this sample were identical to terrestrial formations - this doesn't exactly suggest a good match between extraterrestrial contamination and terrestrial life.

As for your surface area argument (the Oort cloud having a larger surface than the Earth), I think that this is largely negated by only a tiny fraction of the Oort cloud having ever been in contact with the Earth (even ignoring the other objections above).

Zimbel said...

I have a few problems with the theory of Panspermia, although I don't consider it disproven.

1) The first problem is one of definition. From my understanding, the Earth is pretty much a bunch of (mostly iron-heavy) rocks from around the Sun that smashed together to form a planet. If some of those small rocky bodies are the origins of life (or at least interesting organics), is this Panspermia or simply the formation of a large rocky body? I'd argue the later - but note that much of the pro-Panspermia arguments should also apply to this original formation of the planetary body (or the believed re-formation along with the Moon, somewhat later).

Ignoring that, assuming that Panspermia only refers to life/interesting organics after Earth in its (roughly) modern form:

2) Liquids are wonderful for complex chemistry. The problem with gases is that they don't adhere to each other well; the problem with solids are that any non-trivial Chemistry is extremely slow, and bound to only surface or near-surface interactions. There are relatively few places in the Solar System which support significant amounts of liquids that are anywhere near a reasonable temperature for organic molecules to form, thus life (i.e. very complex chemistry) is unlikely in most of the Solar System.

3) Any Panspermia requires the material to get there in a non-destructive fashion. Life, for example, would have many challenges - and while some could be resolved by hiding on the inner surface of an asteroid, there still would be the problems of food supply, and actually opening up that surface to interact with the Earth. Also, it would have to intersect with the Earth - instead of Jupiter or the Sun, to name two major bodies that might be hit instead (which, by the way, is the main problem I have with your Oort cloud surface area argument - what percentage of that extremely large area has ever actually been in contact with the Earth? My assumption is that it's very small). Finally, in most cases, any such contamination would be an extremely tiny percentage of Earth's chemistry.

4) That chemistry/life would need to compete with anything already established on Earth. I think that this is why the fairly small amount of contamination we get now from interesting chemicals is largely irrelevant - the chemicals that are already abundant on Earth are used just like another chemical from Earth, whereas the other ones are pretty much unused. Even worse, if a life form somehow made it onto Earth, it would not only be immediately competing with any life on Earth, but it may be a radically different amino acid mix - in other words, it may be unable to make proteins in this environment, and therefore die very quickly. As a side-note, it seems that some amino acids are relatively new to our protein composition (and no, that doesn't necessarily suggest an extraterrestrial source - there are biological explanations for "new" amino acids).

5) The evidence that Earth-based life has to do with amino acids from meteorites appears to be somewhat negative. Take the Murchison meteorite as an example - 12 amino acids found aren't used in proteins on Earth. Many of the amino acids identified have the wrong chirality for life on Earth. One would think that if meteorites were a major source of early Amino Acids, most of those amino acids would be incorporated into life on Earth.

Here's what I see in the present data: amino acids (and a variety of other organic chemicals) are both easier to make, and more prevalent than we thought off of the Earth. That bodes somewhat better for life off of the Earth than I'd previously thought.

Zimbel said...

Finally, on Red Rain - showing that those apparently interesting cells function well in high pressure and temperature seems to suggest a very terrestrial origin to me, as I wouldn't expect to find that sort of environment in the upper atmosphere or extra-terrestrially. Apparently, I'm not the only sceptic: (sorry - behind a paywall) "Red rain fantasies There appears to be an increasing tendency among scientists to come up with wild explanations when asked by the press to comment on unusual, novel phenomena. A good example is provided by comments about the recent Indian red rain phenomenon (4 March, p 34).

Red rain is morphologically similar to fungal spores or algae, as I have recently been able to confirm by microscope analysis of samples. There is no evidence that I am aware of to support suggestions that red rain is dust, sand, fat globules or blood... "