Looking For Life on Titan

For my final life on other worlds themed entry, no really, I promise, I have saved my favorite object within our own solar system, for last. And if for some reason it strikes as odd that I might actually have a favorite such object, well then you've clearly underestimated just how much of a geek I truly am. The alien world to which I am referring in this case is Saturn's sixth moon, Titan. Which, if you're unfamiliar, is an amazing place.

Like most objects in the outer solar system, Titan is a frigid place, one where surface temperatures regularly dip down to a frosty -300 degrees F. But unlike any other known planetary satellite, Titan is veiled in a thick atmosphere, a soupy, haze of methane and nitrogen that allows for the formation of, amongst other things, weather patterns. Titan's atmosphere is so dense, in fact, that it effectively shielded the moon's surface from the view of probes until the arrival of the Cassini spacecraft and it's companion Hyugens lander, in 2004. The data and images Cassini collected, as well as the images hyugens managed to return during its brief life on Titan's surface, revealed what is without a doubt the most spectacular and Earth-like features of Titan- standing lakes, rivers, and even seas, of what is believed to be liquid methane and ethane, and a landscape which seemed to bear clear evidence of liquid erosion.

It goes without saying, that there are obviously major fundamental differences between our own world and Titan, but the more we learn about it, the clearer it becomes that this distant moon really is, in many ways, a mirror-image of Earth. Which is why some scientists have begun to speculate that if so many other processes could be mirrored using alternative chemistry -such as methane and ethane taking the place of water in it's weather cycle- why couldn't life do the same?

To be clear, there is as of yet no confirmed evidence of life of any form on this distant moon. But several papers analyzing data collected by the Cassini craft emerged last year, which described the seeming disappearance of hydrogen from the moon's atmosphere, as well as a lack of acetylene on it's surface. Theories have suggested that methane-based life, if it were to exist, would likely consume both hydrogen and acetylene as part of it's natural biological process. Such a methanogenic life form is, of course, entirely theoretical at this point, and some as of yet unidentified chemical process is much more likely to proven as the ultimate source of the missing materials. But, as always, there remains a chance that these apparent chemical anomalies could be the sign of an entirely new form of life, on a world some 890 million miles away from our own.

Though all suggestion of life on any world other than our own remains entirely speculative at this point, Titan, along with all the other worlds I have mentioned in this series of entries, are just a few of the known places, even within our own solar system, that could potentially serve as home for some basic form of life. And with the continued discovery of exoplanets orbiting in the habitable zones of distant stars and even the still fairly recent revelation that oxygen and water are far more abundant on other worlds than was previously believed, the notion that life too -basic life anyway, intelligent life is a whole other story- will eventually prove to be equally common place, seems a reasonable conclusion. For now of course, we'll all just have to wait and see.

-CAINE-

Image credit: NASA/JPL

Newly Identified Lake on Europa Could Increase The Odds it Harbors Life

Though I have concluded that I am not a huge fan of the whole theme-week thing, as I suspected I would not be. There were at least two other planets I had intended to get to during last week's little experiment. Both are places that I think are particularly exciting worlds to ponder because of the unique set of conditions on each. And since it is my blog...

At first glance, Jupiter's sixth closest moon would seem to be a near featureless, dead ball of ice, hardly the kind of place most would think of as being hospitable to life. But there's an ever growing body of evidence which clearly suggests that beneath it's icy surface, there is a deep sea of liquid water with an estimated volume of two to three times that of all the oceans on Earth, covering Europa's rocky interior. Most recently, researches analyzing data collected by NASA’s Galileo spacecraft in 1995-2003, identified what they believe to be signs of a body of water about the size of the great lakes sitting just a few miles beneath the planet's surface.

Then there are the dark lines which form the moon's most prominent features, which are actually deep cracks in the ice shell which covers it. Those cracks are believed to be formed by the gravitational pull of Jupiter essentially stretching and squeezing the planet like a rubber ball, causing the ice to crack and in turn, allowing warm salty water to flow up from beneath and fill them. Some theorize that process alone could generate enough heat to sustain a liquid ocean beneath Europa's ice sheets. But even if not, other processes like thermal venting from within the planet's core could also be contributing heat, as well as various minerals into the watery subsurface, minerals which could potentially aid in the development of life. There isn't yet any way of knowing for sure weather or not any of this is true of course. The idea that life might exist on Europa if it is, is a particularly speculative one. But it does make for an undeniably interesting thought experiment; trying to visualize how life might have developed on a world where ice becomes the atmosphere that shields you from the radiation of the sun, the vacuum of space, and serves to hold in the heat needed to sustain your existence. A world devoid of light, where there is no such thing as open air, and no way to leave the water into which you were born.

If there is life on Europa, it's a safe bet that it isn't advanced enough to ponder it's existence. But it's also within the realm of possibility to think that if there is life on the frozen moon, it might have managed to develop into something more complex than the types of microbial life we're most likely to find Mars. The odds are admittedly against such a thing on either account. But it's still cool to think about.

-CAINE-

Source: Wired Science
Image Credit: NASA/JPL

Some of The Building Blocks of DNA May Have Come From Space

In two of the meteorites, the team also discovered for the first time, trace amounts of three molecules related to nucleobases (nucleobase analogues), purine, 2,6-diaminopurine, and 6,8-diaminopurine; two of which rarely appear in biology. According to Dr. Michael Callahan, lead author of a paper on the discovery appearing in Proceedings of the National Academy of Sciences of the United States of America;

"You would not expect to see these nucleobase analogs if contamination from terrestrial life was the source, because they're not used in biology, aside from one report of 2,6-diaminopurinecyanophage S-2L,"

While the presence of molecules not known to commonly appear in biology was a strong indication that the findings were not the result of contamination. Callahan's group further confirmed this fact by analyzing a sample of ice taken from Antarctica, where most of the meteorites in the study were found. The result showed much smaller concentrations of the nucleobases, as well as xanthine and hypoxanthine, all of which appeared in parts per trillion in the ice sample, as oppose to the parts per billion generally found within the samples taken from the meteorites. None of the Nucleobase analogues were discovered in the sample. Analysis of the soil taken from the surrounding area where one of the meteorites used in study fell in Austraila, also failed to detect those analogs.

In one final experiment designed to rule out terrestrial contamination and confirm the extraterrestrial origin of the molecules. Callahan's team was able to successfully generate all of the nucleobases and analogues found within the meteorite samples in a completely non-biological chemical reaction in the lab, using hydrogen cyanide, ammonia, and water. Showing not only that the find was almost certainly not the result of contamination, but more importantly, that chemical processes taking place within certain types of asteroids could potentially produce all of the molecules detected in the study.

If confirmed by further research, the findings of Callahan and his team could be a major step towards understanding the true origins of life on Earth. Particularly when considered along with previous research conducted by the team which detected amino acids, the molecules responsible for building proteins, within similar samples; as well samples taken from the Comet Wild 2 during NASA's stardust mission. All of which, adds to the growing body of evidence supporting the theory that the chemistry taking place within comets and asteroids is capable of generating the basic building blocks of essential biological molecules, and that life may owe it's existence, at least in part, to materials delivered from space via meteorite and comet impacts.

-CAINE-

Source: NASA
Image credit: NASA's Goddard Space Flight Center/Chris Smith

Matt Ridley and Richard Dawkins on DNA, Extraterrestrial Life and More...

NASA Press Conference Disappoints Many, But it Really Shouldn't Have

[*UPDATE*]Turns out, not only have NASA's observations NOT been confirmed by any other researchers, but there's also been no shortage of scientists coming forward to criticize the conclusions as well as the methods of NASA scientists. Some have even gone so far as labeling the entire thing one big publicity stunt and given this new information, I largely agree. So maybe we should have been disappointed after all. [*UPDATE*]

In case you missed it, yesterday NASA held a press conference to announce the discovery of a bacteria (GFAJ-1 of Halomonadaceae) living in the highly alkaline waters as well as in the mud surrounding Mono Lake in California. Lab tests showed that this bacteria is capable of not only surviving in an environment saturated with arsenic, but that it can actually incorporate the normally highly toxic chemical into it's DNA and use it in place of phosphorous.


One would be hard pressed to exaggerate the "wow-factor" of this discovery from a biological stand point as it is a real life living breathing example of an organism capable of sustaining it's existence by utilizing a biochemistry unlike any other organism on the planet. As far as the impact this finding will have on astrobiology- The search for life on other worlds has to begin by looking for the conditions necessary to sustain life as we know it and this discovery helps to expand our understanding of the conditions under which life can exist. In short, the space agency made good on it's promise to deliver something which would impact the field of astrobiology and this organism itself is an astonishing discovery well worth the attention it received.

However-

To the average person, this discovery probably doesn't mean much, and it certainly isn't as cool as it would have been if this same discovery had been made on another planet; which is obviously what the majority of people thought was going to be the case. I myself was aware of the existence of organisms capable of surviving on arsenic ( the part about the DNA is new microbes living on arsenic is not) and that the subject of the press conference would most likely focus primarily on some terrestrial finding. But even I assumed that the topic would be somehow tied to a specific discovery on another world and it is, in a fundamental non-specific sort of way. But still, a lot of people were both disappointed and even irritated by the subject of the conference and quite frankly, I don't blame them.

To be fair, 99% of the hype about alien life came from outside NASA. But when the general public(right or wrong) sees your organization's primary mission as the search for extraterrestrials, you have to know that holding a special event to share an announcement relating to astrobiology is GOING to generate hype, speculation, and ultimately resentment when reality doesn't live up to their expectations.

-CAINE-

Source: Bad Astronomy

For more about the true significance of this find check out Nancy Atkinson's article on Universe Tody.

Oxygen on Rhea and NASA's Big Astrobiological Revelation

The Cassini probe was recently sent to analyze the atmosphere of Saturn's second largest moon Rhea, revealing the planet to be covered in a thin veil of oxygen (70%) and carbon dioxide (30%). This finding represents the first ever confirmation of the existence of oxygen in the atmosphere of any world other than our own.But it's the presence of carbon dioxide that peaked most peoples interest in this story as one of the possible causes for the gas is of course, alien biology.

Though Rhea's low surface temperature -ranging from -281 f to -364 f- the exceedingly thin nature of it's atmosphere, and the subsequent lack of liquid water, make it an unlikely home for any form of life as we know it. But Cassini's find does place the planet's name on an ever growing list of recent discoveries which show that elements essential for life as we understand it actually exist in often surprising quantities and concentrations on planets throughout our solar system.

In fact, the discovery of elements and conditions potentially conducive to life on our neighboring bodies has become so common place, that I have actually stopped writing about many of them. Not because they're not intriguing scientific discoveries, but because the story pretty much always goes the same: I tell you planet X displays a chemical or environmental anomaly which COULD -after years worth of additional analysis- prove to be signs of life on another world. But until that analysis is done, we'll all just have to go with the odds and assume that it isn't. I say, wouldn't it be cool if it was, make a logical argument for why it could be and we all move on to something else.

Well, according to NASA, by this time tomorrow there just might be something new to say about the potential for life on other worlds, as earlier this week the space agency announced it's plans to hold a conference tomorrow at 2:00PM ET, during which it promises to: "discuss an astrobiology finding that will impact the search for evidence of extraterrestrial life."

Pretty much since the moment the press conference was announced the speculations have been flying, the most popular and outrageous of which being that the agency plans to admit some previously withheld knowledge about contact with little gray men. But being the logical creature that I am, I'm going to follow Phil Plait's lead and side with Kottke.org in guessing that the people scheduled to be involved in tomorrows press conference make it likely it will have something to do with previous discoveries on Titan, at least in part anyway.

But who knows, maybe they have somehow confirmed the existence of some sort of extraterrestrial microbes thriving on arsenic on the surface of mars or some alien fungus living off acetylene in Titan's lakes of methane. But while Id be lying if I said I wasn't waiting eagerly to hear just what this new discovery is, if you're holding out for the big "We come in peace moment" in tomorrows press conference, I would say you should prepare yourself for disappointment.

-CAINE-

Source: New Scientist, Bad Astronomy

Image credit: NASA, Voyager, Copyright Calvin J. Hamilton

Titan's Atmosphere Could Be Producing the Basic Ingredients For Life

There are many theories about how exactly life began on our planet. The most commonly held belief of course, is that life began in the oceans. But a recent experiment using radio waves to simulate the effects of ultraviolet radiation from the sun striking the top of Saturn's largest moon Titan's thick atmosphere, has shown that life may actually have begun in the sky.

The experiment showed that when the ultraviolet radiation strikes Titan's atmosphere it can break apart molecules in the air, like molecular nitrogen and methane, leading to the production of amino acids and the nucleotide bases which make up DNA and RNA, without the need for liquid water.

More than merely having the potential to redefine how life began on earth, as if that weren't enough, if researchers could confirm the presence of nucleotide bases and amino acids in Titan's atmosphere, it would be one more piece of evidence pointing to the possible existence of life on Titan itself. Which is already seen by many as a potential home for some, perhaps alternative, form of life.

According to planetary scientist Jonathan Lunine, Cassini has already detected heavy ions in Titan's atmosphere which could potentially be the Nucleotide bases and amino acids found in the study, but the particles were too large for Cassini's instruments to identify. Lunine says that confirming these particles are actually being produced in Titan’s atmosphere will require an orbiter that can carry instruments 100 to 200 kilometers deeper than Cassini does into Titan’s haze layer.

-CAINE-

Source:Wired Science

For more about the potential for life on Titan read: Methanogenic Life on Titan?

Does the methane cycle on mars point to life?(probably not but it's still pretty cool.)

According to a study conducted by Italian scientists using five years worth of data collected by NASA's Mars Global Surveyor, methane concentrations on mars change with the seasons as well as location.

led by Sergio Fonti of Italy's Universita del Salento, scientists studied around three million observations from the Mars Global Serveyor made between July 1999 and October 2004, which is around three years on Mars. They found that during the fall methane peaks in three regions on the planet: Elysium, Arabias Terre, and Tharsis. The methane concentration in these regions then falls to it's lowest level in winter before rising to it's highest level of concentration in summer, allowing the gas to spread throughout the Martian atmosphere before dissipating and then somehow being replenished, beginning the cycle again.

The discovery and observation of extraterrestrial methane tends to excite researchers and the public alike because methane is most commonly produced one of two ways. Either through geologic activity, volcanic eruptions, or biological processes, the life cycle of plants and animals. But methane can also be produced through chemical processes such as carbon dioxide combining with melted ice beneath mars' surface. This, obviously, seems the most likely scenario given that the Tharsis and Elysium regions are home to the two largest volcanoes on Mars, and the Arabia Terrae region is believed to poses a vast amount of water ice beneath it's sands.
-CAINE-

Source:Popsci

Methanogenic Life on Titan?

Saturn's moon Titan is one of my absolute favorite objects in our solar system. The above image, taken by the Casini spacecraft using infrared imaging to cut through Titans thick atmosphere, reveals the sun glinting off the surface of what are believed to be standing lakes or even an ocean of methane near Titans north pole. The largest of Saturn's moons, Titan is the only natural satellite known to have a dense atmosphere,1.19 times as massive as Earth's, and is the only object other than Earth for which clear evidence of stable bodies of surface liquid exists.

Titan's dense hazy atmosphere made it impossible for the first probes to pass near enough to image the moon to penetrate through to the surface, until The Cassini–Huygens spacecraft reached Saturn on July 1, 2004 and began the process of mapping it's surface by radar. On January 14, 2005,The Huygens Probe touched down on the surface of Titan after a three hour descent through the moons thick atmosphere, revealing that many of the moon's surface features seemed to have been formed by flowing liquid. Now, new evidence has arisen seeming to suggest there may be life on Titan, or so the headlines would have you believe. But as with the recent hype surrounding the creation of so called synthetic life, the evidence for life on Titan has been greatly exaggerated for the sake of a story.

The first thing you need to understand is that Titan is extremely cold, around minus 290 degrees Fahrenheit or minus 179 degrees Celsius, so water cannot exist on the surface of Titan in liquid form. That means any organism that did live on Titan would have evolved to use a substance which would remain liquid at those temperatures, methane being the most likely candidate. While there are liquid-water-based microbes on Earth that thrive on methane or produce it as a waste product, methane based life remains speculative.

All of this speculation is the result of two recently released papers based on the analysis of chemical data returned by the Casini spacecraft. The first paper by Darrell Strobel suggests that hydrogen molecules flowing down through Titan's atmosphere are disappearing on the surface. The second paper by Roger Clark maps hydrocarbons on Titan's surface and finds a surprising lack of acetylene. Both substances would be essential to methanogenic life which would use hydrogen as we do oxygen and could potentially consume acetylene as food, thus accounting for the seeming lack of each substance in Casini's data. Could all this be evidence that methane based life exists on Titan? Absolutely. But as always Occam's razor applies and it's far more likely that further analysis will reveal a less spectacular reason for the seeming anomalies.

Here on earth, the existence of creatures living hundreds of feet below the ice in the arctic, thriving in poisonous lakes in under ground caves or living in sulfur vents in the deep ocean make it clear that life can adapt to most anything, and I personally believe we will find life outside of Earth. Weather that life will be as simple as some alien cave slime or microbe or as exotic as silicone based lifeforms thriving in oceans of methane I certainly don't know. But as tantalizing as it may be, it's too soon to say that Casini's most recent findings represent proof of such life on Titan.
-CAINE-


First, check out the Space.com and Universe Today articles on this story, which were my primary sources for today's entry then, this video from the ESA which condenses the hours of data the Huygens probe collected down to 4 mins and 40 seconds.(The sounds added to this video get annoying you might want to consider muting it.)

Video posted by Youtube user:nequest
Image Credit:NASA