Interesting news coming from the Cassani probe:
Something strange is afoot in the atmosphere of Saturn’s moon Titan, according to data sent back from the Cassini mission. Data returned from a spectrometer on Cassini indicates that there’s a large flux of hydrogen in the moon’s atmosphere, with the gas forming in the upper atmosphere and being removed from the atmosphere at Titan’s surface. We don’t currently know what process is ensuring its removal, but the amounts of hydrogen being taken out of the atmosphere are consistent with an earlier proposal of methane-based life.
Titan’s atmosphere is rich in hydrocarbon compounds, and chemical changes in the upper atmosphere are driven by the arrival of ultraviolet light from the sun. One of the expected results of the UV exposure is the liberation of molecular hydrogen from methane via a process that produces more complex hydrocarbons. With little oxygen to react with, the molecular hydrogen should remain stable. Some of it will escape into space, but a new paper indicates that a substantial amount of that hydrogen migrates down through the atmosphere towards Titan’s surface.
Since it’s not accumulating there, some chemical process must be removing it from the atmosphere; right now, we don’t know what that process is, and, as NASA’s own news piece on the topic notes, the first option for scientists is to consider simple chemistry.
However, the abstract of the paper notes that this level of hydrogen consumption is consistent with an earlier prediction of methanogenic life. In short, the life would get its energy by “burning” the hydrogen with a carbon source instead of oxygen, releasing methane (CH4) in the process. The source of the carbon is where a second paper (not yet online) comes in. Models of Titan’s upper atmosphere suggest that significant amounts of acetylene should be produced by the reactions there, and this would provide an excellent source of carbon to any hypothetical metabolisms. The surprise of the second paper is that there’s very little acetylene to be found on Titan’s surface.
I will now step out of the way while those more competent than I evaluate this. Right now it appears at least intriguing.
Very intriguing, indeed. I swear, Cassini has given us so many wonderful things to check out, we’ll need to send a whole FLEET of probes to dig deeper!
I wouldn’t be too caught up in the possibility of life, though. Biology is no prerequisite for carbon chemistry, which tends to be murky and weird in it’s own right.
I’m not getting my hopes up. Still, I hope…. o_O
Intriquing, but as yet no more convincing as a sign of life than the methane on Mars without further data. As a biologist, I find the possibility of microbial Martian life to be much more plausible than the possibility of life on Titan. Titan is just way too cold for most biochemical reactions to occur at any reasonable rate. And there is still a great deal that we don’t know about general planetology, so there’s an equally good possibility that the situations on both Mars and Titan are due to some abiotic processes that we don’t understand yet.
My position? Cool speculation, nothing more. Wait for more data.
I agree, but…
“Titan is just way too cold for most biochemical reactions to occur at any reasonable rate”
You mean known biochemical reactions or it is an impossibility for any biochemical reaction in general?
And there is also methane in Titan.
On the meantime, I’m going to imagine flying jellyfish-like animals floating in Titan’s atmosphere eating acetylene (hey, imagination is free!)
Chemical reactions in general happen at slower and slower rates as the temperature decreases. At some point, you reach a temperature where any chemical reaction happens at such a low rate that even an exotic alternative biochemistry becomes untenable. Reactions each have a certain energy of activation, and if there is not energy energy available in the environment to overcome that energy barrier, that reaction effectively ceases. Regardless of the reactions involved, it is just difficult to imagine anything that fits a description we would recognize as “alive” (e.g., gathering energy and materials from its environment, growing and reproducing copies of itself) under very cold conditions.
The real question is, where does the point of no return lie on the thermometer? I don’t know for sure, and neither does anyone else, but it is reasonable to postulate that it lies somewhere south of 223 K/ -50 C, and quite possibly not very far below that point at all.
I knew there was life on Titan way before this article: http://www.amazon.com/Titan-Gaea-John-Varley/dp/0441813046 The jury is still out if it’s hermaphrodite centaurs living there, but we can hope.
Wow, way to go old school.
Only the classics, man.
I think life is the least likely of all the possible explanations for this. I think it is much more likely that the alien factories that are building the Earth invasion armada are cranking out hydrogen as a byproduct of their manufacturing techniques.
You don’t think that god’s doing it again on Titan, do you? I mean the Garden of Eden thing. He screwed up here on Earth, so why not try again on a moon. If the Titanics come here spreading the good news of Jesus, I jump ship for sure!
From what I got out of this article it seems more that they are saying this is a sign of environmental factors which would favor the development of one type of hypothetical life. Still pretty cool, but ‘signs of life’ may be just a bit hasty.
http://www.nasa.gov/topics/solarsystem/features/titan20100603.html
“”We suggested hydrogen consumption because it’s the obvious gas for life to consume on Titan, similar to the way we consume oxygen on Earth,” McKay said. “If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water-based life on Earth.”
To date, methane-based life forms are only hypothetical. Scientists have not yet detected this form of life anywhere, though there are liquid-water-based microbes on Earth that thrive on methane or produce it as a waste product. On Titan, where temperatures are around 90 Kelvin (minus 290 degrees Fahrenheit), a methane-based organism would have to use a substance that is liquid as its medium for living processes, but not water itself. Water is frozen solid on Titan’s surface and much too cold to support life as we know it.
The list of liquid candidates is very short: liquid methane and related molecules like ethane. While liquid water is widely regarded as necessary for life, there has been extensive speculation published in the scientific literature that this is not a strict requirement.
The new hydrogen findings are consistent with conditions that could produce an exotic, methane-based life form, but do not definitively prove its existence, said Darrell Strobel, a Cassini interdisciplinary scientist based at Johns Hopkins University in Baltimore, Md., who authored the paper on hydrogen.”
I don’t buy methane/ethane as an alternative solvent for life for chemical reasons. It’s an outside possibility, perhaps, but not on the biologists’ short list. The major drawback is that hydrocarbons are nonpolar and have a limited repertoire of things that they can act as solvents for. And, more damningly, they are definitely not solvents for compounds with polar function groups- the sorts of things you need to build working catalytic enzymes and structural molecules. Water, on the other hand, is as close as you can get to a truly universal solvent. It has several other unusual and important properties not shared by methane/ethane, too.
Ammonia is a much more plausible alternative solvent for life (especially at low temperature and high pressure). It’s a fine polar solvent, like water. But it does have its drawbacks compared to water. The solid form is denser than the liquid form, so ammonia lakes and oceans will freeze from the bottom up, and that ice will be insulated from the spring thaw by the overlying liquid. On Earth, ice forms over the top of the water and acts to keep the liquid underneath warm, and it is exposed directly to the sun during the spring thaw so that it melts quickly. Another drawback is that ammonia is easily broken up by UV radiation from the sun. These problems are not insurmountable, so maybe on a large, cold planet with a thick atmosphere under a red dwarf sun, ammonia would work. But methane and ethane? I could be wrong, but they just don’t look like they’d do the job on Titan, or anywhere else that I can envision.
Iron or nickel pentacarbonyl might work as a solvent for life, if you could get enough of either one together to form a biosphere. A planet like that would pretty much be instant death to any lifeforms from Earth.
So…. No beautiful, naked, blue-skinned women with three breasts, saying “Show me more of this Earth thing called kissing”, then?
(Cookie for anybody who spots the reference).
Sorry. Three-breasted women are probably silicon-based lifeforms anyway.
I see what you did there :D
Nobody got the reference? Disappointing!
I remember the debate of life on Titan from grade school. Whatever it turns out to be, this news is really cool!
http://www.nasa.gov/centers/glenn/technology/warp/scales.html
The most obvious challenge to practical interstellar travel is speed. Our nearest neighboring star is 4.2 Light Years away. Trip times to reach our nearest neighboring star at conventional speeds would be prohibitively long. At 55 miles-per-hour for example, it would take over 50 million years to get there! I don’t think even the twinkies in the glove box would survive that long. At a more typical spacecraft speed, for example the 3-day trip time that it took the Apollo spacecraft to reach the moon, it would still take over 900 thousand years.
I still don’t think the twinkies will make it. And even if we consider the staggering speed of 37-thousand miles-per-hour, which was the speed of the NASA Voyager spacecraft as it left our solar system years ago, the trip would still take 80,000 years. Maybe the twinkies would make it, but there would be nothing left on board to eat them. In conclusion, if we want to cruise to other stars within comfortable and fundable time spans (say, less than a term in Congress), we have to figure out a way to go faster than light.