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Could there be life on Titan? If so, one astrobiologist says humans probably couldn’t be in the same room with a Titanian and live to tell about it. “Hollywood would have problems with these aliens” said Dr. William Bains. “Beam one onto the Starship Enterprise and it would boil and then burst into flames, and the fumes would kill everyone in range. Even a tiny whiff of its breath would smell unbelievably horrible. But I think it is all the more interesting for that reason. Wouldn’t it be sad if the most alien things we found in the galaxy were just like us, but blue and with tails?”
While giving an obvious nod to the recent movie “Avatar,” Bains’ research provides insight to the difficulties we might encounter – beyond cultural – if we ever meet up with alien life. There could be unintended harmful consequences for one species, or both.
Bains is working to find out just how extreme the chemistry of life can be. Life on Titan, Saturn’s largest moon, represents one of the more bizarre scenarios being studied. While images sent back by the Cassini/Huygens mission might make Titan look Earth-like and maybe even inviting, it has a thick atmosphere of frozen, orange smog. At ten times our distance from the Sun, it is a frigid place, with a surface temperature of -180 degrees Celsius. Water is permanently frozen into ice and the only liquid available is liquid methane and ethane.
So instead of water based-life (like us), life on Titan would likely be based on methane.
“Life needs a liquid; even the driest desert plant on Earth needs water for its metabolism to work. So, if life were to exist on Titan, it must have blood based on liquid methane, not water. That means its whole chemistry is radically different. The molecules must be made of a wider variety of elements than we use, but put together in smaller molecules. It would also be much more chemically reactive,” said Bains.
Additionally, Bains said a metabolism running in liquid methane would have to be built of smaller molecules than terrestrial biochemistry.
“Terrestrial life uses about 700 molecules, but to find the right 700 there is reason to suppose that you need to be able to make 10 million or more,” Bains said. “The issue is not how many molecules you can make, but whether you can make the collection you need to assemble a metabolism.”
Bains said doing such assembling is like trying to find bits of wood in a lumber-yard to make a table.
“In theory you only need 5,” he said. “But you may have a lumber-yard full of offcuts and still not find exactly the right five that fit together. So you need the potential to make many more molecules than you actually need. Thus the 6-atom chemicals on Titan would have to include much more diverse bond types and probably more diverse elements, including sulphur and phosphorus in much more diverse and (to us) unstable forms, and other elements such as silicon.”
Energy is another factor that would affect the type of life that could evolve on Titan. With Sunlight a tenth of a percent as intense on Titan’s surface as on the surface of Earth, energy is likely to be in short supply.
“Rapid movement or growth needs a lot of energy, so slow-growing, lichen-like organisms are possible in theory, but velociraptors are pretty much ruled out,” said Bains.
Whatever life may be on Titan, at least we know there won’t be a Jurassic Park.
Bains, whose research is carried out through Rufus Scientific in Cambridge, UK, and MIT in the USA, is presenting his research at the National Astronomy Meeting in Glasgow, Scotland on April 13, 2010.
Source: RAS NAM
This is IMO wrong.
While we don’t know how metabolism evolved, if this early evolution was something like todays inheritable one it moves as descent with modification. Also, a problem that biologists (but perhaps not astrobiologists) discuss is exactly the problem with side reactions. It is how to achieve metabolic closure in a robust way that is the problem.
And to nitpick Bain: here he means basic component molecules of metabolism, not the actual composite ones.
The other point of Bain, that you need variation to have useful selection, is well taken. That isn’t a problem on Titan, where complex organics rain down from the ionosphere. In fact, his lichen-like organisms are unlikely to evolve with such a readily available energy/organics flow already in place.
Alternative biochemistries are interesting to speclate about. You still need energy flow through to drive life.
If there is a lab which studies Titanian life, no smoking signs are advised.
LC
Not only do you need energy flow, but you need to have a barrier to energy at some point in the system. If there is no barrier, then simple chemical reactions will take care of the entire flow of energy, from highest to lowest energies.
On Earth the barrier comes in the form of CO2. It contains a lot of energy, but it is very difficult to break down into lower energy forms via simple reactions. Hence a bloat of energy (or perhaps “fuel” would be a better term) built up in one form, and life formed to utilize that fuel.
Dr. William Bains:
I am tempted to make a satirical comment about that with reference to our EU/PC ‘friends’ here, especially one certain individual named after a snake, but I have to restrain myself because of what Jean Tate stated about Fraser’s “Be nice” comment policy. Alas, my whole comedy routine is now ruined. 😐
I started off that “hence” sentence intending to say something else, and then changed my mind, but left the “hence” in there. Oops:P.
@gopher65: Carbon dioxide is pretty low on the chemical energy ladder. About the only chemical reaction possible is of the form
2Fe_2O_3 + CO_2 + SI —> SiC + 2Fe_2O_4,
which is not very exo-enegetic. SiC (silicon carbide) is useful though.
LC
Hmm – I guess that that would put an Titanians at a distinct disadvantage when it came to interplanetary warfare… Although they could use Kamikaze to devastating effect.
Curiously, intelligent life on planets with hot NOx atmospheres, sulfuric acid seas and sulfur-based biology write very similar speculations about cryogenic planets (i.e. colder than frozen sulfur) which feature liquified water, elemental oxygen and carbon-based biologies. Wildly speculative fiction most conservative biologists on such planets have concluded about such imagined biologies.
It’s not the amount of energy available that really counts, but the delta E – the difference in energy. As long as there’s chemistry, there can be theoretically enough for chemical life to exist. Unfortunately, we Earthlings know very little about low-temperature chemistry – most familiar organic chemistry ceases at the temperatures on Titan.
I feel we may have already detected Titan life – “paint-like layers” have been mentioned by Cassini – I think they could be stromatolithic. As discussed in the article, their astro-biochemistry will be totally different then that of Earth.
I just want to point out: “with a surface temperature of -180 degrees Celsius. Water is permanently frozen into ice…”
That is like saying on Earth: “with a surface temperature of 75 degrees Fahrenheit lava is permanently frozen into ice…”
Water is a mineral on Titan, folks. Essentially, it is a rock, like quartz is on Earth. Okay, that’s semantics, but it does say more about the harshness of the environment and the nonavailability of water.
sulfur or methane-based life !!
that was mind-blowing !! It is a quite unusual way of looking to life… that´s how science grows up…
I vote for cryro-life as more likely than thermo-life. In the article it is mentioned there are 700 chemicals, things like surgar rings, carboxyl groups, amino acids etc, form the blocks that construct complex molecules. That complexity is a measure of information. At high temperatures these rather floppy structures will have their bonds thermally fluctuate or oscillate, and large complex floppy structures might be prevented.. So temperatures can’t be too high. I will say that maybe a 300C planet could harbor life, and the water planet found a couple of months ago might, just might, bear life. Detecting it will be a neat trick though. I’d kiss my butt if Venus turned up with some sort of life on its surface — though maybe the upper atmosphere has something.
LC
Lawrence B. Crowell:
That’s the point. It’s very difficult to *directly* get energy out of CO2. You need multiple intermediate steps, and some of those steps are endothermic. That’s why you need life:P. Simple, direct chemical reactions just don’t cut it.