It's recently been found that Saturn's moon Titan appears to be more earth-like than any other planet or moon in our solar system that has been studied. Not only does it have an atmosphere, but National Geographic has reported that it not only
rains on Titan, but that it also has
lakes. The liquid is not water though, but hydrocarbons, like methane or ethane (although it is thought that there is water ice on Titan). So it's not exactly the same and obviously much colder, but it's similar. But could life still develop in an environment like that? Why not? Why should we assume that life can only develop the same way it has here?
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| Images of lakes on Titan from the Cassini probe. |
In the 2001 movie
Evolution, a meteorite with a alien organism in it crashes on earth. The organism begins to rapidly evolve into recognizable lifeforms, except the lifeforms are nitrogen based instead of carbon based. Of course, the movie is fictional, but what if life elsewhere could be based on another element? If so, what kind of life could potentially be on Titan? And just how close to the surface would we have to get to be able to see if there is life on it? If you look at satellite imagery of North America from space, you can't even see that there are bustling metropolises such as New York City, Chicago, and Los Angeles on the surface until you zoom in closer to the surface.
While I seriously doubt there are any bustling metropolises on Titan, how close to the surface would we need to get to see if there is any recognizable life there? Something larger than microbial? The Huygens probe landed on Titan and took a picture of the surface, and it appeared to be a barren wasteland like Mars.
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| Surface of Titan |
But if a probe from space were to land in the Sahara desert on earth and take a picture, that picture would be of a barren wasteland too. But the Sahara desert only represents a small fraction of the earth's surface and and even smaller fraction of the earth as a whole. What if the Huygens probe had landed somewhere else? Would it still have found a barren wasteland? Despite the lakes of liquid hydrocarbons and water ice, Titan is still drier than earth, so if there is any recognizable life as we know it there, it may very well be considerably less populated and more confined to a specific area or areas.
Hopefully in time we will learn more about Titan and get more close up images of its surface.
One difference between the Hugyens landing site and the Sahara desert... The European Space Agency people carefully monitored what happened when Huygens touched down, and they described the impact as neither a "thud" nor a "splash", but a "splat", implying that the ground is a mud-like mixture of solid and fluid. http://www.esa.int/esaMI/Cassini-Huygens/SEM5YW71Y3E_0.html If there are living things there, at least they have stuff to drink (if they like to drink liquid methane)... You've asked how close we would have to get to observe life-forms bigger than microbes... Surely an extra-terrestrial life-form would be of huge interest, even if it isn't bigger than a microbe? After all, mainstream paleontology says that Earth itself was populated by microbes alone for billions of years... There are also quite large organisms, here on Earth today, which neither sprout leaves nor move about -- I mean the fungi... How would you distinguish a fungus-like Titanian organism from a Titanian rock formation? I doubt that you could, just by observing from a distance. You might need to pick it up, break it open, look at it under a microscope, do chemical tests to see what it is made of...
ReplyDeleteThanks for the link...that was an interesting article. Although I wasn't necessarily suggesting that the Sahara and the surface of Titan were identical or had the exact same conditions, I merely used the Sahara as an example of a barren wasteland on earth. Alternatively, you might could use a random glacier near the north pole as a similar example. If an alien probe landing on a glacier around the north pole, depending on the landing spot, it may just appear to be nothing but a frozen wasteland.
DeleteAs for microbial life, I guess I don't get all that excited about finding microbial life on other worlds for the same reason I don't find it exciting here on earth. I'm just not that fascinated by microbial life. Don't get me wrong though, I'm glad some people are fascinated by it. A lot can be learned from studying microbial life. I just don't find it that interesting myself. I know a lot of people find it exciting to think that there may be some kind of life on other worlds, but I guess to me, when I consider how vast the universe is and how many galaxies there are, it just seems very likely that there is developed life elsewhere in the universe. So microbial life just isn't all that exciting to me personally. But I'm glad it excites someone!
What interests me here on Earth is not so much microbial life in itself, but the eco-system that includes microbial life. Without the soil bacteria and the phytoplankton, Gaia would not be what she is.
ReplyDeleteWhat interests me about Titan is not just the possibility of other organisms, but the possibility of another ecosystem -- another world with energy flows and a carbon cycle, organic stuff building up and breaking down again.
Another thing I find exciting about the possibility of life on Titan -- even if the life-forms there are very simple, their existence could tell us a lot about how easily life gets started on any particular world.
If life does form easily on habitable planets and moons, then yes, large, active organisms like you and me probably do exist on many worlds. I have to say, though, that I don't currently expect them to be found on Titan itself.
My reason for saying this is not just because of the apparent absence of animals and plants in the photos taken by Huygens. It is because (based on scientific literature I've looked at, by people such as Chris McKay), I don't think the energy sources on Titan are sufficient for large active organisms.
Another place they should stop by is Jupiter's moon Europe. It's thought to not only have an atmosphere with oxygen, but also water ice and possibly oceans under the ice.
DeleteEuropa* that is.
DeleteYes, Europa is another interesting place, for sure. It not only seems to have subsurface liquid water, but also oxygen molecules (produced by the effects of radiation on water ice) which living things could use to oxidize organic compounds and obtain energy. On the other hand, it is also possible that those oxygen molecules may actually have prevented life from getting started on Europa. Variations of the Miller/Urey experiment show that the building blocks of life are much more likely to form in low-oxygen conditions. (It is thought that Earth had very little free oxygen when life began here.) So, Europa may, conceivably, have living things as large and active as fish, but it is also quite conceivable that it has nothing at all of biological interest, not even complex organic compounds...
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