Slashdot Mirror
A Moment Of Reckoning for Cassini
No_Weak_Heart writes "The NASA/ESA Cassini-Huygens probe has caught sight of Titan and is now returning images that 'rival anything scientists have seen before - and that includes images from the Hubble telescope.' See more detailed images at the mission homepage."
But this is a fuzzy dot!Can't we just wait a few months untill it's there.
Nothing in the world is more dangerous than sincere ignorance and conscientious stupidity.
I remember when Cassini was launched - I considered it my birthday present from NASA at the time. Now, it's not long to go... suspense is rising.
Let's hope they find something that gives the general public a run for their money; We need another space race or something to get people out of bed in the mornings.
When was the last time you saw a teenager staring at the sky in awe?
It can take a photo of all of Saturn in super high resolution. One piece at a time, digitally stitched together. We'll get one of those, don't worry.
Fascism trolls keeping me up every night. When I starts a preachin', he HITS ME WITH HIS REICH!
No, just the oposite. If you want to have a thick atmosphere on a planet, you want to have very little energy at the surface. The smaller the planet, the lower ambient surface temperature (hence energy at the surface) required to sustain an atmosphere. If the ambient surface temperature is too high the average velocity of a molecule in the atmostphere exceeds the planet's escape velocity and all the atmostpheric gasses boil off into space.
Titan is a very small planet (larger than Earth's moon but smaller than the planet Mars), so the gravitational pull of Titan is somewhere between 1/3 and 1/6 that of the earth. Similarly, the escape velocity from Titan is much lower than the escape velocity for Earth, somewhere between the escape velocities of the moon and mars.
The only reason that Titan has any atmosphere at all is because it is so far from the sun that it is very cold. Primordial gasses that long since boiled off from the Earth's atmostphere (or Mars') are still trapped by Titan's weak gravity.
The point the other posters were trying to make is that decades worth of spectrographic studies of Titan's atmosphere have shown the atmosphere to be chemically neutral. It is thought that the presence of life would result in a chemically active atmosphere (one that could support oxidation, which the life-forms would use as part of their metabolic processes, just as we extract oxygen from the air in order to metabolize sugars, producing carbon-dioxide). We are not saying that the atmosphere must contain oxygen, or that all life must be based on a carbon/oxygen metabolism, only that the atmosphere must present some way for life to extract energy, or the by-products of some kind of metabolism must be evident in the atmosphere.
Since Titan's atmosphere is chemically neutral (mostly methane) there is no latent energy that could power living organisms, hence no organisms (at least, none that are still alive: they would have suffocated or frozen). If you say "But what if they are able to breath methane?" then you need to account for what they would do with the methane. Either you need to burn it (for which you need oxygen) or you need to get the energy from somewhere else (sunlight, for example). There isn't any oxygen in Titan's atmosphere, so burning isn't an option, and Titan is too far from the sun for sunlight to be of much use. That exhausts most of the possibilities.
None of this should be taken as proof that there is no life on Titan, or that life on Titan is impossible: it's just not very likely, given what we expect life to be like. If there were life on Titan, it would have to be very different from what we generally expect: it would have to use very small amounts of energy, and it might have to extract that energy from some very novel sources. We are talking something that is, essentially, indistinguishable from pebbles, rocks and sand. Even then, this life-form would need to have little or no interaction with Titan's atmosphere, otherwise we would see some effect from it's respiration in the atmosphereic chemistry.