Lake On Titan Winks From a Billion Kilometers Away 139
The Bad Astronomer writes "NASA's Cassini spacecraft took an image of Saturn's giant moon Titan earlier this year that serendipitously provides proof of liquid (probably methane) on its surface. The picture shows a glint of reflected sunlight off of a monster lake called Kraken Mare (larger than the Caspian Sea!). Scientists have been getting better and better evidence of liquid methane on Titan, but this is the first direct proof."
And given the possibility of life... (Score:5, Informative)
Prior to this, the main evidence that Titan might have liquid methane was based on the reflection of radio waves detected by the Cassini probe. In particular, there were discrepancies between what one would expect and what was observed in the percentage of reflection in the ELF range (about 2 to 30 Hz). This discrepancy suggests some form of boundary layer, such as a boundary between liquid and solid methane or between liquid methane and some other solid substance. There's also a lot of evidence for a large internal methane sea under the solid surface. We still know very little about Titan. We've only sent a single probe (Huygens) actually dedicated to investigating it. However, even Huygens wasn't much and was just a part of the larger Cassini mission. The next scheduled mission is the TSSM (Titan Saturn System Mission) (http://en.wikipedia.org/wiki/Titan_Saturn_System_Mission [wikipedia.org] http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=44033 [esa.int]) which will focus a lot more on Titan. Hopefully a lot of the mysteries about the moon will then be answered.
Titan is routinely used as an example of a moon that might have life. Unfortunately, if there is any life, it is almost certainly microbial. So no one is appreciating the view from the planet.
Re:billion kilometers (Score:4, Informative)
Just be glad it's not "Lake on Titan Winks from 621 Million Miles Away"
Or "Lake on Titan Winks from 4.97 billion Furlongs Away"
Or "Lake on Titan Winks from 10^-12 Diopters Away"
Re:How do they know it's methane (Score:5, Informative)
Re:billion kilometers (Score:3, Informative)
Depends on whether those are British billions or normal billions.
http://www.askoxford.com/asktheexperts/faq/aboutwords/billion?view=uk [askoxford.com]
Re:Proof (Score:4, Informative)
Re:And given the possibility of life... (Score:3, Informative)
The Huygens probe was actually designed to float in liquid in case it encountered a pond, lake, or ocean. It would have been interesting if it did, but alas it landed on just dry land (or at least frozen-solid land). However, the rocks (possibly water-ice) it imaged at the surface were rounded off, suggesting that they used to be embedded in liquid.
Re:billion kilometers (Score:1, Informative)
Exactly; if they used a metric prefix, there would not be that ambiguity.
Re:Where do the hydrocarbons come from? (Score:5, Informative)
Methane is the precursor to organic molecules, in a more general sense, not the result of biological processes. When you're the simplest combination of carbon (what, the fourth most abundant element in the universe?) and hydrogen (the most abundant element), it's hard to argue that your existence requires biological processes. (Particularly as methane is found everywhere volatiles can be found in our solar system and outside of it.)
Perhaps you're confused by the fact that methane on Earth is usually the result of biological activity? That's because in our peculiar atmosphere, methane can't survive long before oxidation.
Re:Where do the hydrocarbons come from? (Score:3, Informative)
Re:billion kilometers (Score:3, Informative)
Even if Diopter was a proper measure of length (and it isn't), it would actually be 1/(10^-12 Diopter) as Diopter is the reciprocal of a focal length to measure optical power. Still, it's an interesting way of putting it.
Re:How do they know it's methane (Score:1, Informative)
The text parent is paraphrasing belongs to 2010: Odyssey Two, directed by Peter Hyams. No Kubrick around.
Re:billion kilometers (Score:2, Informative)
I'm afraid you are being pedantic. Both are acceptable. The "-re" suffix is an influence from French. If you look at French words for measuring devices as well as units of measure, you will understand this.
Re:billion kilometers (Score:1, Informative)
Mod parent +1E0 Informative but Pedantic.
I'll show you pedantic; it's spelled terametre.
It's spelt "spelt", not "spelled", if you insist on using British English, my pedantic friend.
Re:billion kilometers (Score:5, Informative)
No matter how you say it, it's wrong. It winks from 200,000 kilometers away. The rest of the distance was just data transfer.
Re:Where do the hydrocarbons come from? (Score:3, Informative)
Lets try to find life that has nothing to do with the life we know and endure on this planet and would die if it tried to live amongst us.
No. What you are saying is basically, "We should be looking for something we can't imagine." I'd like to point out that this is basically the same as saying "Let's find some shit," and doesn't help whatsoever in directing us WHERE we ought to be looking for life. If you want to find life, you need some kind of strategy to narrow down the billions of possible places to look to something that's likely to turn up some results. Looking for something that, by definition, you have no idea how to look for, is not a fruitful use of resources.
Water, carbon, nitrogen, these are not rare materials in the universe. Chances are pretty good that if life could form from these materials here, it could form elsewhere. And we know WHAT to look for to recognize the signs of life as we know it. Only if we look long and hard, and find no signs of life as we know it anywhere in the measurable universe, should we turn to such vague propositions as "Let's look for something we can't imagine."
Re:Where do the hydrocarbons come from? (Score:2, Informative)
> There's also a ton of helium. It is not really surprising that these common elements might be found, in combination, in large quantities.
I don't think you'll find helium combining with anything much ;-) I think you meant 'hydrogen' :-P
Re:billion kilometers (Score:5, Informative)
Actually it's one and a half hour away. At light' speed, I mean.
I happen to have been tech resp. of the european Huygens probe that Cassini brought to Titan, and what I remember the most from the time of Huygens descent and landing years ago, is this feeling that all the active descent has *already* happened, while here on Earth we didn't yet have received the first bits of info, radiowave that were still into the travel.
Indeed that was a very real way of measuring distance. Saturn definitely is not close...
Hervé S. (now back on more conventional Earth observation spacecraft designs ;-)
Re:How do they know it's methane (Score:3, Informative)
indeed on Titan the ground rocks are constituted of almost pure water ice, and over there ice just will be rock-hard forever.
The pebble on these Cassini-Huygens lander photos are ice: http://www.esa.int/SPECIALS/Cassini-Huygens/SEMEMY71Y3E_0.html [esa.int] (visible on the orange vertical image that is the "last photo" Huygens took once on ground)
Hervé
Re:billion kilometers (Score:3, Informative)
Both work [wiktionary.org]
I, at least, prefer reducing the sheer number of irregular verbs out there.
Re:Titan life bleak. (Score:3, Informative)
The other problem, I think, is a lack of oxygen.
There's plenty of oxygen on Titan. The whole crust is made out of water ice. True there is no free molecular oxygen, but neither was there on Earth before about a billion years ago.
As for life on Titan, the suggestion is that there might be an opportunity when the liquid water beneath Titan's 50-km-thick ice crust bubbles to the surface (a "cryovolcano"), or when a meteor impact leaves a patch of melted local bedrock (which is water ice, so the patch would be a lake). When liquid water from one of these sources combines with the organics in the atmosphere, who knows what happens. But it better happen fast -- the whole thing freezes over in 10^4 years!