Pamela: Welcome to another episode of Slacker Astronomy. Each week we bring you a recent news event in the world of astronomy. And when there is nothing to report, we'll spend our time coming up with excuses for skipping every now and then.
 	Travis: Like we need excuses, hah! We'll skip a week when we darn well feel like it!
 	Pamela: Which, sadly for our social lives, is rare as this show is kind of addictive.
 	Travis: In a crack whore kind of way?
 	Pamela: Well we don't have to sell ourselves to do the show.
 	Travis: Good point!
 	Pamela: This week report on the discovery of liquid water on Saturn's Moon Enceladus. What's so special about liquid water? Well, Slacker Law #14 to be exact. Travis?
 (trumpet fanfare)
	Travis: Slacker Law #14 states that if you have liquid water, heat and time - you get life.
 	Pamela: Add milk and time, and you get soggy life.
	Travis: And while Mikey enjoys his cereal he can listen to our cool news from one of our favorite places: Saturn. The spacecraft Cassini, currently orbiting said planet, took an image of water spraying away from one of its Moons called Enceladus. The image is in the show notes on our site and in the album artwork of this mp3.
	Pamela: In fact, we're putting album artwork in all of the podcast MP3s now, so remember to check it out when listening to the show.
	Travis: This particular eruption was on the far side of the Moon so Cassini didn't see where it originated on the ground. What it saw instead was the water spraying into space out from the limb of the moon, like water from a spray gun. They traced back the path of the water and found that it came from a dark line on the surface.
	Pamela: Over the last year, Cassini has discovered lots of such dark lines across the surface of Encaladus, which scientists described as tiger stripes in their press release.
	sample: tony the tiger they're not good they're grrrreat. (if we can get it)
	Travis: It is believed that these tiger stripes are areas where warm water from below the surface has made its away to the top and then frozen over. These strips are seen all over Jupiter's moon Europa, for which there is a very strong case for a subsurface saltwater ocean that is in either a liquid or slush form.
 (slush puppy mp3?)
	Pamela: So the ice in these cracked areas is very thin compared to the rest of the moon's surface. It stands to reason that pressure was building up beneath the surface as the warmer water attempted to break through the thin ice. Eventually the ice gives away and the liquid water erupts as a geyser.
	Travis: I prefer the term ice volcano!
	Pamela: What about Cryovolcano?
	Travis: Too nerdy, ice volcano! Prefereably with ice dinosaurs.
	Pamela: *Cryovolcanos* aren't entirely unheard of. Voyager 2 directly imaged one on Neptune's moon Triton and Cassini caught one earlier on Encaladus's larger sister moon Titan. The difference is these volcanoes where not made up of water, but mainly nitrogen and methane respectively.
	Travis: We have a cool animation of Triton's ice geyser in the show notes. You can not only see the ice erupting, but you can see it get blown down wind and watch its shadow move on the surface. It's a compelling bunch of images from Voyager that didn't get nearly as much play as it should at the time it was discovered.
	Pamela: So why is this a big deal? First, the plume of water that sprayed away from the moon wasn't made up of just ice, it also had water vapor in it which means that the water below the surface must have been a liquid at boiling temperature.
	Travis: Secondly, separate heat maps of the moon show that the surface is warmer near the dark tiger cracks, which tend of be found on the south side of the moon. In fact, the surface is so warm that it's possible for the liquid water ocean to exist up to just 10 meters below the surface.
	Pamela: And again, we see these same features on Europa where we have other independent evidence supporting the existence of a subsurface ocean there too. So, scientists feel pretty strongly that these tiger marks are associated with subsurface liquid water.
	Travis: Which mean's surf's up for life!
	Pamela: Let's be clear. Any dreams of life on Enceladus are just that - dreams.
	Travis: For now. But the Slacker Law has spoken. We have liquid water, a heat source...
	Pamela: We haven't explain that part yet. How can liquid water exist so far from the Sun?
	Travis: You can handle that question while I check the Flying Spaghetti Handbook for its official take on extraterrestrial life.
	Pamela: Enceladus is only 15% the size of Europa which makes it too small to be able to sustain a molten core. Yet the existence of water vapor, which is a gas, in the plume means that some of the subsurface water has to have had reached the boiling point at some time. The most logical explanation is molten rock. But how does one get molten rock on such a small world? That is a huge unanswered question. The best current theory is that the core of Enceladus is slightly offcenter, which can remain molten longer based on some pretty advanced geologic modelling that I don't pretend to understand. It also would explain why the warm water is confined to a specific region of the moon, in this case its south pole.
	Travis: Okay, I found it. On page 42 of the Flying Spaghetti Handbook it says that the FSM's take on extraterrestrial life is that life should remain on Earth as it is difficult to eat cereal in zero gravity. (pause)
	Pamela: Fat amount of good that did us.
	Travis: Does that mean that the FSM likes to eat people in bowls of milk?
	Pamela: No, it's referring to the cereal Life. The one we've been joking about for the past seven minutes?
	Travis: Oooohhh.. Liiiffee. I get it now. I just thought it was another bad show.
	Pamela: That too..
	Travis: So what does this have to do with life, the real kind? Well, on Earth we have found lots of life in environments similar to what may exist on Enceladus, which needs liquid water, a heat source and some organic material.
	Pamela: Organic material is found all over our solar system, which accounts for the time element in the Slacker Law. Given time, organic material will find its way to the water, usually through cometary or meteor impacts.
	Travis: The life we find in similar environments on Earth is microbial, so we don't expect any radio transmissions, invasion fleets, or...
	Pamela: ...Enceladian corporations selling us breakfast cereal.
	Travis: But it is still life, which is a cool thing.
	Pamela: It's *the* coolest of the cool.
	Travis: And possibly hanging out on Encaladus thanks to a little bit of unexplained heat, some water, some time... and a little space probe that could.
	Pamela: And did.
	Travis: Thanks for listening to another edition of Slacker Astronomy. Don't forget the second XML feed on our web site where we post unscripted shows, interviews and more. Click on the SA Extra feed on our home page or search for Slacker Astronomy on itunes.
	Pamela: I'm Pamela, for Travis and our author Aaron thanks for listening to Slacker Astronomy. A podcast for you, for fun for the voices in our head.