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	<description>Take a weekly facts-based journey through the cosmos with Astronomy Cast.</description>
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		<title>Ep. 175: Mysteries of the Solar System, Part 2</title>
		<link>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-175-mysteries-of-the-solar-system-part-2/</link>
		<comments>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-175-mysteries-of-the-solar-system-part-2/#comments</comments>
		<pubDate>Wed, 03 Mar 2010 00:32:44 +0000</pubDate>
		<dc:creator>Astronomy Cast</dc:creator>
				<category><![CDATA[Our Solar System]]></category>

		<guid isPermaLink="false">http://www.astronomycast.com/?p=1282</guid>
		<description><![CDATA[Apparently this is at least a 2 part series. This week we continue examining some of the baffling mysteries of the Solar System, where we fill your head with more questions than answers. Sometimes we&#039;ve just got to share the enjoyment of not knowing the answer.





Download Ep. 175: Mysteries of the Solar System, Part 2 [...]]]></description>
			<content:encoded><![CDATA[<p>Apparently this is at least a 2 part series. This week we continue examining some of the baffling mysteries of the Solar System, where we fill your head with more questions than answers. Sometimes we&#039;ve just got to share the enjoyment of not knowing the answer.</p>
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		<title>Ep. 174: Mysteries of the Solar System, Part 1</title>
		<link>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-174-mysteries-of-the-solar-system-part-1/</link>
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		<pubDate>Thu, 25 Feb 2010 06:51:19 +0000</pubDate>
		<dc:creator>Astronomy Cast</dc:creator>
				<category><![CDATA[Our Solar System]]></category>

		<guid isPermaLink="false">http://www.astronomycast.com/?p=1273</guid>
		<description><![CDATA[We know a lot about our Solar System, but there&#039;s an awful lot that&#039;s a complete and total mystery. Today we&#039;re going to begin a series of unknown length examining some of these mysteries, and explain the best theories astronomers have so far. 





Download Ep. 174: Mysteries of the Solar System, Part 1 [mp3]
Jump to [...]]]></description>
			<content:encoded><![CDATA[<p>We know a lot about our Solar System, but there&#039;s an awful lot that&#039;s a complete and total mystery. Today we&#039;re going to begin a series of unknown length examining some of these mysteries, and explain the best theories astronomers have so far. </p>
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<li><strong><a href="http://traffic.libsyn.com/astronomycast/AstroCast-100125.mp3">Download Ep. 174: Mysteries of the Solar System, Part 1 [mp3]</a></strong></li>
<li><a href="#shownotes">Jump to Shownotes</a></li>
<li><a href="#transcript">Jump to Transcript</a> or <a href="http://www.astronomycast.com/transcripts/AstroCast-100125_transcript.pdf">Download</a></li>
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<h3>Transcript: Mysteries of the Solar System, Part 1</h3>
<p></a><strong><a href="http://www.astronomycast.com/transcripts/AstroCast-100125_transcript.pdf">Download the transcript</a></strong></p>
<p><b>Fraser:</b>  Astronomy Cast Episode 174 for Monday January 25, 2010, Mysteries of the Solar System, Part 1. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I&#039;m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville. Hi Pamela, how&#039;re you doing?
</p>
<p><b>Pamela:</b>  I&#039;m doing well Fraser, how are you doing?
</p>
<p><b>Fraser:</b>  I&#039;m doing great! So this week&#8230; well, we know a lot about our solar system, and there&#039;s an awful lot that is a complete and total mystery. Today we&#039;re going to begin a series of unknown length examining some of these mysteries and explain the best theories that astronomers have so far. So I think that one of the problems that we do is that we kinda come up with an idea for a show, and we have a schedule, and I&#039;m often rushing Pamela to kind of meet the schedule, meet the time. Well, I&#039;m not going to be time&#039;s slave anymore&#8230; so we have no idea how many part series this is going to be. Could be a one-part series&#8230; but, you know, more likely no&#8230; it&#039;ll probably stretch on further. But, it&#039;s so cool&#8230; and you know what&#039;s kind of interesting is&#8230; now, I&#039;m kinda going off on a tangent&#8211;sorry&#8230; my daughter is studying space and astronomy in her school, and I&#039;m going to come in and give a presentation to her class that is essentially the podcast we&#039;re going to do today, which is a collection of crazy mysteries in the solar system and the best ideas that we have. But I get to show pictures to the class&#8230; you&#039;ll just have to use your imaginations&#8230; or follow along on the web as you go&#8230; so, let&#039;s get on with it! These are big mysteries in the solar system&#8230; in some cases astronomers have some idea of what we&#039;re talking about&#8230; in other cases&#8211;no idea. Should we start with the Pioneer anomaly?
</p>
<p><b>Pamela:</b>  Let&#039;s go ahead and start with that. It&#039;s kind of the oldest of the mysteries, I think.
</p>
<p><b>Fraser:</b>  Alright, let&#039;s do it. So, in case you weren&#039;t aware, there is a weird situation where the Pioneer spacecraft aren&#039;t where they&#039;re supposed to be. So what&#039;s going on?
</p>
<p><b>Pamela:</b>  Well, as they&#039;re moving out towards the edge of our solar system, as they move out towards leaving our solar system we have calculations on how much they should be slowing down as they go because the sun and the solar system&#039;s gravity is pulling on them, we have calculations on&#8230; ok, we fired the rockets here this amount&#8230; We should know everything about how these suckers are moving through space. We know that there might be some factors to correct for&#8230; they fire off radio transmissions toward Earth&#8211;that might have an effect. They get heated up by the sun&#8211;that might have an effect. And when you put all these pieces together and you figure out where they should be&#8211;they&#039;re not there. It turns out that for reasons we can&#039;t really explain&#8211;and this is true for Pioneer I and  Pioneer II&#8211;both the missions seem to be slowing down more than they should be, and we can&#039;t explain it.
</p>
<p><b>Fraser:</b>  So, they&#039;re not as far from the sun as we would expect them to be.
</p>
<p><b>Pamela:</b>  Right.
</p>
<p><b>Fraser:</b>  And even when you plug in Newton&#039;s formulas for gravity and then you try Einstein&#039;s formulas for gravity and you include all that stuff&#8211;the additional push of them using the radio transmitters&#8230; that&#039;s a pretty weak amount of push that they must be getting&#8211;they&#039;re still slowing down too quickly.
</p>
<p><b>Pamela:</b>  Right. And the thing is, all of these things that we&#039;ve tried to blame the Pioneer anomaly on&#8211;the fact that that they are using their antennae to blast radio signals&#8230; that should be accelerating them away from the solar system, the fact that the sun is heating them on one side and not the other&#8230; that should be pushing them away from the solar system&#8230; So, for some reason those things aren&#039;t pushing them out of the solar system, or at least there&#039;s something else keeping them in the solar system with an even stronger force. And all we can really do is go over the numbers again and start scrutinizing how we built the missions. And the crazy thing is, within error, it looks like we might have the exact same results for the Cassini and Galileo missions as well on their way out to Jupiter and Saturn.
</p>
<p><b>Fraser:</b>  What about the Voyagers?
</p>
<p><b>Pamela:</b>  The Voyager missions&#8230; and now we&#039;re going to hopefully have New Horizons as another case study to look at. But we&#039;re not sure how to explain how these different missions all have, with their different architectures, seemingly the same anomaly. Now the thing is so far, Cassini, New Horizons, and Galileo haven&#039;t gotten that far out and we have a completely different design for those missions than we have for the older ones. And we also, more importantly, have a different way of transmitting and storing the data. And one of the things that&#039;s being scrutinized is are changes in how we look at the data&#8230; are those differences over all the years and all the different format changes&#8211;are those the responsible party? Or does it actually have something to do with the spacecraft and its fuel cells perhaps giving off heat in one direction but not the other.
</p>
<p><b>Fraser:</b>  And so it&#039;s either a measurement error&#8230;
</p>
<p><b>Pamela:</b>  Yep.
</p>
<p><b>Fraser:</b>  It&#039;s an unknown&#8230; sort of something going on with the spacecraft, some interaction that we&#039;re not thinking of, like&#8230;
</p>
<p><b>Pamela:</b>  One side is hot due to the fuel cell, and that side is the one that&#039;s away from the sun and that heat from the fuel cell is creating a force.
</p>
<p><b>Fraser:</b>  Or, it is deep and fundamental&#8230; that there is some understanding of basic physics of about how things move in space over long distances that we just don&#039;t understand.
</p>
<p><b>Pamela:</b>  And that&#039;s the most painful one to deal with because when we look at the orbit&#039;s of the Kuiper Belt objects&#8212;they make sense. When we look at the orbits of Uranus and Neptune&#8211;they make sense. When we look at the orbits of even all of their moons&#8211;they make sense. So, whatever it is, if it is fundamental physics, is only working on this radial axis from the sun, and it&#039;s not affecting things orbiting the sun. And that just seems crazy.
</p>
<p><b>Fraser:</b>  So, things moving away from the sun experience this thing&#8230; whatever it is. And it could be, you know&#8230;
</p>
<p><b>Pamela:</b>  Just the way we built the suckers causes them to behave differently&#8230; that could be it.
</p>
<p><b>Fraser:</b>  Right. And this is one of those things&#8230; it&#039;s so great because it&#039;s so simple. It could be either&#8230; oh, yeah, we have a slight modification to our math&#8230; oh, we wrote down the numbers wrong, or we don&#039;t understand gravity&#8230; you know&#8230;. It&#039;s quite a wide range of possibilities, so&#8230; anyway&#8230; so that&#039;s it&#8211;mystery! We don&#039;t know&#8230; stay tuned! So, mystery number two&#8211;the strange axes of Uranus and Venus. So, Venus is flipped completely upside down, so&#8230;
</p>
<p><b>Pamela:</b>  177.3 degrees off of normal.
</p>
<p><b>Fraser:</b>  Right, so imagine you take the earth spinning&#8230; you flip it upside down but still keep it spinning in the same direction&#8230; from your perspective looking at the planet now&#8230; it&#039;s going the wrong direction. Venus rotates backwards to all the other planets in the solar system. Uranus has just been rolled only onto its side, so, you know, sometimes it&#039;s pointing its south pole at the sun, and other times it&#039;s pointing its north pole at the sun, and&#8230; you know&#8230; is spinning on its side.
</p>
<p><b>Pamela:</b>  It&#039;s tilted 97.7 degrees. So neither of them are quite dead on&#8230; but, wow they&#039;re close.
</p>
<p><b>Fraser:</b>  So what is up with that?
</p>
<p><b>Pamela:</b>  Well, we don&#039;t quite know.
</p>
<p><b>Fraser:</b>  Right, the earth has an axial tilt of 23.5 degrees&#8230; Mars is kinda similar&#8230; Mercury is kinda similar&#8230; Jupiter, Saturn, they&#039;re all close to that.
</p>
<p><b>Pamela:</b>  So, we have two different mainstream theories. The first is that in both cases&#8230; take a planet, whack a planet with another planet, and it flips over. With Uranus, that starts to get a little bit troubling because you need to get things really big to hit it, and we just don&#039;t know if there was anything that big hanging out doing the colliding back then.
</p>
<p><b>Fraser:</b>  But couldn&#039;t just time do the trick for you? You hit it with something&#8230; I don&#039;t know&#8230; Mars-sized, and then you just give it 4.5 billion years to roll over?
</p>
<p><b>Pamela:</b>  No, because these things tend to either keep rolling once set into motion&#8211;it&#039;s &#034;things in motion stay in motion&#034; that&#039;s a problem&#8211;or, once you whack it, it just stays put. That&#039;s the way it normally works out is you just whack something into a new stability. Rotating objects are very consistent in keeping their axes pointing in one direction&#8211;this is how gyroscopes work on space stations, on spacecraft. Without this characteristic of spinning objects, we wouldn&#039;t be able to move spacecraft around. Planets are just spinning tops, they&#039;re their own form of gyroscopes so they&#039;re spin-stabilized is one way to think of it.
</p>
<p><b>Fraser:</b>  Right, and here on Earth we have the precession, right&#8230; where we have a bit of a wobble, but that wobble stays within that very specific range, and so you still have the wobbling of the top but it&#039;s not like it wobbles over to one point and then just stays there&#8230; it&#039;s always kind of moving back and forth and back and forth.
</p>
<p><b>Pamela:</b>  And so here&#8230; it could be that we played &#034;Whack-a-World&#034; but the other option is&#8230;. well, maybe this is just tidal effects, maybe this is resonances. One of the things about the formation of the solar system that people are playing with is it&#039;s hard to explain how to explain how Uranus and Neptune could have formed where they are located today. But, what is easier to imagine, is that all of the gassy planets, all of the two ice giants and the two giant gases&#8211;Jupiter and Saturn, Uranus and Neptune&#8211;what if they all formed closer to the sun but Saturn and Jupiter hit a resonance where their resonance caused all sorts of crazy things to happen. There are several different ways of modeling this that start out with all four planets basically tumbling in a gas-giant ball and then moving apart and you basically end up flinging Uranus and Neptune out to the outer solar system. Other cases they start out as four distinct orbits but Saturn ends up on a more and more elliptical orbit over time due to a resonance with Jupiter until it finally settles into an almost circular much larger orbit and in the process also flings Uranus and Neptune out to the outer solar system.
</p>
<p><b>Fraser:</b>  So it&#039;s almost like you need one process to start the movement and then a second process to stop it. You need the start, and then you need the brakes&#8230; to kick on the brakes again to make it stop.
</p>
<p><b>Pamela:</b>  And this is where ending the resonance is essentially putting the brakes on.
</p>
<p><b>Fraser:</b>  Right, right. Because, I mean, we have examples of asteroids that are tumbling in two directions&#8230; they&#039;re rotating and they&#039;re also tumbling because&#8230; and they&#039;ll never stop because nothing&#039;s ever stopping them from doing the tumbling part.
</p>
<p><b>Pamela:</b>  Right. And with Venus it&#039;s thought that maybe some sort of a chaotic process where it was getting gravitationally beat up by the planet Earth in some ways was what got it into its situation. If you look at how long its day is&#8230; it&#039;s a resonance with how often Venus and Earth and the Sun all line up into a nice straight line. So it&#039;s possible that this is just the pull of gravity over time gradually tilting and tilting and flipping through all the different resonances in the solar system. Venus just happened to be the one that was susceptible to being put on its head.
</p>
<p><b>Fraser:</b>  So why are Uranus and Venus&#8230; they&#039;re axial tilts off the plane of the ecliptic? It&#039;s a mystery. Alright, mystery number three&#8230; what is underneath the ice on Europa?
</p>
<p><b>Pamela:</b>  Hopefully water.
</p>
<p><b>Fraser:</b>  Hopefully water&#8230; right, so once again, we&#039;ve got the situation where Jupiter has its four Jovian moons: Io, Europa, Ganymede, Callisto, and the tidal flexing from the gravity of Jupiter is kinda squishing these moons and then&#8230; keeping them softer than they ought to be. With Io, it&#039;s full-blown volcanism with huge&#8230; magma and lava coming out, with Europa it&#039;s not quite as devastating, but you can see&#8230; astronomers are pretty certain that there&#039;s a shell of ice and underneath that is a great big liquid water ocean&#8230; maybe?
</p>
<p><b>Pamela:</b>  Maybe. And this is what we&#039;re hoping. What we do know is that when you look at images of Europa, it&#039;s one of the most beautiful moons in the solar system, I think, it in many ways looks like some sort of a blown-glass ball covered in cracks in the glaze. It highlights in blues and in oranges in many of the different Galileo images. This strange little icy world is actually the reason that we plunged Galileo into the Jovian atmosphere. This moon, through cracks in its surface, is constantly resurfacing. What this means is craters that form on Europa don&#039;t get to stay there. They instead get filled in. Basically, a  geophysical Zamboni is constantly clearing the ice of Europa.
</p>
<p><b>Fraser:</b>  I was going to use the Zamboni reference! That&#039;s exactly what it is, right? Every now and then the ice gets all smoothed over again.
</p>
<p><b>Pamela:</b>  Right, and the easiest way to explain this is the Zamboni method&#8230;. you just spray the sucker with liquid and the liquid refreezes and you&#039;re back to a nice smooth surface.
</p>
<p><b>Fraser:</b>  And where&#039;s the spray coming from?
</p>
<p><b>Pamela:</b>  And that&#039;s the question&#8230; we don&#039;t see it directly, but more likely we simply have this slow coming-up, this slow puddling&#8230; more like what you see if you go to Yellowstone and visit the bubbling mud pots than if you go and visit the geyser of Old Faithful. So somehow liquid is coming up to the surface, and if liquid is coming up to the surface, that means there is liquid below the surface.
</p>
<p><b>Fraser:</b>  Right.
</p>
<p><b>Pamela:</b>  And the models&#8230; some of them say the ice is a kilometer deep, some of them say it&#039;s tens of kilometers deep&#8230; but no matter how deep it is, there&#039;s probably an active rocky core underneath that&#039;s doing the heating.
</p>
<p><b>Fraser:</b>  Io&#8230; what&#039;s happening to Io is happening to the core of Europa&#8230; it&#039;s being flexed and heated, and putting out heat, but it&#039;s not turning into great big plumes of lava&#8230; it&#039;s just keeping this ocean warm.
</p>
<p><b>Pamela:</b>  And the amazing thing to think about&#8211;and there are a few papers related to this&#8211;is it could be that you have mid-European ocean volcanoes and basically lava plumes just like you find in the deep trenches here on the planet Earth. And it&#039;s those deep ocean plumes that are so rich with life that never sees any sunlight, so we know that this form of volcanism under water is capable of supporting life. This makes people wonder, very honestly, could there be life supported under the ice on Europa?
</p>
<p><b>Fraser:</b>  Yeah, people don&#039;t realize you could destroy the sun and there would still be life on Earth.
</p>
<p><b>Pamela:</b>  Until it cooled off&#8230;
</p>
<p><b>Fraser:</b>  Until it cooled off, but for billions of years you would have the geothermal heat heating the oceans, keeping life going&#8230; no problem. So, who knows what&#039;s under there&#8230; Now, is there going to be any way that we&#039;re going to know? I know there were ideas to send a probe that could melt down through the ice and try to make its way down to the ocean.
</p>
<p><b>Pamela:</b>  Like so many problems, this is one that comes strictly down to money. There are robots being designed and tested right now that, if you drop them into an underground lake, are capable of going down and on their own exploring and mapping what exists down beneath the surface of the planet Earth. Then they come back and they radio their results. So what we need is to develop a robot that takes this one step further and digs a hole for itself through the ice and drops itself into what is hopefully not too far down&#8230; liquid water, and then digs itself back up to the surface and beams its results back.
</p>
<p><b>Fraser:</b>  Or, leaves a tether behind, right&#8230; some kind of communication tether&#8230; it leaves that up on the surface, melts its way or bores its way down through the ice, gets down to the ocean, leaves that as a way to communicate and then travels down into the ocean to see what&#039;s below. It&#039;s a monumental engineering challenge to make that work.
</p>
<p><b>Pamela:</b>  And beyond just the budget difficulties, anything that&#039;s swimming around underneath the ocean of Europa&#8230; or underneath the ice of Europa, rather&#8230; won&#039;t be able to use solar panels. To continue exploring the outer solar system, and to explore places where literally the sun doesn&#039;t shine, we need to use radioactive fuel cells, we need to use radioisotopes. Right now, here in the United States, we have a shortage of these. We&#039;re simply not developing the fuels that are needed to power spacecraft. A lot of international treaties govern what nuclear isotopes you develop and you process and you refine and all those other different things. And under treaty, it&#039;s unclear if we can create fuel cells we need for our space program.
</p>
<p><b>Fraser:</b>  So, who knows&#8230; this is one of those situations where I&#039;ll bet you someone&#039;s going to come up with a clever way to analyze the ice on the surface and detect evidence of life&#039;s outputs&#8230; right?  Micropoop in the ice on Europa&#8230; so we&#039;ll stay tuned on that one&#8230;<br />
Ok, so next&#8230; mystery number four&#8230; what is creating the methane on Mars?
</p>
<p><b>Pamela:</b>  Yeah, we don&#039;t know that one either&#8230;
</p>
<p><b>Fraser:</b>  No, I know&#8230; but this is huge!
</p>
<p><b>Pamela:</b>  This is one of those amazing discoveries!
</p>
<p><b>Fraser:</b>  Yeah, so once again, to set the scene&#8230; the European Space Agency&#039;s Mars Express spacecraft discovered the faintest whiff of methane in the atmosphere of Mars. This is really shocking and surprising because methane is destroyed by sunlight in a very short period of time so there has to be some source replenishing the methane. What&#039;s creating it?
</p>
<p><b>Pamela:</b>  And during the northern summer, they were actually finding as much as 30 parts per billion of methane in the Martian atmosphere, and methane is something that gets actively destroyed by the sun. Sunlight&#8230; ultraviolet light hits methane&#8230; methane stops being methane, it&#039;s happy to do that. So this is something that&#039;s being actively produced, and we only know of two sources of methane.
</p>
<p><b>Fraser:</b>  Source number one?
</p>
<p><b>Pamela:</b>  &#8230;is lava, geophysical activity, something indicative of the planet being alive geophysically.
</p>
<p><b>Fraser:</b>  And that would be very exciting to discover&#8230; we could see Olympus Mons erupt again&#8230;
</p>
<p><b>Pamela:</b>  I&#039;m not quite sure we could go that far&#8230; but it does mean that there is some sort of process going on that&#8211;well, it&#039;s always cool when rocks are alive&#8211;but the other process is&#8230; well, life produces methane. Meet a cow&#8211;you&#039;ve met a methane-producer. Small biological entities, bacteria, single-celled organisms in all their different forms, there&#039;s many different ways to produce methane and so if Mars is as geophysically dead as we&#039;ve been teaching for, well, as long as I&#039;ve been alive, that means that there&#039;s methanogens or some other form of methane-producing life in Mars.
</p>
<p><b>Fraser:</b>  And, I mean, if they can find that, the ramifications of that are gigantic. That means that there&#039;s life on Earth and there&#039;s life on Mars. And if there&#039;s life on two planets, then life could be all over the place in the universe. And you would, in theory, eventually be able to find the source and be able to study it and see if the two are connected. Did life begin on Earth and separately on Mars, or are they somehow interconnected? Do they share a common ancestor? The ramifications of this are mind-boggling. Now there are plans to get to the bottom of this mystery.
</p>
<p><b>Pamela:</b>  Yes, and everything from the upcoming Mars Science Laboratory to most of the plans for the future for Mars all include going and digging in the surface and looking for signs of life. One of the most exciting ideas that I haven&#039;t seen any missions attached to yet, is going and&#8230; there&#039;s several different places that we&#039;ve seen along the volcanoes on Mars skylights into deep dark caves that are likely completely protected from radiation. If we can go and explore in those caves&#8230; those caves may represent our best bet for places capable of supporting human colonies and supporting life that exists in the dark.
</p>
<p><b>Fraser:</b>  And there&#039;s also been some orbital missions proposed that will map out the methane concentrations with more accuracy and try and even find out exactly where it&#039;s coming from.
</p>
<p><b>Pamela:</b>  And everyone just wants to go dig&#8230; because who doesn&#039;t like digging in the dirt?
</p>
<p><b>Fraser:</b>  Oh, for sure&#8230; but I mean this discovery&#8230; this could change everything.
</p>
<p><b>Pamela:</b>  Yes.
</p>
<p><b>Fraser:</b>  So if there&#039;s one mystery that we&#039;ve really got to get to the bottom of&#8230; it is this one. But, let&#039;s move on&#8230; so, mystery number five&#8211;where did Titan&#039;s atmosphere come from? Titan is Saturn&#039;s largest moon&#8230; second largest moon in the solar system&#8230; and it has an atmosphere that is thick&#8230; like as thick as Earth&#039;s&#8230; and rich in hydrocarbons which scientists think is a very similar environment that we had here on Earth early on. How on Earth&#8230; ha, ha! How on Titan could you get an atmosphere like that so far out in the solar system orbiting Saturn? It should just be a block of ice, right? A ball of ice&#8230;
</p>
<p><b>Pamela:</b>  Right, right&#8230; and this is where Titan gets to be a really interesting planet to look at.. it&#039;s not even a planet, it&#039;s a moon&#8230; it gets to be a really interesting object to look at from a geophysics perspective because it doesn&#039;t just have a thick atmosphere, but it has a &#034;insert the expletive of your choice&#034; thick atmosphere. This is atmosphere that is 1.5 atmospheric pressure&#8211;or atmospheric bars, rather. That&#039;s thicker than the atmosphere on the planet Earth.
</p>
<p><b>Fraser:</b>  You could take off your spacesuit and not freeze-dry&#8230; you would merely freeze!
</p>
<p><b>Pamela:</b>  And the thing about having an atmosphere this thick is&#8230; I love this&#8230; it&#039;s a low-gravity world. It&#039;s a tiny, tiny moon&#8211;compared to the size of the planet Earth&#8211;and so with this low gravity, if you attached a pair of Icarus&#039; wings to your arms, you could actually fly around in this really thick atmosphere. Now, the majority of the atmosphere is nitrogen&#8211;it&#039;s 98.4% nitrogen. But, along with that nitrogen, there&#039;s another 1.6% composed of methane and other organics, and like I just said about Mars, methane is destroyed by the sun. So, somehow there&#039;s something about Titan that&#039;s causing it to constantly generate methane that&#039;s getting replenished in its atmosphere. People have looked to see&#8230; well, maybe it just captured the methane and it still hasn&#039;t had enough time to all be destroyed from the solar nebula. No, that model doesn&#039;t work.  Well, maybe it just comes from getting clobbered by comets. No, that doesn&#039;t work either&#8230; the composition ratios are all wrong. Somehow, something inside Titan is generating this, and one of the really awesome things about the combination of Titan being really cold, really tiny, and having this carbon-atom rich environment, is it can have geophysical processes that carve rivers, that carve canals, that in many ways look just like the processes that we have with water here on Earth. So, for Titan, the methane in the atmosphere is like the water in the Earth&#039;s atmosphere. It can rain, it can form rivers on the surface, it can freeze, and so you can have an entire environmental cycle built out of methane&#8230; but we don&#039;t know where it&#039;s coming from.
</p>
<p><b>Fraser:</b>  Right. So, methane is too short-lived to have been left over from the solar nebula, so some thing is either protecting or replenishing it on Titan.
</p>
<p><b>Pamela:</b>  Exactly.
</p>
<p><b>Fraser:</b>  Crazy. Alright, well I think we&#039;re actually out of time. We&#039;ve gotten through five, and we&#039;ve got more. So this is going to at least be a two-part series, so stay tuned for next week. Thanks Pamela!
</p>
<p><b>Pamela:</b>  Sounds good Fraser.</p>
<p>
</p>
</div>
<p><small>This transcript is not an exact match to the audio file. It has been edited for clarity. </small></p>
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		<title>Ep. 159: Planet X</title>
		<link>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-159-planet-x/</link>
		<comments>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-159-planet-x/#comments</comments>
		<pubDate>Tue, 03 Nov 2009 23:00:10 +0000</pubDate>
		<dc:creator>Astronomy Cast</dc:creator>
				<category><![CDATA[Our Solar System]]></category>

		<guid isPermaLink="false">http://www.astronomycast.com/?p=1003</guid>
		<description><![CDATA[Astronomers have been searching for the mysterious Planet X for hundreds of years. It was the search for a theoretical planet beyond Uranus that turned up Neptune, and then again for Pluto. And even now there are some astronomers who think there&#039;s a more distant planet out there. Oh, and there are a bunch of [...]]]></description>
			<content:encoded><![CDATA[<div id="attachment_1004" class="wp-caption alignleft" style="width: 160px"><img class="size-thumbnail wp-image-1004" title="Artist's illustration of the dwarf planet Eris. Image credit: NASA" src="http://www.astronomycast.com/wp-content/uploads/2009/11/eris-150x150.jpg" alt="Artist's illustration of the dwarf planet Eris. Image credit: NASA" width="150" height="150" /><p class="wp-caption-text">Artist&#39;s illustration of the dwarf planet Eris. Image credit: NASA</p></div>
<p>Astronomers have been searching for the mysterious Planet X for hundreds of years. It was the search for a theoretical planet beyond Uranus that turned up Neptune, and then again for Pluto. And even now there are some astronomers who think there&#039;s a more distant planet out there. Oh, and there are a bunch of pseudoscience cranks trying to freak people out about the end of the world. Don&#039;t worry, we&#039;ll make time for them too, but first let&#039;s start with some real science.</p>
<p><span id="more-1003"></span></p>
<table>
<tr>
<td>
<li><strong><a href="http://media.libsyn.com/media/astronomycast/AstroCast-091012.mp3">Ep. 159: Planet X</a></strong></li>
<li><a href="#shownotes">Jump to Shownotes</a></li>
<li><a href="#transcript">Jump to Transcript</a> or Download (coming soon!)</li>
</td>
</tr>
</table>
<div style="clear: both;"></div>
<div class="shownotes">
<h3><a name="shownotes">Shownotes</a></h3>
<p><strong>Planet X</strong></p>
<ul>
<li><a href="http://www.windows.ucar.edu/tour/link=/kids_space/planetx.html">Planet X as placeholder </a>&#8211; Windows to the Universe</li>
<li><a href="http://www.unmuseum.org/planetx.htm">Planet X </a>&#8211; The UnMuseum</li>
<li><a href="http://www.badastronomy.com/bad/misc/planetx/">The Planet X Saga</a> &#8212; Bad Astronomy</li>
</ul>
<p><strong>Neptune</strong> <strong>as Planet X</strong></p>
<ul>
<li><a href="http://www.skyandtelescope.com/news/3307531.html?page=1&amp;c=y">The Discovery of Neptune </a>&#8211; Sky &amp; Telescope</li>
<li><a href="http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/adams.html">John Couch Adams</a> &#8212; NASA</li>
<li><a href="http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/leverrier.html">Urbain Le Verrier -</a>- NASA</li>
<li><a href="http://en.wikipedia.org/wiki/Johann_Gottfried_Galle">Johann Gottfried Galle</a> &#8212; Wiki</li>
<li><a href="http://astronomy.library.wisc.edu/resources/eggen/eggen.html">O.J. Eggen (the Breakfast Astronomer!) </a>&#8211; UW-Madison</li>
<li><a href="http://www.dioi.org/kn/neptune/takes.htm">The British Case for C0-Prediction of Neptune</a></li>
<li><a href="http://www.astronomycast.com/astronomy/episode-63-neptune/">Ep. 63 &#8212; Neptune</a></li>
</ul>
<p><strong>Pluto as Planet X</strong></p>
<ul>
<li><a href="http://www.lowell.edu/Research/library/paper/lowell.html">Percival Lowell</a> &#8212; Lowell Observatory</li>
<li><a href="http://www.icstars.com/HTML/icstars/graphics/clyde.htm">Clyde Tombaugh</a></li>
<li><a href="http://www.gps.caltech.edu/~mbrown/bio.html">Mike Brown</a> &#8212; Caltech</li>
<li><a href="http://www.mikebrownsplanets.com/">Mike Brown&#039;s Planets</a></li>
<li><a href="http://www.astronomycast.com/solar-system/plutos-planetary-identity-crisis/">Ep. 1: Pluto&#039;s Planetary Identity Crisis</a></li>
<li><a href="http://www.astronomycast.com/astronomy/episode-64-pluto-and-the-icy-outer-solar-system/">Ep. 64: Pluto and the Icy Outer Solar System</a></li>
<li><a href="http://en.wikipedia.org/wiki/IAU_definition_of_planet">IAU definition of a planet</a></li>
<li><a href="http://www.gps.caltech.edu/~mbrown/planetlila/">The Discovery of Eris</a> &#8212; Caltech</li>
<li><a href="http://coyoteprime-runningcauseicantfly.blogspot.com/2009/04/astronomy-what-is-kuiper-cliff-planet-x.html">Kuiper Belt Cliff</a> &#8212; Running &#039;Cause I Can&#039;t Fly</li>
</ul>
<p><strong>Other Planets Out There Anywhere?</strong></p>
<ul>
<li><a href="http://web.ipac.caltech.edu/staff/tchester/iras/no_tenth_planet_yet.html">No Tenth Planet Yet from IRAS</a></li>
<li> <a href="http://articles.adsabs.harvard.edu/full/1984ApJ...278L..63H">Astrophysical Journal Letters (278:L63) (1984) by Houck et al titled Unidentified point sources in the IRAS minisurvey</a></li>
<li><a href="http://www.universetoday.com/2009/04/15/constraining-the-orbits-of-planet-x-and-nemesis/">Constraining the Orbits of Planet X and Nibiru</a> &#8212; Universe Today</li>
<li><a href="http://spaceguard.iasf-roma.inaf.it/NScience/neo/neo-what/com-prop.htm">Short and Long Period Comets</a></li>
<li><a href="http://en.wikipedia.org/wiki/Extinction_event">Earth Extinction Events</a> &#8212; Wiki</li>
<li><a href="http://muller.lbl.gov/">Richard Muller&#039;s research on Moon impacts</a></li>
<li><a href="http://muller.lbl.gov/pages/lbl-nem.htm">Nemesis Theory</a> &#8212; Richard Muller</li>
</ul>
<p><strong>Take a look for yourself: </strong></p>
<ul>
<li><a href="http://heasarc.gsfc.nasa.gov/W3Browse/all/hipparcos.html">HIPPARCOS Catalog</a></li>
<li><a href="http://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/ucac">US Naval Observatory Catalog</a></li>
<li><a href="http://tdc-www.harvard.edu/catalogs/hstgsc.html">Hubble Guide Star Catalog</a></li>
<li><a href="http://www.sdss.org/">Sloan Digital Sky Survey</a></li>
</ul>
<p><strong>Future Telescopes to look for &#034;Planet X&#034;</strong></p>
<ul>
<li><a href="http://pan-starrs.ifa.hawaii.edu/public/">Pan-STARRS telescope</a></li>
<li><a href="http://www.lsst.org/lsst">LSST</a></li>
</ul>
<p><strong>2012 Nonsense</strong></p>
<ul>
<li><a href="http://www.universetoday.com/2008/05/25/2012-no-planet-x/">2012: No Planet X </a>&#8211; Universe Today</li>
<li><a href="http://www.universetoday.com/2008/06/19/2012-planet-x-is-not-nibiru/">2012:  Planet X is Not Nibiru</a> &#8212; UT</li>
<li><a href="http://www.universetoday.com/2009/10/14/2012-combat-the-nonsense/">2012:  Combat the Nonsense</a> &#8212; UT</li>
</ul>
</div>
<div class="transcript">
<h3><a name="transcript">Transcript</a></h3>
<p>Coming Soon!
</p></div>
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		<title>Ep. 151: Atmospheres</title>
		<link>http://www.astronomycast.com/astronomy/planets/ep-151-atmospheres/</link>
		<comments>http://www.astronomycast.com/astronomy/planets/ep-151-atmospheres/#comments</comments>
		<pubDate>Thu, 24 Sep 2009 16:32:11 +0000</pubDate>
		<dc:creator>Astronomy Cast</dc:creator>
				<category><![CDATA[Planets]]></category>

		<guid isPermaLink="false">http://www.astronomycast.com/?p=953</guid>
		<description><![CDATA[Take a quick breath. There, that&#039;s what we&#039;re going to talk about today &#8211; the atmosphere. And not just the Earth&#039;s familiar atmosphere, but the strange, exotic and deadly atmospheres we find in the Solar System and surrounding extrasolar planets.
Ep. 151: Atmospheres

Earth&#039;s Atmosphere:

Atmosphere overview: UTK
Troposphere &#8211;Windows to the Universe
Tropopause &#8211; Wiki
Stratosphere &#8212; WTTU
Thermosphere &#8212; WTTU
Geosynchronous [...]]]></description>
			<content:encoded><![CDATA[<div id="attachment_954" class="wp-caption alignleft" style="width: 160px"><img class="size-thumbnail wp-image-954" title="The Earth's atmosphere" src="http://www.astronomycast.com/wp-content/uploads/2009/09/earthorbit-150x150.jpg" alt="The Earth's atmosphere" width="150" height="150" /><p class="wp-caption-text">The Earth&#39;s atmosphere</p></div>
<p>Take a quick breath. There, that&#039;s what we&#039;re going to talk about today &#8211; the atmosphere. And not just the Earth&#039;s familiar atmosphere, but the strange, exotic and deadly atmospheres we find in the Solar System and surrounding extrasolar planets.</p>
<p><strong><a href="http://media.libsyn.com/media/astronomycast/AstroCast-090817.mp3">Ep. 151: Atmospheres</a></strong></p>
<p><span id="more-953"></span></p>
<p><strong>Earth&#039;s Atmosphere:</strong></p>
<ul>
<li><a href="http://csep10.phys.utk.edu/astr161/lect/earth/atmosphere.html">Atmosphere overview:</a> UTK</li>
<li><a href="http://www.windows.ucar.edu/tour/link=/earth/Atmosphere/troposphere.html&amp;edu=high">Troposphere</a> &#8211;Windows to the Universe</li>
<li><a href="http://en.wikipedia.org/wiki/Tropopause">Tropopause </a>&#8211; Wiki</li>
<li><a href="http://www.windows.ucar.edu/tour/link=/earth/Atmosphere/stratosphere.html&amp;edu=high">Stratosphere</a> &#8212; WTTU</li>
<li><a href="http://http://www.windows.ucar.edu/tour/link=/earth/Atmosphere/structure_thermo.html&amp;edu=high">Thermosphere</a> &#8212; WTTU</li>
<li><a href="http://www.gsfc.nasa.gov/gsfc/educ/fyeo/faq/gorbit.htm">Geosynchronous Orbit </a>&#8211; Goddard Space Flight Center</li>
<li><a href="http://www.exploratorium.edu/learning_studio/auroras/fromspace.html">Info on auroras </a>&#8211; Exploratorium</li>
<li><a href="http://www.wisegeek.com/what-is-the-history-of-the-earths-atmosphere.htm">History of Earth&#039;s Atmosphere </a>&#8211; WiseGeek</li>
</ul>
<p><a href="http://www.astronomynotes.com/solarsys/s3.htm">Info on atmosphere and gravity</a> &#8212; Nick Strobel</p>
<p><a href="http://www.universetoday.com/guide-to-space/mercury/atmosphere-of-mercury/">Atmosphere of Mercury</a> &#8212; Universe Today</p>
<ul>
<li><a href="http://www.universetoday.com/2009/06/03/how-magnetic-tornadoes-might-regenerate-mercurys-atmosphere/">How Magnetic Tornadoes Might Replenish Mercury&#039;s Atmosphere </a></li>
</ul>
<p><a href="http://www.universetoday.com/guide-to-space/venus/atmosphere-of-venus/">Atmosphere of Venus </a></p>
<ul>
<li><a href="http://www.universetoday.com/2008/05/15/elusive-molecule-found-in-venus-atmosphere/">Hydroxyl in Venus&#039; Atmosphere</a></li>
<li><a href="http://www.universetoday.com/2008/07/16/colonizing-venus-with-floating-cities/">Colonizing Venus with Floating Cities</a></li>
</ul>
<p><a href="http://www.universetoday.com/guide-to-space/mars/atmosphere-of-mars/">Atmosphere of Mars</a></p>
<ul>
<li><a href="http://www.universetoday.com/2009/01/15/large-quantities-of-methane-being-replenished-on-mars/">Large Quantities of Methane Being Replenished on Mars</a></li>
</ul>
<p><a href="http://www.universetoday.com/guide-to-space/jupiter/jupiters-atmosphere/">Atmosphere of Jupiter </a></p>
<ul>
<li><a href="http://news.nationalgeographic.com/news/2007/10/071009-jupiter-lightning.html">Lightning Strikes, Changing Climate Revealed on Jupiter</a> &#8212; Nat Geo</li>
<li><a href="http://www.universetoday.com/guide-to-space/jupiter/jupiters-great-red-spot/">Jupiter&#039;s Great Red Spot</a> &#8212; UT</li>
<li><a href="http://www.universetoday.com/2008/01/25/gigantic-storms-on-jupiter-grow-in-a-single-day/">Gigantic Storms on Jupiter Grow in a Single Day</a></li>
</ul>
<p><a href="http://www.universetoday.com/guide-to-space/saturn/atmosphere-of-saturn/">Atmosphere of Saturn</a></p>
<ul>
<li><a href="http://www.universetoday.com/guide-to-space/saturn/saturn-hexagon/">Saturn Hexagon</a></li>
<li><a href="http://www.windows.ucar.edu/tour/link=/saturn/moons/titan_atmosphere_overview.html&amp;edu=high">Titan&#039;s atmosphere </a>&#8211; WTTU</li>
</ul>
<p><a href="http://www.universetoday.com/guide-to-space/uranus/atmosphere-of-uranus/">Atmosphere of Uranus</a></p>
<p><a href="http://www.universetoday.com/guide-to-space/neptune/atmosphere-of-neptune/">Atmosphere of Neptune</a></p>
<p><a href="http://www.universetoday.com/guide-to-space/pluto/plutos-atmosphere/">Atmosphere of Pluto</a></p>
<p>Extrasolar planets with atmospheres:</p>
<ul>
<li><a href="http://www.universetoday.com/2007/12/05/atmosphere-of-an-extrasolar-planet-measured/">Atmosphere of Extrasolar Planet Measured</a></li>
<li><a href="http://www.universetoday.com/2009/05/26/new-technique-could-find-another-pale-blue-dot/">New Technique Could Find Another Pale Blue Dot</a></li>
<li><a href="http://planetquest.jpl.nasa.gov/TPF/tpf_index.cfm">Terrestrial Planet Finder</a> &#8212; JPL</li>
</ul>
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		<title>Ep. 114: The Moon, Part 2 &#8211; Exploration of the Moon</title>
		<link>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-114-the-moon-part-2-exploration-of-the-moon/</link>
		<comments>http://www.astronomycast.com/astronomy/planets/our-solar-system/ep-114-the-moon-part-2-exploration-of-the-moon/#comments</comments>
		<pubDate>Wed, 12 Nov 2008 17:47:59 +0000</pubDate>
		<dc:creator>Astronomy Cast</dc:creator>
				<category><![CDATA[Our Solar System]]></category>

		<guid isPermaLink="false">http://www.astronomycast.com/?p=411</guid>
		<description><![CDATA[Let&#039;s continue on our journey to the Moon. Last week we talked about the physical characteristics of the Moon, its appearance in the sky and how it interacts with the Earth. This week we&#039;re going to take a look at how scientists have expanded our understanding of the Moon. From ancient astronomers using nothing more [...]]]></description>
			<content:encoded><![CDATA[<div id="attachment_412" class="wp-caption alignleft" style="width: 160px"><a href="http://www.astronomycast.com/wp-content/uploads/2008/11/surveyor_nasa_lunar_lander.jpg"><img class="size-thumbnail wp-image-412" title="Surveyor Lander. Image credit: NASA" src="http://www.astronomycast.com/wp-content/uploads/2008/11/surveyor_nasa_lunar_lander-150x150.jpg" alt="Surveyor Lander. Image credit: NASA" width="150" height="150" /></a><p class="wp-caption-text">Surveyor Lander. Image credit: NASA</p></div>
<p>Let&#039;s continue on our journey to the Moon. Last week we talked about the physical characteristics of the Moon, its appearance in the sky and how it interacts with the Earth. This week we&#039;re going to take a look at how scientists have expanded our understanding of the Moon. From ancient astronomers using nothing more than their eyes and the first telescope observations of Galileo to the exploration by robotic spacecraft. And of course, the first tentative steps by the human explorers of the Apollo program.</p>
<p><strong><a href="http://media.libsyn.com/media/astronomycast/AstroCast-081110.mp3">Ep. 114: The Moon, Part 2 &#8211; Exploration of the Moon</a></strong><br />
<span id="more-411"></span></p>
<p><strong>Before we went&#8230;</strong></p>
<ul>
<li><a href="http://galileo.rice.edu/sci/observations/moon.html">Aristotle, Galileo and the Moon</a> &#8212; Galileo Project</li>
<li><a href="http://www.absoluteastronomy.com/topics/Lunar_mare">Lunar mare </a>&#8211; Absolute Astronomy</li>
<li><a href="http://en.wikipedia.org/wiki/Basalt#Lunar_and_Martian_basalt">Lunar Basalt </a>&#8211; Wiki</li>
<li><a href="http://www.daviddarling.info/encyclopedia/G/Gruithuisen.html">Franz von Paula Gruithuisen</a> &#8212; Internet Encyclopedia of Science</li>
<li><a href="http://www.gearthblog.com/blog/archives/2005/10/meteor_craters.html">Finding craters on Earth with Google Earth</a> &#8212; Google Earth Blog</li>
<li><a href="http://lunar.arc.nasa.gov/printerready/science/geography_items/carters/craters_p.html">Nomenclature of Lunar craters </a>&#8211; NASA</li>
</ul>
<p><strong>Early Missions to the Moon</strong></p>
<ul>
<li><a href="http://nssdc.gsfc.nasa.gov/planetary/lunar/lunartimeline.html">NASA&#039;s timeline of lunar missions</a></li>
<li><a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1959-012A">Russian Luna 1</a> ( 1959 flyby), <a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1959-014A">Luna 2</a> (1959 impact), <a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1959-008A">Luna 3 </a>(1959 probe)</li>
<li><a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1959-013A">US Pioneer 4</a> (1959 flyby)</li>
<li><a href="http://nssdc.gsfc.nasa.gov/planetary/lunar/ranger.html">Ranger missions</a> (1961-1965)</li>
<li><a href="http://saturn.jpl.nasa.gov/spacecraft/instruments-huygens.cfm">Huygens probe to Saturn&#039;s moon Titan</a></li>
<li><a href="http://nssdc.gsfc.nasa.gov/planetary/lunar/surveyor.html">Surveyor missions </a>(1966-1968)</li>
</ul>
<p><strong>Apollo</strong></p>
<ul>
<li><a href="http://nssdc.gsfc.nasa.gov/planetary/lunar/apollo.html">Apollo missions overview (</a>1968-1972)</li>
<li>Book:  <a href="http://www.amazon.com/Man-Moon-Voyages-Apollo-Astronauts/dp/B0018ZRERI/ref=sr_1_2?ie=UTF8&amp;s=books&amp;qid=1226585751&amp;sr=1-2">A Man on the Moon by Andrew Chaikin</a></li>
<li>Movie:  <a href="http://www.amazon.com/Earth-Moon-Signature-Mason-Adams/dp/B000A0GYD2/ref=sr_1_12?ie=UTF8&amp;s=dvd&amp;qid=1226585896&amp;sr=1-12">From the Earth to the Moon</a></li>
<li>Movie:  <a href="http://www.amazon.com/Apollo-13-DVD-Tom-Hanks/dp/B000FA57NK/ref=sr_1_2?ie=UTF8&amp;s=dvd&amp;qid=1226585896&amp;sr=1-2">Apollo 13</a></li>
<li>Movie:  <a href="http://www.amazon.com/Shadow-Moon-Harrison-Schmitt/dp/B000XJ5TPE/ref=sr_1_1?ie=UTF8&amp;s=dvd&amp;qid=1226586102&amp;sr=1-1">In the Shadow of the Moon</a></li>
<li>Movie:  <a href="http://www.amazon.com/When-We-Left-Earth-Missions/dp/B001B1520A">When We Left Earth</a></li>
</ul>
<p><strong>Subsequent robotic Moon exploration </strong></p>
<ul>
<li><a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=1990-007A">Hitan</a> (1990)</li>
<li><a href="http://nssdc.gsfc.nasa.gov/planetary/lunar/clementine1.html">Clementine </a>(1994)</li>
<li><a href="http://ser.sese.asu.edu/MOON/clem_color.html">Clementine Color Mosaics of the Moon</a></li>
<li><a href="http://nssdc.gsfc.nasa.gov/planetary/lunarprosp.html">Lunar Prospector</a> (1998)</li>
<li><a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=2003-043C">Smart-1</a> (2003)</li>
<li><a href="http://www.esa.int/esaMI/SMART-1/SEMLB6XO4HD_0.html">The Magic of Ion Engines</a> &#8212; ESA</li>
<li><a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=2007-039A">Kaguya (SELENE) 2007-present</a></li>
<li>J<a href="http://www.selene.jaxa.jp/en/index.htm">AXA&#039;s Kaguya site,</a> includes Hi-def movies of the moon</li>
<li><a href="http://nssdc.gsfc.nasa.gov/nmc/masterCatalog.do?sc=2007-051A">Chang&#039;e 1</a> 2007- present</li>
<li><a href="http://www.planetary.org/explore/topics/chang_e_1/">More on Chang&#039;e 1 from the Planetary Society</a></li>
</ul>
<p><strong>Download the transcript</strong></p>
<hr />
<h3>Transcript: The Moon, Part 2 &#8211; Exploration of the Moon</h3>
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<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser Cain:</strong> Let’s continue on in our journey to the Moon.   Last week we talked about the physical characteristics of the Moon, its appearance in the Sky and how it interacts with the Earth.</p>
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<p style="margin-left: 0.63in; margin-bottom: 0in;">This week we’re going to look at how Scientists have expanded our understanding of the Moon from ancient Astronomers using nothing more than their eyes and the first telescope observations of Galileo to the exploration by robotic Spacecraft.</p>
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<p style="margin-left: 0.63in; margin-bottom: 0in;">And of course, the first tentative steps by human explorers of the Apollo Program.  So, let’s go right back to the first discoveries that humans have made about the Moon.  I guess in the beginning we just had eyes.</p>
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<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Dr. Pamela Gay:</strong> Well and initially it’s not like we didn’t know the Earth had a Moon.  It is probably one of the first things people noticed – Oh, there’s a giant bright object in the Sky that changes phases.</p>
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<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Who discovered that?</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> Yeah, I don’t know his name.  [Laughter]  It’s not in Wikipedia. But the main record that Western thought bases itself on in studying the Moon goes back mostly to Aristotle and Plutarch.  Aristotle in looking at the Heavens saw all of the heavenly bodies as perfect spheres because well, the sphere is the perfect shape therefore everything in the Sky must be the perfect sphere.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">However, when you look at the Moon it is mottled in color. There’s the ‘Old Man’ or the ‘Rabbit’ in the Moon depending on your cultural perspective and many other shapes as well.</p>
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<p style="margin-left: 0.63in; margin-bottom: 0in;">When Plutarch looked up, what he saw instead was that the dark places were corrupted.  They were chasms, they were craters (well they didn’t know what craters were back then) they were pits; they were cut-aways from rivers.  They were places where the Sun wasn’t able to reach the bottom in and instead we’re looking into deep shadow.</p>
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<p style="margin-left: 0.63in; margin-bottom: 0in;">So, we have these two completely different views.  Aristotle going: spheres, perfect wonderful it’s in the heavens.  Plutarch going: no, corrupted body, deeply shadowed, large chunks missing that the Sun can’t reach the bottom of.  So there is this wonderful dichotomy.  Most people listened to Aristotle.</p>
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<p style="margin-left: 0.63in; margin-bottom: 0in;">It wasn’t until Galileo and his “well let me look up with the telescope” way of looking at the Universe that we started to realize that for certain the Moon wasn’t a perfect sphere.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The Moon had mountains; it had these weird round pits.  It had all of these different surface features and he was able to say for certain that the two different colors were two different surfaces.  That’s kinda cool.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> And how are they two different surfaces?  What’s the difference between the parts that are dark and the parts that are lighter from our point of view?</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> We didn’t know that for a long time.  He was simply able to say that the dark stuff is not a giant pit.  He was able to say that’s just a surface.  It wasn’t until we went and started exploring it that we were able to confirm for certain that the dark stuff is basalt, it is lava.  It’s melted rock that has been cooled and solidified. It’s either from actual volcanic type stuff or just more oozing of lava out through the surface or from re-melting of the surface during cratering. The light stuff is in the inner highlands, it’s just rock.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">What’s kind of cool to me is we look at the Moon – and having grown up learning about Asteroids at about first or second grade, the difference between a Meteor a Meteorite or a Meteoroid – we look at the Moon and see the round spots as craters.  But it wasn’t actually until the 1820s that a man whose name I’m going to horribly mispronounce, Franz von Paula Gruithuisen got the idea that maybe these things were Meteor strikes.  He thought maybe these round pits with crater walls are actually crater marks on the Moon.</p>
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<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> And there’s an object like that here on Earth, the Meteor crater in Arizona which looks very similar.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> Right and now that people are starting to peer through all sorts of satellite imagery there are major craters that look like craters all over the planet Earth.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">There are actually all sorts of projects in Google Sky or Google Earth as the case may be, to try and locate other potential crater walls scattered around the Planet.  And that’s just cool our Planet is pock-marked too.</p>
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<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Well, after Galileo you can imagine that every Astronomer worth their salt was pointing their telescope at the Moon when they weren’t discovering the Rings of Saturn [Laughter] or something.  Beyond that what kinds of discoveries started to pour out?</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> Mostly we were happily mapping the surface of the Moon, naming things in all sorts of different ways.  There were many different naming conventions that were used. The one that was eventually settled on is the idea that large naked eye blobs on the surface are named as seas (mare). The little spots that you can only see through telescopes which we now know are craters are named after philosophers and I just like this dichotomy.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Since then we’ve broken it and so there’s shackles and craters and things like that.  It wasn’t until 1753 that we realized that the Moon doesn’t have an atmosphere.  Up until then people had randomly thought maybe there was life on the Moon.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">It was actually Plutarch who started that idea.  As early as essentially the beginning of Western Civilization there was the concept that maybe there was life on the Moon.  Then in 1753 we realized no, there’s not, there’s no atmosphere there.  Then as I said in the 1820s we realized that the craters were made by Meteor strikes.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">From then on, we basically mapped and that was all we could do without having any solid compositional data.  Even with the mapping we could only map a little more than fifty percent of the Moon because the Moon, as we talked about in the last episode is tidally locked to the Earth.  We can only see one side of it.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The Moon has what we call vibrations.  It vibrates a little bit and we can see around the edges a little bit as it oscillates slightly.  But we mapped the one side we could see really, really well.  Then we waited for manned Space flight and unmanned Space flight to get invented so that we could start looking at other things as well.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> So then fast forward, I mean beyond just mapping, [Laughter] fast forward to the first attempts to actually reach out with Spacecrafts and explore the Moon.  So what were the first attempts to get to the Moon?</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> Well, back as early as 1959 actually we were flinging things at the Moon.  It was initially mostly the Soviets flinging things.  There were three different Luna missions, one, two and three, conveniently named in 1959 as well as one Pioneer mission from the United States.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The Luna missions were off to first take pictures of the Moon and second to go land on the surface and find out what the surface is made of.  So the first mission was intended to land on the surface – well impact on the surface – landing is a bit strong of a statement.  But it missed.  It flew by, took pictures and then it kept going.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">It was actually the very first object to end up orbiting the Sun instead of the planet Earth.  Then after that the United States launched its Pioneer mission.  That again was a fly-by, took pictures, and happily explored the environment.  It did a radiation experiment and then we went back to the land of the Luna missions.  We had Luna 2 which did manage to successfully hit the surface of the Moon and then</p>
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<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> It landed.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> It landed.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> The hard way [Laughter]</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> But they intended to land the hard way.  So it was alright.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser: </strong> Right, that was all part of the plan.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> It was all part of the plan and then finally, Luna 3, toward the end of 1959 allowed us to see for the first time – this was a Soviet mission – it returned the first ever pictures of the back side of the Moon, the unknown, the dark side of the Moon that really does get lit up as much as the front.  So finally in 1959 we were able to see this mysterious other side of the Moon.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">What’s cool is the back side of the Moon is radically different.  It is cratered completely differently.  It has much, much less lava on it so it’s coloration is very different.  And so that was just a fabulous moment.  Then no one went back to the Moon for a year.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> [Laughter] Right, now I’m assuming that you’re glazing over all of the failures, all of the rockets that exploded on the pad and crashed into the atmosphere and so on.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">That’s fine, we don’t want to repeat – we had a lot of complaints on the Mars episode about the failure after failure so we’ll gloss over the failure after failure.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> But the thing is those four missions I just named, according to the NASA Lunar Exploration Timeline which does list lots of failed missions – those were the only four.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Yeah, Luna 1 missed and kept going but it still returned data.  So the Moon doesn’t have quite the same curse that Mars suffers from.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser: </strong> Right, okay so we’ve gotten to the point that we’ve seen the far side of the Moon for the first time.  What about landing?</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> There was a gap.  Here’s where the United States started to get involved again with things that didn’t like to fly in the 1960s with the Ranger program, it was not one of America’s more successful programs.  It had two attempted test flights in 1961 and both of them failed.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Then we had in 1962 an attempted impact and we missed.  Ranger 4 did successfully find and crash into the surface.  It was designed to transmit pictures.  It was able to do this for about 10 minutes prior to impacting the surface.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">What’s kind of cool is one of our goals was to basically shake the Moon to collect data on what happens when you have a rough landing.  This is sort of like when we landed the Huygens Probe on Saturn’s Moon Titan. We wanted to find out what the surface is like.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">One way to do that is to land a bit more violently than you might like and Huygens didn’t really do that.  But then to see what shakes, what is the impact like, if you have a nice slow deceleration then you landed on something squishy.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">If you have a bit abruptive landing that means you landed on something a bit more solid than you might have liked.  So there are reasons to fling yourself into the surface of a foreign body.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Well the surface of the Moon is a bit of a mystery, right?  I mean they knew that it was covered with dust probably from billions of years of micro-meteor impact but they didn’t really know how hard this stuff was going to be.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> Right.  This is the problem with the Regula.  The Moon is constantly being barraged by micro-meteors.  Fred Hoyle was one of the people who put forward the idea that “yeah you’re going to land and you’re just going to sink into the dust.”</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">We eventually ended up building an entire series of missions – the Surveyor missions – that started launching in 1966 with a goal to land purposely, land softly and send back data.  They had Solar Arrays, TV cameras, all the nice little things including arms to dig into the surface.  You can see these as kind of the baby precursor version of our current Mars Polar Lander.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">These happy little tiny robots that are really quite darling.  They look like tripods that have been overburdened with electronics.  These little robots successfully landed in many cases and were able to send data back to the planet Earth.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">So, now instead of impacting the surface, we’re purposely landing on the surface.  We did our first purposeful landing May 30<sup>th</sup> of 1966; tried again in September – didn’t work so well – kept trying and these were the precursors to the Apollo landings.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Right, so these were the ones that really sent out the first pictures of the surface of the Moon, tried to dig around and see what the surface was like, but you already kind of mentioned the next big plan which was the Apollo mission.  Maybe rewind a bit and talk about that.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> This all started with John F. Kennedy from my home state of Massachusetts.  When he became president he wanted to give our Nation a vision and part of that vision was violently beating the Russians to the Moon (well, not with violence but peacefully) beating the Russians to the Moon.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">He put this idea forth very eloquently in his speech where he said: <em>“We choose to go to the Moon.  We choose to go to the Moon in this decade and to do other things.  Not because they are easy but because they are hard.  Because that goal will serve to organize and measure the best of our energies and skills because that challenge is one that we are willing to accept, one we are unwilling to postpone and one which we intend to win and the others too.” </em>He goes on it’s a really cool speech.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Then they start throwing resources at it.  That was the cool thing, NASA didn’t have a lot of money but they did a lot of deficit spending.  Nowadays I don’t think NASA would be quite so allowed (not even a strong enough a word) no one would allow NASA to keep going if they went into the same amount of deficit spending that we had during the Apollo era.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">They were able to in less than 10 years go from not really being able to get things consistently to the Moon to landing human beings on the Moon and returning them with a lot of rocks.  Rocks don’t weigh small amounts and that’s just cool.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">We accomplished an amazing amount of stuff – all of this before I was born.  The last crewed landing on the Moon occurred in December of 1972, more than a year before I was born.  This is I think part of why people of my generation are a bit, yeah NASA, do something now please because we haven’t seen any really cool accomplishments.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">No one has landed on the Moon in our lifetime.  But in that one brief wonderful deficit spending period of time, NASA went from missing the Moon to successfully landing and returning people.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> I don’t think we have the time in this episode to really go into the details of how the Apollo program worked but there are some wonderful documentaries and TV shows and movies that you can watch that will show you them. “From the Earth to the Moon” is amazing.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> It’s a must see.  I make my students watch it.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Apollo 13; there’s a new one by the Discovery channel which is “When we Went to the Moon”. There’s a lot of great material out there to be able to sort of bring you up to speed on all of the missions. Yeah, “From the Earth to the Moon” I think is the most entertaining, comprehensive accessible look at the Apollo mission.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">So, if you’re older and you want to get your kids into the Apollo missions, that’s the show to watch.  They really make it quite entertaining, very much in the style of Apollo 13 as well.  It all kind of mixes together quite well.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela: </strong>What’s really cool about this stuff is how much history is involved in it.  So, if you have a friend who thinks, yeah science, I don’t care, but is interested in politics and history, the Apollo mission is the way to suck them into science as well.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">We’re dealing with personalities, how to fund all of this, dealing with everything else that was going on in the world at that time.  It’s just very fascinating to watch.  While America so far is the only nation that has managed to successfully get people to the Moon and back, the Soviets also helped returned rocks.  Returning rock – if you’re not into rocks and I admit to not being into rocks – really doesn’t sound that all exciting because they’re rocks.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The thing about Lunar rock is you can use it to start dating different surfaces.  So by sending people to different areas on the Moon and by sending Lunar Return Landers to the Moon, we were able to gather rocks that we could bring back and we could use carbon isotope dating to say, this region that has very few craters is this age.  This region that has this number of craters is this age.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Using the rocks gathered on the Moon and assuming that impact crater rates are fairly consistent across the Solar System (which we think is a reasonable thing to assume) we’re able to make rough estimates of the ages of all the rocky non-weathered bodies in the Solar System.  That’s just really cool.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> So, July 19, 1969, Neil Armstrong and Buzz Aldrin step out on the Moon for the first time and stay out there for a few hours and come back.  Several missions after that leading up to 1972 I think Gene Cernan was the last person to walk off the Moon.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Humans haven’t set foot on the Moon since then.  But that’s not the end of their exploration of the Moon.  There have been missions ever since and right now.  So, let’s not get stuck in 1972 [Laughter] let’s get going and talk about some of the other missions.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> The NASA timeline which includes everything else – it’s on the NASA.gov website shows how in January 1973 there was a Soviet Rover.  In 1974 there was a Soviet Orbiter and Lander.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">In 1976 there is another sample return mission. Then the Moon gets ignored until 1990.  Through pretty much my entire child adolescence there was nothing to do with the Moon anywhere.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Right it’s all about the Space Shuttle.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> It was all about the Space Shuttle and the Space Shuttle is cool but it only goes 300 miles up which in terms of exploring the Universe is nowhere.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Fine, the Voyagers.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> The Voyagers were awesome.  They were out on the edge of the Solar System.  They were what got me excited in Astronomy.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Me too.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> But, we ignored the Moon and then the Japanese got involved.  They sent this wonderful little mission that was called Hiten – I’m sorry I’m going to mispronounce things because they don’t teach you about this in graduate school.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">It translated into Flying Angel.  A wonderful little mission that went out and it was taking pictures and basically re-opened the door.  It got us back exploring the Moon a second time.  This wonderful little Japanese craft was mostly out there looking at dust.  It checked out the Lagrange Points.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">It eventually ran out of fuel and they crashed it into the Moon which doesn’t sound all that exciting.  But when you hit things into the surface of the Moon you can make the Moon vibrate.  The way they vibrate allows us to start probing the density of the Moon, probing how it reacts to different things.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The Apollo Astronauts left mirrors on the Moon so when we hit the Moon with things like this cute little Japanese Spacecraft it makes the Moon vibrate and we can see those vibrations in laser light reflected off these mirrors.  That again is just kind of cool.  So, in 1990, the Japanese re-opened the doors to Lunar exploration.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">A few years go by, nothing much happens and then America gets back in the game.  We go out and start doing detailed imaging again.  Here we have the Clementine mission.  This is the point at which the United States starts thinking again about going out and figuring out how do we get people back on the Moon.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Mapping the Moon in great detail is one of the first ways to do this.  The Clementine mission had lots of different ways of imaging the Moon.  It had a laser imaging detection and ranging system.  They were flying over the Moon bouncing laser light up and down which allows you to get very accurate altimetry of the Moon, very accurate altimetry of the Moon and very accurate measurements of the rise and fall of the surface.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">They had radar, high-resolution cameras, they had ultra-violet invisible cameras and they were even able to detect charged particles coming up off the surface of the Moon.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser</strong>:  Yeah, Clementine REALLY mapped the Moon to within an inch of its life. [Laughter] Nothing had ever been mapped at that level, to that detail; like just REALLY amazing contour maps.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">I was actually doing some work on this recently and all of the Clementine maps have been turned into these really amazing mosaics.  You can search for like Clementine, Moon Map or Mosaic on Google and you can get access to these really detailed maps that have been stitched together of the images that Clementine took of the Lunar surface.  It’s quite amazing.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> They weren’t the perfect images.  They weren’t high enough resolution that we could start looking for ice down in the bottoms of craters.  We’re going to do better in the future.  But it was a great start to getting back.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The resolutions were less than about 5 meters when the Orbiter was in its closest approach.  It was great work.  We were able to get great measurements of altitude of different surfaces.  It was a wonderful way to get back and get started and start figuring out this little body so close by one more time.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">From Clementine we’ve gone on to there was a Lunar Flyby with a mission in 1997 – not so exciting, I’m going to move on.  Then we had Lunar Prospector in 1998 which was another mission to go out and in this case it was looking out in all sorts of ways that you wouldn’t think to look.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">We had a Gamma Ray Spectrometer, a Neutron Spectrometer, and an Alpha Particle Detector that detects high energy Helium Nuclei flying off.  They had a Doppler Gravity experiment.  They had all sorts of different ways of looking at it other than through photography.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">This allows you to start probing for what’s below the surface.  It starts allowing you to probe for how the surface reacts when it gets hit with a Coronal Mass Ejection and flares from the Sun.  All of these things start to give us hints of the chemistry of the Moon at the density structure of the Moon.  This allows us to start trying to figure out is there water on the Moon.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> The goal here with Lunar Prospector is just with its name, to beyond mapping the surface but to try and map the locations in quantities of chemicals and minerals on the surface of the Moon.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Are there vast stockpiles of water ice?  What elements are there?  Are there elements that reacted with other chemicals in the past?  You really just get a sense of what’s there and where it is.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> So the Neutron Spectrometer is perhaps one of the most important instruments for this search for water.  Using it, Scientists were able to detect the Neutron emissions that you would expect if there’s water hiding under the surface.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">The frustration we’re having is as we look for it with other missions we can’t directly image it and we talked about this in the last show.  So, any water there is on the Moon appears to be trapped in different things.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">According to the Lunar Prospector data, there should be about 3 billion metric tons of water ice in the polar crusts of the Moon.  Now we just need to figure out how to get to it.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">So Lunar Prospector got us to yeah, the Moon has a lot of really interesting chemistry for why we should go back.  Then we went another span of several years without visiting the Moon until the European Space Agency went back with Smart-1.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> This is the coolest mission ever.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> [Laughter] Why do you say it is the coolest mission ever?</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Because the way they used to get to the Moon is that they used an Ion Drive.  We’ve talked about this in the past.  This is where instead of having a chemical rocket where you shoot it out really fast &#8211; you turn on this Ion engine which accelerates with electricity &#8211; Ions out the back of the Spacecraft.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">You don’t need to carry very much fuel so you can launch with a very low Mass.  It’s fairly inexpensive.  It doesn’t let you go very quickly – accelerate very quickly &#8211; but over very long periods of time you can accelerate.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">What they did with Smart-1 is they turned on this engine and increased the size of the orbit around the Earth slowly.  It just kept getting bigger and bigger elliptical circles around the Earth for like the better part of a month [Laughter] until the ellipse was so big that it included the Moon.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Then they just turned it the other way and slowly brought the orbit back down until it was only orbiting around the Moon.  So while normally a Spacecraft just takes from the Earth to the Moon it does it in 2 days, Smart-1 took the better part of a month to make its journey from the Earth to the Moon.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">But it did it at a fraction of the cost that any other Spacecraft would do which I though was just wonderful.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> And what was amazing was just how tiny this little mission was.  It had a mass of just 367 kilograms – about 800 pounds.  A hundred kilograms of that was propellant related they were using Xenon.  But still we’re looking at like a 600 pound (once you get rid of the propellant) Spacecraft that’s tiny.  We have like random laboratory equipment hanging around here that is way, way bigger than that.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Here again we’re looking at detecting stuff in a lot of different ways.  There was a standard CCD Imager that looked at <span style="background: transparent none repeat scroll 0% 0%; -moz-background-clip: border; -moz-background-origin: padding; -moz-background-inline-policy: continuous;">my s</span>tandard optical wavelengths of light and took images with about 80 meter resolutions so each pixel in the image is about 80 meters across.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">They were doing x-ray spectroscopy trying to study the chemicals.  They were also using an x-ray Solar monitor to just keep track of what the Sun was up to because depending upon what radiation from the Sun is hitting the Moon, you’re going to get different data.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Lots of really good science including the discovery of Calcium came out of this mission.  So Smart-1 again, following up on Prospector we’re starting to now study the chemistry of the Moon.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">That was back in 2003 and then we had another gap, four years this time from 2004-2007 happened and then everything started happening all at once last year.  We had&#8230;</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser: </strong> This is about the coolest time of Lunar exploration I think – apart from some of the early discoveries.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> It was like we suddenly re-discovered there was a rock nearby that we could go land on.  So then just one after another we start seeing all these missions.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">There was the Kengoya or Selene missions launched out of Japan.  Japan returned.  They have a high-definition camera on their mission.  It’s producing some of THE coolest videos ever.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser: </strong> They did a re-creation of the Earth rise images. They did it like a movie though.  It’s just beautiful and if you just want amazing pictures of the Earth and the Moon these are some of the most beautiful ones ever done.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> They’re all designed for today’s High-Definition television set so go buy your wonderful high quality Japanese TV and watch your wonderful high quality Japanese Lunar videos – it’s a great combination.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> But not just Japan, China is there.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Pamela:</strong> China is there as well with Chang’e 1 which had the result last week I believe, that no we can’t find visually the water ice on the Moon which is kind of frustrating.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">And then just 2 or 3 weeks ago, another mission took off.  In this case from India.  The Chandrayaan-1 took off October 22 and is off imaging more chemistry experiments.</p>
<p style="margin-left: 0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; margin-bottom: 0in;">Then we’re looking in 2009 here in the United States to launch the Lunar Reconnaissance Orbiter and LCROSS which is going to careen itself into the Moon and then into the Moon again.</p>
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;">
<p style="margin-left: 0.63in; text-indent: -0.63in; margin-bottom: 0in;"><strong>Fraser:</strong> Oh, oh, we’re out of time.  That’s what we want to talk about next week [Laughter] which was the future of Lunar exploration including the plans to send humans back to the Moon. So save that part.</p>
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