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thanks everybody for sticking around

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after lunch so it's kind of a weird

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juxtaposition and I will readily admit

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that I know very little about Mars so

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the first part of this talk is mostly

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going to be about here's what's

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interesting about Mars it may not

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actually deal with some of the talks but

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and you know interesting information you

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can have as you can see this is a

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picture of the limb of Mars so we've got

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both of n picture of the atmosphere

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involved there and then solid surface

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and craters which we will hear a little

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bit more about later today so first I

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want to introduce the major players we

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have the Earth and Mars just give you

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guys a little bit of particulars the

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Martian day is a little longer than the

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earth day it takes about six hundred in

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some days to get around the Sun those

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are Martian days by the way and it

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weighs know about a tenth of the mass of

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the earth and it's about half the size

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so it's cold it's dry the surface

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temperature actually varies by more than

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a factor of two goes from 130 k at its

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lease point2 about 310 k and the surface

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pressure is actually about six millibars

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and varies from about four millibars to

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greater than eight millibars so that

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also varies by more than a factor of two

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the surface gravity is a little lower

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and clearly my slide didn't show up

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entirely but for example the Earth's

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atmosphere is made up of principally

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nitrogen and oxygen and argon with a

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little tiny bit of water and co2 whereas

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the Martian atmosphere is mostly co2 and

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nitrogen and argon and a little bit of

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oxygen and then water vapor and the

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Martian atmosphere is very very tenuous

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just to give you a little picture of

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what the earth-moon system looks like in

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perspective this is to scale because

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we're going to be talking about Mars we

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should also look at the Martian moons to

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there yeah that's right you should laugh

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if you can't see it this is Phobos and

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this is Deimos and those are to scale

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we're taking an interesting betting pool

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because Phobos is actually on a

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degrading orbit so sometime in the next

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50 million years from now not then now

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now it will eventually thank someone got

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the reference it will eventually collide

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with the solid surface of Mars so if you

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want in on the betting pool you have to

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play with some pretty big names like

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Emperor on the fourth and the cyber

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hegemony hegemony haga mom hey yeah

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there's a couple different

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pronunciations there so moving on the

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reason why you can't see it is because

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this is the size of Phobos here's

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Madison for scale so very tiny moon its

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most likely captured if we start looking

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at the solid surface of Mars we get some

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very interesting features these are the

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Northern Plains they're relatively

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crater under full whereas the southern

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portion of Mars is incredibly cratered

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one of our talks will feature the a

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Sedalia platinum Leisha I'm sorry again

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I'm not an expert on Mars or Martian

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pronunciation but it's this this plane

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right here that has a few impact

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structures that could give us some clues

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about some of the sedimentary structures

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that may underlie a lot of the surface

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of Mars and so you can still you can see

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this dichotomy where you have a fairly

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flat Northern Hemisphere and a very well

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cratered southern hemisphere and that

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dichotomy between the low-lying northern

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hemisphere and the up did or

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high-altitude southern hemisphere is

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very interesting I don't think there's

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been a very good explanation as to why

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that is there have been some suggestions

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that it could be an impact structure or

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a weird heterogeneity in the mantle

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that's

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early on its history but when someone

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solves that please let me know this is

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crazy and awesome you can see some of

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the big mountains like Olympus Mons they

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stand out in relief biggest mountain in

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the solar system including the mountains

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on Pluto which aren't very interesting

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so through the history of Mars we've had

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a number of really interesting things

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happen you've got these very large

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impacts that show up early in its

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history even prior to the noachian which

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is the oldest period of Martian history

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the magnetic field is thought to have

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shut off about four billion years ago

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that would have protected its atmosphere

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from erosion by the solar wind you've

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got large periods of volcanism

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stretching through the noachian into the

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Hesperian so from about 4 billion years

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ago to about 3 billion years ago and

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then you've got some suggestion of

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hydrothermal subsurface circulation or

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flow of water even on the surface

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potentially so you have this open system

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where you have potential surface waters

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whether or not those are long-lived

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episodes of liquid water on the surface

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is still an open question and minerals

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are complicated I won't get into them

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very much but we will have a couple of

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talks about looking at terrestre analogs

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for those this is not a big image thank

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you so another one of the talks were

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going to be getting is looking at the

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subsurface of Mars and so I wanted to

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make sure everyone was on board with

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what that might look like so for example

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early in the Martian history where it

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had a higher higher geothermal gradient

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you can see that the temperature below

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the surface gets up above freezing but

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there's still a suggestion that early in

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its history the surface was below

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freezing at least in some places which

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may have been the location for a paleo

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cryosphere so you could have potential

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living organisms in these salt brians

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close to the surface fueled by these geo

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thermal gradients nowadays things are

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not cooler so in order to get down to

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the

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freezing point you have to be about five

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kilometers death depth these are still

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purely hypothetical geo thermal

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gradients we have to actually send

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somebody there to measure these go

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geology and so this is a very sort of

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simplistic view of it and really what

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you could have is these very complex

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systems where you get penetration of for

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example brines or even liquid co2 could

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be stable in the surface or subsurface

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you could get circulation through a lot

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of different strata you could get

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mineral water co2 interactions you could

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get magnetic fluids or deep hydrothermal

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circulation again you got to send

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somebody to go drill another thing we

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may hear about today is the Gale Crater

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eponymously because of the fact that we

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put a couple of Landers in here or just

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the one I guess MSL just one you know

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they put so many Landers on the damn

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thing and it's got this suggested

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alluvial fan structure so you could have

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liquid water flowing on the surface into

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this crater which could get you some

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sedimentary minerals on the surface

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which may be easy to see now speaking of

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minerals there's been some suggestion

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that for example looking at John Kline

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with one of the Sam instruments or the

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Sam instrument i should say you get the

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presence of water carbon dioxide oxygen

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and some forms of sulfur what those

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might be still little nebulous trying to

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work out the details sulfur chemistry is

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complex we'll get back to that later

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when we talk about a different planet

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and one of the talks is going to talk

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about ala night and jerra site Allen aye

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tis the aluminum bearing sulphur mineral

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and jerra site is the iron bearing one I

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can't tell the difference hopefully

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we're going to completely switch gears

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Mars is super interesting but we have to

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talk about the other session which is

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talking about planetary atmospheres

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the going interior to the earth we have

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Venus here to scale the orbits are not

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right though so don't take that at face

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value but Venus is exceptionally warm

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again my atmospheric compositions didn't

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show up but we're going to play with it

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so the day is about 6,000 hours long and

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the year is about yeah ninety percent of

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a day so it's super slow rotating it's

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in a retrograde rotation so it's really

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weird it interacts with its atmosphere

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in crazy ways and it's about the same

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mass and radius as the earth it's often

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considered to be the earth twin if earth

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had a really hot twin and I need that

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thank you and it gets it gets a lot of

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radiation it gets nearly twice as much

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as the earth does so it's a very hot

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place it has a 90 bar surface atmosphere

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that has like 700 it's hot enough to

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melt lead it's really crazy and its

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atmosphere is mostly co2 about 90 bars

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of the stuff and there's a little bit of

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nitrogen a little bit of argon

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essentially no water there has been some

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suggestion that there chlorine is pretty

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present in its atmosphere because you

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get melting of sodium chloride which is

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just crazy and so speaking of crazy this

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is an example of some of the chemistry

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we think is happening in Venus's

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atmosphere I'm not going to go through

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this all but you can see that

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essentially we're starting with like so2

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I can't even find it here it is so2 and

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we're using esos some for example

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photochemistry is happening you're

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getting some chlorine chemistry that's

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also happening and so you get the

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exchange between these reservoirs

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between like so2 and pure self or

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species you can get some sulfur aerosols

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some complex sulfur species again like I

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don't even know what that's called but

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basically chlorine is a big part of a

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lot of the chemistry that's happening in

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Venus's atmosphere

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just to show you it a different way you

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can do a lot of emissions for example

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these are photon emissions I'm not going

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to suggest that I know what these

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symbols represent but you can see that

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the reservoirs are exchanging

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constituents so for example co2 gets

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fertilized in 20 and co and then those

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that's not at all like what's happening

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on the earth and so on the earth you can

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see here that you do get some oxygen

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production from the Potala size of co2

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but on the earth oxygen is entirely

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within the domain of biology at least in

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the present earth if we look at oxygen

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through time oxygen prior to the rise of

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oxygen at the great oxidation event

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about two and a half billion years ago

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was oxygen was very low and rose to

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between one and fifty percent of modern

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and then there was a second rise of

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oxygen about six or eight hundred

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million years ago that it rose into

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about present values if we look at

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oxygen on other planets though as an

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analogy for building out a photochemical

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framework for understanding terrestrial

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planets there's been a suggestion that

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the incident stellar illumination as a

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function of wavelength can alter the

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photochemistry and the foot of

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photochemical steady state of a

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terrestrial planetary atmosphere and so

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these are the fluxes with respect to

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wavelength and these are some of the

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relevant cross sections for example for

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dissociating co2 and oxygen and ozone

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absorption so with that I will take

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questions because I'm 30 seconds over

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questions for Sonny okay cool come on

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somebody's got to know it gotta wanted

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to know something about Mars okay right

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in the back um great talk you said there

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hypothetically hydrothermal fluids on

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Mars does anyone have any hypothesis on

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what the geochemistry of those fluids

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might be I mean so the suggested liquid

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water layer in the Martian subsurface is

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fairly deep because the geothermal

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gradient is so weak so it's really a

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question of what composition those

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liquid water layers are going to have I

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would suggest that they're going to be

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if they are liquid they're going to be

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incredibly briny so you know thirty or

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forty percent salt solutions like it

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unlike it I mean you can find some of

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those crazy brines and a lot of there's

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environments where you can get those

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Brides on the surface of the earth I

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don't know if they're great analogies

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for the subsurface of Mars because you

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also have to worry about the pressure

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that you're at I didn't suggest it but I

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mean you're at a like a million

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atmospheres at five kilometers below the

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Martian surface so it's going to be

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pretty weird like welcome to terrestrial

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I'm not as a question up Pluto just

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because people talk about Pluto is

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having an atmosphere and part of your

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talk was about planetary atmospheres

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does Pluto actually have an atmosphere

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is it more like a surface-bound

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exosphere like what's on the moon do

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you've any idea um I think that I mean

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the the classical idea was that it was a

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surface pond exosphere but one of the I

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think that that's still pretty commonly

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held it actually when Pluto and Charon

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come close enough together Pluto and

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Charon share an atmosphere it's actually

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the scale height rises to the point

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where you get actually atmosphere

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transfer from Pluto to Sharon which is

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again pretty crazy I just that just

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blows my mind but I think that it's

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still considered an exosphere at that