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[Music]

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[Applause]

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alright thanks and Katie really wanted

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to come but she's in a wedding tomorrow

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so this was the only day she couldn't

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make it so of course I got got scheduled

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here so uh so I'm filling in so it's

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just a long the last two talks we pretty

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much have the same ideas I think can

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habitable Bryan's occur on Mars today

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and I believe you already know the

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answer that so before you can have a

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bride you got to have salt and so

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everyone's excited about these

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perchlorate salts on there at every

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landing site they allow to these very

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cold temperatures and they can absorb

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water right out of the atmosphere just

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as this as we've been seeing in this

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picture we think we might have actually

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seen this at the Phoenix landing site so

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how do we calculate how much and when

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Brian forms from assault so we use these

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phase diagrams as everyone's explained

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before so this was the phase diagram I

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was used to using before Katie and I

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started working together this is one of

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the melting one that her mom talked

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about where you have the the weight

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concentration of the salt going down and

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you've got different phases where you'd

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have liquid and liquid plus ice and

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different things and then when Katie

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started working with me we started using

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this relative humidity water activity

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versus temperature and how the how these

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two combined is very interesting so

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here's your DRH again so as you increase

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so so we're using Katy's favorite salt

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here sorry this is a magnesium

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perchlorate instead of the the previous

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ones for calcium perchlorate so as you

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increase your relative humidity you get

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liquid and then you get this

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efflorescence relative humidity over

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here which for magnesium perchlorate is

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not temperature dependent while the

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relative age actually is and so so what

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we've been trying to do is actually

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combine these two models to figure out

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what's going to happen in the subsurface

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um so when if you actually had that but

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chloride down there and it starts at

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Zoar bring water it's going to start

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moving to be to have a lower lower

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weight concentration and we're also

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trying to look at the kinetics of this

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in the lab which is not going to be

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presented today but will at another time

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um so so this is just another way of

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looking at this phase diagram so this is

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just showing how much a volume of

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of brine that we have so if you're in

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this area you have a hundred percent if

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you're mixed in these other two areas

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and then if you're you're out of the the

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brine zone you have hydrate instead and

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then so what we can do there is is then

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look at the the the water activity

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based on these same parameters in the

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phase diagram and then we do the same

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thing so we were actually using the

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coast bar definitions just because they

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were a little more liberal they were

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going all the way up to 0.5 water

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activities and any temperature greater

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than 248 K just to try to get some sort

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of habitability in here and then just

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going back what we did is we just we

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just use this water activity uh-huh

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that that's right here and then just

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kind of went with what the volume

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percent is and and that way we can

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actually make this daily questons phase

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diagram kind of the same way and so here

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you know it's just it's just showing the

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same thing that the model works this is

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just kind of numerical errors in here

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but this is this is the the model that

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we're going to be using to figure out

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how how long this brine is actually

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stable anywhere in the subsurface so so

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we're using this model we have to pick a

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place on Mars to use it so naturally I

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just picked palak your crater because

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it's got a ton of significant RSL

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activity I'm kind of an Arsenal guy and

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tourism might have found perchlorate

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here others would disagree with that so

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what we did was we use Mars flow

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modeling and you know while we're trying

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to get daily quests and efflorescence to

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happen in Mars flow it's not quite there

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yes we had to do some post-processing on

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that so Mars flow right now is the

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version we're using is his three-phase

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simulator for water migration in

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partially frozen media it does not do

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salts so if there were any phase changes

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that just they happen at the at pure

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water like at 273 K and what we're

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outputting here among other things is

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temperature RH versus time and the time

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interval that we say that is this 10

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minutes we do this we do a 1d model on

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west facing slopes on at 30 degrees

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because we're trying to get at

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these RSL are occurring at pellicer

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crater here we have 24 different layers

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into the subsurface from 0 to 10

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centimeters and then in that we have

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different geologic zones where we have

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like a silty dry unit on top a sandy dry

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unit and then a bedrock that would be

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saturated with ice below that which

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which purview provides a lot of water

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vapor there and then afterwards after

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after we output all this then we go into

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this post-processing where we use the

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daily quest since in efflorescence to

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actually calculate how much Brian would

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actually be there and so by doing this

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and not having it all coupled we were

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not accounting for any latent heat

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effects when when you actually form this

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liquid there's there's no changes of

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thermal connectivity when you have a

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Brian compared to just a dry salt and

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there's a there's really no vapor

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diffusion either so just going towards

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temperature so so this is a bit of bit

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complicated so this is seasonality this

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is a solar longitude up here or start at

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10 so so we're just moving over the

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entire season and then this is the

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temperature and then this is going to be

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the maximum temperature at every Sall

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and the minimum temperature at every saw

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so they're color coded the color the the

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legend is kind of over here we're o

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being at the surface and then this blue

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being our deepest layer 9.5 centimeters

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and so so you can see as you go down you

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don't you get less temperature variation

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that the surface you get a lot of

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temperature variation and so clearly

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there's no way we're gonna have brines

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in the wintertime because our maximum

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temperatures aren't even getting above

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the eutectic which is what we need for

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for Brian formation so now we're gonna

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look at relative humidity versus

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seasonality as well and so so this DRH

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we actually have two lines here

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representing the DRH because at colder

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temperatures it's going to be around

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this value and that warmer temperature

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it goes lower so during the wintertime

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we have a very high DRH and and this is

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because there's you know it's colder on

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Mars there's no there's a lot of ice in

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the system with this this icy bedrock

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and so that's actually keeping the the

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relative humidity high during the

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wintertime but then during the the

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summertime we get very low relative

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humidities and you can see this distinct

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jump that's happening

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right here and so what actually happens

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here is in the wintertime when we look

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at this data in a different way we can

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actually see all sorts of cold trapping

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that's happening in these upper surface

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layers during the winter time so we're

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getting ice forming in there and then

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right around this Elsa vest right here

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at the surface all of that ice that had

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been trapped during the winter goes away

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it sublimates away and so now we're

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dropping to these very very low minimum

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humidities and then just to lastly to

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say on this slide is that you know

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obviously during the the summer time

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when we would have our SL it's it's get

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definitely going to be too dry for any

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magnesium perchlorate Brian's to form

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because the this RHS is never going to

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get to the DRH and then just to make

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this plot very complicated I'm just

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gonna add three more of these layers in

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and and just kind of why I'm showing

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that's taking the risk of show on this

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is it's just it's interesting to see

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where that cold trapping that ice goes

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away so as you get deeper and deeper you

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can hold on to that cold trapped ice a

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little bit longer every year but then

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that goes away and then you can also see

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these these little blips right here

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which we're on what the heck are these

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and this is actually where you get a

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little bit of cold trapping even after

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that's after the summer peak is has has

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occurred and so this will this will have

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a little bit of a cold trap a little bit

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of ice which will increase the relative

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humidity there in the subsurface and

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then the next day it will sublimate away

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and and you'll go back down to kind of

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at the trend there so yeah so then what

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we did I'm just kind of like when Ed and

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Vince had been talking about before is

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we were looking at combining the the

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temperature and the relative humidity

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just to see where we would actually get

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into that DRH range where where we'd

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actually have brine and then if it was

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brine then then we we looked to see when

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it would go away and that we'd use the

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erh for that so we had that medicine

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that kind of medicine in here

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and so you can see that yeah I'm doing

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it - all right so at the at the the very

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deep

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unit here so I'm just showing the the

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bottom unit in the top unit at the

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bottom unit where we have I

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and then we also put perchlorate in

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there you're gonna have brines all the

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time anytime it's above the eutectic

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temperature so this is just a melting

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effect this is where the Bryan's are

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going to be between the ice grains a

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triple Junction affects things like that

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and then the surface you know you're

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gonna be way too cold during the winter

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time and you're gonna be too trunk dry

248
00:09:20,940 --> 00:09:19,060
during the summertime but in these

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00:09:22,920 --> 00:09:20,950
transition phases in the spring the

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summer you're actually gonna have enough

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humidity and temperature to actually

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have brines there for a significant part

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of the day again and then just to

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complicate things showing everything

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else you know I'm just showing this

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because it's like five point one

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centimeters you can actually have Brian

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there for an entire Seoul again and and

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even up to three centimeters there are

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times where you get enough coal trapping

261
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occurring in that that hasn't sublimated

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gone away yet that you could actually

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have Brian there for a very long period

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of time and then just a instead of

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showing the the nun plot like Vince day

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yeah the Brian is isn't is never

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habitable even according to the East

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Coast bar deadline Coast bar deadlines

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guidelines so yeah so the the water

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activity is never greater than 0.5 or

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and if it was greater than 0.5 then the

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temperature is never greater than 248

273
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yeah so you know so we can try different

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places trying different obliquity too

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and then just to kind of show what's

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happening on a diurnal scale we're gonna

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look right here at 206 K and so that's

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that's what's shown here so again for

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paliku carry there 206 and and instead

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of being at the surface we're gonna be

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right under the surface so at half a

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millimeter just to have pores in there

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instead of just degassing out to the

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atmosphere this is our temperature it's

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going to be on the Left plot and then

286
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this is going to be a relative humidity

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or water activity that's going to be

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shown here on the right and then we

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should show the eutectic temperature on

290
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there the erh the DRH was just

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temperature dependent again and then

292
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what we do is this is this

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post-processing that we're doing we're

294
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taking this initial RH or water activity

295
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and then we're going to decrease it to

296
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the DRH so if it's above this it should

297
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be daily questing out so it's going to

298
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be pulling water out of the APUs

299
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and we're gonna add that to the

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condensed face how much is in that

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condensed face and then likewise we're

302
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gonna do the same when it gets below the

303
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erh so it's if it's too low in humidity

304
00:11:23,629 --> 00:11:21,060
we're gonna take that condensed phase

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out and actually sublimate it away so

306
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it's it provides a more humid

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environment and when we do that we can

308
00:11:34,069 --> 00:11:32,819
calculate the volume of different

309
00:11:36,410 --> 00:11:34,079
mixtures I would get so when it's below

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two of when it's below the eutectic

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temperature like yeah before like 9:00

312
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a.m. here we're not gonna have any

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brines but then after that we can

314
00:11:48,309 --> 00:11:45,360
actually start having brines and these

315
00:11:52,400 --> 00:11:48,319
brines are going to exist even through

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where the erh s and and so I'll explain

317
00:11:56,240 --> 00:11:54,360
that more kind of in the conclusions

318
00:11:57,980 --> 00:11:56,250
here but first the assumption so so to

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00:12:00,079 --> 00:11:57,990
get get these volumes we needed to

320
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assume how much h2o was there and how

321
00:12:03,290 --> 00:12:01,920
much per chlorate was there so we just

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used these assumptions this is just

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based on on the neutron data at Pala

324
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care crater and this based on Phoenix

325
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and so just kind of to conclude here is

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that these brines are not going to be

327
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habitable even though it looks like they

328
00:12:18,610 --> 00:12:16,290
can form under this this situation that

329
00:12:21,410 --> 00:12:18,620
we showed which is very favorable

330
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temperature seems to dominate here so we

331
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have a lot of brines

332
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occurring in here and this is just

333
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really as the temperature increases more

334
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this ice starts melting away and and in

335
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a is able to form the brine and then

336
00:12:35,930 --> 00:12:33,810
even through efflorescence when we're

337
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below efflorescence would predict we can

338
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actually sublimate or evaporate enough

339
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of that condensed material to increase

340
00:12:47,389 --> 00:12:43,680
the relative humidity here and and keep

341
00:12:48,949 --> 00:12:47,399
that brine stable there now we need to

342
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do better modeling with this to figure

343
00:12:53,480 --> 00:12:51,810
out you know so this is a nap or so so

344
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that is you know it's eventually going

345
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to vapour diffuse out but you know we're

346
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gonna do that modeling next and so

347
00:13:01,519 --> 00:12:59,610
that's part of this future work where

348
00:13:03,559 --> 00:13:01,529
we're looking at in the laboratory with

349
00:13:06,019 --> 00:13:03,569
macroscopic more daily quests type

350
00:13:07,730 --> 00:13:06,029
measurements to really look at the the

351
00:13:09,499 --> 00:13:07,740
kinetics that are going on and then

352
00:13:11,809 --> 00:13:09,509
we're we're we're trying hard everyday

353
00:13:13,460 --> 00:13:11,819
trying to get this Marsh flow salt model

354
00:13:15,379 --> 00:13:13,470
to work where we can actually add salt

355
00:13:17,179 --> 00:13:15,389
and and do all this all in one model so

356
00:13:19,610 --> 00:13:17,189
will presenting that at a poster ninth

357
00:13:21,800 --> 00:13:19,620
Mars on under kati's Katie will lead

358
00:13:23,120 --> 00:13:21,810
that so with that I take any questions

359
00:13:26,020 --> 00:13:23,130
thanks

360
00:13:28,340 --> 00:13:26,030
[Applause]

361
00:13:30,500 --> 00:13:28,350
we have time just for one quick question

362
00:13:31,850 --> 00:13:30,510
okay it's more of a comment Andy sure

363
00:13:33,770 --> 00:13:31,860
from the University of Florida

364
00:13:36,470 --> 00:13:33,780
I've just finished I've got a Marche

365
00:13:39,320 --> 00:13:36,480
chamber in my lab a real highly capable

366
00:13:41,750 --> 00:13:39,330
system and I've just completed a series

367
00:13:45,560 --> 00:13:41,760
of experiments where I've taken rocks of

368
00:13:48,350 --> 00:13:45,570
different geochemical composition and

369
00:13:50,630 --> 00:13:48,360
figured out a way to put all frost

370
00:13:52,730 --> 00:13:50,640
layers on it up to a centimeter thick

371
00:13:54,980 --> 00:13:52,740
and then heating that up by either

372
00:13:56,960 --> 00:13:54,990
turning on the UV visible and near

373
00:14:01,310 --> 00:13:56,970
infrared illumination system or heating

374
00:14:03,980 --> 00:14:01,320
from below and the classic Haverly at

375
00:14:06,170 --> 00:14:03,990
all paper in 2001 predicted this really

376
00:14:08,960 --> 00:14:06,180
tight window around the triple point of

377
00:14:14,860 --> 00:14:08,970
water of liquid a triple point for water

378
00:14:18,410 --> 00:14:14,870
on Mars and I can see clearly pure water

379
00:14:21,320 --> 00:14:18,420
flowing off the ice and into the rock

380
00:14:23,990 --> 00:14:21,330
and hydrating the rock not a salty brine

381
00:14:26,060 --> 00:14:24,000
at a depressed temperature but liquid

382
00:14:28,790 --> 00:14:26,070
water flowing off the rock at seven

383
00:14:31,670 --> 00:14:28,800
millibars in a Mars atmosphere between

384
00:14:33,500 --> 00:14:31,680
zero and four degrees centigrade so this

385
00:14:36,380 --> 00:14:33,510
has been really interesting Lester talks

386
00:14:38,210 --> 00:14:36,390
but I would say that where that niche

387
00:14:40,580 --> 00:14:38,220
that you you may not have considered yet

388
00:14:43,400 --> 00:14:40,590
would be underneath underneath frost

389
00:14:45,290 --> 00:14:43,410
layers at the places where that might

390
00:14:47,000 --> 00:14:45,300
occur it might not be something that

391
00:14:49,040 --> 00:14:47,010
happens generically out on the open

392
00:14:51,140 --> 00:14:49,050
terrain as you're cycling through

393
00:14:53,510 --> 00:14:51,150
diurnal temperature swings but there