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hello

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i'm gabrielle jones an undergraduate

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senior at northern arizona university

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and i will be presenting on the

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detectability of service bio signatures

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previous studies have examined how

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spectral observations are influenced by

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noise sources

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and how the vegetation red edge could be

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used as a potential bile signature

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but it is currently unknown if noise

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sources

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and technological capabilities will

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allow for the detection of surface bowel

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our study modeled an exoplanet's

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atmosphere with earth-like conditions

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and computed definitive detection times

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of surface biosignatures

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using the atmospheric radiative transfer

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model smart

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so what are surface biosignatures well

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the surface biosignatures we are

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focusing on

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are biological pigments and the

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vegetation red edge

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they are features present in a reflected

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light spectrum

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that are created from living organisms

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on the figure on the right we have a

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reflected light spectrum of an orange

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microbial mat

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and here are the specific surface box

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initials we are looking for

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absorption features and the vegetation

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so what are pigments pigments are

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produced by living organisms

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that have a color resulting from

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selective color

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absorption pigment absorption features

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are troughs in the spectra of plant

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microbial life

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caused by biological pigments such as

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chlorophyll a

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and b as seen on the right

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they are created when primary

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photosynthetic molecules

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absorb energy from light as they process

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water and carbon

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into sugar and oxygen however some

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pigment absorption features

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are not dependent on life to produce

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oxygen as a byproduct of photosynthesis

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and as a result non-photosynthetic

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pigments

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the vegetation red edge is characterized

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by the region

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of rapid increase in reflectance of

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vegetation

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in the near infrared region of a

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spectrum

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around 0.6 to 0.8

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as seen in the figure here it is

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a spectral feature produced by the

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absorption of chlorophyll

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and other pigments in the ultraviolet

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invisible wavelength ranges

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and the scattering of light in the near

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infrared region

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as a result of internal cell structure

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and it is indicative of photosynthetic

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so why microbial mats microbial mats are

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composed of layers of microorganisms

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and they are the extremophiles we are

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focusing on specifically orange and

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black mats

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they are a reasonable candidate for

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detection of life on other planets

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because they are a simple light form

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making it more probable

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to exist on an exoplanet they have been

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prevalent on earth throughout its

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history

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containing some of the oldest life on

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earth and they have prominent

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vegetation red edge and pigment

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absorption features within the

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reflecting spectra

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the picture on the right showcases

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orange and black microbial mats

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in a stream bed called green creek in

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if you want to know more about microbial

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mats visit my co-author

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skylar borges talk on high resolution

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satellite mapping of microbial matte and

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moss cover

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so are surface biosignatures detectable

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from directly image earth-like

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and what kind of extremophile life can

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be detected

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to answer these questions we are using

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models to simulate the spectra of an

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exoplanet

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and test whether surface biosignatures

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are detectable

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using future and current technologies

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such as

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our first step is to create realistic

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surfaces

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of exoplanets we did this using a linear

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mixing model to mix multiple

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and members at desired percentages and

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we created various percentages of soil

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black matte and orange mat to see which

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combination would be the fastest to

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detect

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and even if some combinations are

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here are our results from our linear

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mixing model

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we mix black matte and soil with soil in

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the red

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and black 100 black matte in purple

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then we mix combinations of 25

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here are the specific surface bio

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signatures we are looking for

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the absorption pigment of chlorophyll

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and the red edge characterized by a

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we did the same combinations for orange

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matte with soil and red

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and 100 orange matte and purple with

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combinations 25

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here are the chlorophyll absorption

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pigments

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and then the steep red edge feature

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then we created mixtures of black bat

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orange matte

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and soil to represent a realistic world

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with these extremophiles here you can

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see

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the pigment features and the vegetation

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red edge

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after creating surface spectra we take

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it a step further

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and simulate an earth-like atmosphere

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using smart

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or spectral mapping atmospheric

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radiative transfer model

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and with our mixed spectrum as input

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smart will produce

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top of the atmosphere radians that we

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here are results for smart we used

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our black matte surface spectrum as

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input

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and used our output values for solar

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flux

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and radians to calculate the reflectance

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for each wavelength

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the spectrum contains surface bowel

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signatures as well as key absorption

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bands

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here is a comparative figure of our

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surface spectrum

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and smart spectrum for black matte you

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can see the vegetation red edge

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present in both spectrum and

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the pigment absorption feature in the

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surface spectrum but it is unclear

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where the the pigment absorption feature

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here are smart results for orange matte

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and here you could

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distinctly see the chlorophyll pigments

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and the vegetation red edge

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in our comparative figure we have the

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pigments and red edge again

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and that translates very well in our

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next we run those radiant spectra

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through a luvar noise model

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to output realistic detection times for

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each spectrum

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at 10 parsecs the detection times are

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calculated

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by how well the levoir noise model can

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tell the difference between

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a model with a spectrum containing

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surface biocenters

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and a model with a spectrum that has

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those features scrubbed out

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which in our case would be soil we wrote

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a script that

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individually compared our mixed spectra

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to soil

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and stored the corresponding detection

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here are our results from our noise

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detection model

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we created a table with the percentage

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abundance

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of each end member of our mixed spectrum

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and its corresponding detection time

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value

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here you can see a hundred percent black

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matte has a detection time of 12 hours

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100 orange matte has a second fastest

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detection time of 22 hours

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and our combination of 75 percent

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black matte 15 orange mat and 10

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soil has a close third of about 24 hours

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past this line is over 100 hours

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here's a plot of our percentage

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abundance of orange matte and black

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matte with the corresponding detection

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time values

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you can see a nice trend that as the

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percentage abundance of orange matte and

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black matte

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increases the detection time

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exponentially decreases

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and here are the values for 25 percent

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orange and black matte

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and 100 and as you can see

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with a higher percentage abundance

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orange matte and black matte are

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relatively

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close in detection time but the

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less abundance of each matte

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then the more separation between the

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detection times

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we found that if the percentage of

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biological was greater than or equal to

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75 percent

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then the detection time was less than

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100 hours

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and with our fastest detection time

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being blackmai at around 12 hours

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then to be able to detect life on

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another planet it is quite reasonable to

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devote tens of hours of observation time

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so why is this important understanding

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techniques for detecting life

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on an exoplanet's surface will aid in

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our

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search for life beyond earth and will

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inform future space telescope mission

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design

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moving forward we will test different a

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biologic

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spectra for our noise model to compare

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to our spectra with our surface

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biosignatures

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this is because reflectance is

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dominating detection times

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not bio signatures so to isolate the bio

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signature

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we are going to create a spectrum that

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has those features

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more specifically removed to really

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focus on detecting those signatures

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we will also run smart with clouds

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for each of our surface spectra with 25

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50 and 75 cloud coverage

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we will test other extremophiles with

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non-photosynthetic pigments and without

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the vegetation red edge

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to compare the detectability with our

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results for orange mat

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thank you so much for listening to my

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talk and please feel free to reach out