Goal: To understand life in our galaxy.

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Goal To understand life in our galaxy.

• Objectives
• To understand the Basic building blocks for life
  in general
• To learn about What type of stars and planets to
  look for if we want to find life
• To understand How to find these planets
• To examine The search for intelligent life
• To learn about The Drake equation

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Brainstorm!

• Try to find 6 characteristics of the most basic
  life (note this is life in general so if you
  can think of a life form that does not need it,
  it is not a basic building block).
• Note also this is not for human life, just the
  most basic life (like bacteria).
• Finally, this is for life as we know it.

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Lets find them in our solar system!

• Venus too hot, not enough water, very
  unpleasant.
• Earth I am not 100 sure, but I think we may
  have those building blocks on that planet.
• Moon maybe some ice at the pole, but nope not
  going to find life there.
• Mars very tempting to be optimistic. It has
  most of what you need (underground water, frozen
  surface, but below that). However, it is
  lacking in Nitrogen.

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I think the best place to look

• Is a moon of Jupiter called Europa.
• About the size of our moon.
• No atmosphere.
• However, due to tidal heating, underneath about
  1-10 miles of frozen surface lies a gigantic
  underground ocean!
• It has all the possible blocks for life so does
  it have life?
• We need to send a probe there to find out.

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SIM PlanetQuest

• Is a NASA mission scheduled to launch in 2015
  (which means you should expect it about 2020).
• What this instrument will do different is that it
  will be an interferometer.
• An interferometer is a telescope that is slit
  into two or more parts and spread out over a
  large area.
• What this does is effectively gives you a bigger
  diameter to your telescope.
• Since resolution ONLY depends on diameter, and
  not the amount of light your collect, this can
  give you very good resolution.

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Why not done already

• One complication, you have to be able to know the
  distance between telescopes accurate to the
  wavelength of light.
• For radio this is easy because the wavelengths
  are long.
• For infrared and optical this is hard because the
  wavelengths are very tiny.
• For more info go to
• http//planetquest.jpl.nasa.gov/SIM/sim_index.cfm

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What it will do

• With a really good resolution you can measure the
  positions of stars very accurately.
• Measure their positions once every month or so
  and you can watch the stars move with time.
• Some of this will be due to parallax motion (due
  to the earths motion around the sun).
• Some will be due to proper motion which is
  the motion of the star with respect to our sun.
• Once you subtract those out you get the orbital
  motion yes you will be able to watch the star
  orbit around an imaginary point.

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Advantages

• Can be used on any star.
• Can be used to detect planets as small as the
  earth!
• Can be used to find planets further away.
• Disadvantage you are still finding the planet
  indirectly.
• You have no real info on the planet other than
  its mass and orbital characteristics.

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We want to find LIFE!

• To do this we have to look at a planet.
• However, planets are so small that we have no
  hope of actually imagine their surface features
  from many light years away sorry no finding
  oceans and continents.
• So what can we do?

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Chronographs

• When you have multiple detectors for measuring
  light you can determine how you add those
  together.
• If you are clever you can get them to add
  together.
• If you are even more clever you can get them to
  cancel out!

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Blocking the star

• To image a planet directly you have to get rid of
  all the light from the star.
• If you can do that then you have a better shot at
  imagine a planet.
• If you can image the planet you can take its
  spectrum.
• What will the spectrum tell you about the planet?

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Which molecule, if found in some abundance, would
indicate that there was some form of life on the
planet?

• A) Carbon Dioxide
• B) Nitrogen
• C) Water
• D) Ozone

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What determines the makeup of the atmosphere?

• There are 3 processes
• 1) geological volcanoes mostly.
• Volcanoes spew water, Carbon Dioxide, Nitrogen,
  and Sulfur Dioxide into the atmosphere

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Interactions with the sun

• Two ways here
• 1) UV rays can break apart molecules.
• This will form some oxygen in an atmosphere for
  example, but only trace amounts.
• As we saw for the earth, this can also break
  apart water molecules.
• 2) Solar wind if a planet has no sizable
  magnetic field certain gasses (such as water
  vapor) will be removed from the atmosphere.

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Biological

• This is the one we want to search for.
• If there are molecules that are a result of
  biological processes, are short lived, and do not
  occur much naturally, if we find them, we have
  found life!
• Note this will be life in general, like bacterial
  and plant life, not intelligent life.
• So, what do we look for?

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Smoking guns for life?

• Nitrogen can be useful.
• However, it is difficult to detect, and many
  atmospheres have it naturally (Venus Mars have
  3, and Titan has mostly Nitrogen).
• How about molecular Oxygen (O2)?
• Well, it is even more difficult to observe.
• Very trace amounts are produced naturally, so you
  would have to show a lot of it (like our 26) to
  be able to say it was life induced, but we still
  cant detect it

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The true guns

• Methane and Nitrous Oxide
• Methane does not survive long in an atmosphere as
  it gets destroyed by UV rays.
• NO tends to react with Oxygen or goes to
  molecular Nitrogen.
• Either way both are too trace to be seen with the
  instruments coming out.
• However OZONE is the key!
• To have significant amounts of Ozone you need a
  lot of free Oxygen, which means life!
• Also, Ozone is fairly easy to detect!

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With what will we find it?

• Now that we know what to look for, what will
  actually be doing the looking?
• NASAs Terrestrial Planet Finder (TPF for short)
  should be able to do all of this and is scheduled
  for completion in 2020.
• However, their funding is being cut, so there is
  a chance it wont get off for awhile (2030?).
• Anyhow, within our lifetimes we should be able to
  find life outside our solar system!

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Intelligent life

• This is great for life in general, but what about
  ET?
• There is an agency that is searching for
  intelligent life
• SETI (Search for Extra Terrestrial Intelligence).

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What does SETI look for?

• SETI scours the radio section of the
  electromagnetic spectrum.
• SETI tries to find signals that could not occur
  naturally.
• Some examples include beamed transmission,
  repeated patterns, very narrow band emission, or
  anything else that can only be created
  intentionally by an alien civilization.

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Suppose we find life, then what?

• If it is unintelligent life we can do NOTHING!
• Lets suppose we sent a craft to the alpha
  Centauri system at a speed of 0.1 c.
• It would take 43 years to get there
• The large distances make interplanetary travel
  unlikely for a long time and even then very
  impractical.

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How far away will life be?

• Do figure this one out we will use what is called
  the Drake Equation.
• The Drake Equation is just a giant unit
  conversion basically
• There are a few forms to it.
• We will be examining an offshoot here

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Number of stars in galaxy

• 400 billion

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However, how many of those stars can have planets
with intelligent life?

• Big stars die too fast not enough time to
  evolve and a lot of UV light
• Small stars have planets tidally locked
• Slow rotation of planet means no magnetic field
  which means no life on surface

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So, need

• Stars like our sun
• Only about 10 are like our sun
• 2/3rds of those are in binary systems
• So, that leaves about 10 billion possible
  intelligent life bearing suns

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What fraction of those have planets?

• This is the last of the factors that we know
  well.
• It seems that 50-90 of stars form a planet
  system.
• But even if it is only 1 in 10 then we still have
  1 billion useful planetary systems.

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How many planets or moons like our Earth in a
region where you can have life (in general)?

• This one is tricky.
• Stars with too low metals wont form big enough
  planets.
• Stars with too much metal will form hot Jupiters.
• Also, some of these systems will have more than 1
  planet in a habitable zone (we have 3)
• If we say 1 planet per say 10 systems then we
  still have 100 million Earth like planets in a
  habitable zone.

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What fraction of those have actually developed
life?

• Here we have to guess.
• Is life really easy to form when conditions are
  right or were we fortunate?
• If only 1 in a thousand form life though that is
  100,000 planets with life on it!

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What fraction of those have develop intelligent
life?

• This one is the biggest guess.
• However if only 1 in a thousand develop
  intelligent life that is 100 intelligent
  civilizations in just our own galaxy.

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For what fraction of their planets life do they
use technology that we could use to communicate
with them?

• We have only been at this for 60 years.
• Even if the average is a million years well there
  would have to have been 5000 civilizations for us
  to be able to detect one.
• So that would now mean that we would need 50
  galaxies such as ours to find another intelligent
  civilization such as ours.

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Light speed!

• Instead of going there, lets just communicate (if
  we can figure out how to do this and we both have
  a wish to).
• How long will it take us to get a response?

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Universe

• Remember there are about 100 billion spiral
  galaxies in the observable universe!
• It would be very unlucky, a great shame, and a
  big waste of space if we truly were alone in the
  universe.
• Will we find life probably (and maybe within
  our own solar system too) and maybe within our
  lifetimes!
• Intelligent life? Well, we shall see.

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Conclusion

• We have found what a planet needs to be capable
  of supporting life.
• We have found what to look for to determine if a
  planet has life.
• We have estimated the of intelligent
  civilizations in our galaxy.
• Sadly, getting from place to place is really hard
  (after all as we found at the start of the
  semester, the distances between stars is really
  big).