Transcript Goal: To understand life in our universe.

Goal: To understand life in
our universe.
Objectives:
1) To understand the Basic building blocks for life
in general
2) To learn about What type of stars and planets
to look for if we want to find life
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.
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.
I think the best place to look:
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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.
Some other places:
• Ganymede/Callisto – also have salty
oceans
• Titan – methane rain + lakes + rivers.
• Titan also has a large ocean the “crust”
floats on top of
• Enceladus – water geysers
• Pluto – does it also have volcanoes and a
subsurface ocean?
Looking for life outside our solar
system:
• To find life we first need to be able to
image planets directly.
• We need a spectrum
Which molecule, if found in some
abundance, would indicate that
there was some form of life on the
planet?
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A) Carbon Dioxide
B) Nitrogen
C) Water
D) Ozone
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
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.
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?
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 can’t detect it…
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!
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.