THE SEARCH FOR EXTRA-TERRESTRIAL LIFE

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OVERVIEW

• Why we search
• Celestial bodies
• Space exploration
• How we define life
• Requirements for life
• The drake equation

WHY WE SEARCH

• Curiosity
• Survival
• Population
• Resources

CELESTIAL BODIES

• Stars
• Black holes
• Planets

STARS

BLACK HOLES

PLANETS

Space exploration

v2-rocket

Yuri gagarin

vostok-1

The moon landing

Space shuttles

The challenger explosion

satellite imagery

ISS

how we define life

• No simple answer
• Any molecular structure that can contain the information and means for reproduction

Requirements for life

• Stellar system requirements
• Planetary requirements

Stellar system requirements

• A suitable planet
• A suitable star

A Suitable planet

• Right size (too big = strong gravity = thick atmosphere = hot temperature and vice versa)
• Stable orbit to maintain consistent conditions throughout the year
• Located in the habitable zone

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A Suitable star

• The right spectral class
• Spectral classes are sorted from the most massive, brightest and hottest O-class stars to the lightest/dimmest/coldest M-class stars

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Planetary requirements

• Energy
• Temperature
• Liquid water
• Essential chemicals
• An atmosphere

Energy

• Fuels chemical reactions
• Comes in the form of light & chemical energy

Temperature

• Required to allow liqiud water to be present
• Range -15C to 115C

Liquid water

• Medium that allows molecules to dissolve and move between cells

Essential chemicals

• Carbon (in combination with nitrogen, oxygen and hydrogen among others
• All life as we know it is carbon based because of the wide variety of chemical bonds it can make

An Atmosphere

• Traps heat
• Protects against radiation

The drake equation

• Allows us to estimate the amount of intelligent civilizations in our galaxy
• N = R*·Fp·Ne·Fl·Fi·Fc·L

N = R*·Fp·Ne·Fl·Fi·Fc·L

• N = number of civilizations
• R* = Amount of suitable stars formed per year in our galaxy
• Fp = Fraction of those stars that form planets
• Ne = Average number of habitable planets per star that forms planets

N = R*·Fp·Ne·Fl·Fi·Fc·L

• Fl = The fraction of those habitable planets where life emerges
• Fi = ^ where intelligence evolves
• Fc = ^ that is capable of interstellar communication
• L = The amount of years a civilization remains detectable

The problem?

• We only know 3 of the variables
• R* = 1
• Fp = 1
• Ne = 0.25~
• The rest is currently unknown

Conclusion