1. Is There Life Beyond Earth?

2. Warm-Up
How many students got an “A” in marking period 2 in 11th grade science?
What information would you need to figure this out?
How many homerooms are there in 11th grade?
How many students in each homeroom?
How many possible grades are there?
A, B, C, D, F 5 possible grades (20% A)

3. How many intelligent alien civilizations do you think exist?
Drake equation-an attempt to estimate the number of extraterrestrial civilizations in our galaxy with which we might come in contact
N = N* fp ne fl fi fc fL
The equation can really be looked at as a number of questions

4. N = N* fp ne fl fi fc fL
N: number of communicating civilizations in the galaxy.
N*: represents the number of stars in the Milky Way Galaxy
fp: fraction of stars that have planets around them
ne: number of planets per star that are capable of sustaining life
fl: fraction of planets in ne where life evolves
fi: fraction of fl where intelligent life evolves
fc: fraction of fi that communicate
fL : fraction of the planet's life during which the communicating civilizations live

5. Try the Drake Equation Yourself
What was the number of communicating civilizations in the galaxy that your class came up with?
___________

6. SETI Program SETI — the Search for Extraterrestrial Intelligence
The Mission of the SETI Institute
is to explore, understand and explain the origin, nature and prevalence of life in the universe

7. Why Complex Life May Be Rare
The Rare Earth Hypothesis argues that life on Earth required an improbable combination of astrophysical and geological events and circumstances
Some conditions that a planet needs for complex life to exist
Habitable zone
the necessary existence of liquid water requires that the temperature of the planet be neither too high nor too low.
A central star of the right character

8. Continued… Planetary system: Inner and Outer Planets
Need a large Jupiter-sized planet to keep asteroids away
Size of planet –
Too large, the planet will become a gaseous planet
If it is too small, it will not be able to maintains an atmosphere.
Large moon- keeps the climate stable
Chemistry of the atmosphere

10. Life on Earth All living things: Are made up of one or more cells
Take in energy and use it to grow and develop
Reproduce
Give off waste

11. The “Goldilocks” Conditions
Life exists on Earth…No one knows whether life exists anywhere other than Earth
Earth has:
Liquid water
Suitable temperature range
Atmosphere for living things to survive
Scientists call these favorable conditions the “Goldilocks” conditions

12. Extreme Conditions Giant tubeworms in the deep ocean
Scientists have discovered living things in places where it was once believed that life could not exist:
Examples:
Giant tubeworms in the deep ocean
Single-celled organisms in hot springs
Tiny life-forms inside solid rock

13. The range of conditions in which life can exist is much greater than scientists once thought
Organisms can survive in conditions without water, in extreme heat, extreme cold, and extreme acidity

15. Life on Mars?
Spacecraft have found regions on the surface of Mars that look like streambeds with crisscrossing paths of water
Life requires water so scientists hypothesize that Mars may have once had conditions for life to exist

16. Life on Europa? One of Jupiter’s moons explored by Voyager spacecraft
Europa has a smooth, icy crust with giant cracks
Similar patterns occur in the ice crust over Earth’s Arctic Ocean
Scientists hypothesize that there is a liquid ocean under Europa’s ice-the water could be kept liquid by heat coming from inside Europa

18. Water on Saturn’s Moon?
Images from NASA’s Cassini spacecraft indicate that one of Saturn’s moons, Enceladus, may contain pockets of liquid water below its icy crust
                                                                                                                                                                                                             

19. Water on Saturn’s Moon
Liquid water geysers make Enceladus a very exciting place to look for life
Unknown heat sources inside Enceladus melt ice into deposits of subsurface water and under pressure, these water pockets burst through the icy crust
The white streaks in this image are backlit geysers of water ice, rising hundreds of miles into space from Enceladus’s dark disc

21. More Recent Discovery: Water Ice on the Moon
In 2009, a NASA probe on India’s lunar orbiter discovered 600 million metric tons (158 billion gallons) of water ice in 40 craters at the Moon’s North Pole.
In 2009, NASA crashed two probes into the Moon’s South Pole and there was significant amounts of water in the debris cloud