1. Class 31:
Astrobiology

2. Class 31: Astrobiology Class Updates • Homework #5 due Wed. 4/30
• Final Review Wed. 4/30
- study guide, practice exam
• Final Exam:
Mon. May 10am

3. Astrobiology

4. Life’s Sequence on Earth
3.75
Billion
years ago
1.7
Billion
years ago
4.5
Billion
years ago
600
Million
years ago
500
Million
years ago
225
Million
years ago

5. Life As We Know It

6. Conditions for Life (I)
Liquid water

7. Conditions for Life (II)
Carbon

8. Conditions for Life (III)
Energy

9. Conditions for Life (IV)
Stable Environment

10. Life on Mercury? Moon?

11. Life on Venus? Earth? Mars?

12. Life on the Gas Giants?

13. Life on Europa?

14. Life on Titan?

15. Life on Mars?

16. The Habitable Zone

17. Searching for Life: Biomarkers

18. The Drake Equation Nc = N* x fp x nLZ x fL x fI x Fs
= # of communicative civilization in galaxy
Pessimistic
Estimate
Optimistic
Estimate
N*= # stars in galaxy x x1011
fp = fraction of stars w/planets
nLZ = number of planets in habitable zone
fL = fraction of planets where life could begin
fI = fraction of life forms that evolve to intelligence
Fs = fraction of star’s life where life communicates
Nc = 2x x106
• Pessimist: we are alone
• Optimist: many civilizations

19. Search for Extraterrestrial Intelligence
(SETI)
Search for Extraterrestrial
Intelligence
SETI Institute
Aricebo

20. SETI Projects nonprofit, $20M astronomy data - 2.3 million users,
• Project Phoenix: primary search,
nonprofit, $20M
SETI Projects
• SERENDIP: piggyback search of ordinary
astronomy data
Jill Tarter •
- 2.3 million users,
yrs computer
time each day

21. SETI Telescopes Effelsberg Big Ear Haystack Square Kilometer Array
Arecibo
Square Kilometer Array

22. The hmmmm….. Factor

23. Life on Other
Planets?

24. Challenge Question
Suppose we find an extra solar planet whose distance from its star indicates that it could have liquid water and an energy source. What other conditions must be met for it to have the potential for life?
a. A stable surface and a hydrogen atmosphere
b. Plate tectonics and biogenic elements
c. Carbon and a stable surface
d. Plate tectonics and an oxygen atmosphere
e. Plate tectonics and a magnetic field

25. Challenge Question Do you think life might exist beyond Earth?
If there is life, will it be discovered in our lifetime?
If life is discovered, do you think it could be intelligent?