Astrobiology in the Context of a Research University

2. Astrobiology in the Context of a Research University Dimitar D. Sasselov Center for Planetary Astrophysics & Department of Astronomy Harvard University

3. One of Humankind’s Biggest Questions: What is the path from Stars to Life ? • One of the last remaining unresolved questions • It has become tractable by modern science • Major emerging discipline - one could lead !

4. The “Essence” of Life • Resolving the “Chicken-&-Egg” problem • of nucleic acids vs. proteins - • too much complexity ? • Solution: • RNA-catalyzed • RNA replication !

5. The “Essence” of Life • Find how Darwinian • behavior can emerge • from chemistry • Develop synthetic • self-replicating • molecules • Membranes & • vesicles - cell division • before cells ! RNA (red) adsorbed into clay, inside a vesicle (green) - Szostak lab (2004).

6. The Ultimate Leap: Chemistry to Life • Prebiotic chemistry: find a plausible route to “self-replicators”; • Prebiotic chemistry: on mineral surfaces, inside atmospheric particles, and ice-eutectic reactions; • Prebiotic chemistry: on the young Earth, other planets and in space ?

7. Co-evolution of Planets and Life • Life as a planetary phenomenon: • constraining the chemical pathways that led to life. • Unearthing the evidence - • how did it all begun on Earth ? • The next big question - • was Mars alive ? A fossil cyanobacterium in circa 1.5 Gyr old sedimentary rocks - (A. Knoll).

8. Mars, Endurance Crater distinct layers of sedimentary rocks (A. Knoll, Sept. 2004)

10. The Universe is the “stage”… • Planets - cradles for life • in a hostile Universe • Search & exploration: • by end of decade - • know planets like Earth • Formation & stability • of planetary systems Artist concept of a hot Jupiter

11. The Planetary Perspective • The initial condition: • chemical makeup & isotopes; • Precise timeline of early events. A pre-solar SiC grain from the Murchison meteorite. 2 microns

12. The Planetary Perspective • Precise timeline of early events. Jacobsen (2003)

13. Planets Orbiting Other Stars Number of planets discovered around stars like our Sun: 154 planets 14 multiple planet systems

14. Transits: A New Method for Planet Discovery

15. Venus in Front of the Sun

16. TransitMeasurements

17. Evidence for Planet OGLE-TR-56b Doppler Shift Light Dimming Konacki, Torres, Jha, Sasselov, 2003, Nature

18. Mass-Radius diagram: All known transiting extra-solar planets Konacki, Torres, Sasselov, Jha (2005)

19. HD 209458b: a Hot Jupiter

20. The Next Step:Find Planets like Earth Lynnette Cook

21. KEPLER: Search for Earth Twins NASA Mission - launch in 2007 Transit Search: ~100,000 stars Can detect planets like our Earth GOAL: discover ~12 Earths in habitable zones; also - thousands of giant planets like Jupiter.

23. Why in a University ? • A major emerging discipline. • Education: a bridge b/n life & physical sciences • Undergraduate: e.g. Harvard Melton/Gross committee • Graduate: specialized courses; workshops • Public outreach: immense potential (lecture series, etc)

24. Special thanks to team members: S. Jacobsen, J. Szostak, A. Knoll, S. Martin, M. Shair

26. Additional Slides

27. The Other Known Transiting Extrasolar Planet HD 209458b: Dimming of light due to transit, observed with HST. Tells us DIRECTLY: Planet radius, INDIRECTLY: Planet density Planet composition Brown, Charbonneau, Gilliland, Noyes, Burrows (2001)

28. Model: Seager & Sasselov 2000 Detection: Charbonneau et al 2002

29. NASA’s Terrestrial Planet Finder • Find and characterize Earth-like planets • Reduce the glare of the parent star by one million to one billion • Launch date 2015 • Observe stars within 50 light years Alcatel Space Industries

30. At Harvard NOW:

31. NEXT:

32. The Ultimate Leap: Chemistry to Life RNA (r