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

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. Transit Measurements

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

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

19. HD 209458b: a Hot Jupiter

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

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

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. Brown, Charbonneau, Gilliland, Noyes, Burrows (2001) Tells us DIRECTLY: Planet radius, INDIRECTLY: Planet density Planet composition

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