1. Glen Langston: Chautauqua 2012 1 Signs of Life: Pre-biotic Chemistry New Discoveries with the NRAO 100m Diameter Green Bank Telescope (GBT) Glen Langston Astrobiology Review Green Bank Discoveries What Radio Astronomers Observe Future Directions NRAO glangsto@nrao.edu

2. Glen Langston: Chautauqua 2012 2Astrobiology Credit: Pascal Ehrenfreund

3. Glen Langston: Chautauqua 2012 3 Ingredients for Life

4. Glen Langston: Chautauqua 2012 4 Miller-Urey-Type Synthese (1953)

5. Glen Langston: Chautauqua 2012 5 “It must be admitted from the beginning that we do not know how life began. It is generally believed that a variety of processes led to the formation of simple organic compounds on the primitive Earth. These compounds were combined together to give more and more complex structures until one was formed that could be called living. No one should be satisfied with an explanation as general as this.” Miller & Orgel: The origin of life on Earth, 1974

6. Glen Langston: Chautauqua 2012 6 Background   Two groups of life origin theories: Terrestrial origin. Extraterrestrial origin. Planets are not isolated in terms of biology and exchange of organic material could occur between them.   Possibility for cosmic delivery of basic molecules: Amount of micrometeorites (from 50 to 500  m in size) – 50-100 tons daily. Meteorite flux - 0.03 tons per day. Heavy bombardment in early Earth - 1000 times more than present amount. High percentage of organic components in carbonaceous chondrites Credit: Natalia Gontareva

7. Glen Langston: Chautauqua 2012 7 Astronomical Life Cycle Credit: Ehrenfreund and Charnley

8. Glen Langston: Chautauqua 2012 8 5 % of the mass of the Galaxy Lifetime: 10 7 - 10 8 years Site of star formation NGC 604 T ~ 10 K r ~ 10 6 H atoms per cm 3 Cosmic rays drive a rich ion-molecule chemistry supplemented by neutral-neutral processes organic molecules organic molecules Interstellar Clouds

9. Glen Langston: Chautauqua 2012 9 H 1 He 7.5. 10 -3 O 8.3. 10 -4 C 4.0. 10 -4 N 1.0. 10 -4 Ne 0.8. 10 -4 Si 4.3. 10 -5 Mg 4.2. 10 -5 S1.7. 10 -5 Fe4.3. 10 -5 Na2.1. 10 -6 P3.0. 10 -7 Elemental abundances

10. Glen Langston: Chautauqua 2012 10 Astronomer’s Periodic Table Credit: Ben McCall

11. Glen Langston: Chautauqua 2012 11 Many organic molecules were first discovered in with the 43m telescope in Green Bank. These detections were a surprise. The experts thought interstellar space was too harsh for chemistry! FORMAMIDE FORMALDEHYDE FORMIC ACID CYANO- ACETYLENE METHANOL ACETALDEHYDE Molecular Discoveries: 43m

12. Glen Langston: Chautauqua 2012 12 Interstellar Molecules Credits: Pat Thaddeus, Al Wootten Galactic Chemistry: Carbon Rich Life on Earth: Carbon based Coincidence?

13. Glen Langston: Chautauqua 2012 13 Field of View SensitivityResolution

14. Glen Langston: Chautauqua 2012 14 Molecular Discoveries: 100m World’s most sensitive Telescope in frequency range 10 to 50 GHz Discovered new interstellar molecules, including propenal and propanal

15. Glen Langston: Chautauqua 2012 15 Sugars in Space Ethylene glycol was discovered in a massive interstellar cloud of dust and gas near the center of the Milky Way Galaxy. Ethylene glycol was discovered in a massive interstellar cloud of dust and gas near the center of the Milky Way Galaxy. Ethylene glycol (a 10-atom molecule made up of carbon, hydrogen, and oxygen) is one of the five largest molecules ever discovered in space. Ethylene glycol (a 10-atom molecule made up of carbon, hydrogen, and oxygen) is one of the five largest molecules ever discovered in space.

16. Glen Langston: Chautauqua 2012 16 Evidence of Astro-Chemistry

17. Glen Langston: Chautauqua 2012 17 What do Radio Astronomers Observe? There’s no Eye piece on a Radio Telescope… Astronomers measure signal strengths as a function of frequency. With enough observations and imagination, we can see the first steps in the formation of life.

18. Glen Langston: Chautauqua 2012 18 Intensity versus Frequency Intensity (Volts) Frequency (MHz) 0.0 900 1800 0.0 900 1800 80 98 116 80 98 116

19. Glen Langston: Chautauqua 2012 19 Fundamental Laws International Law: 88.000 - 108.000 FM Broadcast (200 kHz steps) Physics Laws: Quantum Mechanics and Molecular Structure. (GBT observations of HC 5 N, HC 7 N and HC 9 N) Frequency (MHz) Intensity (Kelvin) Intensity (Volts) 101 102 HC 5 N HC 7 N HC 9 N

20. Glen Langston: Chautauqua 2012 20 GBT: Cyanopolyynes + HC 13 N Cyanopolyynes are ideal molecules for radio astronomy: Simple Structure, easy to model.Simple Structure, easy to model. Large dipole moment, strong lines.Large dipole moment, strong lines. Simple spectra.Simple spectra. If detected, suggest more biologically relevant molecules are present HCN HC 7 N

21. Glen Langston: Chautauqua 2012 21 UV radiation field ~ 10 8 photons cm -2 s -1 photochemistry simple di- and triatomic species: CH, CN, C 2, HCN, C 2 H 3 …. Soot, PAHs, carbonaceous networks….. T ~ 10 to 100 K (-400 F)  ~ 100-300 cm -3 Diffuse Interstellar Medium

22. GBT K-Band Ammonia Maps 15 KFPA NH 3 (1,1) Ammonia mapping of dark clouds Finn & Jackson 22 Glen Langston: Cambridge 2011 April 26

23. Compare NH 3 and Cyanopolyyenes Glen Langston: Chautauqua 2012 23

24. Glen Langston: Chautauqua 2012 24 Cyanopolyyne Line Intensities With the GBT, observations that took many hours with the 43m, now take only minutes. Rarer, weaker, isotopic versions ( 13 C instead of 12 C) of the molecules can be discovered with the GBT.

25. Glen Langston: Chautauqua 2012 25 Weak lines: HC 7 N Isotopomers Comparison of HC 7 N molecule 13 C/ 12 C Isotopomers: Abundance Ratio 1/80 TMC-1 is nearby (140 pc from Earth), so 13 C/ 12 C abundance is expected to be similar that abundance ratio observed on Earth. (Galactic variation observed.) We share a common history with TMC-1!

26. Glen Langston: Chautauqua 2012 26 Future Directions Radio Astronomers detect (in seconds) the molecules critical for life Lower frequency (5 to 20 GHz) observations are critical for study of important large molecules. Need *many* simultaneous lines for weak detections