Synthesis of Molecules by Cosmic Ion Bombardment M. H. Moore NASA Goddard Space Flight Center R. L. Hudson Eckerd College International Workshop Trans Neptunian Objects Dynamical and Physical Properties July 2006

Outline Introduction-motivation for laboratory work How we study ices in the laboratory Review four cases Predictions Goal is to develop a good understanding of important volatile and less-volatile molecules relevant to TNO ice environments

Processes affecting original ices and dust in Proto-planetary Disks. The composition of disk material is extremely sensitive to initial composition, nebular processing, and nebular dynamics. mumma_100903.3.3

Original Interstellar Abundances > ½ IS organics are nitriles Some Ice Environments Original Interstellar Abundances >100 known species Largest has 13 atoms > ½ IS organics are nitriles

Comparison of Cometary Volatiles with Volatiles in Interstellar Environments Underlined molecules identified also in condensed phase aBased on Table 1, Ehrenfreund et al. Comets II, 2004 bFrom Table 1, Knez et al. ApJ 635, 2005 and Blake, private communication

Comparison of Cometary Volatiles with Ices in the Solar System aBased on Table 1, Ehrenfreund et al. Comets II, 2004 bFrom Table 1, Knez et al. ApJ 635, 2005 and Blake, private communication

Radiation processes on KBO surfaces Cosmic Rays MeV p+ ~30 - 50 K UV Photons Chemical Reactions Sputtering

Estimated radiation doses after 4.6 × 109 years a a = Cooper et al., 2003

Schematic of laboratory set-up at NASA Goddard’s Cosmic Ice Laboratory

IR Spectrometer UV p+

Synthesis of Complex Organics 1. H2O + CH3OH 2. H2O + HCN 3. NH3 + HCN 4. N2 + CH4

Studies of ices rich in water are motivated by observations of TNOs such as Quaoar and Charon

Ice studies with methane are motivated by observations of TNOs such as Pluto and 2005 FY9

Case 1 H2O + CH3OH

7% 12% % carbon converted in H2O + CO (5:1) ice after 22 eV molecule−1 20% 40%

H2O + CH3OH (~3:1), T = 20 K Hudson and Moore, Icarus, 145, 661 (2000)

Ethylene Glycol

Discovered in 2002 in the ISM & in Comet Hale-Bopp in 2004! Ethylene Glycol Discovered in 2002 in the ISM & in Comet Hale-Bopp in 2004! (Hollis et al., 2000) (Crovisier et al., 2004)

Case 2 H2O +HCN

H2O + HCN (5:1), T= 20 K Gerakines et al., Icarus, 170, 202 (2004)

Case 3 NH3 + HCN



Gerakines et al., Icarus, 170, 202 (2004) NH3 + HCN (5:1), T = 20 K CN - dicyandiamide H2CNH NH3 NH3 HCN NH4+ HCN Gerakines et al., Icarus, 170, 202 (2004)

Case 4 N2 + CH4

C3H8 N2:CH4 Hudson and Moore Icarus, 172, 466 (2004)

3.54 m Ethylene Glycol 2.16 m Hydrogen Peroxide Carbon Suboxide Carbonic Acid Ammonium Cyanate Moore et al. Earth, Moon and Planets 92, 291 (2004) Hudson and Moore, Astrobiology, 6, 483 (2006)

Reggie Hudson hudsonrl@eckerd.edu Eckerd College St Petersburg, Florida Funding through NASA’s Planetary Atmospheres, Planetary Geology and Geophysics, Outer Planets, and

Univ. of Alabama at Birmingham Thanks --- to collaborators Perry Gerakines Univ. of Alabama at Birmingham Gerak@uab.edu Robert Ferrante US Naval Academy Ferrante@usna.edu

www-691.gsfc.nasa.gov/cosmic.ice.lab