Laboratory Chemistry of the Outer Solar System Marla Moore NASA/Goddard Space Flight Center January 28, 2008 Cosmic Ice Lab Polar Gateways Arctic Circle Sunrise 2008, Barrow Alaska

What we do ? Laboratory radiation chemistry of relevant outer solar system ices. What we need! A good understanding of outer solar system environments, e.g.: Temperature Radiation environment Ice composition of surfaces Laboratory Chemistry Goal Help explain observations and predict likely new products yet to be discovered

50 years ago Explorer I. January 31, 1958 Temperature – calculated – assuming black bodies T ≈ 300 r -1/2 Radiation environment Cosmic ray energy spectrum of primary cosmic rays was known Launch of Explorer I— discovery of Van Allen radiation belts e.g. Pluto 55 K

50 years ago Ice Composition Near-Infrared water-ice feature detected on: Mars polar cap Rings of Saturn Europa and Ganymede Suspected water ice on inner satellites of Saturn based on reflectivity Laboratory radiation chemistry 1953 (origin of life study) gas phase mixtures (rocket fuel?) Frozen free radical experiments 1963 ( comets) 77 K mixture H 2 O+CH 4 +NH 3 5 MeV electrons John Oro Gerald Kuiper

Some Ice Environments KBOs water carbon dioxide ammonia methane nitrogen carbon monoxide

* * * Based onTable 4 from T. Roush, JGR, 2001 *

Water Methane Ammonia

Radiolysis Photolysis / Magnetospheric

How do we study ices in the laboratory ?

Ice at 10 K Vacuum Infrared Spectrum Infrared Light Laboratory Set-Up MeV p + 10 −7 mm Hg H 2 O CO 2 NH 3 Gas

p+p+ IR Spectrometer UV

Examples 1. H 2 O 2 and sulfur--Europa 2. Fate of methane--Pluto 3. If methanol then sugar ? --Comets

EUROPA Energy MeV H 2 O, SO 2, SH, CO 2, CH, XCN, H 2 O 2, H 2 SO 4, carbonate salt, hydrous sulfate

Laboratory ice studies used to: IDENTIFY Hydrogen Peroxide on Europa

H 2 O + SO 2 Sulfuric acid p+p+ Laboratory ice studies shows that on Europa

The dashed curve shows the spectrum of a mixture of C 2 H 2 :C 2 H 6 :CH 4 (Sasaki et al., 2005) PLUTO N 2 CH 4 -methane CO Irradiated methane forms ethane and propane Pluto spectrum

COMET HALE-BOPP

H 2 O + CO, T= 15 K (~10 8 yr) Methanol

40% 7% 12% 20% Ethylene Glycol Discovered in 2002 in the ISM & in Comet Hale-Bopp in 2004! (Hollis et al., 2000) (Crovisier et al., 2004) Methanol

Discovered in the ISM (Hollis et al., 2002) Ethylene GlycolGlycolaldehyde p+

Looking to the future

Room temperature residues

New Tools for Chemical Analyses HPLC & Detectors MS Liquid Chromatography Mass Spectrometry LC-MS Gas Chromatography Mass Spectrometry GC-MS MSGC

New Horizons will reach the Pluto system in July 2015 The ESA Rosetta spacecraft will reach comet 67P/Churyumov-Gerasimenko in 2014

Radiation processing complex molecules, and ions Reactions generally understood Laboratory work predicts new molecules and ions awaiting detection SUMMARY

Reggie Hudson Collaborators Reggie Hudson Robert Ferrante Paul Cooper Reggie Hudson Robert Ferrante Paul Cooper

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