The ORGANIC experiment on EXPOSE-R on the ISS: Flight sample preparation and ground control spectroscopy

Bryson KL, Peeters Z, Salama F, Foing B, Ehrenfreund P, Ricco AJ, Jessberger E, Bischoff A, Breitfellner M, Schmidt W, Robert F

Abstract

In March of 2009, the ORGANIC experiment integrated into the European multi-user facility EXPOSE-R, containing experiments dedicated to Astrobiology, was mounted through Extra Vehicular Activity (EVA) externally on the International Space Station (ISS). The experiment exposed organic samples of astronomical interest for a duration of 97 weeks (∼22 months) to the space environment. The samples that were returned to Earth in spring 2011, received a total UV radiation dose during their exposure including direct solar irradiation of >2500 h, exceeding the limits of laboratory simulations. We report flight sample preparation and pre-flight ultraviolet-visible (UV-Vis) characterization of the ORGANIC samples, which include 11 polycyclic aromatic hydrocarbons (PAHs) and three fullerenes. The corresponding time-dependent ground control monitoring experiments for ORGANIC measured over ∼19 months are presented and the results anticipated upon return of the samples are discussed. We present the first UV-Vis spectrum of solid circobiphenyl (C38H16). Further, we present the first published UV-Vis spectra of diphenanthro[9,10-b′,10′-d]thiophene (C28H16S), dinaphtho[8,1,2-abc,2′,1′,8′-klm]coronene (C36H16), tetrabenzo[de,no,st,c′d′]heptacene (C42H22), and dibenzo[jk,a′b′]octacene (C40H22) in solid phase and in solution. The results of the ORGANIC experiment are expected to enhance our knowledge of the evolution and degradation of large carbon-containing molecules in space environments.