The O/OREOS Mission: First Science Data from the Space Environment Viability of Organics (SEVO) Payload Andrew Mattioda, 1 Amanda Cook, 1 Pascale Ehrenfreund, 2 Richard Quinn, 3 Antonio J. Ricco, 1 David Squires, 1 Nathan Bramall, 3 Kathryn Bryson, 4 Julie Chittenden, 1 Giovanni Minelli, 1 Elwood Agasid, 1 Lou Allamandola, 1 Chris Beasley, 1 Roland Burton, 1 Greg Defouw, 1 Millan Diaz-Aguado, 1 Mark Fonda, 1 Charles Friedericks, 1 Chris Kitts, 5 David Landis, 6 Mike McIntyre, 1 Michael Neumann, 5 Mike Rasay, 5 Robert Ricks, 1 Farid Salama, 1 Orlando Santos, 1 Aaron Schooley, 1 Bruce Yost, 1 and Anthony Young 5 Abstract We report the first science results from the Space Environment Viability of Organics (SEVO) payload aboard the Organism/Organic Exposure to Orbital Stresses (O/OREOS) free-flying nanosatellite, which completed its nominal spaceflight mission in May 2011 but continues to acquire data biweekly. The SEVO payload integrates a compact UV-visible-NIR spectrometer, utilizing the Sun as its light source, with a 24-cell sample carousel that houses four classes of vacuum-deposited organic thin films: polycyclic aromatic hydrocarbon (PAH), amino acid, metalloporphyrin, and quinone. The organic films are enclosed in hermetically sealed sample cells that contain one of four astrobiologically relevant microenvironments. Results are reported in this paper for the first 309 days of the mission, during which the samples were exposed for *2210 h to direct solar illumination ( *1080 kJ/cm 2 of solar energy over the 124–2600 nm range). Transmission spectra (200–1000 nm) were recorded for each film, at first daily and subsequently every 15 days, along with a solar spectrum and the dark response of the detector array. Results presented here include eight preflight and 16 in-flight spectra of eight SEVO sample cells. Spectra from the PAH thin film in a water-vapor-containing microenvironment indicate measurable change due to solar irradiation in orbit, while three other nominally water-free microenvironments show no appreciable change. The quinone anthrarufin showed high photostability and no significant spectroscopically measurable change in any of the four microenvironments during the same period. The SEVO experiment provides the first in situ real-time analysis of the photostability of organic compounds and biomarkers in orbit. Key Words: Cubesat— Nanosatellite—O/OREOS—SEVO—Low-Earth orbit—Astrobiology—UV-visible spectroscopy—Photochemistry— Photodegradation of organics—Polycyclic aromatic hydrocarbons—Quinone. Astrobiology 12, 841–853. 1. Introduction K nowledge of the stability and degradation pathways of biomarkers and organic precursors to life in the outer space environment are key to our understanding of life’s or- igins and limits and the search for extraterrestrial bio- signatures. Over the past three decades, experiments on space exposure facilities, including the Long Duration Exposure Facility, Biopan/Foton, EXPOSE-E (EXPOSE-Eutef ), and EXPOSE-R, have investigated the evolution of both biological and organic materials in Earth orbit (e.g., Ehrenfreund et al., 2007; Cottin et al., 2008; Guan et al., 2010; Horneck et al., 2010) as a consequence of their exposure to the ambient solar, cos- mic, and ‘‘trapped’’ (in the inner Van Allen belt) radiation. In those experiments, a range of molecules were characterized by spectroscopic and other techniques before their launch and deployment in outer space and subsequently re-characterized following their return to Earth to determine overall changes. Kinetic or dynamic reaction details, however, can be most efficiently studied in real time. Polycyclic aromatic hydrocarbons (PAHs) are among the most-studied organic molecules in space-exposure 1 NASA Ames Research Center, Moffett Field, California. 2 Space Policy Institute, Washington, DC. 3 SETI Institute, Mountain View, California. 4 Bay Area Environmental Research Institute, Sonoma, California. 5 Robotic Systems Laboratory, Santa Clara University, Santa Clara, California. 6 Charles Stark Draper Laboratory, Cambridge, Massachusetts. ASTROBIOLOGY Volume 12, Number 9, 2012 ª Mary Ann Liebert, Inc. DOI: 10.1089/ast.2012.0861 841