<title>Explorer-class astrobiology mission</title>

Abstract

In this paper we describe a potential new Explorer-class space mission, the AstroBiology Explorer (ABE), consisting of a relatively modest dedicated space observatory having a 50 cm aperture primary mirror which is passively cooled to T<65 K, resides in a low-background orbit (heliocentric orbit at i AU, Earth drift-away), and is equipped with a suite of three moderate order (m~10) dispersive spectrographs equipped with first-order cross-dispersers in an "echel lette" configuration and large format (1024x1024 pixel) near-and mid-IR detector arrays cooled by a modest amount of cryogen. Such a systemwould be capable of addressing outstanding problems in Astrochemistry and Astrophysics that are particularly relevant to Astrobiology and addressable via astronomical observation.The observational program of this mission would make fundamental scientific progress in each of the key areas of the cosmic history of molecular carbon, the distribution and chemistry of organic compounds in the diffuse and dense interstellar media, and the evolution of ices and organic matter in young planetary systems. ABE could make fundamental progress in all of these areas by conducting an approximately one year mission to obtain a coordinated set of infrared spectroscopic observations over the 2.5-20 tim spectral range at spectral resolutions of R > 1000 of approximately 1000 galaxies, stars, planetary nebulae, and young star planetary systems. Keywords:Astrobiology, infrared spectroscopy, Explorers, interstellar organics, telescope, spectrometer 1, INTRODUCTIONThe field of Astrobiology, the study of the origin, evolution, and future of life in the universe, has received considerable attention in recent years. One of the principal overlaps between astrophysics and astrobiology is in the area of quantifying the role that interstellar materials may play in the origin of life. Tremendous strides have been made in our understanding of interstellar material over the past fifteen years thanks to parallel developments in observational astronomy and laboratory astrophysics. Dust in the diffuse interstellar medium (ISM) is now known to consist largely of cold refractory materials comprised of amorphous and crystalline silicates mixed with an amorphous carbonaceous material containing aromatic structural units and short, branched aliphatic chains. In the dense ISM, these cold dust particles are coated with mixed molecular ices, of which the major constituents are known. Lastly, the signature of carbon-rich polycyclic aromatic hydrocarbons (PAHs) is widespread throughout the ISM. These organics and ices play a central role in the chemistry of dense, dark molecular clouds-with the ices acting as both reservoir and reaction center for the species detected in the gas; and together with the organics, setting the stage for the chemistry that occurs when stars, planets, and ultimately life form.This great progress has only been made possible by the close collaboration of observers with laboratory experimentalists, all with the goal of applying th...