title: Narrow horizons in astrobiology.
authors.affiliation: Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721-0092, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Drake
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Jakosky
mesh_terms: D001256:Astronomy / Q000191:economics / Q000639:trends*; D005075:Biological Evolution; D001695:Biology / Q000191:economics / Q000639:trends*; D005118:Extraterrestrial Environment; D019369:Life; D016083:Planets; D018531:Spacecraft / Q000191:economics; D014481:United States