Sun’s movement through Milky way and fossil microbes on Mars

Welcome! “Alien Life” tracks the latest discoveries and thoughts in the various elements of the famous Drake Equation. You may notice that this and future entries are shorter than usual; career, family and book deal commitments have forced me to cut back some of my projects. Now, here’s today’s news:
g Stars - The sun's movement through the Milky Way regularly sends comets hurtling into the inner solar system - coinciding with mass life extinctions on earth, a new study claims. The study suggests a link between comet bombardment and the movement through the galaxy. See article.
g Abodes - Materials blasted into space from the surface of early Earth may preserve a unique record of our planet's early surface environment. Armstrong et al. (2002) pointed out that such materials, in the form of terrestrial meteorites, may exist on the Moon and be of considerable astrobiological interest if biomarkers from early Earth are preserved within them. See article.
g Life - Fossil microbes found along an iron-rich river in Spain reveal how signs of life could be preserved in minerals found on Mars. The discovery may help to equip the next generation Mars rover with the tools it would need to find evidence of past life on the planet. See article.
g Intelligence - By examining marks on the teeth of ancient human ancestors, scientists have found that their diet was far different than previously believed. The research sheds light on the evolutionary history of complex organisms on Earth. See article.
g Message - The Fermi paradox is the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilizations and the lack of evidence for, or contact with, such civilizations. See article.
g Learning - The international astrobiology community recently gathered at AbSciCon 2008 to present new discoveries, to build collaborations, and to celebrate a decade of cross-disciplinary science. AbSciCon 2008 was hosted by the SETI Institute, and it attracted more than 675 scientists, students, educators, and journalists from 28 countries. See article.
g Aftermath - Would dutiful American citizens trust the government to handle first contact with extraterrestrials and rush to get information to the public? See article. Note: This article is from 1999.