title: Space Station gas-grain simulation facility: application to exobiology.
abstract: The Space Station provides an environment in which the forces required to suspend particles during an experiment can be reduced by as much as six orders of magnitude.  This reduction in levitation force enables us to perform many new experiments in a variety of disciplines.  We have grouped these experiments into two categories: 1) those involving an individual particle or the interaction between a few particles and 2) those involving clouds in particles.  We consider only particle experiments at this stage because cloud experiments suffer from electrostatic interactions and levitation-forced coalescence therefore requiring considerably more space, mass and crew interaction.  The displacement of a particle resulting from g-jitter for ballistic, Knudsen and Stokes flow regimes is considered in detail and the radiation, acoustic, electrostatic and electromagnetic levitation mechanisms to control this motion are reviewed.  We have selected the simulation of organic haze production ion Titan as an example experiment for detailed study.  The objective of this experiment is to simulate the photolysis of methane and the subsequent formation of the organic haze particles in the upper atmosphere of Titan.
authors.affiliation: Life Science Division, NASA/Ames Research Center, Moffett Field, CA 94025, USA.
authors.forename: C P
authors.initials: CP
authors.lastname: McKay
authors.forename: C R
authors.initials: CR
authors.lastname: Stoker
authors.forename: J
authors.initials: J
authors.lastname: Morris
authors.forename: G
authors.initials: G
authors.lastname: Conley
authors.forename: D
authors.initials: D
authors.lastname: Schwartz
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D019443:Cosmic Dust; D003359:Cosmic Radiation; D018559:Exobiology / Q000295:instrumentation*; D005118:Extraterrestrial Environment; D005740:Gases / Q000737:chemistry*; D006112:Gravitation; D010316:Particle Size; D055585:Physical Phenomena; D010825:Physics; D018539:Saturn; D013026:Space Flight / Q000295:instrumentation*; D018531:Spacecraft; D014618:Vacuum; D014732:Vibration; D014893:Weightlessness
chemical_list: D000336:Aerosols; D019443:Cosmic Dust; D005740:Gases