title: Microbial Morphology and Motility as Biosignatures for Outer Planet Missions.
abstract: Meaningful motion is an unambiguous biosignature, but because life in the Solar System is most likely to be microbial, the question is whether such motion may be detected effectively on the micrometer scale. Recent results on microbial motility in various Earth environments have provided insight into the physics and biology that determine whether and how microorganisms as small as bacteria and archaea swim, under which conditions, and at which speeds. These discoveries have not yet been reviewed in an astrobiological context. This paper discusses these findings in the context of Earth analog environments and environments expected to be encountered in the outer Solar System, particularly the jovian and saturnian moons. We also review the imaging technologies capable of recording motility of submicrometer-sized organisms and discuss how an instrument would interface with several types of sample-collection strategies. Key Words: In situ measurement-Biosignatures-Microbiology-Europa-Ice. Astrobiology 16, 755-774.
authors.affiliation: 1 GALCIT, California Institute of Technology , Pasadena, California.
authors.forename: Jay
authors.initials: J
authors.lastname: Nadeau
authors.affiliation: 2 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California.
authors.forename: Chris
authors.initials: C
authors.lastname: Lindensmith
authors.affiliation: 3 Department of Biological Oceanography, University of Washington , Seattle, Washington.
authors.forename: Jody W
authors.initials: JW
authors.lastname: Deming
authors.affiliation: 4 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts.
authors.forename: Vicente I
authors.initials: VI
authors.lastname: Fernandez
authors.affiliation: 4 Department of Civil and Environmental Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts.
authors.forename: Roman
authors.initials: R
authors.lastname: Stocker
mesh_terms: D001105:Archaea / Q000166:cytology*; D001419:Bacteria / Q000166:cytology*; D003595:Cytoplasmic Streaming; D018534:Earth, Planet; D018559:Exobiology / Q000379:methods*; D005118:Extraterrestrial Environment; D046448:Ice Cover / Q000382:microbiology; D018538:Jupiter; D008853:Microscopy; D009792:Oceans and Seas; D018539:Saturn; D013026:Space Flight; D014871:Water Microbiology