title: The Galileo probe mass spectrometer: composition of Jupiter's atmosphere.
abstract: The composition of the jovian atmosphere from 0.5 to 21 bars along the descent trajectory was determined by a quadrupole mass spectrometer on the Galileo probe. The mixing ratio of He (helium) to H2 (hydrogen), 0.156, is close to the solar ratio. The abundances of methane, water, argon, neon, and hydrogen sulfide were measured; krypton and xenon were detected. As measured in the jovian atmosphere, the amount of carbon is 2.9 times the solar abundance relative to H2, the amount of sulfur is greater than the solar abundance, and the amount of oxygen is much less than the solar abundance. The neon abundance compared with that of hydrogen is about an order of magnitude less than the solar abundance. Isotopic ratios of carbon and the noble gases are consistent with solar values. The measured ratio of deuterium to hydrogen (D/H) of (5 +/- 2) x 10(-5) indicates that this ratio is greater in solar-system hydrogen than in local interstellar hydrogen, and the 3He/4He ratio of (1.1 +/- 0.2) x 10(-4) provides a new value for protosolar (solar nebula) helium isotopes. Together, the D/H and 3He/4He ratios are consistent with conversion in the sun of protosolar deuterium to present-day 3He.
authors.affiliation: Goddard Space Flight Center, Greenbelt, MD 20771, USA.
authors.forename: H B
authors.initials: HB
authors.lastname: Niemann
authors.forename: S K
authors.initials: SK
authors.lastname: Atreya
authors.forename: G R
authors.initials: GR
authors.lastname: Carignan
authors.forename: T M
authors.initials: TM
authors.lastname: Donahue
authors.forename: J A
authors.initials: JA
authors.lastname: Haberman
authors.forename: D N
authors.initials: DN
authors.lastname: Harpold
authors.forename: R E
authors.initials: RE
authors.lastname: Hartle
authors.forename: D M
authors.initials: DM
authors.lastname: Hunten
authors.forename: W T
authors.initials: WT
authors.lastname: Kasprzak
authors.forename: P R
authors.initials: PR
authors.lastname: Mahaffy
authors.forename: T C
authors.initials: TC
authors.lastname: Owen
authors.forename: N W
authors.initials: NW
authors.lastname: Spencer
authors.forename: S H
authors.initials: SH
authors.lastname: Way
mesh_terms: D000641:Ammonia / Q000032:analysis; D001272:Atmosphere; D002244:Carbon / Q000032:analysis; D005118:Extraterrestrial Environment; D006371:Helium / Q000032:analysis; D006859:Hydrogen / Q000032:analysis; D018538:Jupiter; D013058:Mass Spectrometry; D009584:Nitrogen / Q000032:analysis; D005741:Noble Gases / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D014867:Water / Q000032:analysis*
chemical_list: D005741:Noble Gases; D014867:Water; D006371:Helium; D002244:Carbon; D000641:Ammonia; D006859:Hydrogen; D009584:Nitrogen; D010100:Oxygen