Niemann H B, Atreya S K, Carignan G R, Donahue T M, Haberman J A, Harpold D N, Hartle R E, Hunten D M, Kasprzak W T, Mahaffy P R, Owen T C, Spencer N W, Way S H
Goddard Space Flight Center, Greenbelt, MD 20771, USA.
Science. 1996 May 10;272(5263):846-9. doi: 10.1126/science.272.5263.846.
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.
沿着下降轨迹，从0.5巴到21巴的木星大气成分由伽利略探测器上的四极质谱仪测定。氦（He）与氢（H₂）的混合比为0.156，接近太阳比例。测量了甲烷、水、氩、氖和硫化氢的丰度；检测到了氪和氙。在木星大气中测量发现，相对于H₂，碳的含量是太阳丰度的2.9倍，硫的含量大于太阳丰度，而氧的含量远低于太阳丰度。与氢相比，氖的丰度比太阳丰度小约一个数量级。碳和惰性气体的同位素比率与太阳值一致。测得的氘与氢（D/H）的比率为(5±2)×10⁻⁵，表明该比率在太阳系氢中比在本地星际氢中更大，而³He/⁴He比率为(1.1±0.2)×10⁻⁴，为原太阳（太阳星云）氦同位素提供了一个新值。D/H和³He/⁴He比率共同表明，原太阳氘在太阳中转化为了如今的³He。
