willner@cfa.HARVARD.EDU (Steve Willner) (09/13/89)
From article <25868@iuvax.cs.indiana.edu>, by chiaravi@silver.bacs.indiana.edu (Lucius Chiaraviglio): > It has been a long time since I read an article about the composition > of the Jovian atmosphere, and much (if not all) of what I remember is > pre-Pioneer and all of it is certainly pre-Voyager. However, I do remember > that carbon, nitrogen, oxygen, hydrogen, and sulfur are present in the Jovian > atmosphere. I have no data about the amounts of other elements in the Jovian > atmosphere One recent paper on Jupiter's atmosphere (Bjoraker et al. 1986, Icarus, vol. 66, p. 579) discusses ammonia, phosphine (PH3), methane, mono- deuterated methane, carbon monoxide, and germane (GeH4). And of course, most of the atmosphere is hydrogen. The authors conclude that N/H, P/H, and Ge/H are near solar abundance at the 5 bar pressure level. I would expect most elements to be near solar abundances except for iron and other dense elements that might be concentrated in the core. The outstanding feature of the Jovian atmospheric chemistry is how strongly reducing it is. Incidentally, most of what we know about the constituents of Jupiter's atmosphere comes from the Kuiper Airborne Observatory. Spacecraft missions do measure how density and temperature vary with altitude. This information is needed to extract quantitative abundances. And for some bodies, the density information has revealed constituents (e.g. nitrogen) that are not easily studied with spectroscopy from near-Earth platforms. [discussion of possible life in Jupiter's atmosphere] > It would be nice to find this out before we introduce life there, even > though the probability of its long-term survival there seems low Finding microscopic life forms in Jupiter's atmosphere obviously involves sending a probe sometime, with a non-zero probability of contamination. On the other hand, apparently no effort at all has been made to sterilize the Galileo probe. It doesn't seem to me to be possible to sterilize the Galileo probe at this late date. The only options I can see are to go ahead as planned or to cancel the probe portion of the mission. (Delays for major modifications would be just as expensive as a new mission.) Obviously reasonable people can differ on which is preferable, depending on their views of (1) the probability of Jovian life, (2) the risk of contamination, and (3) the value of the data the probe will return. Since I rate 1 and 2 low and 3 high, I favor going ahead, but others may reach a different conclusion. ------------------------------------------------------------------------- Steve Willner Phone 617-495-7123 Bitnet: willner@cfa 60 Garden St. FTS: 830-7123 UUCP: willner@cfa Cambridge, MA 02138 USA Internet: willner@cfa.harvard.edu