Saturn's A Ring Has Oxygen, But Not Life

http://www.umich.edu/news/index.html.../Feb05/r022405

Saturn's A Ring has oxygen, but not life
University of Michigan
February 23, 2005

ANN ARBOR, Mich. - Data from the Cassini-Huygens satellite showing
oxygen
ions in the atmosphere around Saturn's rings suggests once again that
molecular oxygen alone isn't a reliable indicator of whether a planet
can support life.

That and other data are outlined in two papers in the Feb. 25 issue of
the journal Science co-authored by University of Michigan engineering
professors Tamas Gombosi, J. Hunter Waite and Kenneth Hansen; and T.E.
Cravens from the University of Kansas. The papers belong to a series of
publications on data collected by Cassini as it passed through the
rings
of Saturn on July 1.

Molecular oxygen forms when two oxygen atoms bond together and is known
in chemical shorthand as O2. On Earth, it is a continual byproduct of
plant respiration, and animals need this oxygen for life. But in
Saturn's atmosphere, molecular oxygen was created without life present,
through a chemical reaction with the sun's radiation and icy particles
that comprise Saturn's rings.

"That means you don't need biology to produce an O2 atmosphere," Waite
said. "If we want indicators to use in the search for life on other
planets, we need to know what to look for. But oxygen alone isn't it."

Because Saturn's rings are made of water ice, one would expect to find
atoms derived from water, such as atomic oxygen (one atom) rather than
O2, Waite said. However, the paper, called "Oxygen Ions Observed Near
Saturn's A Ring," suggests the formation of molecular oxygen
atmospheres
happens more often in the outer solar system than expected. There is
earlier evidence of molecular oxygen atmospheres elsewhere in the solar
system - for instance above the icy Galilean moons of Jupiter - he
said.

Four U-M College of Engineering faculty members are involved in the
Cassini mission to explore Saturn's rings and some of its moons. Waite
leads the team operating the ion and neutral mass spectrometer, the
instrument that detected and measured the molecular oxygen ions. Other
team members are J.G. Luhmann of the University of California,
Berkeley;
R.V. Yelle, of the University of Arizona, Tuscon; W.T. Kasprzak, of the
Goddard Space Flight Center; R.L. McNutt of Johns Hopkins University;
and W.H. Ip, of the National Central University, Taiwan.

A second, viewpoint paper called, "Saturn's Variable Magnetosphere," by
Hansen and Gombosi, who is chair of the College of Engineering's
department of Atmospheric, Oceanic and Space Sciences, reviews key
findings from the other Cassini teams, including new information that
contradicts data gathered 25 years ago, when the space craft Voyager
passed by the planet.

The University of Michigan College of Engineering is ranked among the
top engineering schools in the country. Michigan Engineering boasts one
of the largest research budgets of any public university, at $135
million for 2004. Michigan Engineering has 11 departments and two NSF
Engineering Research Centers. Within those departments and centers,
there is a special emphasis on research in three emerging industries:
Nanotechnology and integrated microsystems; cellular and molecular
biotechnology; and information technology. The College advances
academic
scholarship and markets cutting edge research to improve public heath
and well-being.

For more information see the CoE home page:
http://www.engin.umich.edu/index.html