NASA Probe Finds Jupiter Moon has Atmosphere

July 18, 1997 5:01 PM EDT

PASADENA, Calif. (Reuter) - The space probe Galileo has found evidence that Jupiter's moon, Europa, may have an atmosphere, scientists reported Friday.

NASA's Jet Propulsion Laboratory here said Galileo, which is exploring Jupiter and some of its moons, discovered that Europa has an ionosphere, a strong indicator that the icy moon also has an atmosphere.

An ionosphere is a layer of charged particles such as ions and electrons found in the upper levels of atmospheres.

``While this discovery does not relate to the question of possible life on Europa, it does show us there is a surface process occurring there, and Europa is not just some dead hunk of material,'' said Arvydas Kliore, the lead Galileo investigator.

Some scientists believe Europa could nurture life because of the presence of water on the Jovian moon in addition to oxygen.

Kliore, who also reported his findings in Friday's issue of Science magazine, said Europa's ionosphere was discovered during a series of experiments carried out between December 1996 and February, when Europa was positioned between the spacecraft and Earth.

Measurements of the Galileo radio signal received by the Deep Space Network in Goldstone, Calif., and Canberra, Australia, showed that the radio beam was refracted by a layer of charged particles that make up Europa's ionosphere.

Another Jovian moon, Io, was found to have an ionosphere in 1973 by the Pioneer 10 space probe. The finding was confirmed recently by Galileo, the Jet Propulsion Laboratory said.