----- Original Message -----
From: NASA Jet Propulsion Laboratory
Sent: Thursday, February 27, 2003 9:38 PM
To: [EMAIL PROTECTED]
Subject: New Spacecraft Tool Reveals Massive Gas Cloud Around Jupiter
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov http://www.jpl.nasa.gov/
Michael Buckley (240) 228-7536 or (443) 778-7536
Johns Hopkins University Applied Physics Laboratory, Laurel, Md.
Guy Webster (818) 354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
News Release: 2003-028
February 27, 2003
New Spacecraft Tool Reveals Massive Gas Cloud Around Jupiter
Using a sensitive new imaging instrument on NASA's Cassini spacecraft,
researchers have discovered a large and surprisingly dense gas cloud
sharing an orbit with Jupiter's icy moon Europa.
Stretching millions of miles around Jupiter, the donut-shaped cloud,
known as a "torus," is believed to result from the uncommonly severe
bombardment of ion radiation the jovian giant sends toward Europa.
That radiation damages Europa's surface, kicking up and pulling apart
water-ice molecules and dispersing them along the moon's orbit into a
neutral-gas torus with a mass of about 60,000 tons.
The cloud's mass indicates the intense radiation Europa faces has more
severe consequences than scientists thought, said Dr. Barry Mauk of
Johns Hopkins University Applied Physics Laboratory, Laurel, Md. Mauk
heads the laboratory's research team whose findings appear in the Feb.
27 issue of the journal Nature. The mass also shows that Europa, in
an orbit some 671,000 kilometers (416,000 miles) from Jupiter, wields
considerable influence on the magnetic configuration around the giant
planet.
"Surprisingly, Europa's gas cloud compares to that generated by the
volcanically active satellite Io," Mauk said. "But where Io's
volcanoes are constantly spewing materials, mostly sulfur and oxygen,
Europa is a comparatively quiet moon, and the water gas we see is a
direct consequence of its icy surface being bombarded so intensely."
he said.
"By acting as both a source and a sink of charged radiation particles,
the dense gas torus gives Europa much greater influence than was
previously thought on the structure of, and energy flow within,
Jupiter's huge space environment, its magnetosphere," Mauk said.
The Applied Physics Laboratory team studied images of Jupiter taken in
late 2000 and early 2001 with the laboratory's ion and neutral camera
on NASA's Cassini spacecraft, now en route to Saturn. Mauk says this
is the first substantial discovery made at an extraterrestrial planet
using an innovative technique known as energetic neutral atom imaging.
"Planetary magnetospheres glow with energetic neutral atoms, much like
a red-hot piece of iron glows with photons of light, and such
neutral-atom glows can be remotely imaged," Mauk said. "To this point,
no instrument has imaged that activity beyond Earth's magnetosphere.
Energetic neutral atom imaging makes visible the three-dimensional
structure of planetary space environments, which, until recently, were
invisible to remote imaging techniques."
Research team members at the Applied Physics Laboratory and co-authors
on the Nature paper, "Energetic Neutral Atoms from a Trans-Europa Gas
Torus at Jupiter," include Dr. Donald Mitchell, Dr. Stamatios
Krimigis, Dr. Edmond Roelof and Dr. Christopher Paranicas. Krimigis,
head of the space department at the laboratory, is principal
investigator for Cassini's magnetospheric imaging instrument, which
includes the ion and neutral camera.
The magnetospheric imaging instrument built by the Applied Physics
Laboratory is one of 12 science instruments on the main spacecraft and
one of six instruments designed to investigate the space environments
around Saturn and its moons. Cassini will begin orbiting Saturn on
July 1, 2004, and release its piggybacked Huygens probe about six
months later for descent through the thick atmosphere of the moon
Titan. Cassini-Huygens is a cooperative mission of NASA, the European
Space Agency and the Italian Space Agency. NASA's Jet Propulsion
Laboratory, Pasadena, Calif., manages the mission for NASA's Office of
Space Science, Washington, D.C. JPL is a division of the California
Institute of Technology in Pasadena.
An energetic neutral atom image showing the donut-shaped cloud around
Jupiter is available at
http://photojournal.jpl.nasa.gov/catalog/PIA04432 and at
http://www.jhuapl.edu/newscenter/pressreleases/2003/030227.htm .
For more information on Cassini visit http://saturn.jpl.nasa.gov
http://saturn.jpl.nasa.gov/ .
For more information on the magnetospheric imaging instrument and its
science mission visit http://sd-www.jhuapl.edu/CASSINI .
-end-
