[meteorite-list] Rosetta's Singing Comet

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 11 Nov 2014 22:16:53 -0800 (PST)
Message-ID: <201411120616.sAC6GrY7003162_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.php?feature=4374

Rosetta's Singing Comet
Jet Propulsion Laboratory
November 11, 2014

[Audio File]
Sound wave superimposed on an image of comet 67P/Churyumov-Gerasimenko
A set of instruments on the European Space Agency's Rosetta spacecraft
has picked up a mysterious "song" from Comet 67P/Churyumov-Gerasimenko.
Image credit: ESA/NASA/JPL-Caltech

A set of instruments on the European Space Agency's Rosetta spacecraft
has picked up a mysterious "song" from Comet 67P/Churyumov-Gerasimenko.
On Wednesday, Nov. 12, Rosetta will attempt the first-ever soft landing
on a comet when it dispatches its Philae lander to the surface of comet
67P.

The sounds are thought to be oscillations in the magnetic field around
the comet. They were picked up by the Rosetta Plasma Consortium -- a suite
of five instruments on the spacecraft that is orbiting the comet.

The comet's song would not be audible to the human ear because it is being
emitted at 40 to 50 millihertz, far below the range of human hearing,
which typically picks up sound between 20 hertz and 20 kilohertz. To make
the sounds audible to humans, Rosetta scientists have increased the frequencies
by 10,000 times.

The Rosetta's Rosetta Plasma Consortium consists of five instruments on
the Rosetta orbiter that provide a wide variety of complementary information
about the plasma environment surrounding Comet 67P/C-G. Plasma is the
fourth state of matter -- an electrically conductive gas that can carry
magnetic fields and electrical currents.

The consortium instruments are designed to study a number of phenomena,
including the interaction of 67P/C-G with the solar wind, a continuous
stream of plasma emitted by the sun; changes of activity on the comet;
the structure and dynamics of the comet's tenuous plasma atmosphere, known
as the coma; and the physical properties of the comet's nucleus and surface.

The comet sounds were heard clearly by Rosetta's magnetometer experiment
for the first time in August, when Rosetta drew to within 62 miles (100
kilometers) of 67P/C-G. Scientists think the sounds must be produced by
the comet's activity, perhaps as it releases neutral particles into space
where they become electrically charged, or ionized. The precise physical
mechanism behind the oscillations remains a mystery.

"This is exciting because it is completely new to us. We did not expect
this and we are still working to understand the physics of what is happening,"
said Karl-Heinz Glassmeier, head of Space Physics and Space Sensorics
at the Technical University of Braunschweig, Germany.

Rosetta is a European Space Agency mission with contributions from its
member states and NASA. Rosetta's Philae lander is provided by a consortium
led by the German Aerospace Center, Cologne; Max Planck Institute for
Solar System Research, Gottingen; National Center of Space Studies of
France (CNES), Paris; and the Italian Space Agency, Rome. NASA's Jet Propulsion
Laboratory in Pasadena, California, a division of the California Institute
of Technology, manages the U.S. participation in the Rosetta mission for
NASA's Science Mission Directorate in Washington.

For more information on the U.S. instruments aboard Rosetta, visit:
http://rosetta.jpl.nasa.gov

More information about Rosetta is available at:
http://www.esa.int/rosetta

Media Contact
DC Agle
818-393-9011
Jet Propulsion Laboratory, Pasadena, Calif.
agle at jpl.nasa.gov

Dwayne Brown
202-358-1726
NASA Headquarters, Washington
dwayne.c.brown at nasa.gov

Markus Bauer
011-31-71-565-6799
European Space Agency, Noordwijk, Netherlands
markus.bauer at esa.int

2014-393
Received on Wed 12 Nov 2014 01:16:53 AM PST