[Baps] BU talk - Thursday 3/8, Jim Slavin / University of Michigan, Messenger at Mercury

[Paul Withers]

-------- Original Message --------
Subject: 	[Csp_seminar] Thursday 3/8 James A. Slavin / University of
Michigan
Date: 	Mon, 5 Mar 2012 18:11:44 +0000
From: 	Rochette, Amanda E <rochette at bu.edu>
To: 	announce at skynet.bu.edu <announce at skynet.bu.edu>,
Csp_seminar at bu-ast.bu.edu <Csp_seminar at bu-ast.bu.edu>



Speaker: James A. Slavin

Affiliation: Department of Atmospheric, Oceanic and Space Sciences,
University of Michigan

Title: MESSENGER Observations of Mercury’s Dynamic Magnetosphere

Date: Thursday, March 8th, 2012

Time: 3:30 PM Refreshments in CAS 500, 4:00 PM Talk
Place: 725 Commonwealth Ave. CAS 502

Abstract:

The MESSENGER mission to Mercury is now providing our first observations
of the innermost planet and its space environment since Mariner 10’s
brief fly-bys in 1974-5. The magnetosphere of Mercury is the smallest in
the solar system with the shielding effect of the planetary magnetic
field standing off the solar wind at a distance of only ~ 1000 km above
the surface. An overview of the MESSENGER mission and its scientific
results are presented with an emphasis on the planetary magnetic field
and its interaction with the solar wind. New observations of the
magnetic field from orbit have confirmed its dipolar nature and close
alignment with the planetary spin-axis, but its intensity is now known
to be less than 1% that of Earth and shifted from the planetary center
by ~ 20% of Mercury’s radius. MESSENGER experiences its maximum thermal
input during “hot seasons” when the spacecraft orbit has its closest
approach to the surface near local noon over the dayside hemisphere.
However, these orbits also “skim” the dayside magnetopause and provide
detailed observations of fundamental plasma processes taking place in
this boundary region. Fully developed Kelvin-Helmholtz boundary waves
are observed close to the nose of the magnetosphere, but only over the
dusk hemisphere. Magnetic reconnection linking the interplanetary and
planetary magnetic fields proceeds at a rate ~ 10 times faster than at
Earth or any of the other magnetized planets. “Showers” of flux transfer
event – and plasmoid – type magnetic flux ropes lasting from the dayside
magnetopause and magnetic cusps and the nightside magnetic tail and
appear to drive the circulation of magnetic flux and plasma within this
magnetosphere. Despite the small dimensions of this magnetosphere
MESSENGER frequently observes it to be the source of intense bursts of
energetic electrons with energies reaching up to several hundred
electron Volts. The underlying causes of the extreme space weather
discovered by the MESSENGER mission at Mercury are believed to be the
lack of an electrically conducting ionosphere and strong solar wind
forcing associated with this planet’s proximity to the Sun.

//

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*Amanda Rochette*

Proposal Development Administrator

Boston University

Center for Space Physics

725 Commonwealth Avenue, Room 506, Boston, MA 02215

Tel: (617) 353-5992 Fax: (617) 353-6463

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