[Baps] 2/17 Ronald Vervack (The Johns Hopkins University Applied Physics Laboratory)

[Paul Withers]

-------- Original Message --------
Subject: [Csp_seminar] 2/17 Ronald Vervack (The Johns Hopkins University 
Applied Physics Laboratory)
Date: Mon, 14 Feb 2011 09:35:01 -0500
From: Despina Bokios <dbokios at bu.edu>
To: csp_seminar at bu-ast.bu.edu

Speaker: Ronald Vervack
Affiliation: The Johns Hopkins University Applied Physics Laboratory

Title: Mercury’s complex exosphere: Intriguing observations from the
three MESSENGER flybys

Date: Thursday, February 17, 2011
Time: 3:30 PM Refreshments in CAS 500, 4:00 PM Talk
Place: 725 Commonwealth Ave. CAS 502


Abstract:
The MESSENGER spacecraft has completed three flybys of Mercury as it
heads for orbit in-sertion in March 2011. During the flybys, the
Ultraviolet and Visible Spectrometer (UVVS) channel of the Mercury
Atmospheric and Surface Composition Spectrometer (MASCS) conduct-ed
numerous observations of Mercury’s tenuous exosphere in five more or
less distinct regions: (1) extended tail, (2) polar regions, (3)
nightside, (4) near-dawn terminator, and (5) dayside. The high spatial
resolution and wavelength coverage afforded by UVVS have resulted in the
discov-ery of emission from two new species, magnesium and ionized
calcium, and revealed detailed and often unexpected structure in the
exosphere. A persistent dawn-dusk asymmetry in the calci-um
distribution, dramatic differences in the altitude profiles of magnesium
over the northern and southern polar regions, and a concentration of
ionized calcium tailward of the planet all point to an exospheric system
that is more complex and more intertwined with the surface and
magneto-sphere than previously thought. The observations have also
captured changes in the distributions that are a consequence of
“seasonal” effects and which provide additional, important insight into
the workings of the exosphere. Although MESSENGER’s flybys have provided
important new details about the distributions of several geochemically
important exospheric species, resulting in an unprecedented glimpse into
the structure of the exosphere and the processes that control it, the
MASCS observations to date are only snapshots of the complicated Mercury
exospheric system. A full understanding of the exosphere will require
many observations spanning a variety of conditions during the orbital
phase of the mission. This talk will summarize the MASCS observations
from the flybys, what has been learned from them, and what the big
questions are as MESSENGER goes into orbit about Mercury.

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Despina Bokios
Proposal Development Administrator
Boston University
Center for Space Physics
725 Commonwealth Avenue, Room 506, Boston, MA 02215
Email: dbokios at bu.edu
Website: bu.edu/csp
Tel: (617) 353-7418
Fax: (617) 353-6463

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