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January 19, 2018, 1:00 pm - 2:00 pm

January 19, 2018, 1:00 pm - 2:00 pm, Heliophysics Director's Seminar, Hosted by the Geospace Physics Laboratory (673)

New constraints on the Escape of Sodium from the Moon



Menelaos Sarantos

Recent measurements and models of the lunar sodium exosphere enable us to better understand the effect of the Sun on the escape of the Moon's weak atmosphere. Sodium gas is an important tracer of microphysical processes on the Moon because it can be easily observed both from Earth as well as from lunar orbiters. Comparing exospheric transport to recent high-resolution spectroscopic measurements from Earth we may significantly constrain the velocity distribution of sodium liberated from the lunar surface and the surface release processes.

How Bursty Bulk Flows Sow the Diffuse Aurora



Deirdre Wendel

The diffuse aurora is one of many forms of aurora-one that is faint and spread over large areas of the Earth's polar cap boundary. It occurs where waves at equatorial latitudes have precipitated electrons along closed magnetic field lines (field lines that have both footpoints in the Earth) into the Earth's upper atmosphere of ionized plasma. The Earth's magnetotail - the stretched part of the magnetosphere on the Earth's nightside-harbors the plasma sheet. Magnetic reconnection in the magnetotail disturbs the plasma sheet, producing so-called "bursty bulk flows" of the plasma as field lines slingshot away from the reconnection site. Investigators do not yet understand which waves scatter electrons from within bursty bulk flows to the diffuse aurora. Here we present surprising connections between reconnection, shrinking magnetic field lines, parallel electron beams, and electromagnetic whistler waves that in turn sow electrons into the diffuse aurora from bursty bulk flows.

Characteristics of Ionospheric Escape as Observed by the MMS Mission



Barbara Giles

With its 150ms-resolution ion observations, the Magnetospheric Multiscale (MMS) mission is able to trace the evolution of ionospheric-source plasmas as they escape outward through the lobes of the Earth's magnetotail, interact with the plasma sheet boundary layer, and subsequently become part of the magnetotail's central plasma sheet. This presentation summarizes the characteristics of these populations as observed during the first MMS magnetotail observation period, examines the ability of the FPI plasma spectrometers to resolve the processes at work, and contrasts the properties of the heating and acceleration mechanisms detected with those observed with previous missions.

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