June 17, 2011, 12:00 pm - 1:00 pm
Director's Seminar: the MMS mission
Dr. John Dorelli (NASA Goddard Space Flight Center),
Toward a "Standard Model" of Magnetic Reconnection
Abstract: Magnetic reconnection is the primary mode by which magnetic energy is rapidly converted into plasma energy, making possible such diverse astrophysical phenomena as solar flares, coronal mass ejections and magnetospheric substorms. While the occurrence and importance of magnetic reconnection is widely accepted, theorists have been struggling for over 50 years to understand why it is so explosive (with significant energy conversion often occurring in only a few Alfven times). Since Parker's first magnetohydrodynamic (MHD) theory appeared in 1958, we have made slow but steady progress in unraveling the time scale puzzle, and a "Standard Model" of magnetic reconnection has emerged. In this talk, I briefly review the developments leading up to the Standard Model, outlining some important unresolved questions along the way. I conclude by summarizing how NASA's Magnetospheric Multiscale (MMS) mission will finally put the Standard Model to a rigorous experimental test.
Dr. Thomas Moore (NASA Goddard Space Flight Center), MMS:
The Grand Challenge of Heliophysics
Abstract: We all know magnets exert forces, but magnetic fields also act like muscles that connect space plasmas together. Connections switch in a process called "reconnection" that controls space weather energy flows. The "brains" of reconnection are believed to lie in tiny volumes of space called "diffusion regions" where the magnetic fields have an "X" shape separating field lines that connect two plasmas from field lines that do not. MMS will let us observe how, when and where the magneto-muscular switch occurs and why it is often explosive, especially when one plasma tears free of another.
Dr. Craig Pollock (NASA Goddard Space Flight Center),
Fast Plasma Observations for MMS
Abstract: The Fast Plasma Investigation [FPI] that is under development at GSFC for flight on MMS will provide the 3D velocity space distribution functions for ions at 150ms cadence and for electrons at 30ms cadence. This time resolution exceeds the current state of the art by at least two orders of magnitude and is required in order to resolve small scale features (few km) in reconnection plasmas that are drifting by the MMS spacecraft at up to 50km/s. For FPI, this requirement drives a unique instrument architecture and introduces design and test challenges throughout the system. We will describe the FPI design arrived at and will show examples of test performance at the final pre-flight (ETU) level.