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March 15, 2013, 12:00 pm - 1:00 pm

March 15, 2013, 12:00 pm - 1:00 pm, Heliophysics Director's Seminar

The Structure of Solar Wind Magnetic Fields (and Why We Care)



D. Aaron Roberts, NASA/GSFC (672)

The magnetic field in the solar wind has strong fluctuations about the simple Parker spiral solution. This talk shows how these fluctuations can be represented analytically by adjusting the relative phases of the components of the fields at all scales to constrain the variations in the magnitude of the field, consistent with observations. The resulting representations, which are useful for studying energetic particle propagation and for initializing simulations, also show "discontinuities" as observed in the solar wind, thus showing a deep connection between seemingly unrelated problems.

MaRBLES - MeAsuring Radiation Belt Low Earth Sources/Sinks



E. J. Summerlin, NASA/GSFC (672)

MaRBLES, MeAsuring Radiation Belt Low Earth Sources/Sinks, is a 6U CubeSat mission addressing compelling science and flight proving cutting edge technologies. MaRBLES engages early-career civil servants with the goal of training them, thus addressing the primary purpose of the HOPE program. The science goals of MaRBLES are to advance our understanding of the terrestrial radiation belts by: I.characterizing electron energization and loss in the outer Van Allen belt, and, II.measuring the cosmic ray albedo neutron source in the inner Van Allen belt. MaRBLES will use data collected by two onboard sensors: the CREPT (Compact Relativistic Electron Proton Telescope) and SNUG (A Spectrometer for NeUtrons and Gamma-rays) in a highly inclined LEO orbit, to achieve these science goals. These sensors as well as the mission employ state of the art technologies while providing learning opportunities to early-career scien- tists, engineers, and mission planners.
MaRBLES effectively satisfies the primary focus of the HOPE program by providing hands-on training for early-career scientists and engineers (mentees) on a mission addressing compelling science utilizing cutting edge technologies. Our team comprises 10 energetic early-career civil servants eager to acquire new skills and experience in all aspects of a space mission, from planning, designing and developing scientific and spacecraft hardware, to testing and integration, mission ops, and data analysis. The MaRBLES experience will prepare them for long-term careers thereby improving NASA’s institutional capabilities. Our team also includes highly experienced mentors providing each mentee the necessary direction, guidance, and, assistance, enabling them to excel in their respective tasks.
The MaRBLES mission is highly relevant to several important elements of NASA’s overall strategic plan. MaRBLES enables NASA’s strategic goal 1, to extend and sustain both human and robotic activities in space by mitigating radiation hazards through improved understanding of charged radiation near the Earth. MARBLES enhances our understanding of the Earth’s radiation belt responses to solar influences thus addressing NASA’s strategic goal 2, to understand the Sun and its interactions with Earth and the solar system. Through the use of cutting edge technologies, MaRBLES facilitates NASA’s strategic goal 3, to create the innovative new space technologies for our exploration, science, and economic future. In addition, MaRBLES greatly enhances institutional capabilities to conduct NASA’s space activities (strategic goal 5) by training the next generation of scientists and engineers that will devise, build, and manage the mis- sions of tomorrow.

Modeling the effects of ionospheric oxygen on magnetotail flows



Katherine Garcia-Sage, NASA/GSFC (NPP)

Numerous THEMIS observations in the magnetotail have shown the presence of bursty, fast Earthward flows in the plasma sheet. Although the magnetospheric community has been aware of these flows for years, the ubiquitous THEMIS observations have renewed interest in these phenomena, their origin, and their effects on particle acceleration and plasma and magnetic flux transport into the inner magnetosphere. We simulate these bursty flows with a global, multi-fluid magnetospheric model (Multi-Fluid Lyon-Fedder-Mobarry model), focusing on the effects of heavy O+ ions that originate in the ionosphere. We present simulations that suggest O+ is not only affected by these flows but can fundamentally alter them, demonstrating that effects of O+ need to be taken into account when modeling bursty flows, dipolarization fronts, and the resulting plasma energization.

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