May 19, 2017, 1:00 pm - 2:00 pm
May 19, 2017, 1:00 pm - 2:00 pm, Heliophysics Director's Seminar
Dellingr: NASA GSFC's first 6U cubesat
Larry Kepko (674)
The Dellingr spacecraft is NASA Goddard Space Flight Center's (GSFC's) first build of a 6U CubeSat. A key driver of the Dellingr project is the recognition that NASA needs to infuse the emergent CubeSat capability into our science missions to support small, focused science objectives while also enabling larger strategic constellation missions in support of Decadal Survey science goals. The primary objective of the Dellingr project was to develop a cost-effective model for CubeSat and SmallSat builds at GSFC with lean end-to-end systems and processes to enable lower-cost, scalable risk, systems. Dellingr is a balance of commercial off the shelf (COTS) and in-house subsystems, leveraging the strengths of both the booming commercial market and existing GSFC infrastructure, capabilities, and experience with similar 'Do No Harm' missions, such as sounding rockets. Dellingr carries an advanced gated time-of-flight ion/neutral mass spectrometer (INMS) and three fluxgate magnetometers. Two of these magnetometers are internal to the spacecraft, and will be used to test and validate a new software algorithm that compensates for and removes spacecraft interference; the third magnetometer sits at the end of a 50 cm boom. Together, these instruments will measure the space weather effects of solar wind-magnetosphere coupling on Earth's ion and neutral upper atmosphere. Dellingr is slated to be the first 6U deployed off the ISS via the Nanoracks deployer, with launch on a Falcon 9 resupply in August, 2017. This paper covers the wealth of lesson learned from the project.
A Universal Model for Solar Eruptions
C. R. DeVore (674)
Magnetically driven eruptions on the Sun, from large-scale coronal mass ejections to small-scale coronal X-ray and EUV jets, frequently are observed to involve the ejection of a highly stressed filament. We describe the first simulations of a coronal jet driven by filament ejection, whereby the highly sheared magnetic field of the filament becomes unstable and erupts. In addition, we conclude that if coronal mass ejections and coronal jets indeed are of physically identical origin, then the magnetic breakout mechanism is a universal model for solar eruptions. [Wyper, Antiochos, & DeVore 2017, Nature, 544, 452]
A New Paradigm for Impulsive Flare Particle Acceleration in Magnetic Islands
Silvina Guidoni (674)
The mechanism that accelerates particles to the energies required to produce the observed high-energy impulsive emission and energy spectra in solar flares is not well understood. Here, I propose a first-principle-based, universal, and easy to understand model of particle acceleration that produces energy spectra that closely resemble those derived from hard X-ray observations. Our mechanism uses contracting magnetic islands formed during fast reconnection in solar flares to accelerate electrons, as first proposed by Drake et al. (2006). We apply these ideas to islands formed during fast reconnection in a simulated eruptive flare. A simple analytic model is used to calculate the energy gain of particles orbiting field lines in our ultrahigh-resolution 2.5D magnetohydrodynamic numerical simulation of a solar eruption (flare + CME). Then, we analytically model electrons visiting multiple contracting islands to account for the observed high-energy flare emission. Our acceleration mechanism should produce sporadic emission because island formation is intermittent. Moreover, a large number of particles could be accelerated in each large-scale island, which may explain the inferred rates of energetic-electron production in flares. We conclude that island contraction in the flare current sheet is a promising candidate for electron acceleration in solar eruptions.
