Using the Galileo Solid-State Imaging Instrument as a Sensor of Jovian Energetic Electrons

We quantitatively describe the Jovian energetic electron environment using the Solid State Imager (SSI) on the Galileo spacecraft. We post-process raw SSI images by removing the target object and dark current to obtain frames only with the radiation contribution. The camera settings (gain state, filter, etc.) are used to compute the energy deposited in each pixel, which corresponds to the intensity of the observed radiation hits (the actual measurements are expressed with the digital number (DN), from which the energy deposited can be computed). Histograms of the number of pixels versus energy deposited by incident particles from processed SSI images are compared with the results from 3D Monte Carlo transport simulations of the SSI using Geant4. We use Geant4 to simulate the response of the SSI instrument to mono-energetic electron environments from 1 to 100 MeV. We fit the modeled instrument response to the SSI data using a linear combination of the simulated mono-energetic histograms to match the SSI observations. We then estimate the spectra of the energetic electron environment at Jupiter, or we estimate the integral flux when there is lower confidence in the spectra fits. We validate the SSI results by comparing the environment predictions to the observations from the Energetic Particle Detector (EPD) on the Galileo spacecraft, examining the electron differential fluxes from 10’s of keV to 11 MeV. For higher energies (up to 31.0 MeV), we compare our findings with the NASA GIRE model, which is based on measurements from the Pioneer spacecraft. This approach could be applied to other sets of imaging data in energetic electron environments, such as from star trackers in geostationary Earth orbits.Funding for A. Carlton’s work is provided by a NASA Space Technology Research Fellowship (NNX16AM74H)

MAGESTIC: Magnetically Enabled Structures Using Interacting Coils

In our NIAC Phase I study, awarded September 2011, the MIT Space Systems Lab (MIT SSL) began investigating a new structural and mechanical technique aimed at reducing the mass and increasing the stowed-to-deployed ratio of spacecraft systems. This technique uses the magnetic fields from current passing through coils of high temperature superconductors (HTSs) to support spacecraft structures and deploy them to operational configurations from their positions as stowed inside a launch vehicle fairing. These electromagnetic coils are tethered or hinged together in such a way that their motion in some directions or around some axes is constrained, as in Figure 1. Our Phase II study,awarded in Fall 2012, continued this work on electromagnetic structures, with an added focus on developing a new thermal system, investigating additional, non-structural electromagnet functions, and creating a maturation roadmap and plan for addressing barriers to feasibility of the technology. We now call the project MAGESTIC, or Magnetically Enabled STructures using Interacting Coils

Strong whistler mode waves observed in the vicinity of Jupiter’s moons

Understanding of wave environments is critical for the understanding of how particles are accelerated and lost in space. This study shows that in the vicinity of Europa and Ganymede, that respectively have induced and internal magnetic fields, chorus wave power is significantly increased. The observed enhancements are persistent and exceed median values of wave activity by up to 6 orders of magnitude for Ganymede. Produced waves may have a pronounced effect on the acceleration and loss of particles in the Jovian magnetosphere and other astrophysical objects. The generated waves are capable of significantly modifying the energetic particle environment, accelerating particles to very high energies, or producing depletions in phase space density. Observations of Jupiter’s magnetosphere provide a unique opportunity to observe how objects with an internal magnetic field can interact with particles trapped in magnetic fields of larger scale objects

Educación Superior y Pandemia. Aprendizajes y buenas prácticas en Iberoamérica

La aportación actual no entra en analizar aspectos generales de la pandemia (naturaleza, origen, extensión general y en el país, etc.) o de otras situaciones que se derivan del confinamiento, por considerar que son suficientemente conocidos. Tampoco pretende realizar una recensión de informes sobre la temática elaborados por organismos como la UNESCO-IESALC, el Banco Mundial, el BID o la CRUE y revisar las aportaciones de investigadores de la temática. Más bien trata de aportar concreciones y dimensiones prácticas de la Educación Superior de cada país que puedan ayudar en los aspectos de organización y gestión de estas instituciones. En este sentido considera aspectos referidos a: (1) Desarrollo de las enseñanzas: alteraciones en la duración y estructura de los títulos; modificaciones de objetivos, metodologías y sistemas de evaluación; atención a colectivos vulnerables; etc.(2) Organización institucional: atención a las personas (gestión del alumnado, profesorado y personal de administración y servicios, rol de los directivos, etc.); infraestructuras; desarrollo de procesos (matriculación, gestión administrativa y económica, etc.); y resultados (académicos como tasa de aprobados, nivel de abandono u otros; y no académicos). (3) Vinculación con el entorno: actuaciones de y con la comunidad o colaboraciones significativas. Incluye el escrito de cada país con referencias y reflexiones sobre los anteriores aspectos, así como algunas experiencias de interés y, por último, reflexiones, valoraciones y retos sobre la gestión en los momentos de confinamiento y reapertura, con la idea de identificar aprendizajes significativos y orientaciones de cara a la actuación en la situación actual y similares que se puedan producir en el futuro. Las diferentes aportaciones se centran en la enseñanza universitaria, incluyendo los estudios superiores, que en muchos países tienen gran importancia y desarrollo, y tratan de proporcionar una visión general de los diferentes países sin obviar descender a las particularidades concretas que exigen el identificar buenas prácticas o medidas específicas de organización y desarrollo de la formación. Hablamos del trabajo de 41 especialistas de 13países iberoamericanos que permiten conocer y analizar las actuaciones por países, pero también realizar un estudio de las iniciativas que se han tomado en todos los países considerando algunos de los tópicos que considera el Informe. En todo caso, cabe destacar la actualidad y trascendencia del tema y la rapidez por trasladar a la sociedad un Informe detallado sobre las actuaciones universitarias existentes y sus resultados

Controlled precipitation of energetic Van Allen belt protons by electromagnetic ion cyclotron (EMIC) waves : scientific and engineering implications

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2014.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 235-247).The inner Van Allen radiation belt traps highly energetic protons sourced from solar storms, cosmic rays and other processes. These particles can rapidly damage the space systems orbiting the inner region, limiting access to Low Earth Orbit (LEO). Decades of modeling and observations, however, show that naturally generated ULF/VLF waves have the capability of precipitating energetic trapped electrons and protons. This fact suggests that there could be human control over the stable inner belt proton population by artificially transmitting Electromagnetic Ion Cyclotron (EMIC) waves from space-based antennas (named remediation). These waves are naturally generated by equatorial ring current ions in the outer belt region, which explains the absence of EMIC waves at lower altitudes. Consequently, the precipitation of high-energy protons requires artificial generation of EMIC waves into the inner zone. The controlled removal of energetic outer belt electrons by man-made whistler waves has been widely studied, and a space test of a linear antenna for this purpose is in preparation. Contrarily, the interaction between inner belt protons and EMIC waves from in-situ transmitters is an unexplored solution to the radiation environment that should be addressed given its relevance to the scientific and engineering communities. This dissertation focuses on four interconnected research efforts in this direction, which are (1) the radiation of EMIC waves from a space-based antenna, (2) the propagation of these waves in the inner radiation belt, (3) the wave-particle interactions with energetic trapped protons and (4) the feasibility of a mission capable of significantly reducing this hazardous radiation. Our analyses show that a DC rotating coil antenna would be capable of radiating EMIC waves into space. Magnetic dipoles, however, have a very small radiation resistance. Additionally, the interaction between these waves and energetic protons is very inefficient. Our simulations show that, with the current technology, it is not engineeringly feasible to clean up the proton belt using space-based transmitters. A mission scaled down to detectability of the precipitating protons, however, could be launched easily and would allow us to better understand the science and test the technology involved in the concept of remediation.by Maria de Soria-Santacruz Pich.Ph. D

Radiation of very low frequency/extremely low frequency waves from a magnetospheric tether

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 129-130).The high energy particles of the Van Allen belts coming from cosmic rays, solar storms, high altitude nuclear explosions (HANEs) and other processes represent a significant danger to humans and spacecraft operating in those regions, as well as an obstacle to exploration and development of space technologies. The "Radiation Belt Remediation" (RBR) concept has been proposed as a way to try to solve this problem through VLF/ELF transmissions in the ionosphere, which will create a pitch-angle scattering of these energetic particles with some of them falling into their loss cone, thus reentering the Earth. The aim of this thesis is to develop an analytical model of propagation and radiation of Electromagnetic Ion Cyclotron Waves (EMIC) from a high-voltage magnetospheric tether, which are the waves proposed to scatter protons. The plasma is anisotropic due to the external Earth's magnetic field and it is assumed to have sufficiently low density, temperature and degree of ionization so that collisions and thermal velocities can be neglected. An asymptotic analysis is developed to calculate the fields and power flux radiated by the tether that reach a specified observation point located in the far-field region. The effect of the antenna-plasma interaction in the far-field region is studied by adding to the conventional triangular source current distribution along the antenna a radial current arising from the sheath region. The near-field case and the radiation impedance are as well studied. Finally, the results are analyzed and compared with previous models for limiting cases.by Maria de Soria-Santacruz Pich.S.M

The GIRE2 Model and Its Application to the Europa Mission

We present an empirical model of Jupiter's electron radiation environment and its application to the design of the future NASA mission to Europa. The model is based on data from the Galileo spacecraft. Measurements of the high-energy, omni-directional electrons from the Energetic Particle Detector (EPD) and magnetic field from the Magnetometer (MAG) onboard Galileo are used for this purpose. Ten-minute averages of the EPD data are used to provide an omni-directional electron flux spectrum at 0.238, 0.416, 0.706, 1.5, 2.0, and 11.0 MeV. Additionally, data from the Geiger Tube Telescope onboard Pioneer 10 and 11 are used to calculate the flux of 31 MeV electrons. The Galileo Interim Radiation Electron model v.2 (GIRE2) combines these datasets with the original Divine model and synchrotron observations to estimate the trapped electron radiation environment. Unlike the original Divine model, which was based on flybys of the Voyager and Pioneer spacecraft, the new GIRE2 model covers about 7 years of data and more than 30 orbits around Jupiter from the Galileo spacecraft. The model represents a step forward in the study of the Jovian radiation environment and is a valuable tool to assist in the design of future missions to Jupiter. This paper gives an overview of GIRE2 and focuses on its application to the design of the future NASA mission to Europa. The spacecraft will orbit Jupiter and perform multiple flybys of the moon Europa, which is embedded in the middle of a very strong radiation environment. The radiation environment surrounding the moon as well as along the trajectory are described in the paper together with the implications of this environment on the design of a mission