Shrikanth G. Kanekal

We use the REPT (relativistic Electron Proton Telescope) data onboard the Van Allen Probes mission to examine the penetration of solar energeetic Helium into the magnetosphere. Specidfically we the pulse height analyzed data (PHA) in the REPT solid state detector stack for each individual particle measured. we identify SEP-He is by using active periods with identified SEP events. We will specifically focus on the large SEP events that occurede during the September of 2017. Using PHA data we derive the incident spectrum nd its evolution during the event. From a space weather perspective It is important note that He ions deposit energy through rapid ionization resulting in single event upsets (SEU) whereas protons do that via nuclear interactions.

Modern solid state detector readout circuits are limited by the operating range of the first stage charge sensitive amplifier or CSA. This in turn limits the energy range of systems using solid state detectors. Such systems are used in a variety of applications ranging from measuring solar energetic particles in space to use in medical devices on Earth. The current paper provides a novel solution implemented in the Boston Extended Amplitude Range (BEAR) integrated circuit. BEAR uses a CSA with two switchable capacitors to increase the range of the amplifier by 2 orders of magnitude higher than traditional CSAs. In this model the capacitors are dynamically switched in at set thresholds and are added in parallel to the detector to share the input charge. The integrated circuit (IC) has been fabricated and evaluated. Here we provide simulation and experimental results which demonstrate performance over measured signals from particles with energies from 1.4 MeV to 1 GeV with an average dE/E of 41%. Detector systems could measure a wide range of energetic particles when used with BEAR ICs.

We describe the ELectron Microburst Observatory mission, ELMO which is proposed as aCubeSat constellation mission to fully characterize microburst event spatial extent systematically for the first time both in latitude and longitude. ELMO comprises 4 CubeSats two per orbit plane in two orbit planes. ELMO will fly in a high inclination LEO at about 500 km in altitude. The CubeSats will systematically separate both in latitude and longitude over the mission lifetime and will carry MERIT, Miniaturized Electron and Proton Telescope as the the payload. MERIT has been built,tested and delivered to fly on NASA's HERMES, Lunar Gateway mission. MERIT is a solid state detector particle telescope with two identical sensor heads pointed zenith- and nadir-wards enabling measurement of both downgpoing and upwelling electrons thereby accurately estimating electron precipitation into the atmosphere. MERIT will measure electron and protons over a wide energy range in multiple differential channels with a very time resolution of less than 4 ms. ELMO will quantify for the first time the contribution of microbursts to radiation belt electron loss using systematic coordinated multipoint measurements. Energetic electron precipitation affects atmospheric chemistry and therefore climate change. ELMO measuresmicrobursts with unprecedented time and energy resolution. ELMO provides critical knowledge of electron loss processes required for quantitative prediction of global electron fluxes.

We describe the prototype of a novel particle telescope, the Advanced enerGetic Ion eLectron tElescope (AGILE), which utilizes for the first time in space, full pulse shape discrimination (PSD) to identify energetic ions such as solar energetic particles (SEP), anomalous cosmic rays (ACR), and characterize their spectra for various ion species. The prototype AGILE is a compact, low mass, and low-power particle telescope suitable for CubeSat platforms that enable low-cost multi-point in-situ measurements in geo- and interplanetary space. AGILE employs high heritage solid state detectors, a state-of-art high-speed sampling ASIC (Application Specific Integrated Circuit), as well as novel algorithms to characterize SEP to advance the understanding of charged particle energization, loss, and transport throughout the heliosphere. The prototype AGILE has been built and will be the science payload on the GenSat-1 CubeSat. GenSat-1 is manifested to be launched in the autumn of 2025 into a high inclination low earth orbit. AGILE will collect data over the polar regions, i.e. the open field line regions accessed by SEP.

Electrons in Earth's outer radiation belt are highly dynamic, with fluxes changing by up to orders of magnitude. The penetration of electrons from the outer belt to the inner belt is one such change observed during geomagnetic storms and was previously observed in electrons up to 1 MeV for some strong storms observed by the Van Allen Probes. We analyze pulse height analysis data from the Relativistic Electric and Proton Telescope (REPT) on the Van Allen Probes to produce electron flux measurements with lower minimum energy and significantly improved resolution compared to the standard REPT data and show that electron penetrations into the inner belt (L ≤ 2) extend to at least 1.3 MeV and penetrations into the slot region (2 < L < 2.8) extend to at least 1.5 MeV during certain geomagnetic storms. We also demonstrate that these penetrations are associated with butterfly pitch angle distributions from 1 to 1.3 MeV.

Understanding local loss processes in Earth’s radiation belts is critical to understanding their overall structure. Electromagnetic ion cyclotron waves can cause rapid loss of multi-MeV electrons in the radiation belts and contribute to an uncommon three-belt structure in the radiation belts. These loss effects have been observed at a range of L* values, recently as low as L* = 3.5. Here, we present a case study of an event where a local minimum develops in multi-MeV electron phase space density near L* = 3.5 and evaluate the possibility of EMIC waves in contributing to the observed loss feature. Signatures of EMIC waves are shown including rapid local loss and pitch angle bite outs. Analysis of the wave power spectral density during event shows EMIC wave occurrence at higher L* values. Using these representative wave parameters, we calculate minimum resonant energies, diffusion coefficients, and simulate the evolution of electron PSD during this event. From these results, we find that O+ band EMIC waves could be contributing to the local loss feature during this event. O+ band EMIC waves are uncommon, but do occur in these L* ranges, and therefore may be a significant driver of radiation belt dynamics under certain preconditioning of the radiation belts.

Whitepaper #138 in the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033. Main topics: basic research; infrastructure/workforce/other programmatic. Additional topics: solar physics; state of the profession; space-based missions/projects; inner heliosphere; […]

Pitch Angle Distributions in the radiation belts are well characterized with sinnα. By tracking the exponent ‘n’, termed Pitch Angle Index, we are able to observe persistent and cross energy changes in pitch angle distributions of Van Allen radiation belt electrons using Van Allen Probes particle observations. The pitch angle distributions measurements are well fit down to a single satellite spin, and therefore can track spatially and temporally confined changes to determine connection between particles and waves. We use the Van Allen Probes data in conjunction with Geostationary Operational Environmental Satellites (GOES) spacecraft and several ground magnetometer stations from Canadian Array for Realtime Investigations of Magnetic Activity (CARISMA) and Finnish pulsation magnetometer network of Sodankylä Geophysical Observatory (SGO) to connect particles that become very anisotropic to electromagnetic ion cyclotron (EMIC) waves during a quiet period over two days, June 26 and 27, 2013. The waves and peaks in the particle PADs are both long lasting but spatially separated, suggesting that wave particle interactions in the inner magnetosphere can occur for extend periods of time and have significant impact on the global radiation belts, even during otherwise geomagnetically quiet times and when wave activity is highly localized.

The Lunar Gateway or the Gateway, part of NASA’s Artemis program, is a space station that will orbit around the moon. This cis-lunar Gateway platform provides the opportunity for Heliophysics investigations to advance our knowledge of the coupled Sun-Earth system and the opportunity to better understand the radiation environment in order to support and improve crew safety and operations at the Moon and beyond. The Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES) is a suite of instruments placed on the outside of the Habitation and Logistics Outpost (HALO)  to monitor the Sun’s radiation environment and space weather. HERMES, led by NASA’s Goddard Space Flight Center, will monitor  solar particles critical to scientific investigations of the Sun including the solar winds. Additonal suite of instruments provided by ESA, the European Radiation Sensors Array (ERSA) will complement space weather studies. We report here on the energetic particle instrument, the  Minaturized Electron Proton Telescope (MERiT) on board HERMES. MERiT is  designed to measure electrons and protons in the energy range ~0.3-9. MeV and ~1-190 MeV in 11 and 20 differential energy channels respectively. MERiT is a solid state detector telescope with  two sensor heads: one looking sunward and the other anti-sunward. MERiT will help advance our understanding of solar energetic particles, low energy cosmic rays and energetic electrons in the magnetospheric tail. We will describe the instrument in detail and the science topics it is expected to address. Lunar Gateway is currently expected to launch in October 2025.

Owing to the ever-present solar wind, our vast solar system is full of plasmas. The turbulent solar wind, together with sporadic solar eruptions, introduces various space plasma processes and phenomena in the solar atmosphere all the way to Earth’s ionosphere and atmosphere and outward to interact with the interstellar media to form the heliopause and termination shock. Remarkable progress has been made in space plasma physics in the last 65 years, mainly due to sophisticated in situ measurements of plasmas, plasma waves, neutral particles, energetic particles, and dust via space-borne satellite instrumentation. Additionally, high-technology ground-based instrumentation has led to new and greater knowledge of solar and auroral features. As a result, a new branch of space physics, i.e., space weather, has emerged since many of the space physics processes have a direct or indirect influence on humankind. After briefly reviewing the major space physics discoveries before rockets and satellites (Section I), we aim to review all our updated understanding on coronal holes, solar flares, and coronal mass ejections, which are central to space weather events at Earth (Section II), solar wind (Section III), storms and substorms (Section IV), magnetotail and substorms, emphasizing the role of the magnetotail in substorm dynamics (Section V), radiation belts/energetic magnetospheric particles (Section VI), structures and space weather dynamics in the ionosphere (Section VII), plasma waves, instabilities, and wave-particle interactions (Section VIII), long-period geomagnetic pulsations (Section IX), auroras (Section X), geomagnetically induced currents (GICs, Section XI), planetary magnetospheres and solar/stellar wind interactions with comets, moons and asteroids (Section XII), interplanetary discontinuities, shocks and waves (Section XIII), interplanetary dust (Section XIV), space dusty plasmas (Section XV), and solar energetic particles and shocks, including the heliospheric termination shock (Section XVI). This article is aimed to provide a panoramic view of space physics and space weather.