ABSTRACT. Measurements of heavy ions play two major roles in the study of Earth’s magnetosphere. The first is that they can be used to identify the source of the plasma. The Earth’s magnetosphere consists of a mix of plasma from the ionosphere and the solar wind, and while H+ is the dominant ion from both sources, the heavy ion contributions from the two sources are very different. The solar wind contributes highly ionized plasma, with dominant ions He++ and O+6, while the ionosphere contributes generally singly ionized ions, including O+, N+, He+ and molecular ions such as NO+. Using the composition has allowed a better understanding of ion entry and transport during geomagnetic storms and provided evidence to determine the ultimate fate of ionospheric plasma. The second role for heavy ions is to provide a diagnostic to better understand the physical processes occurring in the magnetosphere. Because the composition of the ionosphere is stratified, the composition of the escaping heavy ions provides information on the altitudes of the ion heating and acceleration processes. Ion transport from the ionosphere to the magnetosphere depends on the mass of the ion. The cross-sections to charge exchange and impacts on generation of waves in the magnetosphere depend on the ion species. Finally, the mass density of the plasma can affect the reconnection rate, affecting overall magnetospheric dynamics. In this talk we will highlight recent results made possible with heavy ion measurements and discuss future directions in improving measurements of heavy ions to better understand the effects of ion composition throughout the magnetosphere.

ABSTRACT. Transpolar arcs (TPAs), growing from the poleward edge of nightside main auroral oval to the dayside, is a part of the theta aurora but its formation mechanism has hotly been debated since the theta aurora had been found in early 80’s. It is well-known that TPAs frequently occur under northward Interplanetary Magnetic Field (IMF) conditions and their locations and motions are predominantly controlled by the dawn-dusk component (By) of IMF. Recently, various uniquely morphological TPAs have been found. They do not have the shape of a simple straightforward bar. For example, the TPAs with the nightside ends distorted toward pre- and post-midnight (nightside distorted TPAs), the bending arcs jointed the dawn and dusk main auroral oval (bending arcs), and several bar-shaped TPAs within the polar cap (multiple TPAs) are raised. These arcs are used as diagnostic tools to know the plasma and its energy transport profiles within a framework of Solar Wind-Magnetosphere-Ionosphere (S-M-I) coupling system under not only northward IMF conditions but also its additional conditions of deformed magnetotail with twisted field lines due to the IMF-By effect. Furthermore, new TPA physical characteristics and TPA formation process have also been reported; 1) TPAs were formed on both closed and open field lines even under dominant radial IMF condition, that is, the IMF conditions with very intense sunward-anti-sunward component (Bx), 2) the TPA occurrence has significantly semiannual variation, and 3) the solar wind plasma entry via magnetotail lobe (tailward-of-cup) reconnection plays a significant role in the TPA formation. Based on these recent new discoveries on the TPA formation mechanisms and physical features, we will discuss importance and perspective of the TPA-associated physics in a framework of S-M-I coupling system.

ABSTRACT. The distant terrestrial magnetotail region (at and beyond the Moon’s orbit) and surrounding shocked solar wind plasma flows have been sampled by various spacecraft during the past several decades – though most of these traversals by spacecraft have been very limited in number and duration. Orbits proximate to the Moon and about the L2 Lagrange point are becoming increasingly more popular destinations for current and future missions. Though many of these new and planned missions do not sample the plasma and fields of the magnetosphere, they are nevertheless exposed continuously to the local radiation environment. This presentation briefly reviews the plasma, field, and boundary observations from past missions sampling the distant magnetotail, including the important contributions from the Geotail mission.

ABSTRACT. After 22 years in space, the Cluster mission is continuing to deliver groundbreaking results, thanks to its ability to move the four spacecraft with respect to each other, according to the science goal to be pursued. The main goal of the Cluster mission, made of four identical spacecraft carrying each 11 complementary instruments, is to study in three dimensions the key plasma processes at work in the main regions of the Earth’s environment: solar wind and bow shock, magnetopause, polar cusps, magnetotail, and auroral zone. During the course of the mission, the relative distance between the four spacecraft has been varied more than 70 times from 3 km up to 67000 km to address the various scientific objectives. We will present science highlights obtained using the tetrahedral shape of the Cluster constellation, such as electric current flowing in various places of the magnetosphere, magnetic reconnection process forming magnetic nulls and accelerating the surrounding plasma, electric fields key role in magnetic reconnection, auroral acceleration processes and Kelvin-Helmholtz rolled-up waves allowing solar wind entry into the magnetosphere. Auroras, polar cusp and magnetopause will also be the focus of the future Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission. SMILE is a mission in collaboration between the Chinese Academy of Sciences (CAS) and the European Space Agency (ESA). It is dedicated to observing the solar wind - magnetosphere coupling via simultaneous in situ solar wind/magnetosheath plasma and magnetic field measurements, soft X-ray imaging of the magnetosheath and polar cusps, and UV imaging of global auroral distributions. SMILE science objectives, payload and spacecraft status will be presented.

ABSTRACT. GEO-X (GEOspace X-ray imager) mission aims at visualization of the Earth’s magnetosphere by X-rays and revealing dynamical couplings between solar wind and magnetosphere. In recent years, X-ray astronomy satellite observations discovered soft X-ray emission originated from the magnetosphere. This emission should increase largely in the sheath region because of the large ambient plasma density, so that the dayside sheath region, i.e., the boundary region between the bow shock and the magnetopause will be detected with the strong soft X-ray emission.

Therefore, we are developing a new satellite GEO-X to realize the global imaging of the magnetosphere by X-ray observations. It is a 50 kg class microsatellite carrying a novel compact X-ray imaging spectrometer payload. The microsatellite having a large delta v (>700 m/s) to increase an altitude from GTO piggyback launch is necessary. We thus combine a 18U Cubesat with the hybrid kick motor composed of liquid N2O and polyethylene. We also develop a novel wide FOV (>5x5 deg) and a good spatial resolution (<10 arcmin) X-ray (0.3-2 keV) imager. We utilize a micromachined X-ray telescope, and a new CMOS detector system with an optical blocking filter. We aim to launch the satellite around the next solar maximum, i.e., 2024-25.

ABSTRACT. One of the major goals of solar-terrestrial physics is to understand how the transfer of Sun and solar wind energy into Geospace and vice versa. In the last decade, there have been several flagship missions in Geospace; NASA/THEMIS, Van Allen Probes, and MMS, and JAXA/Arase, making important contributions to our understanding of how Geospace responds to variations of Sun and solar wind. Solar atmosphere is also observed and monitored by satellites, such as Hinode, and Solar Dynamics Observatory. In 2020, many satellites observe the inner heliosphere and Japanese satellites, BepiColombo/Mio, Akatsuki, MMX (Mars sample return) will contribute to understanding the inner heliosphere. The planned mission SOLAR-C is also important to understand the Sun-interplanetary-Earth coupling. In this presentation, we briefly review highlights from these missions and discuss what subjects are important for the heliospheric system science in the 2020s.

ABSTRACT. The Geospace Dynamics Constellation (GDC) is NASA's next strategic Living With a Star mission. GDC's goals are: 1) Understand how the high-latitude ionosphere-thermosphere system responds to variable solar wind/magnetosphere forcing; and 2) Understand how internal processes in the global ionosphere-thermosphere system redistribute mass, momentum, and energy.

Planned for launch by the end of the decade, GDC will use six identical observatories, each identically instrumented to fully characterize the magnetospheric drivers of the I-T system as well as the global response of the ionized and neutral gases. GDC will do this with a series of orbital conegurations that will enable it to study the widest range of spatial and temporal scales to date, ranging from hundreds of kilometers and several seconds to tens of minutes, and extending through the regional to the global scale.

This poster presents GDC's current status, measurement capabilities, sampling scheme, and model development efforts and show how GDC will et into the larger Heliophysics ecosystem, by 1) obtaining critically needed scientiec observations; 2) providing a source for real-time space weather and situational awareness, as well as retrospective studies to further the science of space weather; 3) serving as a "strategic hub" for other space-based and ground- based efforts that want to leverage GDC to perform complementary science.

ABSTRACT. Global observations of the upper atmosphere have been carried out by operating networks of optical instruments (e.g., all-sky airglow/aurora imagers, Fabry-Perot Interferometers (FPIs), and spectrometers), magnetometers, and HF radars (SuperDARN). Global total electron content (TEC) obtained from the ground-based Global Navigation Satellite System (GNSS) receiver networks is also available. EISCAT_3D will provide three-dimensional (3D) ionospheric plasma parameters with high temporal and spatial resolutions. The observation data obtained from these instruments could be useful for calibration of the Geospace Dynamics Constellation (GDC) measurements, and for studies of global and meso-scale phenomena in the upper atmosphere and ionosphere.

ABSTRACT. We suggest that the next era of Heliophysics should focus on the Sun-Heliosphere and Geospace as a system-of-systems, and recommend a coordinated, deliberate, worldwide scientific effort to answer long-standing questions that will remain unanswered without a unified program. Many of the biggest unanswered science questions that remain across Heliophysics center around the interconnectivity of the different physical systems, and the role of mesoscale dynamics in modulating, regulating, and controlling that interconnected behavior. Heliophysics has made key progress understanding both the large-scale dynamics and the microphysical processes that occur in these dynamic systems. Such understanding grew out of a systematic approach to study both limits of the system, from global, with the coordinated missions of the International Solar Terrestrial Physics (ISTP) program, to micro, with largely uncoordinated missions such as Magnetospheric MultiScale (MMS), Parker Solar Probe, and Cluster. We suggest that Heliophysics should embark on a grand program to study these system-of-systems holistically, with coordinated, multipoint measurements, with particular emphasis on resolving the mesoscale dynamics that links micro to global, and a whole-of-science approach that includes ground-based measurements and advanced numerical modeling. The paradigm and specific approaches outlined in this paper could serve as an imperative and overarching theme that binds our Solar and Space Physics communities together under a common scientific objective.

ABSTRACT. Solar Orbiter is now in its second year of its Nominal Mission Phase, during which two close perihelion passages have been conducted and a third has just begun. I will discuss some of the early science results of the mission so far and give an overview of the spacecraft’s remaining trajectory as it climbs out of the ecliptic plane to give us a first clear view of the sun’s polar regions.

ABSTRACT. On January 2023, NASA's Parker Solar Probe (PSP) mission had completed 14 of its scheduled 24 orbits around the Sun, with the closest approach (i.e., perihelion) of 13.28 solar radii from the Sun's center. PSP's primary science goal is to determine the structure and dynamics of the Sun's coronal magnetic field, understand how the solar corona and wind are heated and accelerated, and determine what processes accelerate energetic particles. The science data returned by PSP led to significant discoveries and potential breakthroughs, yielding more than 700 peer-reviewed publications. The first four years of the prime mission were mainly during the solar cycle minimum. With the rise of solar activity, PSP will explore solar wind variability as the cycle progress to its maximum. I will present an overview of the major scientific discoveries by PSP and the mission's outlook.

ABSTRACT. Firefly is an innovative mission concept study for the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 to fill long-standing knowledge gaps in Heliophysics. A constellation of spacecraft will provide both remote sensing and in situ observations of the Sun and heliosphere from a whole 4π-steradian field of view. The concept implements a holistic observational philosophy that extends from the Sun’s interior, to the photosphere, through the corona, and into the solar wind simultaneously with multiple spacecraft at multiple vantage points optimized for continual global coverage over much of a solar cycle. The mission constellation includes two spacecraft in the ecliptic and two flying as high as ~70º solar latitude. The ecliptic spacecraft will orbit the Sun at fixed angular distances of ±120º from the Earth. Firefly will provide new insights into the fundamental processes that shape the whole heliosphere. The overarching goals of the Firefly concept are to understand the global structure and dynamics of the Sun’s interior, the generation of solar magnetic fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of the corona as it creates the heliosphere. We will provide an overview of the Firefly mission science and architecture and how it will revolutionize our understanding of long-standing heliospheric phenomena such as the solar dynamo, solar cycle, magnetic fields, solar activity, space weather, the solar wind, and energetic particles.

ABSTRACT. Magnetic reconnection has been recognized as one of the key mechanisms for heating and bulk acceleration of space plasmas such as magnetospheric plasma which is discussed by GEOTAIL. To date, many observations have been made on the solar corona to confirm the presence of high-temperature and high-speed plasma flows produced by magnetic reconnection above flare arcades. In this talk, I will introduce the study on plasma heating considers the time-dependent ionization process during a large solar flare on 2017 September 10, observed by Hinode/EUV Imaging Spectrometer (EIS). The observed Fe XXIV/Fe XXIII ratios increase downstream of the reconnection outflow, and they are consistent with the time-dependent ionization effect at a constant electron temperature Te = 25 MK. Moreover, this study also shows that the nonthermal velocity, which can be related to the turbulent velocity, reduces significantly along the downstream of the reconnection outflow, even when considering the time-dependent ionization process. The number of high-temperature lines observed by Hinode/EIS is limited, so it is difficult to make a sufficient diagnosis of the reconnection region. Recently, the next generation solar observation satellite Solar-C (EUVST) has been discussed intensively. An ultraviolet imaging spectrometer with dramatically improved spatial and temporal resolution is planned for this satellite. In the Solar-C era, thermal nonequilibrium plasma will be extensively discussed. I expect that Solar-C (EUVST) will reveal the reconnection region in detail. I will introduce further plan for solar observation discussed in the solar community in Japan.

ABSTRACT. The solar wind, a supersonic plasma flow blowing in the solar system, originates from the solar corona. The mechanisms for heating the solar corona and accelerating the solar wind are major problems of space physics; theories suggest the energy deposition by magnetohydrodynamic waves are important. In order for the high-speed plasma flow to be created, heating of the corona from the coronal base to distances of 10 solar radii is required. The physical processes in this distance region is difficult to observe with optical methods because of the low density of the plasma and is difficult to observe with in-situ methods because of the proximity to the Sun. Radio occultation is one of the powerful methods that can explore this region. Spacecraft radio occultation, in which spacecraft are used as radio sources and ground antennas receive radio signals, is especially useful for retrieving various physical parameters in this region.

We have conducted radio occultation observations of the solar corona repeatedly using JAXA’s Venus orbiter Akatsuki during its superior conjunction periods from 2011 to 2022. In 2021, a coordinated observation campaign using BepiColombo and Akatsuki were also conducted. From the recorded data, we can derive the flow velocity, the density fluctuation spectrum, the characteristics of compressive waves, and the axial ratio and the inner scale of turbulence. From the radial distributions of these physical quantities and the comparison between different solar activity phases, we can investigate the mechanism for solar wind generation and the variation in the solar activity cycle. An overview of the observation campaigns will be