ABSTRACT. Our solar system was formed in a journey around the galaxy as the protosolar nebula plowed through interstellar space filled with gas, dust, plasma and cosmic rays. As magnetic fields were generated after several million years, the magnetic bubble – the heliosphere - was formed and has governed the access of interstellar matter to our home ever since. Over this 4.6-billion-year journey our protective heliosphere has witnessed supernovae along its path including the most recent one occurring 2-3 million years ago with a blast wave likely leaving the entire solar system exposed to the interstellar environment. For the past 60, 000 years our protective heliosphere has traversed the Local Interstellar Cloud (LIC) and will soon enter the unknown environment of the neighboring G-Cloud that will continue to shape the evolution of our home.

An Interstellar Probe will begin its exploration directly after launch to unravel the mechanisms upholding our vast heliosphere and take the first explicit step into the Very Local Interstellar Medium (VLISM) to understand the interstellar environment. An outward trajectory would also offer opportunities for planetary science and astrophysics, such as a flyby of one of the unexplored 130 dwarf planets, circum-solar dust disk observations, and the extra-galactic background light measurements that all would tie in to understanding our home and its evolution in the galaxy.

An international team of scientists and engineers have now completed the NASA-funded study led by The Johns Hopkins University Applied Physics Laboratory (APL) to develop pragmatic concepts for an Interstellar Probe with possibilities to exceed a distance of 500 au. Available and near-term super-heavy launch vehicles, such as the SLS Block 2 have been used for analyzing dozens of staging configurations. A direct launch to Jupiter followed by a gravity assist achieves 7-8 au/year enabling detailed investigations of the expanding solar wind throughout the heliosphere in about 12 years and reaching the VLISM in about 16 years.

In this presentation we provide an overview of the study, the science mission concept, the compelling discoveries that await, and the example science payload ensuring a historic data return that would push the boundaries of space exploration to understand where we came from and where we are going.

ABSTRACT. Although Wind is over 28 years old as of March 2023, it still provides some of the best in situ solar wind measurements of all near-Earth spacecraft. The reason is that it was designed to do so. Most near-Earth spacecraft still in operation were either not focused on in situ solar wind science or not intended for kinetic physics investigations in the solar wind. That is, they were not designed to measure the cold, fast solar wind protons or electrons. We briefly discuss some of the advances Wind has made and go into what is necessary for future progress in solar wind kinetic physics studies.

ABSTRACT. We present an overview of HelioSwarm, a NASA Medium-class Explorer mission concept designed to reveal the 3D, dynamic mechanisms controlling the physics of space plasma turbulence. HelioSwarm measures plasmas and magnetic fields with a novel configuration of spacecraft. Simultaneous multi-point, multi-scale measurements allow us to address two overarching science goals: 1) Reveal the 3D spatial structure and dynamics of turbulence in a weakly collisional plasma and 2) Ascertain the mutual impact of turbulence near boundaries and large-scale structures. HelioSwarm uses a "swarm" of nine spacecraft, consisting of a "hub" spacecraft and eight "node" spacecraft. The spacecraft co-orbit in a 2-week lunar resonant Earth orbit, with an apogee/perigee of ~60/11 Earth radii. Flight dynamics design and on-board propulsion produce inter-spacecraft separations ranging from 10's to 1000's km in geometries needed to distinguish between proposed models of turbulence. Each node possesses an instrument suite consisting of a Faraday cup, a fluxgate magnetometer, and a search coil magnetometer; the hub has the same instruments plus an ion electrostatic analyzer. We discuss HelioSwarm mission science, implementation, and how it will provide unprecedented views into the nature of space plasma turbulence. We show how HelioSwarm's orbit provides for new opportunities to explore the magnetotail, informed by the rich legacy of the Geotail mission.

ABSTRACT. The acceleration of high-energy charged particles is ubiquitous in space and astrophysical plasmas and has attracted significant attention for a long time. The heliosphere has been recognized as a natural laboratory for elementary physical processes involved in particle acceleration. The collisionless shock has been one of the most widely-accepted sites of particle acceleration. Historically, in-situ measurement of interplanetary shocks and planetary bow shocks played a central role in establishing diffusive shock acceleration (DSA), the standard theory of cosmic-ray acceleration at shocks. However, the understanding of shock acceleration based on in-situ measurement had been limited only to protons and heavier elements: The typical time resolution of early spacecraft observation before NASA’s MMS (Magnetospheric Multi-Scale) was not enough to investigate the physics of electron acceleration at shocks.

We present recent progress in theory, simulation, and observations of non-thermal electron acceleration at collisionless shocks. We will focus on a novel particle acceleration mechanism called stochastic shock drift acceleration (SSDA). It was originally formulated based on fully kinetic Particle-In-Cell (PIC) simulations. We then demonstrated that sub-relativistic electron acceleration observed by MMS at the bow shock was consistent with the prediction by SSDA. Furthermore, we have recently shown that, under the simplest limit, SSDA and DSA may be unified into a single model. This model allows us to discuss the injection of sub-relativistic electrons via SSDA and subsequent acceleration to ultra-relativistic energies at collisionless shocks in a consistent fashion. The theory indicates that the bow shock is not strong enough for electron injection to relativistic energies, but the same mechanism will yield efficient injection at young supernova remnant shocks.

ABSTRACT. The Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES) is NASA’s initial space-weather payload for the Artemis program’s lunar-orbiting Gateway space station. The initial Gateway modules, the HALO and the PPE will launch together with HERMES attached to the HALO. After approximately one year of transit to Gateway's polar lunar orbit, HERMES will engage in a science campaign addressing objectives in heliospheric and magnetospheric physics. HERMES also serves as a pathfinder for future space-weather payloads as may be carried on deep-space missions of exploration for which local measurements of space-weather conditions can contribute to accuracy of predictions and thereby contribute to crew safety. HERMES instrumentation includes an electron electrostatic analyzer, an ion mass spectrometer, a proton and electron telescope for energetic particles, and a set of science magnetometers. Analysis of the in-situ measurements from HERMES will leverage observations from other spacecraft missions to enable studies of structure in the solar wind and in the magnetotail. Data, algorithms, calibrations, and related software produced by the instrument teams will be fully open and accessible through a Science Operations Center and through NASA's Space Physics Data Facility. In this presentation we provide an overview of science plans, including expectations for collaboration with other HSO missions and with international partners.

ABSTRACT. The plasma environment of the Moon has been intensely studied in the two decades, mainly based on in situ observations by orbiters. In the 2020s, several exploration plans, including the NASA Artemis program with uncrewed and crewed missions, will provide excellent opportunities for plasma, dust and electromagnetic-field measurements around the Moon and at the lunar surface. We will discuss possible lunar environmental sciences and strategies in the Artemis era.

ABSTRACT. With the great heritage of the Geotail mission, Japanese heliospheric exploration as well as planetary exploration has made significant progress in the last decades. In this talk, I will review the achievements made by solar-terrestrial physics (STP) exploration and its role in planetary exploration, and discuss how future heliospheric system exploration should cooperate with planetary exploration.

ABSTRACT. Retention of substantial atmosphere is one of necessary conditions for habitable surface environment of terrestrial planets. In order to assess the atmospheric evolution, understanding of atmospheric escape processes is a key element. Among various atmospheric escape processes, the planetary ion escape plays an important role in the loss of the secondary atmosphere, which includes heavy species such as CO2, O2, and/or N2, to space from the Earth-size planets. The solar wind induced escape processes of the terrestrial ions are relatively important for Earth-sized planets. Strength of the intrinsic magnetic field drastically affects the ion escape processes. In-situ observations of heavy ions have played important role in our understanding of the atmospheric escape from the terrestrial planets.

Observations of cold O+ beams in the magnetotail showed that effects of circulation by magnetospheric convection should be taken into account to assess the ion escape from Earth [Seki et al., Science, 2001]. Accumulation of in-situ ion observations at Earth, Venus, and Mars now enable us to compare the escape rate and processes operating at each planet [e.g., Ramstad et al., SSR, 2021]. The ion escape can depend on many parameters such as the solar X-ray and EUV radiation, solar wind conditions, and strength of the planetary intrinsic magnetic field. With help of recent global simulation results [e.g., Sakata et al., 2022; Sakai et al., 2023], current understanding and open questions of atmospheric ion escape from terrestrial planets will be discussed in the presentation.

ABSTRACT. The Comet Interceptor mission, led by ESA, aims at a long-period comet or an interstellar object. JAXA will provide an ultra-small (24 U) daughter spacecraft, whose closest approach will be less than 1,000 km, allowing the first-ever multi-spacecraft fly-by observations of a comet. The small gravity and high gas production rate of comets set neutral-plasma environments that are unique in the solar system, which provides insights into the plasma universe. Here we review the previous studies on cometary plasma science, and then present some perspectives on the plasma observations by Comet Interceptor and beyond.

ABSTRACT. The heliospheric system science requires interdisciplinary studies of the sun, solar wind, planetary magnetosphere, and planetary upper atmosphere/exosphere. The international Mercury exploration mission BepiColombo covers all of these areas, and is a mission that should lead future heliospheric system science. In addition, BepiColombo has shown importance and benefit of an international collaborating mission. 　Mercury is the innermost planet in the Solar System and has a unique space environment. Mercury possesses a weak global magnetic field and is subject to the intense solar wind due to its proximity to the Sun (0.31-0.47 AU). In such conditions, Mercury formed a small but highly dynamic magnetosphere. Because of its small size and its proximity to the Sun, Mercury was unable to retain the bulk of its atmosphere and ionosphere. These conditions make Mercury’s space environment unique and an excellent science target for comparative study with Earth. The ESA-JAXA joint mission BepiColombo is now on the track to Mercury. Launched in October 2018, BepiColombo is continuing its long journey through interplanetary space with the goal of arriving at Mercury in December 2025. During the interplanetary cruise, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio) are coupled as a composit spacecraft. Mio is covered by a sun shield, which limits the field of view of plasma particle instruments. Nevertheless, Mio has successfully observed solar wind and solar energetic particles (SEPs) many times since 2021, and has shown that it can contribute sufficiently to the inner heliosphere science even during cruise. BepiColombo will also make nine swing-bys before arriving at Mercury: one on Earth, two on Venus, and six on Mercury, making scientific observations on each occasion. It has already completed an Earth, two Venus, and two Mercury swing-bys. In particular, during the Mercury swing-by, simultaneous observation of low-energy ions and electrons was successfully performed first ever. In order to encourage interdisciplinary studies between Earth’s and Mercury's magnetosphere, here we present the unsolved science issues on Mercury's magnetosphere, updated status of BepiColombo mission, and overview of initial results during cruise. We will also emphasize the importance of international joint mission demonstrated by the BepiColombo team.

ABSTRACT. More than 5000 exoplanets have been already discovered and ~500 of them are potentially terrestrial (rocky) ones (<~1.25 Re).In addtion, some of them are located at the habitable zone.The characterization of these planets would be one of the most important issues in the future space science. Here, the impact of stellar activity on exoplanetary atmosphere should be considered. In this presentation, we will review past observations and introduce new observation plans for exoplanets.