Space Science Reviews最新文献

Stationed in an orbit about the first Sun-Earth Lagrange point, L1, NASA's Interstellar Mapping and Acceleration Probe (IMAP) mission is designed to provide well-coordinated measurements of the in-situ solar wind (SW) plasma and interplanetary magnetic field, interstellar pickup ions (PUIs), suprathermal and energetic ions, interstellar and energetic neutral atoms (ENAs), interstellar dust, and 3-dimensional (3D) maps of the global solar wind structure. Together these measurements from ten instruments address two key Heliophysics objectives, namely, 1) the acceleration of charged particles and 2) the interaction of the solar wind with the local interstellar medium. This paper describes one of the five in-situ instruments - the Compact Dual Ion Composition Experiment (CoDICE) that provides comprehensive measurements of the source populations and the charged particles that are accelerated near the Sun and throughout the heliosphere and beyond. CoDICE also provides the 3D velocity distribution functions (3D VDFs) of interstellar PU He⁺ ions and the isotopic composition of interstellar He and Ne PUIs, thus enabling detailed studies of the properties of the local interstellar medium (LISM) and its interactions with the SW and our heliosphere. CoDICE is a next generation instrument that combines two measurement systems in a novel, compact design to provide 1) the 3D VDFs and mass, isotopic, and ionic charge state composition of the lower energy SW, suprathermal, and PUIs between ∼0.5-80 keV/q, and 2) the arrival directions, and mass and isotopic composition of higher energy H-Fe ions between ∼0.03-5 MeV/nuc. CoDICE also provides measurements of SW abundances and charge states, as well as the intensities of suprathermal protons in four different directions to the real-time I-ALiRT data stream for Space Weather research and monitoring.

NASA's Interstellar Mapping and Acceleration Probe (IMAP) mission simultaneously investigates the acceleration of particles expelled from the Sun, and how the interaction of these particles with the local interstellar medium shapes our heliospheric boundary. The IMAP observatory makes critical measurements that facilitate this ground breaking science by incorporating a spin stabilized spacecraft orbiting around the first Sun-Earth Lagrange point, L1, with a payload comprised of ten unique instruments, making comprehensive and synergistic observations of solar wind, suprathermal, energetic particles and magnetic field, energetic neutral atoms mapping the boundary of our heliosphere, as well as interstellar neutral atoms and dust. This paper provides details on the design, integration, and testing of the IMAP observatory.

This article reviews the emerging field of exo-geoscience, focusing on the geological and geophysical processes thought to influence the evolution and (eu)habitability of rocky exoplanets. We examine the possible roles of planetary interiors, tectonic regimes, continental coverage, volatile cycling, magnetic fields, and atmospheric composition and evolution in shaping long-term climate stability and biospheric potential. Comparisons with Earth and other planets in the Solar System highlight the diversity of planetary conditions and the rarity of conditions relevant to life. We also discuss contingency and convergence in planetary and biological evolution as they relate to the spread of life in the universe. The observational limits of current and planned missions are assessed, emphasizing the need for models that connect internal dynamics to detectable atmospheric and surface signatures as well as the need for laboratory measurements of planetary properties under a wide range of conditions. The large number of exoplanets promises opportunities for empirical and statistical studies of processes that may have occurred earlier in Earth's history, as well as for the other pathways rocky planets and biospheres may take. Thus, exo-geoscience provides a framework for interpreting exoplanet diversity and refining strategies for detecting life beyond the Solar System.

The payload of the Interstellar Mapping and Acceleration Probe (IMAP) includes sophisticated in situ instruments to measure solar wind plasma and magnetic fields, suprathermal and energetic particles at 1 au as well as unprecedented remote sensing instruments to observe the energetic neutral atoms (ENAs) in the outer heliosphere and the ultraviolet glow of the interstellar neutral H interacting with the three-dimensional solar wind. This unique combination of sensors on a single platform allows connections to be made between the inner and outer heliosphere to an extent never before possible. This article focuses on the scientific theme of connecting the physics of particle acceleration and transport throughout the heliosphere. Such studies enabled by IMAP are organized into three broad categories: i) fundamental particle acceleration and transport processes, ii) heliospheric variability that affects those processes, and iii) inner heliospheric science.

Since the dawn of the space age in 1957, humanity has achieved the remarkable feat of exploring all the planets in our Solar System with robotic spacecraft. This glimpse into the diversity of space environments that make up our Solar System has revealed that no two planetary systems are identical; however, each planet harbors key clues in working toward a more unified and predictive understanding of the basic structure and dynamics of all planetary, and even exosolar, magnetospheres. A common feature found in all strongly magnetized planets are regions of trapped, high-energy charged particles called radiation belts. Dedicated missions studying the radiation belts encompassing Earth have led to major space physics discoveries over the past several decades, but Earth's magnetosphere exists in a relatively small swath of the parameter space found in our Solar System. To expand that parameter space, we present a mission concept that was reported in the recent National Academies of Sciences, Engineering, and Medicine (NASEM) Decadal Survey to expand the frontiers of Heliophysics in the 2024-2033 decade. The mission concept is called COMPASS, short for Comprehensive Observations of Magnetospheric Particle Acceleration, Sources, and Sinks. COMPASS is a mission dedicated to the exploration of Jupiter's radiation belts, with an unprecedented suite of instruments covering i) particle species from thermal plasma to 10 tens of MeV electrons and relativistic protons and heavy ions; ii) comprehensive magnetic and electric fields and waves; and iii) dedicated X-ray imaging. COMPASS will enable the scientific community to test existing hypotheses and make new discoveries of how Jupiter's radiation belts are sourced, accelerated, and lost within such a complex system.

The Europa Clipper mission will investigate the geophysical properties of Europa, one of Jupiter's Galilean moons, to assess its habitability. Geodetic measurements will play a critical role in determining Europa's internal structure, including the thickness of the ice shell, the presence and extent of a subsurface ocean, and the distribution of mass in the deeper interior. To build the necessary geodetic data set, the Geodesy Focus Group (GFG) coordinates cross-instrument efforts to measure Europa's global shape, rotational parameters, gravity field, and degree-2 tidal Love numbers ( $k_2$ and $h_2$ ). Here we summarize how data from the Gravity/Radio Science (G/RS) investigation, Europa Imaging System (EIS), Radar for Europa Assessment and Sounding (REASON), and Europa Ultraviolet Spectrograph (Europa-UVS) will be used to infer geodetic constraints on the interior structure and to establish a precise cartographic reference system for geophysical and geological interpretation. Together, the resulting geodetic information will contribute to a deeper understanding of Europa's internal dynamics and the potential habitability of its ocean.

Water and land surfaces on a planet interact in particular ways with gases in the atmosphere and with radiation from the star. These interactions define the environments that prevail on the planet, some of which may be more amenable to prebiotic chemistry, some to the evolution of more complex life. This review article covers (i) the physical conditions that determine the ratio of land to sea on a rocky planet, (ii) how this ratio would affect climatic and biologic processes, and (iii) whether future astronomical observations might constrain this ratio on exoplanets. Water can be delivered in multiple ways to a growing rocky planet - and although we may not agree on the contribution of different mechanism(s) to Earth's bulk water, hydrated building blocks and nebular ingassing could at least in principle supply several oceans' worth. The water that planets can sequester over eons in their solid deep mantles is limited by the water concentration at water saturation of nominally anhydrous mantle minerals, being in sum likely less than 2000 ppm of the planet mass. Water is cycled between mantle and surface through outgassing and ingassing mechanisms that, while tightly linked to tectonics, do not necessarily require plate tectonics in every case. The actual water/land ratio at a given time then emerges from the balance between the volume of surface water on the one hand, and on the other hand, the shape of the planet (its ocean basin volume) that is carved out by dynamic topography, the petrologic evolution of continents, impact cratering, and other surface-sculpting processes. By leveraging the contrast in reflectance properties of water and land surfaces, spatially resolved 2D maps of Earth-as-an-exoplanet have been retrieved from models using real Earth observations, demonstrating that water/land ratios of rocky exoplanets may be determined from data delivered by large-aperture, high-contrast imaging telescopes in the future.

Magnetic switchbacks are fluctuations in the solar wind in which the interplanetary magnetic field sharply deflects away from its background direction so as to create folds in magnetic field lines while remaining of roughly constant magnitude. The magnetic field and velocity fluctuations are extremely well correlated in a way corresponding to Alfvénic fluctuations propagating away from the Sun. For a background field which is nearly radial this causes an outwardly propagating jet to form. Switchbacks and their characteristic velocity jets have recently been observed to be nearly ubiquitous by Parker Solar Probe with in situ measurements in the inner heliosphere within 0.3 AU. Their prevalence, substantial energy content, and potentially fundamental role in the dynamics of the outer corona and solar wind motivate the significant research efforts into their understanding. Here we review the in situ measurements of these structures (primarily by Parker Solar Probe). We discuss how they are identified and measured, and present an overview of the primary observational properties of these structures, both in terms of individual switchbacks and their collective arrangement into "patches". We identify both properties for which there is a strong consensus and those that have limited or qualified support and require further investigation. We identify and collate several open questions and recommendations for future studies.

NASA's Interstellar Mapping and Acceleration Probe (IMAP), a spinner spacecraft in orbit around L1, is taking in situ observations of thermal, pickup, and energetic particles, while simultaneously remotely sensing the effects that these particles have in the outer heliosphere, by measuring Energetic Neutral Atoms (ENA) emissions produced by neutralized energetic ions when they charge exchange with interstellar neutral particles in that region. The IMAP-Ultra instrument (Ultra), one of the three ENA imagers on IMAP, measures the emission of the highest energy ENAs produced in the heliosheath and beyond. Ultra consists of two sensors with one sensor angled at 90° (Ultra₉₀) and the other at 45° (Ultra₄₅) from the spacecraft's spin axis. Ultra was designed and optimized to measure hydrogen (H) ENAs from 5 - 40 keV, but the sensors have been demonstrated to measure H from ∼3 - 300 keV. Additionally, Ultra's large ∼96° × 120° field of view (FoV) is capable of achieving angular resolutions ≤ 6° FWHM for ≥ 10 keV for H ENAs. Ultra provides high spatial resolution, full heliosphere maps, detecting changes in the spatial distribution of ENAs, on time scales sufficient to track both solar cycle as well as other major variations.

An International Space Science Institute (ISSI) workshop was convened to assess recent rapid advances in studies of magnetic reconnection made possible by the NASA Magnetospheric Multiscale (MMS) mission and to place them in context with concurrent advances in solar physics by the Parker Solar Probe, astrophysics, planetary science and laboratory plasma physics. The review papers resulting from this study focus primarily on results obtained by MMS, and these papers are complemented by reports of advances in magnetic reconnection physics in these other plasma environments. This paper introduces the topical collection "Magnetic Reconnection: Explosive Energy Conversion in Space Plasmas", in particular introducing the new capabilities of the MMS mission used in majority of the articles in the collection and briefly summarizing the advances obtained from MMS.