Space Science Reviews最新文献

The primary purpose of the Tandem Reconnection And Cusp Electrodynamics Reconnaissance Satellites (TRACERS) Science Operations Center (SOC) is to ensure that the data necessary to achieve the TRACERS science goals are acquired, processed, and distributed to the scientific community. The SOC role in data acquisition is to facilitate science instrument planning and operations, through a weekly commanding cycle. Data processing includes generation of Level 0 and Level 1 data products, creation of Spacecraft Planet Instrument Camera-matrix Events (SPICE) kernels to provide spacecraft ephemerides and coordinate transforms for the mission, and ensuring consistency of all Level 2+ products produced by the individual instrument teams. Data distribution is undertaken in two ways. First, by hosting TRACERS data products on a public web portal during the active mission, and second by preparing mission data for transfer to the Space Physics Data Facility (SPDF) for long-term archiving.

Here we consider initial steps of how upcoming data from the SMILE Soft X-ray Imager and Ultraviolet Imager may be combined with additional data sources to provide a more holistic view of the coupled magnetosphere-ionosphere system. The Ground-based and Additional Science Working Group aims to embed SMILE in a multi-scale and holistic view of the Earth's magnetosphere by exploring coordination of ground-based and other spacecraft's data with SMILE. This working group is one of four working groups within the SMILE Science Working Team who are tasked with preparing all aspects of the mission. Adequate preparation is essential to optimise the tools, multiple instrument campaigns and procedures to allow the maximum science return from SMILE in the context of the entire available range of temporal and spatial scales in the terrestrial system. SMILE instruments will not work in isolation from each other, nor from other spacecraft or ground-based experiments. Synergies with other missions and ground-based experimentation will be fundamental for full science exploitation of the data. In this paper, we expand on the previous publications by the Ground-Based and Additional Science working group, by exploring the possibilities of using a two-way approach to deriving scientific results from SMILE, using a small isolated substorm as a case study. We use knowledge of the contemporaneous solar wind conditions during the substorm to simulate SMILE Soft X-ray Imager data. We also use observed ultraviolet auroral emissions and field-aligned current data as measured in the high-latitude polar regions to act as either a proxy for the SMILE Ultraviolet Imager, or an alternative source of information for the open-closed field line boundary. The observational data is used to constrain the minimisation of the two-dimensional X-ray images, leading to an improvement in the derived shape of the flank magnetopause position. We also comment on mission's possibilities to inspire the public through various engagement programmes, and current activities to involve diverse communities in the preparations and science exploitation of SMILE.

The Magnetic Search Coil (MSC) instruments on the TRACERS mission provide the three magnetic components of the waves from ∼1 Hz to 1 kHz from two closely spaced spacecraft in low Earth orbit that pass through the magnetospheric cusp. These measurements of Alfvén and other waves help meet the TRACERS Science Objective 3: "Determine to what extent dynamic structures in the cusp are associated with temporal versus spatial reconnection". The TRACERS MSC uses a three axis, dual sensor coil system and amplifiers with current feedback to provide continuous analog outputs to the Electric Field Instrument (EFI) Electric Signal Processing (ESP) Board. The ESP digitally samples each MSC analog output channel with 16-bit resolution at 2048 samples/second and sends the digitally sampled data to the Central Data Processing Unit (CDPU). The TRACERS MSC design, calibration, and performance is described.

Observing Cusp High-altitude Reconnection and Electrodynamics (OCHRE) is a student/early career researcher (ECR) focused sounding rocket that will fly as a compliment to the TRACERS satellites. OCHRE will utilize the deep institutional knowledge of the TRACERS science team to educate and mentor a team of graduate students and ECRs to serve as instrument leads, project manager, and primary investigator. Aiming for a near conjunction with, and at an apogee above, TRACERS in the northern polar cusp, OCHRE will answer some remaining questions from the TRICE-II sounding rockets using TRACERS to contextualize observations in the larger-scale polar cusp dynamics.

A Gamma-Ray and Neutron Spectrometer (GRNS) instrument has been developed as part of the science payload for NASA's Discovery Program Psyche mission to the M-class asteroid (16) Psyche. The GRNS instrument is designed to measure the elemental composition of Psyche with the goal to understand the origin of this mysterious, potentially metal-rich planetary body. The GRNS will measure the near-surface abundances for the elements Ni, Fe, Si, K, S, Al, and Ca, as well as the spatial distribution of Psyche's metal-to-silicate fraction (or metal fraction). These measurements address three of the five Psyche mission science objectives: determine if Psyche is a core; determine whether small metal bodies incorporate light elements into the metal phase; and determine whether Psyche was formed under reducing conditions. The Gamma-Ray Spectrometer (GRS) uses a cryocooled, high-purity Ge (HPGe) sensor to detect cosmic-ray generated gamma rays in the 60 to 9000-keV energy range. The HPGe sensor is surrounded by a borated plastic anticoincidence shield that provides three functions: active background rejection from charged particle interactions in the HPGe sensor; fast neutron measurements; and direct measurements of the incident galactic cosmic ray flux. The Neutron Spectrometer (NS) uses three ³He gas proportional sensors, each with different material wraps to measure thermal (<0.4 eV), low-energy epithermal (0.4 eV to 1 keV), and high-energy epithermal (up to 100 keV) neutrons. This paper provides an overview of the Psyche GRNS, including: its science and measurement objectives; the design of the instrument hardware, software, and operation; pre-launch performance measurements and its initial performance in space; and an overview of its data products and expected operation for different Psyche mission phases.

Introduction: We aimed to investigate the effects of oxytocin on neurite growth, cell viability, cell proliferation and apoptosis to demonstrate its neuroprotective effect on glutamate induced neurotoxicity in human neuroblastoma SH-SY5Y cell culture.

Method: The effect of oxytocin on the toxic effects of glutamate in human neuroblastoma SH-SY5Y cell line with the Neurotoxicity Screening Test (NTT), apoptotic effects by Terminal Transferase dUTP Nick End Labeling (TUNEL) method and cell viability test by 3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide (MTT) method. In the NTT test; Neurotoxicity was induced by adding glutamate at a concentration of 32 μM to the cell culture. Oxytocin was added at 1, 3, 10, 30 and 100 μM concentrations and its effect on neurite elongation was investigated. It was demonstrated by TUNEL method that application of glutamate caused apoptosis. Afterwards, when glutamate and different doses of oxytocin were given, antiapoptotic effect was evaluated with the apoptotic index.

Results: Glutamate was found to have a dose-dependent neurotoxic effect and reduced neurite elongation by 50% at a concentration of 32 μM. It was shown that the inhibition of neurite elongation caused by glutamate decreased in a dose-dependent manner by applying oxytocin. Especially oxytocin was found to significantly reduce neurite inhibition and show a neuroprotective effect starting from 10 μM concentrations. The concentration at which glutamate reduces cell proliferation by 50% was determined as 54 μM in MTT. Subsequently, it was observed that the adverse effect of glutamate on cell proliferation significantly decreased with oxytocin administration, depending on the dose.

Conclusion: It was found that different concentrations of glutamate have a significant toxic effect on cell proliferation and viability, glutamate inhibits neurite elongation in a dose-dependent manner; oxytocin reduces neurite inhibition caused by glutamate, has a neuroprotective effect, increases cell viability and has antiapoptotic effects.

We provide an overview of the isotopic signatures of presolar supernova grains, specifically focusing on ⁴⁴Ti-containing grains with robustly inferred supernova origins and their implications for nucleosynthesis and mixing mechanisms in supernovae. Recent technique advancements have enabled the differentiation between radiogenic (from ⁴⁴Ti decay) and nonradiogenic ⁴⁴Ca excesses in presolar grains, made possible by enhanced spatial resolution of Ca-Ti isotope analyses with the Cameca NanoSIMS (Nano-scale Secondary Ion Mass Spectrometer) instrument. Within the context of presolar supernova grain data, we discuss (i) the production of ⁴⁴Ti in supernovae and the impact of interstellar medium heterogeneities on the galactic chemical evolution of ⁴⁴Ca/⁴⁰Ca, (ii) the nucleosynthesis processes of neutron bursts and explosive H-burning in Type II supernovae, and (iii) challenges in identifying the progenitor supernovae for ⁵⁴Cr-rich presolar nanospinel grains. Drawing on constraints and insights derived from presolar supernova grain data, we also provide an overview of our current understanding of the roles played by various supernova types - including Type II, Type Ia, and electron capture supernovae - in accounting for the diverse array of nucleosynthetic isotopic variations identified in bulk meteorites and meteoritic components. We briefly overview the potential mechanisms that have been proposed to explain these nucleosynthetic variations by describing the transport and distribution of presolar dust carriers in the protoplanetary disk. We highlight existing controversies in the interpretation of presolar grain data and meteoritic nucleosynthetic isotopic variations, while also outlining potential directions for future research.

Strong gravitational lensing and microlensing of supernovae (SNe) are emerging as a new probe of cosmology and astrophysics in recent years. We provide an overview of this nascent research field, starting with a summary of the first discoveries of strongly lensed SNe. We describe the use of the time delays between multiple SN images as a way to measure cosmological distances and thus constrain cosmological parameters, particularly the Hubble constant, whose value is currently under heated debates. New methods for measuring the time delays in lensed SNe have been developed, and the sample of lensed SNe from the upcoming Rubin Observatory Legacy Survey of Space and Time (LSST) is expected to provide competitive cosmological constraints. Lensed SNe are also powerful astrophysical probes. We review the usage of lensed SNe to constrain SN progenitors, acquire high-z SN spectra through lensing magnifications, infer SN sizes via microlensing, and measure properties of dust in galaxies. The current challenge in the field is the rarity and difficulty in finding lensed SNe. We describe various methods and ongoing efforts to find these spectacular explosions, forecast the properties of the expected sample of lensed SNe from upcoming surveys particularly the LSST, and summarize the observational follow-up requirements to enable the various scientific studies. We anticipate the upcoming years to be exciting with a boom in lensed SN discoveries.

As a first step in preparing for the return of samples from the Moon by the Artemis Program, NASA initiated the Apollo Next Generation Sample Analysis Program (ANGSA). ANGSA was designed to function as a low-cost sample return mission and involved the curation and analysis of samples previously returned by the Apollo 17 mission that remained unopened or stored under unique conditions for 50 years. These samples include the lower portion of a double drive tube previously sealed on the lunar surface, the upper portion of that drive tube that had remained unopened, and a variety of Apollo 17 samples that had remained stored at -27 °C for approximately 50 years. ANGSA constitutes the first preliminary examination phase of a lunar "sample return mission" in over 50 years. It also mimics that same phase of an Artemis surface exploration mission, its design included placing samples within the context of local and regional geology through new orbital observations collected since Apollo and additional new "boots-on-the-ground" observations, data synthesis, and interpretations provided by Apollo 17 astronaut Harrison Schmitt. ANGSA used new curation techniques to prepare, document, and allocate these new lunar samples, developed new tools to open and extract gases from their containers, and applied new analytical instrumentation previously unavailable during the Apollo Program to reveal new information about these samples. Most of the 90 scientists, engineers, and curators involved in this mission were not alive during the Apollo Program, and it had been 30 years since the last Apollo core sample was processed in the Apollo curation facility at NASA JSC. There are many firsts associated with ANGSA that have direct relevance to Artemis. ANGSA is the first to open a core sample previously sealed on the surface of the Moon, the first to extract and analyze lunar gases collected in situ, the first to examine a core that penetrated a lunar landslide deposit, and the first to process pristine Apollo samples in a glovebox at -20 °C. All the ANGSA activities have helped to prepare the Artemis generation for what is to come. The timing of this program, the composition of the team, and the preservation of unopened Apollo samples facilitated this generational handoff from Apollo to Artemis that sets up Artemis and the lunar sample science community for additional successes.