Space Environment Data Research Articles

Concerning reconnection‐induction balance at the magnetopause of Mercury

AbstractMercury's weak internal dipole field is subject to an intense solar wind; and thus, only a small magnetospheric cavity is created. The location of the outer boundary, the magnetopause, is mainly controlled by a pressure balance between the solar wind pressure outside and magnetic pressure inside, but during times of intense dayside reconnection the standoff distance may be reduced due to erosion. For the Hermean magnetosphere, different erosion mechanisms such as direct flux transport, neutral current sheet enhancement, field‐aligned currents, and interplanetary magnetic field penetration are compared. As any of these erosion mechanisms change the external field experienced by the planet, currents are induced within the electrically conductive planetary interior. Secondary magnetic fields from these induced currents counteract their source by temporarily increasing the planetary magnetic moment. The amplitude of this compensation depends on the interior electrical conductivity structure. Using a magnetospheric model, that is based on in situ MErcury Surface, Space ENvironment, GEochemistry, and Ranging data, as well as a simple conductivity model for the planetary interior, we give an estimate of the induced magnetic field range possible for various internal conductivity structures and external forcings. Considering the planetary response to the magnetospheric field changes opens a possibility to probe the planetary interior—a method especially suited for the upcoming BepiColombo mission to Mercury.

Measurements from The Heavy-Ion Telescope at The ISS Kibo Exposed Facility

Space radiation such as solar energetic particles, galactic cosmic rays (GCR), and trapped particles affect space activities. Heavy ions, in particular, have high linear energy transfer (LET) that exacerbates the risk of radiation exposure for astronauts and affects the electrical circuits of satellites. The Japan Aerospace Exploration Agency (JAXA) has operated the Space Environment Data Acquisition Equipment - Attached Payload (SEDA-AP) at the International Space Station (ISS) Japanese Experiment Module (Kibo) - Exposed Facility, since 2009. The heavy-ion telescope (HIT) is one of the SEDA-AP instruments, which comprises two position-sensitive silicon detectors and 16 silicon detectors. Based on the ΔE × E particle-identification method, HIT measures fluxes of energetic ions from Li to Fe and calculates the loss of energies at each sensor. The HIT results are consistent with the general GCR model and other ISS experiments in terms of elemental abundances and LET distributions. In addition, HIT might have detected heavy ions from a X5.4 solar flare. Moreover, there is the possibility of detecting the anomalous cosmic rays (ACR) from the ADEOS satellite observations; however, ACR was not observed because the pitch angle was not in the field of view of HIT or no distribution of ACR exists at 400 km altitude.

Initial mapping of Mercury's crustal magnetic field: Relationship to the Caloris impact basin

AbstractSeventy‐eight low‐altitude passes of MErcury Surface, Space ENvironment, GEochemistry, and Ranging magnetometer data from August to September of 2014 have been applied to produce an approximate map of the crustal magnetic field at a constant altitude of 80 km covering latitudes of 50°–80°N and longitudes of 160°–330°E. The strongest anomalies are located in the westernmost part of the mapped region just north and northeast of the Caloris impact basin. The strongest single anomaly group lies over a smooth plains unit that extends northward from Caloris. A second anomaly lies on the Odin Formation, interpreted as primary Caloris ejecta. A third broad anomaly also lies over a smooth plains unit, Suisei Planitia. Although many smooth plains on Mercury may have a volcanic origin, a subset of these plains is concentrated around Caloris and could have a dominantly impact origin. It is therefore proposed that many of the Mercurian anomaly sources consist of impact basin ejecta materials.

MESSENGER survey of in situ low frequency wave storms between 0.3 and 0.7 AU

AbstractMErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) magnetometer data was surveyed between 0.3 and 0.7 AU from 6 June 2007 to 23 March 2011 for low‐frequency wave (LFW) storms, when the magnetometer was sampling at a rate of at least 2 s−1. A total of 12,197 LFW events were identified, of which 5506 lasted 10 min or longer. The events have a high degree of polarization, are circularly polarized, with wave vectors nearly aligned or antialigned with the interplanetary magnetic field (IMF) at frequencies in the vicinity of the proton cyclotron frequency. These events are observed about 6% of the time, preferentially associated with radially directed inward or outward IMF. Their occurrence rate and median duration do not change much with R, where R is the heliocentric radial distance. For a narrow‐frequency window in the solar wind frame, left‐handed storms in the spacecraft frame have a power drop off that is roughly proportional to R−3 which is consistent with a source close the Sun, while right‐handed storms have a power drop off roughly proportional R−1 which is not consistent with a source close to the Sun. The power in the left‐handed LFW storms is on average greater than the right‐handed ones by a factor of 3. In the solar wind frame, the wave frequency decreases from 0.13 to 0.04 Hz moving from 0.3 to 0.7 AU, but the frequency normalized by the local proton cyclotron frequency does not change much with the running median varying from 0.35 to 0.5. The normalized frequency band widths of the wave power spectra increase slightly with R, possibly associated with energy dissipation.

Analysis of radiation induced effects in high-density commercial memories on-board Alsat-1: The impact of extreme solar particle events

This paper presents a long-term study on radiation effects in non-hardened high density memory devices operating within the main on-board computer system of the Algerian microsatellite Alsat-1 in Low Earth Orbit (LEO). A statistical analysis of single-event upset (SEU) activity is presented for commercial SRAM devices, and their response to extreme solar events shows SEU rate significant increases correlated with high-energy protons (E>100MeV). Ground based neutron monitor data are used to illustrate the long-term correlation between galactic cosmic rays and Alsat-1 upsets. The short-term effects of energetic solar particles are illustrated with space environment data from GOES-11. The Alsat-1 observed SEU rates are compared to the predicted rates based on ground test data and environment models. The prediction results are in good agreement with in-flight data.

In-depth Analysis of SREM Count Rate Measurements for Future Use in EnKF Salammbô Data Assimilation Tool

An extension to space environment data analysis proposed by COSPAR/PRBEM in 2008 is proposed in this paper. A detailed analysis of count rate data is applied to PROBA-1/SREM: the definition of regions or times when protons or electrons dominate the measurements is given.

Space environment data acquisition with Kibo exposed facility on the International Space Station (ISS)

AbstractThe Space Environment Data Acquisition equipment (SEDA), which was mounted on the Exposed Facility (EF) of the Japanese Experiment Module (JEM, also known as “Kibo”) on the International Space Station (ISS), was developed to measure the space environment along the orbit of the ISS. This payload module, called the SEDA‐Attached Payload (AP), began to measure the space environment in August 2009. This paper reports the mission objectives, instrumentation, and current status of the SEDA‐AP. © 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 95(9): 10–16, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11418

Space environment measurements by JAXA satellites and ISS/JEM

In order to monitor space environment and its temporal variations, JAXA Space Environment Group has been developing space radiation detectors as well as magnetometers and installing them on Low Earth Orbit (LEO) satellites, Geostationary Orbit (GEO) satellites, Geostationary Transfer Orbit (GTO) satellite, Quasi Zenith Orbit (QZO) satellite and Japanese Experimental Module (JEM) of the International Space Station (ISS). We are using these space environment data to know the situation of space environment and to provide warning messages to the satellite operators as well as ISS/JEM manager, when the space environment will be harmful. Based on our observation data, we also have constructed an advanced electron belt model for the use in satellite manufacturing. With space radiation data obtained by JAXA satellites and ISS, some findings related to the space radiation environment have been obtained. We will review our activities related to the space environment research and development in JAXA.

Predicting solar energetic proton events (E > 10 MeV)

A high level of proton radiation exposure can be dangerous to astronauts, satellite equipment, and air passengers/crew flying along polar routes. The presented solar energetic proton (SEP) event forecaster is based on a dual‐model approach for predicting the time interval within which the integral proton flux is expected to meet or surpass the Space Weather Prediction Center threshold of J (E > 10 MeV) = 10 pr cm−2 sr−1 s−1 and the intensity of the first hours of well‐ and poorly connected SEP events. This forecaster analyzes flare and near‐Earth space environment data (soft X‐ray, differential and integral proton fluxes). The purpose of the first model is to identify precursors of well‐connected events by empirically estimating the magnetic connectivity from the associated CME/flare process zone to the near‐Earth environment and identifying the flare temporally associated with the phenomenon. The goal of the second model is to identify precursors of poorly connected events by using a regression model that checks whether the differential proton flux behavior is similar to that in the beginning phases of previous historically poorly connected SEP events and thus deduce similar consequences. An additional module applies a higher‐level analysis for inferring additional information about the situation by filtering out inconsistent preliminary forecasts and estimating the intensity of the first hours of the predicted SEP events. The high‐level module periodically retrieves solar data and, in the case of well‐connected events, automatically identifies the associated flare and active region. For the events of solar cycles 22 and 23 of the NOAA/SWPC SEP list, the presented dual‐model system, called UMASEP, has a probability of detection of all well‐ and poorly connected events of 80.72% (134/166) and a false alarm rate of 33.99% (69/203), which outperforms current automatic forecasters in predicting >10 MeV SEP events. The presented forecaster has an average warning time of 5 h 10 min for the successfully predicted events, 1 h 5 min for well‐connected events and 8 h 28 min for poorly connected events, with a maximum warning time of 24 h for very gradual SEP events.

「きぼう」暴露部搭載・宇宙環境計測ミッション装置（SEDA-AP）による宇宙環境観測

Space Environment Data Acquisition equipment with attached payload (SEDA-AP) which was mounted on the Exposed Facility (EF) of the Japanese Experiment Module (JEM, also known as “Kibo”) on the International Space Station (ISS) started to measure the space environment along the orbit of ISS from Sept. 2009. This paper reports the mission objectives, instrumentation, and current status of SEDA-AP.

Space Environment Data Acquisition with the Kibo Exposed Facility on the International Space Station (ISS)

The Space Environment Data Acquisition equipment (SEDA), which was mounted on the Exposed Facility (EF) of the Japanese Experiment Module (JEM, also known as Kibo) on the International Space Station (ISS), was developed to measure the space environment along the orbit of the ISS. This payload module, called the SEDA-Attached Payload (AP), began to measure the space environment in August 2009. This paper reports the mission objectives, instrumentation, and current status of the SEDA-AP.

Testing of Inflatable-Structure Shape Control Using Genetic Algorithms and Neural Networks

I NFLATABLE structures have attractedmuch interest in the space community due to their unique advantages in achieving lowmass and high packaging efficiency [1,2]. We are currently working on an in-house research and development project of a membrane synthetic aperture radar antenna and solar array (see Fig. 1). It is expected that the membrane will be subjected to flatness problems during its lifetime in orbit, due to the thermal variation in space. A purely passive control method may not be sufficient to keep the membrane flat. Hence, an active control system is proposed to adjust the tensions according to the thermal variation. Actuators are installed in series with the links, such that the tensions stretching the membrane can be adjusted. A genetic algorithm and neural network (GA–NN) scheme is proposed for modeling and tension optimization. The neural network model of the membrane is established as a mapping from the boundary stretching tensions and space environment to membrane flatness. After the neural network training is completed, the membrane flatness can be estimated by inputting the measured stretching tensions and space environment data to the neural network model. Based on the neural network model, the genetic algorithm is applied to search for the optimal tensions that minimize the membrane wrinkles [3]. Experimental results demonstrate the effectiveness of the proposed scheme.

Data assimilation for magnetohydrodynamics systems

Prediction of solar storms has become a very important issue due to the fact that they can affect dramatically the telecommunication and electrical power systems at the earth. As a result, a lot of research is being done in this direction, space weather forecast. Magnetohydrodynamics systems are being studied in order to analyse the space plasma dynamics, and techniques which have been broadly used in the prediction of earth environmental variables like the Kalman filter (KF), the ensemble Kalman filter (EnKF), the extended Kalman filter (EKF), etc., are being studied and adapted to this new framework. The assimilation of a wide range of space environment data into first-principles-based global numerical models will improve our understanding of the physics of the geospace environment and the forecasting of its behaviour. Therefore, the aim of this paper is to study the performance of nonlinear observers in magnetohydrodynamics systems, namely, the EnKF. The EnKF is based on a Monte Carlo simulation approach for propagation of process and measurement errors. In this paper, the EnKF for a nonlinear two-dimensional magnetohydrodynamic (2D-MHD) system is considered. For its implementation, two software packages are merged, namely, the Versatile Advection Code (VAC) written in Fortran and Matlab of Mathworks. The 2D-MHD is simulated with the VAC code while the EnKF is computed in Matlab. In order to study the performance of the EnKF in MHD systems, different number of measurement points as well as ensemble members are set.

Compact environmental anomaly sensor (CEASE): a novel spacecraft instrument for in situ measurements of environmental conditions

A small, lightweight, and low power, spacecraft instrument, CEASE, has been designed to measure the local space radiation environment. The instrument's on-board processing algorithms use the collected data to generate warnings of the space environment hazards of radiation damage, dielectric charging and single event effects (SEE). In addition, CEASE can provide detailed space environment data to aid in analysis of anomalies that may occur on the host spacecraft.

SPIDR on the Web: Space Physics Interactive Data Resource on‐line analysis tool

The National Geophysical Data Center's innovative Space Physics Interactive Data Resource (SPIDR) is a multidisciplinary on‐line system to search, browse, and access space weather and environmental data sets over the Internet. SPIDR is a tool for the online user to select data or imagery by date and geographical location and deliver an image to the user over the World Wide Web. Currently, Defense Meteorological Satellite Program (DMSP) satellite imagery, geomagnetic variations, ionospheric vertical incidence databases, and NOAA Goestationary Operational Environmental Satellites (GOES) space environment monitor data can be accessed by SPIDR. DMSP visible, infrared, and microwave imagery displays aurora, city lights, fires, lightning strikes, and cloud coverage. Ionospheric and geomagnetic data, as well as GOES X ray, energetic particle, and the magnetic field at the spacecraft, can be plotted from interactive menus. Solar and geomagnetic indices can be generated as plots for comparison. The Web user selects the month and year from pull‐down menus and clicks the worldwide map in the region of interest. Worldwide contour maps of maximum electron density can also be generated from a global model of the ionosphere.

TDRS-1 single event upsets and the effect of the space environment

The systematic recording of single event upsets on TDRS-1 from 1984 to 1990 allows correlations to be drawn between those upsets and the space environment. Ground based neutron monitor data are used to illustrate the long-term relationship between galactic cosmic rays and TDRS-1 upsets. The short-term effects of energetic solar particles are illustrated with space environment data from GOES-7. >