Solar EUV Irradiance Measurements by the Auto-Calibrating EUV Spectrometers (SolACES) Aboard the International Space Station (ISS)

SolACES is part of the ESA SOLAR ISS mission that started aboard the shuttle mission STS-122 on 7 February 2008. The instrument has recorded solar extreme ultraviolet (EUV) irradiance from 16 to 150 nm during the extended solar activity minimum and the beginning solar cycle 24 with rising solar activity and increasingly changing spectral composition. The SOLAR mission has been extended from a period of 18 months to >?8 years until the end of 2016. SolACES is operating three grazing incidence planar grating spectrometers and two three-current ionization chambers. The latter ones are considered as primary radiometric detector standards. Re-filling the ionization chambers with three different gases repeatedly and using overlapping band-pass filters, the absolute EUV fluxes are derived in these spectral intervals. This way the serious problem of continuing efficiency changes in space-borne instrumentation is overcome during the mission. Evaluating the three currents of the ionization chambers, the overlapping spectral ranges of the spectrometers and of the filters plus inter-comparing the results from the EUV photon absorption in the gases with different absorption cross sections, there are manifold instrumental possibilities to cross-check the results providing a high degree of reliability to the spectral irradiance derived. During the mission a very strong up-and-down variability of the spectrometric efficiency by orders of magnitude is observed. One of the effects involved is channeltron degradation. However, there are still open questions on other effects contributing to these changes. A survey of the measurements carried out and first results of the solar spectral irradiance (SSI) data are presented. Inter-comparison with EUV data from other space missions shows good agreement such that the international effort has started to elaborate a complete set of EUV-SSI data taking into account all data available from 2008 to 2013.     

Recognition of Space Weather Impact on the Isophot Detectors

The effects of changes in the space environment on the ISOPHOT photoconductivedetectors over the whole ISO mission were studied using the complete setof responsivity check measurements taken after the curing of the detectors.We found that the responsivity of the Ge-based, low bias voltage far-infrared detectors (P3, C100, and C200) is sensitive to the conditions of the Space Weather.We present evidence that an increased responsivity level (20% – 50%) after curing of the detectors is linked to the onset of geomagnetic storms. TheSi-based, high bias voltage detectors P1, P2 and PHT–SS show only small changesin their responsivity. An exception is the PHT–SL array which shows a similar,but less pronounced behaviour as the FIR detectors. While these relationshave been demonstrated by our study, a detailed physical understanding is still outstanding. The Space Weather dependent scatter of the responsivity,being the photometric scaling factor (conversion from measured photo currentto inband power on the detector), justifies the observing mode design to include frequent monitoring of its actual level.     

Analysis of the Space Debris Impacts Risk on the International Space Station

Öpik's analytical expressions relate in a simple way the semimajor axis, eccentricity and inclination of the projectile orbit to the magnitude and direction of the relative velocity vector at impact on a given target on circular orbit. These interesting quantities, along with the impact probability of any given projectile, can be all represented on a suitable projection giving a comprehensive picture of the impact risk on the selected target. By means of this theory a complete analysis of the impact risk on the International Space Station (ISS) is performed. It is found that the large majority of the debris population is on orbits such that a correlation exists between their impact velocity on the ISS and the angle between the velocity vector of the impactor and that of the ISS. The impactor population also is separated in terms of nature of the projectiles, with most of the low-medium velocity ones being particles related to solid rocket motor slag condensates. On the other hand, the highest velocity projectiles are composed mainly by fragments of past in-orbit explosions.The flux of projectiles on the ISS has been calculated for the planned operative lifetime of the Station, by assuming a realistic scenario of the future debris environment evolution and the actual planned altitude profile for the ISS mission. There is a factor 2-3 variation of the flux due to the changing ISS altitude. The most dangerous part of the mission appears to be the central one, when the ISS will orbit at about 450 km above the Earth.     

法国高层大气所空间综合孔径项目研究进展

概述了法国高层大气所空间综合孔径项目背景、科学目标以及有效载荷,介绍了该项目演示系统的基本工作原理,探讨了该演示系统的望远子系统、指向子系统、共相子系统和成像子系统,并分别给出了该演示系统在非共相控制和共相控制情况下对半导体激光器和白光点光源的成像结果,实验结果表明演示系统不同独立望远镜之间已经基本实现了共相成像。最后对该演示系统进行了总结,并指出该系统可以进一步优化之处。该演示系统对我国综合孔径成像实验研究具有一定的借鉴意义。     

Global Simulation of Magnetospheric Space Weather Effects of the Bastille Day Storm

We present results from a global simulation of the interaction of the solar wind with Earth's magnetosphere, ionosphere, and thermosphere for the Bastille Day geomagnetic storm and compare the results with data. We find that during this event the magnetosphere becomes extremely compressed and eroded, causing 3 geosynchronous GOES satellites to enter the magnetosheath for an extended time period. At its extreme, the magnetopause moves at local noon as close as 4.9 R _E to Earth which is interpreted as the consequence of the combined action of enhanced dynamic pressure and strong dayside reconnection due to the strong southward interplanetary magnetic field component B _z, which at one time reaches a value of −60 nT. The lobes bulge sunward and shield the dayside reconnection region, thereby limiting the reconnection rate and thus the cross polar cap potential. Modeled ground magnetic perturbations are compared with data from 37 sub-auroral, auroral, and polar cap magnetometer stations. While the model can not yet predict the perturbations and fluctuations at individual ground stations, its predictions of the fluctuation spectrum in the 0–3 mHz range for the sub-auroral and high-latitude regions are remarkably good. However, at auroral latitudes (63° to 70° magnetic latitude) the predicted fluctuations are slightly too high. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1014228230714     

Calculation for the Space Environment Background of HXMT

The Hard X-ray Modulation Telescope (HXMT) is a broadband X-ray (1250 keV) astronomical satellite. Its core payload, the High Energy X-ray Telescope (hereafter HE), is operated in the hard X-ray energy range (20250 keV) and dedicated to the hard X-ray high-sensitivity survey observation, hard X-ray sky mapping and high-sensitivity focused observations towards particular celestial bodies. In order to achieve a high sensitivity, it is important to reduce effectively the background that is caused by the interactions between the detector and space particles (γ-ray, protons, electrons, neutrons). Combining a series of references about the near-earth space background with the up-to-date observational data, this paper presents a set of self-consistent data and energy spectrum formulae of near-earth space particles for the convenience of applications. In addition, by the simulative calculations with the software Geant 4, the background of HXMT and its variations with the time and orbit are also given.     

The Sky Polarization Observatory (SPOrt): a project to measure the diffused sky polarization from the International Space Station Alpha (ISSA)

The Sky Polarization Observatory (SPOrt), a project to measure the diffused sky polarization in the frequency range of 22–90 GHz from the International Space Station, is described in its current configuration. Some preliminary considerations about the general topic of polarization in radiometric observations are made, in order to introduce the importance of polarimetric measurements in the more general context of Cosmic Microwave Background observations. The International Space Station is also introduced as a quite good opportunity to address such problematics.     

The development of the Space Environment Viability of Organics (SEVO) experiment aboard the Organism/Organic Exposure to Orbital Stresses (O/OREOS) satellite

The Space Environment Viability of Organics (SEVO) experiment is one of two scientific payloads aboard the triple-cube satellite Organism/ORganic Exposure to Orbital Stresses (O/OREOS). O/OREOS is the first technology demonstration mission of the NASA Astrobiology Small Payloads Program. The 1-kg, 1000-cm³ SEVO cube is investigating the chemical evolution of organic materials in interstellar space and planetary environments by exposing organic molecules under controlled conditions directly to the low-Earth orbit (LEO) particle and electromagnetic radiation environment. O/OREOS was launched on November 19, 2010 into a 650-km, 72°-inclination orbit and has a nominal operational lifetime of six months. Four classes of organic compounds, namely an amino acid, a quinone, a polycyclic aromatic hydrocarbon (PAH), and a metallo-porphyrin are being studied. Initial reaction conditions were established by hermetically sealing the thin-film organic samples in self-contained micro-environments. Chemical changes in the samples caused by direct exposure to LEO radiation and by interactions with the irradiated microenvironments are monitored in situ by ultraviolet/visible/near-infrared (UV/VIS/NIR) absorption spectroscopy using a novel compact fixed-grating CCD spectrometer with the Sun as its light source. The goals of the O/OREOS mission include: (1) demonstrating key small satellite technologies that can enable future low-cost astrobiology experiments, (2) deploying a miniature UV/VIS/NIR spectrometer suitable for in-situ astrobiology and other scientific investigations, (3) testing the capability to establish a variety of experimental reaction conditions to enable the study of astrobiological processes on small satellites, and (4) measuring the chemical evolution of organic molecules in LEO under conditions that can be extrapolated to interstellar and planetary environments. In this paper, the science and technology development of the SEVO instrument payload and its measurements are described.     

Calibrating Photometric Redshift Measurements with the Multi-channel Imager(MCI)of the China Space Station Telescope(CSST)

The China Space Station Telescope(CSST)photometric survey aims to perform a high spatial resolution(～0″.15)photometric imaging for the targets that cover a larg...     

Seyfert Galaxies: A Perspective with the Infrared Space Observatory (ISO)

We present data from the Infrared Space Observatory (ISO) of a complete set of Seyfert galaxies (Seyfert 1 and Seyfert 2) in a wavelength range seldom explored so far. These data allow a detailed study of the far IR Spectral Energy Distribution of these sources. A Bayesian inversion method has been used to invert the Spectral energy Distribution (SED) of these sources yielding two fundamental results, namely that the far IR SED of Seyfert Galaxies can be explained solely through thermal reradiation of high energy photons by dust. And, that this thermal emission is made up of two or three independent components. Comparisons between the parameters obtained from the analysis of the IR SEDs and the emission in other wavelengths ranges (radio and X-rays) show that the host galaxies are key elements in the understanding of the IR emission of Seyferts. Besides, the nuclear properties seem to be adequately explained with the Unified Models of AGN, that state that the differences seen between the broad (Seyfert 1) and narrow (Seyfert 2) line objects are due to geometrical orientation effects. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ensemble Numerical Simulations of Realistic SEP Events and the Inspiration for Space Weather Awareness

The solar energetic particle(SEP)event is a kind of hazardous space weather phenomena,so its quantitative forecast is of great importance from the aspect of spa...     

The 1859 Solar–Terrestrial Disturbance And the Current Limits of Extreme Space Weather Activity

It is generally appreciated that the September 1859 solar–terrestrial disturbance, the first recognized space weather event, was exceptionally large. How large and how exceptional? To answer these questions, we compiled rank order lists of the various measures of solar-induced disturbance for events from 1859 to the present. The parameters considered included: magnetic crochet amplitude, solar energetic proton fluence (McCracken et al., 2001a), Sun–Earth disturbance transit time, geomagnetic storm intensity, and low-latitude auroral extent. While the 1859 event has close rivals or superiors in each of the above categories of space weather activity, it is the only documented event of the last ～150 years that appears at or near the top of all of the lists. Taken together, the top-ranking events in each of the disturbance categories comprise a set of benchmarks for extreme space weather activity.     

Particle aggregation in microgravity: Informal experiments on the International Space Station

We conducted experiments in space to investigate the aggregation of millimeter‐ and submillimeter‐sized particles in microgravity, an important early step in planet formation. Particulate materials included salt (NaCl), sugar (sucrose), coffee, mica, ice, Bjurböle chondrules, ordinary and carbonaceous chondrite meteorite fragments, and acrylic and glass beads, all triply confined in clear plastic containers. Angular submillimeter particles rapidly and spontaneously formed clusters strong enough to survive turbulence in a protoplanetary nebula. Smaller particles generally aggregated more strongly and quickly than larger ones. We observed only a weak dependence of aggregation time on particle number density. We observed no strong dependence on composition. Round, smooth particles aggregated weakly or not at all. In a mixture of particle types, some phases aggregated more readily than others, creating selection effects that controlled the composition of the growing clumps. The physical process of aggregation appears to be electrostatic in nature.     

Conceptual Design of the Chinese-Russian On-Orbit-Assembling Space Telescope (OAST)

Solar System Research - Astronomical space telescopes with large apertures of various spectral ranges have become one of the main tools of exploring the Universe. Conventional technologies do not...     

Prospects for the Development of a Hydrometeorological Service Using the Multipurpose Arktika Space System

A possibility for using the promising multipurpose Arktika space system for the development and support of situational awareness of Arctic weather and ice conditions based on the network-centric principle is considered. This possibility became a reality when the analysis of synoptic conditions using remote sensing tools progressed from theoretical to practical use.     

Precision of the Chinese Space Station Telescope(CSST) stellar radial velocities

The Chinese Space Station Telescope(CSST) spectroscopic survey plans to deliver high-quality low-resolution(R 200) slitless spectra for hundreds of millions of targets down to a limiting magnitude of about 21 mag,covering a large survey area(17500 deg~2) and a wide wavelength range(255-1000 nm by three bands GU,GV,and GI).In this work,we use empirical spectra of the Next Generation Spectral Library to simulate the CSST stellar spectra at R=250,and investigate their capabilities in measuring radial velocities.We find that velocity uncertainties depend strongly on effective temperature,weakly on metallicity for only FGK stars,and hardly on surface gravity.It is possible to deliver stellar radial velocities to a precision of about 3 kms~(-1) for AFGKM stars,and about 10 km s~(-1) for OB stars,at signal-to-noise ratio(SNR) of 100.Velocity uncertainties using single GU/GV/GI band spectra are also explored.Given the same SNR,the GU band performs best,the GV band the second best,and then the GI band.The effects of spectral normalization and the imperfect template on velocity measurements are investigated and found to be very weak.The uncertainties caused by wavelength calibration are considered and found to be moderate.Given the possible precision of radial velocities,the CSST spectroscopic survey can enable interesting science such as searching for hyper-velocity stars.Limitations of our results are also discussed.     

Photometric mapping of Asteroid (4) Vesta’s southern hemisphere with Hubble Space Telescope

We present the surface mapping of the southern hemisphere of Asteroid (4) Vesta obtained from Hubble Space Telescope (HST). From 105 images of Vesta through four filters in the wavelengths best to characterize the 1-μm pyroxene band, we constructed albedo and color-ratio maps of Vesta. These new maps cover latitudes −50° to +20°. The southern hemisphere of Vesta displays more diverse albedo and color features than the northern hemisphere, with about 15 new albedo and color features identified. The overall longitudinal albedo and color variations in the southern hemisphere are comparable with that of the northern hemisphere, with a range of about ±20% and ±10%, respectively. The eastern hemisphere is brighter and displays more diogenitic minerals than the western hemisphere. Correlations between 1-μm band depth and band width, as well as between 1-μm band depth and albedo, are present on a global scale, attributed to pyroxene composition variations. The lack of correlations between albedo and the spectral slope indicates the absence of globalized space weathering. The lack of a global correlation between 1-μm band depth and topography suggests that the surface composition of Vesta is not completely controlled by a single impact. The distribution of compositional variation on Vesta suggests a possible large impact basin. Evidence of space weathering is found in regions, including the bright rim of the south-pole crater where the steepest gravitational slope on Vesta is, and a dark area near a gravitationally flat area. We propose to divide the surface of Vesta into six geological units different from the background according to their 1-μm absorption features and spectral slopes, including two eucrite-rich units, a low-Ca eucrite unit, a diogenite-rich unit, a space weathered unit, and a freshly exposed unit. No evidence of olivine-rich area is present in these data.     

Bidirectional reflectance distribution function measurements of the Winchcombe meteorite using the Visible Oxford Space Environment Goniometer

A laboratory study was performed using the Visible Oxford Space Environment Goniometer in which the broadband (350–1250 nm) bidirectional reflectance distribution function (BRDF) of the Winchcombe meteorite was measured, across a range of viewing angles—reflectance: 0°–70°, in steps of 5°; incidence: 15°, 30°, 45°, and 60°; and azimuthal: 0°, 90°, and 180°. The BRDF dataset was fitted using the Hapke BRDF model to (1) provide a method of comparison to other meteorites and asteroids, and (2) to produce Hapke parameter values that can be used to extrapolate the BRDF to all angles. The study deduced the following Hapke parameters for Winchcombe: w = 0.152 ± 0.030, b = 0.633 ± 0.064, and h_S = 0.016 ± 0.008, demonstrating that it has a similar w value to Tagish Lake (0.157 ± 0.020) and a similar b value to Orgueil (0.671 ± 0.090). Importantly, the surface profile of the sample was characterized using an Alicona 3D® instrument, allowing two of the free parameters within the Hapke model φ and $\overline{\theta }$, which represent porosity and surface roughness, respectively, to be constrained as φ = 0.649 ± 0.023 and $\overline{\theta }$ = 16.113° (at 500 μm size scale). This work serves as part of the characterization process for Winchcombe and provides a reference photometry dataset for current and future asteroid missions.     

GEO空间碎片光度测量标定方法的研究

基于GEO卫星、太阳和观测站的空间几何关系,建立了消除太阳赤纬角对地球同步轨道( Geostationary Orbit,GEO)卫星光学特性的影响的方法.以三轴稳定GEO盒状卫星缩比模型为研究样本,在不同太阳赤纬角下进行仿真实验光度测量,研究太阳赤纬角和相位角的空间几何关系,得出消除太阳赤纬角对其辐亮度值以及以相位角...