CALET Observations during the First 5 Years on the ISS

Physics of Atomic Nuclei - The CALorimetric Electron Telescope CALET is collecting science data on the International Space Station since October 2015 with excellent and continuous performance....     

Radiation measurement on the International Space Station

The results of an investigation of radiation environment on board the ISS with apogee/perigee of 420/380 km and inclination 51.6 degrees are presented. For measurement of important characteristics of cosmic rays (particles fluxes, LET spectrum, equivalent doses and heavy ions with Z > or = 2) a nuclear photographic emulsion as a controllable threshold detector was used. The use of this detector permits a registration of the LET spectrum of charged particles within wide range of dE/dx and during the last years it has already been successfully used on board the MIR station, Space Shuttles and "Kosmos" spacecrafts. An integral LET spectrum was measured in the range 0.5-2.2 x 10(3) keV/micrometers and the value of equivalent dose 360 microSv/day was estimated. The flux of biologically dangerous heavy particles with Z > or = 2 was measured (3.85 x 10(3) particles/cm2).     

Energy spectra of HZE-particles inside the International Space Station

To measure the energy spectra of low energy ions inside the International Space Station (ISS) we will expose three stacks of CR-39 plastic nuclear track detectors aligned to the three coordinate axes of the space station. The energies of cosmic ray nuclei at the stack surfaces can be determined by reconstructing the trajectories of ions stopping inside the detector material and by measuring their ranges. To measure only HZE (high charge Z and energy E) ions with charges of Z6 stopping in our experiment a special batch of CR-39 detectors with low sensitivity will be used. This detector material has been already tested by an exposure to carbon ions at the GSI accelerator in Darmstadt, Germany.     

Electrodynamic Dust Shields on the International Space Station: Exposure to the space environment

Electrodynamic Dust Shields (EDS) have been in development at NASA as a dust mitigation method for lunar and Martian missions. An active dust mitigation strategy, such as that provided by the EDS, that can remove dust from surfaces, is of crucial importance to the planetary exploration program. We report on the development of a flight experiment to fully expose four EDS panels to the space environment. This flight experiment is part of the Materials International Space Station experiment X (MISSE-X), an external platform on the International Space Station that will expose materials to the space environment.     

Stratification of the Generalized Gauge Orbit Space

Different versions for defining Ashtekar's generalized connections are investigated depending on the chosen smoothness category for the paths and graphs – the label set for the projective limit. Our definition covers the analytic case as well as the case of webs. Then the action of Ashtekar's generalized gauge group on the space of generalized connections is investigated for compact structure groups G. Here, first, the orbit types of the generalized connections are determined. The stabilizer of a connection is homeomorphic to the holonomy centralizer, i.e. the centralizer of its holonomy group. It is proven that the gauge orbit type of a connection can be defined by the G-conjugacy class of its holonomy centralizer equivalently to the standard definition via -stabilizers. The connections of one and the same gauge orbit type form a so-called stratum. As the main result of this article a slice theorem is proven on . This yields the openness of the strata. Afterwards, a denseness theorem is proven for the strata. Hence, is topologically regularly stratified by . These results coincide with those of Kondracki and Rogulski for Sobolev connections. Furthermore, the set of all gauge orbit types equals the set of all (conjugacy classes of) Howe subgroups of G. Finally, it is shown that the set of all gauge orbits with maximal type has the full induced Haar measure 1. Received: 12 January 2000 / Accepted: 8 May 2000     

Iron flux inside the International Space Station is measured to be lower than predicted

Iron abundance in cosmic rays impinging on astronauts in space habitats is of paramount importance when calculating the radiation risk for human space exploration. The concurrent high relative abundance of iron in Galactic Cosmic Rays (GCR) and iron ability to produce damages at cellular and molecular levels, together with recent radiobiology results suggests iron as a major candidate to be studied in order to produce accurate radiation hazard assessments. Iron may be in fact responsible for a large percentage of cancer risk during a long interplanetary voyage, and therefore deserves a specific attention. We built a simple model based on CREME96 for the radiation in the International Space Station (ISS) and tested it against recently performed measurements with the ALTEA and Alteino particle detectors. While we can report a good agreement between 50m and 250 keV/μm (very good for several peaks such as Si, Mg, S) we show an overestimation by this model of iron abundances of about 25–80% when compared to the measurements. New analysis on previously published work, supporting this result, are also reported.Reasons for this overestimation are discussed, they are likely to be related to the not detailed enough transport through the multiplicity of the ISS shielding and to the often used simplification of “aluminum equivalent shielding”. The iron sources in LEO, possibly not yet accurate enough when transported in Low Earth Orbit, can also play a role. New concurrent measurements (inside–outside the ISS) are suggested to help resolving this issue.     

Predictions of secondary neutrons and their importance to radiation effects inside the International Space Station

As part of a study funded by NASA MSFC to assess thecontribution of secondary particles in producing radiation damage to optoelectronics devices located on the International Space Station (IS), Monte Carlo calculations have been made to predict secondary spectra vs. shielding inside ISS modules and in electronics boxes attached on the truss (Armstrong and Colborn, 1998). The calculations take into account secondary neutron, proton, and charged pion production from the ambient galactic cosmic-ray (GCR) proton, trapped proton, and neutron albedo environments. Comparisons of the predicted neutron spectra with measurments made on the Mir space station and other spacecraft have also been made (Armstrong and Colborn, 1998). In this paper, some initial results from folding the predicted neutron spectrum inside ISS modules from Armstrong and Colborn (1998) with several types of radiation effects response functions related to electronics damage and astronaut-dose are given. These results provide an estimate of the practical importance of neutrons compared to protons in assessing radiation effects for the ISS. Also, the important neutron energy ranges for producing these effects have been estimated, which provides guidance for onboard neutron measurement requirements.     

Optical Characteristics of the Retroreflector in Space on the ADEOS Satellite in Orbit

Optical characteristics of the retroreflector in space (RIS) on the Advanced Earth Observing Satellite (ADEOS) in orbit were tested using a second harmonics Nd:YAG laser. The intensity of reflection from the RIS was analyzed with an intensified charge coupled device camera by comparing the image with those of stars. It was confirmed that the RIS in orbit is working properly as a retroreflector.     

Orbit design for the Laser Interferometer Space Antenna (LISA)

Based on large quantities of co-orbital phenomena in the motion of natural bodies and spacecraft, a model of the co-orbital restricted three-body problem is put forward. The fundamental results for the planar co-orbital circular restricted three-body problem are given, which include the selection of variables and equations of motion, a set of approximation formulas, and an approximate semi-analytical solution. They are applied to the motion of the barycenter of the planned gravitational observatory LISA con...     

基于天基光学测角的高轨空间目标轨道确定

受到距离和观测条件等因素的影响,地基设施对高轨空间目标的观测能力有限,但天基观测设施可以有效突破地基设施的观测局限,从而提高对高轨空间目标的观测效率和精度.基于此,结合当前天基测量技术的现状,研究基于天基光学测角的高轨空间目标轨道确定方法,包括初始轨道确定方法和轨道改进方法.针对观测量类型对轨道确定结果的影响,推导直接利用天基观测角度的轨道改进方法,以及基于天基观测方向矢量的轨道改进方法.利用仿真数据和实测数据对两种改进方法进行比较.研究结果表明,基于天基观测方向矢量解算得到的高轨目标轨道精度相对较高,可为我国空间态势感知体系的建设提供有益借鉴.     

Development of the fiber neutron monitor for the energy range 15-100 MeV on the International Space Station (ISS)

In order to investigate the space environment, a new neutron monitor has been prepared. The sensor consists of scintillation fibers (FIB) and will be on board the exposed facility of the Japanese Experimental module (Kibo) of the International Space Station (ISS). The sensor is one of the instruments which measures the particle and plasma environment around the ISS. The sensor will be used by the cosmonauts who work on the ISS, to help them avoid a strong particle radiation which may arrive soon. We believe that such an alert is necessary for the cosmonauts to prevent unnecessary radiation from the sun. Furthermore, the sensor will be very useful in understanding the particle acceleration mechanism at the solar surface. The design of the Engineering Model (EM) was finished and its properties were investigated. This report discusses these results.     

Selected Results from the DAMPE Space Mission

Physics of Atomic Nuclei - The DArk Matter Particle Explorer (DAMPE) is a space-based particle detector launched in a sun-synchronous orbit on December 17, 2015 from the Jiuquan Satellite Launch...     

Analysis of radiation dose variations measured by passive dosimeters onboard the International Space Station during the solar quiet period (2007–2008)

The average absorbed dose and dose equivalent rates from space radiation were observed using passive dosimeters with same material and configuration at the same location onboard the International Space Station (ISS) over four different occasions (I–IV) between 2007 and 2008. The passive dosimeters consisted of a combination of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs). Total average absorbed dose rate increased by 68 ± 9% over two years. The observed increase was due to the incremental increase in the altitude of the ISS over the course of the experiment and the corresponding increase in trapped proton flux encountered during passage of the ISS through the SAA (South Atlantic Anomaly), which was confirmed with the results monitored by DB-8 active dosimeter on the ISS. The PNTD data showed that the average absorbed dose and dose equivalent rates from particles of LET_∞H₂O ≥ 100 keV/μm were 28 ± 2% and 51 ± 3% of ≥10 keV/μm during Periods I–III, while the dose contributions of particles ≥100 keV/μm during Period IV were 36 ± 5% and 59 ± 10%, respectively. The integral dose equivalent distribution during Period IV shows significant enhancement from particles ≥100 keV/μm. These facts suggest that a significant fraction of the high LET component is due to short-range recoil nuclei produced in target fragmentation reactions between primary protons and the nuclei of the passive dosimeters and surrounding materials.     

Momentum filtering scheme of cooling atomic clouds for the Chinese Space Station

To obtain cold atom samples with temperatures lower than 100 pK in the cold atom physics rack experiment of the Chinese Space Station, we propose to use the momentum filtering method for deep cooling of atoms. This paper introduces the experimental results of the momentum filtering method verified by our ground testing system. In the experiment, we designed a specific experimental sequence of standing-wave light pulses to control the temperature, atomic number,and size of the atomic cloud. The r...     

双星运行轨道的研究

文章首先把双星运动看做二体问题,研究以一个星体为参照系,另一个星体的轨迹为圆锥曲线,以系统的质心为参照系,每一个星体的轨迹也是圆锥曲线,然后提出了行星与恒星之间也是双星现象,地球与月球之间也是双星现象,解释了困扰物理学与天文学多年的行星运行轨道的共面性、公转的同向性难题,指出了研究行星运行轨道时惯性质量应当用折合质量计算。