Space Weather Outreach: An informal education perspective

Informal science education institutions, such as science centers, play an important role in science education. They serve millions of people, including students and teachers. Within the last decade, many have tried to improve the public’s understanding of science and scientific research through informal education projects. The recent success of several space weather-related missions and research programs and the launch of the International Heliophysical Year (IHY) research and education programs make this an ideal time to inform the public about the importance and relevance of space weather to our understanding of heliophysical science. Communication efforts associated with space weather both benefit and are compromised by analogies to terrestrial weather. This paper summarizes the benefits and challenges of the terrestrial weather analogy using two exhibit evaluation studies. The paper also describes three components of the Space Science Institute’s Space Weather Outreach Program – Space Weather Center Website, Educator Workshops, and Small Exhibits – and how they can help to achieve the education goals of IHY.     

Predictive Space Weather: An information theory approach

It is rather well recognized that the global dynamics of the Sun–Earth relationship involves complex nonlinear phenomena. Here we present a preliminary attempt to characterize the influence and the timing of the solar magnetic activity on the near-Earth environment, based on quite novel tools based on concepts from information theory.     

Space Solar Physics in 2012-2014

The main activities of Chinese space solar physics in 2012–2014 include: to continue studying the mid and long-term(2016–2030) plan of Chinese space solar physics; to arrange a group of pre-study projects of space solar physics; to initiate and continue a few solar mission-level projects.This paper summarizes all these activities briefly.     

First results of operational ionospheric dynamics prediction for the Brazilian Space Weather program

It is shown the development and preliminary results of operational ionosphere dynamics prediction system for the Brazilian Space Weather program. The system is based on the Sheffield University Plasmasphere–Ionosphere Model (SUPIM), a physics-based model computer code describing the distribution of ionization within the Earth mid to equatorial latitude ionosphere and plasmasphere, during geomagnetically quiet periods. The model outputs are given in a 2-dimensional plane aligned with Earth magnetic field lines, with fixed magnetic longitude coordinate. The code was adapted to provide the output in geographical coordinates. It was made referring to the Earth’s magnetic field as an eccentric dipole, using the approximation based on International Geomagnetic Reference Field (IGRF-11). During the system operation, several simulation runs are performed at different longitudes. The original code would not be able to run all simulations serially in reasonable time. So, a parallel version for the code was developed for enhancing the performance. After preliminary tests, it was frequently observed code instability, when negative ion temperatures or concentrations prevented the code from continuing its processing. After a detailed analysis, it was verified that most of these problems occurred due to concentration estimation of simulation points located at high altitudes, typically over 4000 km of altitude. In order to force convergence, an artificial exponential decay for ion–neutral collisional frequency was used above mentioned altitudes. This approach shown no significant difference from original code output, but improved substantially the code stability. In order to make operational system even more stable, the initial altitude and initial ion concentration values used on exponential decay equation are changed when convergence is not achieved, within pre-defined values. When all code runs end, the longitude of every point is then compared with its original reference station longitude, and differences are compensated by changing the simulation point time slot, in a temporal adjustment optimization. Then, an approximate neighbor searching technique was developed to obtain the ion concentration values in a regularly spaced grid, using inverse distance weighting (IDW) interpolation. A 3D grid containing ion and electron concentrations is generated for every hour of simulated day. Its spatial resolution is 1° of latitude per 1° of longitude per 10 km of altitude. The vertical total electron content (VTEC) is calculated from the grid, and plotted in a geographic map. An important feature that was implemented in the system is the capacity of combining observational data and simulation outputs to obtain more appropriate initial conditions to the ionosphere prediction. Newtonian relaxation method was used for this data assimilation process, where ionosonde data from four different locations in South America was used to improve the system accuracy. The whole process runs every day and predicts the VTEC values for South America region with almost 24 h ahead.     

Influence of Fast Global Variations of Solar Magnetic Fields on Space Weather in Cycle 23

It is established that the large-scale and global magnetic fields in the Sun's atmosphere do not change smoothly, and long-lasting periods of gradual variations are superseded by fast structural changes of the global magnetic field. Periods of fast global changes on the Sun are accompanied by anomalous manifestations in the interplanetary space and in the geomagnetic field. There is a regular recurrence of these periods in each cycle of solar activity, and the periods are characterized by enhanced flaring activity that reflects fast changes in magnetic structures. Is demonstrated, that the fast changes have essential influencing on a condition of space weather, as most strong geophysical disturbances are connected to sporadic phenomena on the Sun. An explanation has been offered for the origin of anomalous geomagnetic disturbances that are unidentifiable in traditionally used solar activity indices. Is shown, main physical mechanism that leads to fast variations of the magnetic fields in the Sun's atmosphere is the reconnection process.     

空间探测磁强计安装部件的力学特性分析

对某深空探测器中的有效载荷-高精度磁强计的安装部件进行了有限元分析,分别获取了磁强计安装部件在升空过程中承受40g加速度冲击载荷以及-180～75℃的极限温度情况下,在x,y,z方向上的最大应力和最大位移,给出了由于磁强计安装部件的变形而导致的三个探头在x,y,z方向上的偏转角度,采用扫频实验法分析了磁强计安装部件的频谱特性,为空间探测磁强计的设计提供了依据.     

轻型空间相机主承力基板结构拓扑优化计

针对目前轻型空间相机主承力基板在结构设计过程中难于同时保证重量轻且刚度高的问题,提出了采用拓扑优化设计思想进行设计的方案.通过建立基于变密度方法的拓扑优化设计数学模型,运用Nastran软件对相机主承力基板进行拓扑优化设计,给出了主承力基板的最优设计方案.经过拓扑优化后相机主承力基板质量从初始的36.8 kg降低到15.4 kg,轻量化程度达58.2%.采用有限元分析方法对拓扑优化的结果进行了模态分析,以验证主承力基板刚度分布是否合理.通过0.5 g扫频振动试验对有限元分析结果进行验证,振动试验结果表明,主承力基板结构一阶自然频率理论分析与试验结果偏差1.86%,充分证明理论分析结果的正确性和准确性.整个优化设计过程证明,采用拓扑优化设计方法大大提高了研制效率,增强了空间相机主承力基板结构的性能,有效降低了基板的重量,满足系统设计要求.     

Specification of the Earth’s plasmasphere with data assimilation

In this paper we report on initial work toward data assimilative modeling of the Earth’s plasmasphere. As the medium of propagation for waves which are responsible for acceleration and decay of the radiation belts, an accurate assimilative model of the plasmasphere is crucial for optimizing the accurate prediction of the radiation environments encountered by satellites. On longer time-scales the plasmasphere exhibits significant dynamics. Although these dynamics are modeled well by existing models, they require detailed global knowledge of magnetospheric configuration which is not always readily available. For that reason data assimilation can be expected to be an effective tool in improving the modeling accuracy of the plasmasphere. In this paper we demonstrate that a relatively modest number of measurements, combined with a simple data assimilation scheme, inspired by the ensemble Kalman filtering data assimilation technique does a good job of reproducing the overall structure of the plasmasphere including plume development. This raises hopes that data assimilation will be an effective method for accurately representing the configuration of the plasmasphere for space weather applications.     

Depth dose measurements with the Liulin-5 experiment inside the spherical phantom of the MATROSHKA-R project onboard the International Space Station

The Liulin-5 experiment is a part of the international project MATROSHKA-R on the Russian segment of the ISS, which uses a tissue-equivalent spherical phantom equipped with a set of radiation detectors. The objective of the MATROSHKA-R project is to provide depth dose distribution of the radiation field inside the sphere in order to get more information on the distribution of dose in a human body. Liulin-5 is a charged particle telescope using three silicon detectors. It measures time resolved energy deposition spectra, linear energy transfer (LET) spectra, particle flux, and absorbed doses of electrons, protons and heavy ions, simultaneously at three depths along the radius of the phantom. Measurements during the minimum of the solar activity in cycle 23 show that the average absorbed daily doses at 40 mm depth in the phantom are between 180 μGy/day and 220 μGy/day. The absorbed doses at 165 mm depth in the phantom decrease by a factor of 1.6–1.8 compared to the doses at 40 mm depth due to the self-shielding of the phantom from trapped protons. The average dose equivalent at 40 mm depth is 590 ± 32 μSV/day and the galactic cosmic rays (GCR) contribute at least 70% of the total dose equivalent at that depth. Shown is that due to the South Atlantic Anomaly (SAA) trapped protons asymmetry and the direction of Liulin-5 lowest shielding zone the dose rates on ascending and descending nodes in SAA are different. The data obtained are compared to data from other radiation detectors on ISS.     

串联型MPPT空间电源系统稳定性技术

串联型最大功率点跟踪(MPPT)空间电源系统存在母线电压振荡或跌落等不稳定现象,文章以MPPT不调节母线电源拓扑为研究对象,建立了系统等效电路模型,通过小信号等效分析、状态空间方程特征根求解等手段,分别对MPPT控制域及电压控制域下电源系统的稳定性进行了分析.结果表明,在太阳电池阵及阵列功率调节器特性曲线一定的条件下,通过对二者间电感、电容参数合理配置,可以保证系统稳定.在MATLAB/SIMULINK中搭建了串联型MPPT不调节母线电源系统仿真模型并进行实例仿真,仿真结果验证了理论分析的正确性.     

Study of the radiation fields in LEO with the Space Application of Timepix Radiation Monitor (SATRAM)

We present the analysis of data taken by the Space Application of Timepix Radiation Monitor (SATRAM). It is centred on a Timepix detector (300?$\mathrm{\mu }$m thick silicon sensor, pixel pitch 55?$\mathrm{\mu }$m, 256?×?256 pixels). It was flown on Proba-V, an Earth observing satellite of the European Space Agency (ESA) from an altitude of 820?km on a sun-synchronous orbit, launched on May 7, 2013. A Monte Carlo simulation was conducted to determine the detector response to electrons (0.5–7?MeV) and protons (10–400?MeV) in an omnidirectional field taking into account the shielding of the detector housing and the satellite. With the help of the simulation, a strategy was developed to separate electrons, protons and ions in the data. The measured dose rate and stopping power distribution are presented as well as SATRAM’s capability to measure some of the stronger events in Earth’s magnetosphere. The stopping power, the cluster height and the shape of the particle tracks in the sensor were used to separate electrons, protons and ions. The results are presented as well. Finally, the pitch angles for a short period of time were extracted from the data and corrected with the angular response determined by the simulation.     

Stability analysis of explicit guidance laws for space launch vehicles with varying thrust integrals

In this study, a stability analysis of the explicit guidance laws for space launch vehicles is performed with consideration of varying thrust integrals. Among various forms of explicit guidance, linear tangent guidance in its general form is selected and six different acceleration profiles are considered for this numerical experiment. A linear system modeling which includes all of the significant dynamic elements of a space launcher is performed to analyze the effect of the characteristics of thrust integrals on stability margins. Numerical results show that in an aspect of guidance stability, it is advantageous to have thrust integrals derived from increasing acceleration profiles, such as constant thrust case, which may be considered in the development of propulsion systems. Finally, time-domain simulation with the original nonlinear models is performed to verify the approach and the result shows that the nonlinear dynamics of the system is conserved well in the linear model.     

Korean space food development: Ready-to-eat Kimchi, a traditional Korean fermented vegetable,sterilized with high-dose gamma irradiation

Addition of calcium lactate and vitamin C, a mild heating, deep-freezing, and gamma irradiation at 25 kGy were conducted to prepare Kimchi as a ready-to-eat space food. It was confirmed that the space food was sterilized by an irradiation at 25 kGy through incubation at 37 °C for 30 days. The hardness of the Space Kimchi (SK) was lower than the untreated Kimchi (CON), but higher than the irradiated Kimchi (IR). Also, this result was supported by the scanning electron microscopic observation. Sensory attributes of the SK were similar to CON, and maintained during preservation at 35 °C for 30 days. According to the Ames test, Kimchi sterilized with a high-dose irradiation exerted no mutagenic activity in the bacterial strains of Salmonella typhimurium. And, the SK was certificated for use in space flight conditions during 30 days by the Russian Institute of Biomedical Problems.