System Worth, System Effectiveness, Integrated Logistics Support, and Maintainability

The system worth or cost effectiveness concept covers the measure of a system in terms of total dollar value. System worth encompasses the elements of system effectiveness (a quantitative measure of a system's technical ability) as well as cost. One of the elements of system effectiveness is maintainability. Maintainability is an effective mechanism for the accomplishment of planned maintenance during the early design and development phases of a system. Planned maintenance is an element of integrated logistics support. The intent of this paper is to outline the basic elements associated with system worth, system effectiveness, and integrated logistics support, to outline the interrelation-ships of these concepts, and to cover the discipline of maintainability as an element of each concept.     

空空导弹SINS飞行中对准技术

针对空空导弹捷联惯导系统传递对准的精度和快速性之间的矛盾,设计一种利用弹载北斗卫星导航信息的捷联惯导系统飞行中对准算法,详细推导了惯性系下基于北斗卫星伪距/伪距率的飞行中对准模型,优化了飞行中对准的量测方程,对北斗卫星接收机的钟差和钟漂进行了降维处理.相应的数学仿真试验结果表明,所提算法能够在飞行过程中实现捷联惯导系统的初始对准,在10s内对准精度优于6',同时该算法通过在线标定惯性传感器随机启动误差,能够提高捷联惯导系统导航精度和导弹系统抗干扰能力.     

A call for proactive xenoarchaeological guidelines – Scientific, policy and socio-political considerations

As planetary exploration advances, the likelihood of encountering suspected artifacts of astrobiological activity increases, which, it is argued, should be investigated under the auspices of proto-scientific xenoarchaeology. Considering both the unfavorable conditions under which such an investigation may be undertaken (e.g., while observing international planetary protection protocols, utilizing remote sensing techniques in exotic pressure, temperature, chemical, and gravity environments, or adhering to stringent terrestrial biological quarantine and security measures) as well as the demonstrated propensity of the social mind to romanticize or mythologize even the most benign planetary landforms, it is clear that a reactive and poorly preconceived xenoarchaeological methodology will be plagued by inaccuracies, rushed judgments, unrealized bias, misinformation, and erroneous conclusions, along with the negative socio-political impacts that accompany them. Central principles for establishing a rigorous xenoarchaeological methodology are proposed, scientific and technical difficulties are discussed, pertinent international protocols and agreements are reviewed, and sociological and historical considerations are explored.     

Science and technology for national development: The case of Israel's space program

In the last 25 years Israel developed highly advanced space industry and capable indigenous infrastructure of space technology. The special interconnections between the academia, the industry and different government agencies had a valuable influence on this successful process. This paper identifies and analyzes the characteristics of this partnership. It addresses the issue of sustaining this partnership and maintain it as a major driving force of the Israeli space program in order to provide some conclusions for similar actors, seeking to enhance their space activities and capabilities.     

InSight Mars Lander Robotics Instrument Deployment System

The InSight Mars Lander is equipped with an Instrument Deployment System (IDS) and science payload with accompanying auxiliary peripherals mounted on the Lander. The InSight science payload includes a seismometer (SEIS) and Wind and Thermal Shield (WTS), heat flow probe (Heat Flow and Physical Properties Package, HP³) and a precision tracking system (RISE) to measure the size and state of the core, mantle and crust of Mars. The InSight flight system is a close copy of the Mars Phoenix Lander and comprises a Lander, cruise stage, heatshield and backshell. The IDS comprises an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, motor controller, arm-mounted Instrument Deployment Camera (IDC), lander-mounted Instrument Context Camera (ICC), and control software. IDS is responsible for the first precision robotic instrument placement and release of SEIS and HP³ on a planetary surface that will enable scientists to perform the first comprehensive surface-based geophysical investigation of Mars’ interior structure. This paper describes the design and operations of the Instrument Deployment Systems (IDS), a critical subsystem of the InSight Mars Lander necessary to achieve the primary scientific goals of the mission including robotic arm geology and physical properties (soil mechanics) investigations at the Landing site. In addition, we present test results of flight IDS Verification and Validation activities including thermal characterization and InSight 2017 Assembly, Test, and Launch Operations (ATLO), Deployment Scenario Test at Lockheed Martin, Denver, where all the flight payloads were successfully deployed with a balloon gravity offload fixture to compensate for Mars to Earth gravity.     

一类冗余星载惯性姿态参考系统的可靠性分析

随着航天事业的发展 ,对航天器的长寿命提出越来越高的要求 ,需要简便可行的冗余方案以备工程所需。文中提出一种对于混合冗余系统的可靠性研究的计算方法。并将这种方法应用到星载惯性姿态参考基准上 ,提出了一种有别于常规冗余方案 (工作冗余加N中取K系统和N中取K加冷储备系统 )的新方案 ,为工程实现作了理论上准备     

Modelling the effects of microgravity on the permeability of air interface respiratory epithelial cell layers

Although it has been suggested that microgravity might affect drug absorption in vivo, drug permeability across epithelial barriers has not yet been investigated in vitro during modelled microgravity. Therefore, a cell culture/diffusion chamber was designed specifically to accommodate epithelial cell layers in a 3D-clinostat and allow epithelial permeability to be measured under microgravity conditions in vitro with minimum alteration to established cell culture techniques. Human respiratory epithelial Calu-3 cell layers were used to model the airway epithelium. Cells grown at an air interface in the diffusion chamber from day 1 or day 5 after seeding on 24-well polyester Transwell cell culture inserts developed a similar transepithelial electrical resistance (TER) to cells cultured in conventional cell culture plates. Confluent Calu-3 layers exposed to modelled microgravity in the 3D-clinostat for up to 48 h maintained their high TER. The permeability of the paracellular marker ¹⁴C-mannitol was unaffected after a 24 h rotation of the cell layers in the 3D-clinostat, but was increased 2-fold after 48 h of modelled microgravity. It was demonstrated that the culture/diffusion chamber developed is suitable for culturing epithelial cell layers and, when subjected to rotation in the 3D-clinostat, will be a valuable in vitro system in which to study the influence of microgravity on epithelial permeability and drug transport.     

Inferring Nighttime Ionospheric Parameters with the Far Ultraviolet Imager Onboard the Ionospheric Connection Explorer

The Ionospheric Connection Explorer (ICON) Far Ultraviolet (FUV) imager, ICON FUV, will measure altitude profiles of OI 135.6 nm emissions to infer nighttime ionospheric parameters. Accurate estimation of the ionospheric state requires the development of a comprehensive radiative transfer model from first principles to quantify the effects of physical processes on the production and transport of the 135.6 nm photons in the ionosphere including the mutual neutralization contribution as well as the effect of resonant scattering by atomic oxygen and pure absorption by oxygen molecules. This forward model is then used in conjunction with a constrained optimization algorithm to invert the anticipated ICON FUV line-of-sight integrated measurements. In this paper, we describe the connection between ICON FUV measurements and the nighttime ionosphere, along with the approach to inverting the measured emission profiles to derive the associated O⁺ profiles from 150–450 km in the nighttime ionosphere that directly reflect the electron density in the F-region of the ionosphere.     

Application of neural networks to South African GPS TEC modelling

The propagation of radio signals in the Earth’s atmosphere is dominantly affected by the ionosphere due to its dispersive nature. Global Positioning System (GPS) data provides relevant information that leads to the derivation of total electron content (TEC) which can be considered as the ionosphere’s measure of ionisation. This paper presents part of a feasibility study for the development of a Neural Network (NN) based model for the prediction of South African GPS derived TEC. The South African GPS receiver network is operated and maintained by the Chief Directorate Surveys and Mapping (CDSM) in Cape Town, South Africa. Vertical total electron content (VTEC) was calculated for four GPS receiver stations using the Adjusted Spherical Harmonic (ASHA) model. Factors that influence TEC were then identified and used to derive input parameters for the NN. The well established factors used are seasonal variation, diurnal variation, solar activity and magnetic activity. Comparison of diurnal predicted TEC values from both the NN model and the International Reference Ionosphere (IRI-2001) with GPS TEC revealed that the IRI provides more accurate predictions than the NN model during the spring equinoxes. However, on average the NN model predicts GPS TEC more accurately than the IRI model over the GPS locations considered within South Africa.