A method for calculating the resistance of spacecraft design elements under the action of space debris particles

In this paper, the problems of the application and development of models of space debris when designing means of the anti-meteorite spacecraft protection are considered. The developed method enables us to calculate the resistance of design elements based on the conjugation of a modified spatial model of the distribution of space-debris particles and ballistic limit dependences for a calculated element.     

The Education and Public Outreach Program for NASA��s Dawn Mission

The Dawn mission??s Education and Public Outreach (E/PO) program takes advantage of the length of the mission, an effort to maintain level funding, and the exceptional support of the science and engineering teams to create formal and informal educational materials that bring STEM content and modes of thinking to students of all ages. With materials that are based on researched pedagogical principles and aligned with science education standards, Dawn weaves together many aspects of the mission to engage students, teachers, and the general public. E/PO tells the story of the discovery of the asteroid belt, uncovers principles of physics behind the ion propulsion that powers the spacecraft, and explains what we can learn from the instrumentation and how the mission??s results will expand our understanding of the origins of the solar system. In this way, we not only educate and inform, we build anticipation and expectation in the general public for the spacecraft??s arrival at Vesta in 2011 and three years later at Ceres. This chapter discusses the organization, strategies, formative assessment and dissemination of these materials and activities, and includes a section on lessons learned.     

Medical survey of European astronauts during Mir missions

This paper reviews the medical operations performed on six European astronauts during seven space missions on board the space station Mir. These missions took place between November 1988 and August 1999, and their duration ranged from 14 days to 189 days. Steps of pre-flight medical selection and flight certification are presented. Countermeasures program used during the flight, as well as rehabilitation program following short and long-duration missions are described. Also reviewed are medical problems encountered during the flight, post-flight physiological changes such as orthostatic intolerance, exercise capacity, blood composition, muscle atrophy, bone density, and radiation exposure.     

A mission template for exploration and damage mitigation of potential hazard of Near Earth Asteroids

The Apophis Exploratory and Mitigation Platform (AEMP) concept was developed as a prototype mission to explore and potentially deflect the Near Earth Asteroid (NEA) 99942 Apophis. Deflection of the asteroid from the potential 2036 impact will be achieved using a gravity tractor technique, while a permanent deflection, eliminating future threats, will be imparted using a novel albedo manipulation technique. This mission will serve as an archetypal template for future missions to small NEAs and could be adapted to mitigate the threat of collision with other potential Earth-crossing objects.     

The conundrum of software estimation models

There are many sophisticated models and methods for estimating the size, cost, and schedule of software projects. However, the ability to accurately estimate software cost, size, or schedule is still dubious. In general, the predictive accuracy of models for estimating software development cost and schedule has not been shown to be better than “within 25 percent of actual cost or schedule, about one half of the time”, especially for Department of Defense software efforts. The same is true for software size estimating models and methods, although there are some studies that have shown superior results. For software support (or maintenance) cost estimation, no model has been demonstrated to be accurate. This paper presents a summary of efforts performed to date which demonstrate the accuracy (or lack thereof) of software models. The results of several studies in the areas of software development cost and schedule estimation, size estimation, and support cost estimation are presented to show what these models can and cannot do. Some ideas for improvement are also presented, including the results of some studies which may lead to a resolution of the accuracy conundrum which currently exists     

Embedded information system re-engineering

Currently fielded embedded information systems face readiness challenges imposed by evolving missions and extended service lifespans. The ability to overcome these challenges is constrained by such factors as shrinking budgets, limited computational capacity and diminished manufacturing sources effects that impact both hardware and software options. Wholesale redevelopment is often cost prohibitive, particularly since large portions of embedded applications continue to fulfil mission requirements. Solutions must preserve prior investments while providing efficient pathways for continued technology refresh. A technology solution for affordable modernization of legacy system software is being development. The Embedded Information System Re-engineering (EISR) project is developing an automation-assisted JOVIAL-to-C re-engineering capability that permits simultaneous modernization of both the structure and source language of legacy embedded applications. Engineers will be able to apply the proven labor-saving visualization and analysis features of modern CASE tools to legacy JOVIAL applications. EISR will thus allow the DoD to recapture previous investments in proven legacy algorithms and mission capabilities while permitting the full exploitation of COTS economies of scale. This paper describes in brief the goals and objectives of the EISR project, and provides the current status of the EISR capability.     

Aeronautical telemetry using multiple-antenna transmitters

The placement of multiple antennas on an air vehicle is one possible practice for overcoming signal obstruction created by vehicle maneuvering during air-to-ground transmission. Unfortunately, for vehicle attitudes where more than one of these antennas has a clear path to the receiving station, this practice also leads to self-interference nulls, resulting in dramatic degradation in the average signal integrity. This paper discusses application of unitary space-time codes such as the Alamouti transmit diversity scheme and unitary differential space-time codes to overcome the self-interference effect observed in such systems. The mathematical foundations of these techniques within the context of this application as well as computational performance gains associated with their implementation are provided. Issues such as the cost of channel estimation for trained techniques as well as the throughput performance of nondifferential and differential schemes for realistic air-vehicle motion are analyzed     

Fiber-optic gyros and quartz accelerometers for motion control

In article the opportunity of use strapdown inertial navigation system (SINS) on the base of fiber-optic gyroscopes and quartz accelerometers corrected from star sensors and satellite navigation equipment (SNE) for perspective interplanetary spacecrafts motion control on phases of interplanetary trajectory insertion, trajectory correction, and braking during transition to Mars orbit is investigated. Results of onboard control complex accuracy characteristics estimation are presented at the given dynamic spacecraft scheme which is taking into account the liquid oscillations in tanks and structure elements elasticity. At modelling the errors of measuring devices installation, errors of SINS initial alignment and instrumental errors of SINS sensitive elements, variation of control engines parameters were taken into account. The structure of the developed complex of imitation modelling of interplanetary spacecraft controlled motion is resulted. Estimations of active flight legs realization accuracy were received by a method of statistical modelling of spacecraft controlled motion     

Solar wind turbulence during the solar cycle deduced from Galileo coronal radio-sounding experiments

Seven coronal radio-sounding campaigns were carried out during the active lifetime of the Galileo spacecraft in the years 1994–2002. The observational data analyzed in the present work are S-band frequency fluctuation measurements recorded during the solar conjunctions at different phases of solar activity cycle #23, specifically: periods near solar maximum (three conjunctions), near solar minimum (three conjunctions) and during the ascending phase (one conjunction). These data are all applicable to low heliographic latitudes, i.e. to the slow solar wind. The rms frequency fluctuation and power-law index of the frequency fluctuation temporal spectra are determined as a function of heliocentric distance. The turbulence power spectrum tends to be flatter inside ca. 20 solar radii during all phases of the solar cycle. This coincides with a transition in the flow from the inner acceleration region to the outer region of constant velocity. The radial falloff rate and absolute level of the rms frequency fluctuation are essentially invariant over the solar cycle.     

Integral-projection method and singularities of its application in mating shells with inconsistent parameters of approximation

We describe a numerical integral-projection method used by the authors for the approximate solution of systems of interrelated two-dimensional linear boundary-value problems in mechanics of composite shell systems. The method is based on discretization in each shell substructure of a two-dimensional problem along one of coordinates using a projection-grid variant of the Galerkin-Petrov method and its subsequent transformation to a system of ordinary differential equations; by integration and introduction of sought functions as unknown derivatives, the system is reduced to a system of integral equations being solved by the method of mechanical quadratures. The method is characterized by the fact that its application requires no additional conditions of conformity with discretization parameters of substructures being mated.