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81.
The design of Space Station Freedom's electric power system (EPS) is reviewed, highlighting the key design goals of performance, low cost, reliability, and safety. The EPS design is divided into three separate areas: power generation and storage, power distribution, and power management and control. Both photovoltaic and solar dynamic power generation and storage systems are used. Tradeoff study results that illustrate the competing factors responsible for many of the more important design decisions are discussed. Reliability and maintainability, as well as verification and testing, are addressed 相似文献
82.
Thomas F. Rogers 《Space Policy》2006,22(2):128-132
Since the completion of its original prehistoric migration some 10 000 years ago, humankind has had nowhere else on Earth to go. The Space Age has produced the wherewithal for a new off-Earth human migration to restart, with the Moon as the clear initial destination. As insurance against cataclysmic and human-induced natural disasters, as a means of creating new commercial industrial–financial opportunities at a time of fundamental change in the global economy, and as a way for the USA to regain some international political influence, it should pursue Moon settlement vigorously and soon. However, the developing US space exploration program being designed by NASA for such an undertaking is too narrowly confined to the pursuit of natural-science objectives. There must be fundamental involvement of the private sector and of a much wider range of professionals and federal departments therein. 相似文献
83.
Thomas A. Potemra 《Space Science Reviews》1985,42(3-4):295-311
Following earlier suggestions of Edmond Halley and Anders Celsius for the magnetic behavior of auroral phenomena, Kristian Birkeland discovered in his polar expeditions of 1902–03 that large-scale electric currents were associated with the aurora. He was also the first to suggest that these currents originated far from earth and that they flowed into the upper polar atmosphere and out of it along magnetic field lines; the existence of such field-aligned currents was widely disputed until satellite and rocket-borne instruments confirmed their permanent existence. The importance of these Birkeland currents to the coupling between the magnetosphere and the polar ionosphere is emphasized by their intensity, which ranges between 106 and 107 amperes, and by the energy which they dissipate in the upper atmosphere, which can exceed by a considerable factor the energy dissipated there by auroral particles. The large- and small-scale average properties of field-aligned currents, determined from spacecraft observations, are reviewed here. 相似文献
84.
Joseph M. Davila Roger J. Thomas Jeffrey Brosius Arthur Poland 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(12):2293-2298
Data from the Solar Extreme-ultraviolet Rocket Telescope and Spectrograph (SERTS) have been used to address a number of important scientific problems. The primary strength of the SERTS data is the fact that this spectral range is rich with emission lines. Over 270 lines are seen in the SERTS active Sun spectrum, from 57 different ions. For example, multiple (≥4) lines are observed for all ionization states of iron from Fe IX to Fe XVII. Temperatures and densities have been derived for a number of active and quiet Sun regions, the coronal magnetic field strength has been estimated for both a plage region and an active region. 相似文献
85.
An experimental prototype of a cockpit data link communication interface (modified Navigation Display (ND) and Multi-purpose Control and Display Unit (MCDU)) was developed and tested in an Airbus A340 Full Flight Simulator. 8 crews (16 professional pilots) performed simulator flights in a mixed voice and data link scenario. After each experiment video recordings were presented to the pilots and they were asked to estimate subjective strain (NASA task load index) and situational aspects retrospectively. Results show an increase in subjective strain and a decrease of ‘feeling of sovereignty’ and situation awareness under data link conditions. The effect is similar to the one caused by higher workload. 相似文献
86.
Mayte Vasquez Manfred Gottwald Sebastian Gimeno Garcia Eckhart Krieg Günter Lichtenberg Franz Schreier Sander Slijkhuis Ralph Snel Thomas Trautmann 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
This work shows the capability of observing Venus with a sensor originally designed for Earth remote sensing. SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY), onboard ENVISAT, successfully observed visible and near-infrared spectra from the Venusian atmosphere. The Venus spectra were simulated using a line-by-line radiative transfer model. The single scattering approximation was applied in order to consider the effects of an approximately 20 km-thick haze layer above the main cloud deck, which was considered as a reflecting cloud located in the upper atmosphere of the planet. CO2 absorption lines could be distinguished in both observed and simulated spectra and a good agreement between them was also found. 相似文献
87.
Carolin Früh Thomas Schildknecht 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
In survey series of unknown Earth orbiting objects, no a priori orbital elements are available. In surveys of wide field telescopes possibly many non-resolved object images are present on the single frames of the series. Reliable methods have to be found to associate the object images stemming from the same object with each other, so-called linking. The presence of cosmic ray events, so-called Cosmics, complicates reliable linking of non-resolved images. The tracklets of object images allow to extract exact positions for a first orbit determination. 相似文献
88.
Abstract Various astrophysical events have been suggested as sources of ionizing radiation that, by way of destruction of the ozone layer and the subsequent increase in UVB and deposition of nitrate, could pose a threat to life on Earth. We have investigated whether the nitrate deposition that follows an ionizing event is sufficient to cause an additional stress beyond that of the heightened UVB previously considered. Our results show that, subsequent to the most intense ionization event likely to have occurred in the last billion years, the increase in nitrate concentration in bodies of water would not be sufficient to cause serious additional stress on amphibian populations and may actually provide some benefit by acting as fertilizer. 相似文献
89.
90.
Thomas Hobiger Jun Amagai Masanori Aida Hideki Narita 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
Reflected signals of the Global Navigation Satellite System (GNSS) from the sea or land surface can be utilized to deduce and monitor physical and geophysical parameters of the reflecting area. Unlike most other remote sensing techniques, GNSS-Reflectometry (GNSS-R) operates as a passive radar that takes advantage from the increasing number of navigation satellites that broadcast their L-band signals. Thereby, most of the GNSS-R receiver architectures are based on dedicated hardware solutions. Software-defined radio (SDR) technology has advanced in the recent years and enabled signal processing in real-time, which makes it an ideal candidate for the realization of a flexible GNSS-R system. Additionally, modern commodity graphic cards, which offer massive parallel computing performances, allow to handle the whole signal processing chain without interfering with the PC’s CPU. Thus, this paper describes a GNSS-R system which has been developed on the principles of software-defined radio supported by General Purpose Graphics Processing Units (GPGPUs), and presents results from initial field tests which confirm the anticipated capability of the system. 相似文献