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61.
A method of determining the position of celestial X-ray sources which utilizes a modulation collimator rotating about a fixed axis is presented. The signal from each source in the field of view is modulated by a frequency which is fixed by the radial distance from the intersection of the rotation axis and the celestial sphere. The phase of the modulation is determined by the angular distance of the source from a reference line on the celestial sphere. Thus, the modulation function for each source is unique. The data are reduced by the technique of Fourier analysis. Synthesized experimental data for the cases of a single source and for five sources in the field of view are analysed. The ability to distinguish and accurately locate each source in a multiple source field is a major achievement of this method. Sources can be located with an accuracy which is competitive with other methods. An experiment based on this method can be lifted on an Aerobee 150 system.This work was supported by grant NsG-386 from the National Aeronautics and Space Administration. 相似文献
62.
Churchill F.E. Ogar G.W. Thompson B.J. 《IEEE transactions on aerospace and electronic systems》1981,(1):131-137
A method is presented for correcting the gain and phase imbalances and the bias errors of the in-phase and quadrature channels of a coherent signal processor [1] by means of coefficients which are derived from measurements of a test signal. The residual errors after correction depend upon the signal-to-noise ratio (S/N) of the test signal and the degree of filtering used in deriving the correction coefficients. 相似文献
63.
A. Pedersen N. Cornilleau-Wehrlin B. De la Porte A. Roux A. Bouabdellah P. M. E. Décréau F. Lefeuvre F. X. Sène D. Gurnett R. Huff G. Gustafsson G. Holmgren L. Woolliscroft H. ST. C. Alleyne J. A. Thompson P. H. N. Davies 《Space Science Reviews》1997,79(1-2):93-106
In order to get the maximum scientific return from available resources, the wave experimenters on Cluster established the Wave Experiment Consortium (WEC). The WEC's scientific objectives are described, together with its capability to achieve them in the course of the mission. The five experiments and the interfaces between them are shown in a general block diagram (Figure 1). WEC has organised technical coordination for experiment pre-delivery tests and spacecraft integration, and has also established associated working groups for data analysis and operations in orbit. All science operations aspects of WEC have been worked out in meetings with wide participation of investigators from the five WEC teams. 相似文献
64.
Charles E. Schlemm II Richard D. Starr George C. Ho Kathryn E. Bechtold Sarah A. Hamilton John D. Boldt William V. Boynton Walter Bradley Martin E. Fraeman Robert E. Gold John O. Goldsten John R. Hayes Stephen E. Jaskulek Egidio Rossano Robert A. Rumpf Edward D. Schaefer Kim Strohbehn Richard G. Shelton Raymond E. Thompson Jacob I. Trombka Bruce D. Williams 《Space Science Reviews》2007,131(1-4):393-415
NASA’s MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission will further the understanding of
the formation of the planets by examining the least studied of the terrestrial planets, Mercury. During the one-year orbital
phase (beginning in 2011) and three earlier flybys (2008 and 2009), the X-Ray Spectrometer (XRS) onboard the MESSENGER spacecraft
will measure the surface elemental composition. XRS will measure the characteristic X-ray emissions induced on the surface
of Mercury by the incident solar flux. The Kα lines for the elements Mg, Al, Si, S, Ca, Ti, and Fe will be detected. The 12°
field-of-view of the instrument will allow a spatial resolution that ranges from 42 km at periapsis to 3200 km at apoapsis
due to the spacecraft’s highly elliptical orbit. XRS will provide elemental composition measurements covering the majority
of Mercury’s surface, as well as potential high-spatial-resolution measurements of features of interest. This paper summarizes
XRS’s science objectives, technical design, calibration, and mission observation strategy. 相似文献