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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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We report on measurements of (11-18)-cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator.
improvements in computational capability and DSN technology have renewed interest in examining the possibility of using one-way Doppler data alone to navigate interplanetary spacecraft. The one-way data can be formulated as the standard difference-count Doppler or as phase measurements, and the data can be received at a single station or differenced if obtained simultaneously at two stations. A covariance analysis is performed which analyzes the accuracy obtainable by combinations of one-way Doppler data and compared with similar results using standard tow-way Doppler and range. The sample interplanetary trajectory used was that of the Mars Pathfinder mission to Mars. It is shown that differenced one-way data is capable of determining the angular position of the spacecraft to fairly high accuracy, but has relatively poor sensitivity to the range. When combined with single station data, the position dispersions are roughly an order of magnitude larger in range and comparable in angular position as compared to dispersions obtained with standard data two-way types. It was also found that the phase formulation is less sensitive to data weight variations and data coverage than the differenced-count Doppler formulation.
The center of mass of the Earth, about which a satellite orbits, is determined by the mass distribution of the solid Earth, the oceans, and the atmosphere.
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Writing a tribute paper is fraught with peril. While it is supposed to be about the other’s impact upon your life, in really it cannot help but be all about the author. Back in 2012, after my initial reluctance, the paper I wrote for the Bill Wolfe tribute[1]was so cathartic, that I had to write one for Jim Wyant–to add a chapter to my story, to explain how a path of successes and failures have lead me to the present, and in the process to exorcise more ghosts from my subconscious. While our relationship is complicated, it has always been respectful. In many regards, Jim Wyant may be one of the most important people helping me reach my potential. I am NOT ‘A’ Wyant Student. I am ‘a’ Wyant student. I took three classes from Jim: Interference and Diffraction, Holography and Optical Testing. As a result of those classes, I found something that I loved, something at which I was good, something that became apart of me–I found my technical bliss. And beyond the classroom, my professional career has been inescapably connected with Jim Wyant.