Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) program plays a key part in helping NASA maintain this important role. The NASA STI Program operates under the auspices of the Agency Chief Information Officer. It collects, organizes, provides for archiving, and disseminates NASA's STI. The NASA S...

Recent studies have found the earth's peculiar velocity to be significant in microwave background based tests for compact cosmic topology, and modifications to these tests have been proposed. Tests of non-gaussianity, weak lensing analysis and new tests using improved CMB data will also be sensitive to peculiar velocity. We propose here to simplify matters by showing how to construct a deaberra...

We consider the effect of optical depth of the 2 S level on the nebular recombination spectrum of He I for a spherically symmetric nebula with no systematic velocity gradients. These calculations, using many improvements in atomic data, can be used in place of the earlier calculations of Robbins. We give representative Case B line fluxes for UV, optical, and IR emission lines over a range of ph...

Louisiana Tech University has recently developed a curriculum (NASA-Threads) that integrates engineering, mathematics, and physics. The curriculum, which targets junior and senior high school students, uses hands-on projects that develop student ability to solve realistic multiple-step problems and bring excitement into the classroom. NASA-Threads integrates NASA applications, fundamentals, tec...

Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA scientific and technical information (STI) program plays a key part in helping NASA maintain this important role. The NASA STI program operates under the auspices of the Agency Chief Information Officer. It collects, organizes, provides for archiving, and disseminates NASA's STI. The NASA S...

This paper describes preconditioned conjugate gradient methods for solving sparse symmetric and positive definite systems of linear equations. Necessary and sufficient conditions are given for when these preconditioners can be used and an analysis of their effectiveness is given. Efficient computer implementations of these methods are discussed and results on the CYBER 203 and the Finite Elemen...

NASA’s Expansive Reach Each year, NASA produces Spin­ off, a report outlining its con­ tributions to the US (see www. sti.nasa.gov/tto). Many derivative technologies in medicine and per­ sonal comfort have emerged from NASA missions, positively affect­ ing our lives. However, beneficial technologies have also emerged in computing and information processing over the more than 60 years since the ...

The NASA-funded opticai communications program being conducted at JPL is described, The spacecraft transceiver terminal developments, a test infrastructure for assessing the performance of future space terminals, an atmospheric visibility monitoring program, some recent systems-level demonstrations, and a communications technology roadmap for planetary missions over the next 25 years are presen...