We perform a statistical study of 3-s ultra-low frequency (ULF) waves using Magnetospheric Multiscale observations in the Earth's foreshock region. The average phase velocity plasma rest frame is determined to be anti-sunward, and intrinsic polarization right-handed. further examine linear instability conditions based on drift-bi-Maxwellian distribution functions according observed conditions. ...

We calculate the direction of the rotational angular momentum vector, M, of comet 19P/Borrelly based on rotational lightcurve data from 2000, groundbased imaging of the coma during the Deep Space 1 encounter, and the basic near-nucleus coma morphology as revealed by the Deep Space 1 spacecraft. For the most likely direction, we derive a family of solutions (with center at RA=221◦, Dec=−7◦) if t...

High-accuracy pointing capabilities are desired for many three-axis stabilized small satellites. Momentum-based attitude control system actuators, initially developed for larger satellites. are being utilized by small satellites to meetthesc pointing requirements. This paper provides an overview of momentum devices available for small satellite applications and three-axis attitude control syste...

We describe a new series of band-limited image masks for coronagraphy that are insensitive to pointing errors and other low-spatial-frequency optical aberrations. For a modest cost in throughput, these “eighth-order” masks would allow the Terrestrial Planet Finder Coronagraph (TPF-C) to operate with a pointing accuracy no better than that of the Hubble Space Telescope. We also provide eighth-or...

This paper describes the control system analysis and design for the three principal axes of the 2.5 mts SDSS Telescope. The telescope requirements are good tracking performance with errors lower than 165 marcsec rms in the speed range between 0 to 45 arcsec/sec for all the axes. The pointing error is about 2 arcsec rms per axis with a maximum absolute value of 5 arcsec. The telescope has the ad...

Three experiments have provided a rough evaluation of the pointing errors of the 28-foot paraboloid and its mount. One examined the errors introduced by the pedestal, including the azimuth bearing, the second evaluated the pointing of an optical telescope attached to the backup structure, and the third showed that the departure between the telescope boresight and the millimeter-wave boresight i...

Using a variable-radius roll swing motion paradigm, we examined the influence of interaural (y-axis) and dorsoventral (z-axis) force modulation on perceived tilt and translation by measuring perception of horizontal translation, roll tilt, and distance from center of rotation (radius) at 0.45 and 0.8 Hz using standard magnitude estimation techniques (primarily verbal reports) in darkness. Resul...