Solar array thermal snap and the characteristics of its effect on UARS

The single solar array on the Upper Atmosphere Research Satellite (UARS) is subjected to a thermal distortion when the spacecraft enters and exits the Earth's shadow. The distortion results in a torque that alters the spacecraft attitude. Due to the sudden nature of the attitude discontinuity, the effect has been termed 'thermal snap'. Thermal snap has also been experienced by Landsats 4 and 5. Analyses by the spacecraft builder addressed the impact of the resultant torque on the onboard control system. This paper discusses the results of comparisons between the predicted effects of thermal snap on UARS and actual attitude solutions from UARS telemetry data. In addition, this paper describes the characteristics of the thermal snap on UARS in terms of maximum displacement, solar beta angle, and solar array drive angle. Comparisons are made between the actual times of thermal snaps and the predicted spacecraft sunrise and sunset times. The effects of the UARS thermal snap are summarized and a general comment is made relating possible effects of thermal snap on other satellites. Also, an analysis of UARS attitude solutions that span periods of thermal snap was performed to determine whether the gyro sampling time of 1/8 second is sufficient to properly model the resulting spacecraft attitude without compromising the accuracy requirements. The results of this analysis are discussed

Conductor\u27s Study Guides / Advanced Conducting Project

Contents include: Suite Francaise Prelude,Siciliano and Rondo On A Hymnsong of Philip Bliss Chorale Prelude: Be Thou My Vision Sedon

Neutral atmospheric models compatible with satellite orbital decay and incoherent scatter measurements

A correlation study was made of the variations of the exospheric temperature extrema with various combinations of the monthly mean and daily values of the 2800 MHz and Ca:2 solar indices. The phase and amplitude of the semi-annual component and the term dependent on Kp were found to remain almost the same for the maximum and minimum temperature. The term dependent on the 27 day component of the solar activity was found to be about four times as large for the diurnal maximum as for the minimum. Measurements at Arecibo have shown that temperature gradient changes at 125 km are consistent with the phase difference between the neutral temperature and density maxima. This is used to develop an empirical model which is compatible with both the satellite measurements and the available incoherent scatter measurements. A main feature of this model is that day length is included as a major model parameter

Resistance training induces supraspinal adaptations: Evidence from movement-related cortical potentials

Early effects of a resistance training program include neural adaptations at multiple levels of the neuraxis, but direct evidence of central changes is lacking. Plasticity exhibited by multiple supraspinal centers following training may alter slow negative electroencephalographic activity, referred to as movement-related cortical potentials (MRCP). The purpose of this study was to determine whether MRCPs are altered in response to resistance training. Eleven healthy participants (24.6 ± 3.5 years) performed 3 weeks of explosive unilateral leg extensor resistance training. MRCP were assessed during 60 self-paced leg extensions against a constant nominal load before and after training. Resistance training was effective (P < 0.001) in increasing leg extensor peak force (+22%), rate of force production (+32%) as well as muscle activity (iEMG; +47%, P < 0.05). These changes were accompanied by several MRCP effects. Following training, MRCP amplitude was attenuated at several scalp sites overlying motor-related cortical areas (P < 0.05), and the onset of MRCP at the vertex was 28% (561 ms) earlier. In conclusion, the 3-week training protocol in the present study elicited significant strength gains which were accompanied by neural adaptations at the level of the cortex. We interpret our findings of attenuated cortical demand for submaximal voluntary movement as evidence for enhanced neural economy as a result of resistance training

Submillimeter Wave Astronomy Satellite (SWAS) Launch and Early Orbit Support Experiences

The Submillimeter Wave Astronomy Satellite (SWAS) was successfully launched on December 6, 1998 at 00:58 UTC. The two year mission is the fourth in the series of Small Explorer (SMEX) missions. SWAS is dedicated to the study of star formation and interstellar chemistry. SWAS was injected into a 635 km by 650 km orbit with an inclination of nearly 70 deg by an Orbital Sciences Corporation Pegasus XL launch vehicle. The Flight Dynamics attitude and navigation teams supported all phases of the early mission. This support included orbit determination, attitude determination, real-time monitoring, and sensor calibration. This paper reports the main results and lessons learned concerning navigation, support software, star tracker performance, magnetometer and gyroscope calibrations, and anomaly resolution. This includes information on spacecraft tip-off rates, first-day navigation problems, target acquisition anomalies, star tracker anomalies, and significant sensor improvements due to calibration efforts

BUMC Annual Report

Annual report of the Boston University Medical Center

Deciphering the Grand Village of the Illinois: A Preliminary Assessment of the Grand Village Research Project

On April 24, 1987, Thomas Emerson at the State Historic Preservation Office received a telephone call from a Chicago lawyer who wanted an answer to a simple question: Are there any laws that protect old Indian villages and graves that are on the National Register? Unfortunately, the answer was a simple “no.” At the time, Emerson did not suspect that this question would initiate a more than four-year struggle to save one of the most important historic sites in the country. The site, known variously as the Zimmerman site, the Grand Village of the Kaskaskia, Old Kaskaskia Village, the Grand Village of the Illinois, or simply llLS13, was purchased by developers who planned to build vacation homes on it. Eventually, after a private and public campaign that reached an international level, Governor James Thompson authorized the Illinois Historic Preservation Agency (IHPA) to seek condemnation of the property to bring it into public ownership. In April 1991, a final settlement was reached and the site was purchased by the state. It is currently under the administration of the IHPA and has been renamed the Grand Village of the Illinois State Historic Site. The Grand Village is the most important surviving village and burial site of the seventeenth-century Illinois Confederacy. In addition, it is the location of the initial French-Illinois contact and of the first Catholic mission in the Illinois Country. The site also contains materials that represent an unbroken sequence of late prehistoric, protohistoric, and Historic Indian cultural development from the ninth to the last quarter of the eighteenth century