ABSTRACT
Here we describe the first neutral wind sensor developed specifically for use on resource limited nano-satellite platforms. The instrument is a next generation redesign of the ram wind sensor flown on the Communications/Navigation Outage Forecasting System satellite for measurements of neutral velocity, temperature, and composition. Results of subsystem tests in vacuum conditions show low-power operation, promising design, and good resolution of measured parameters over the operational pressure and energy ranges expected in the low Earth orbit environment.
ABSTRACT
The design of the first retarding potential analyzer (RPA) built specifically for use on resource-limited cubesat platforms is described. The size, mass, and power consumption are consistent with the limitations of a nano-satellite, but the performance specifications are commensurate with those of RPAs flown on much larger platforms. The instrument is capable of measuring the ion density, temperature, and the ram component of the ion velocity in the spacecraft reference frame, while also providing estimates of the ion composition. The mechanical and electrical designs are described, as are the operating modes, command and data structure, and timing scheme. Test data obtained using an ion source inside a laboratory vacuum chamber are presented to validate the performance of the new design.
ABSTRACT
Most studies of sports-related injuries have been investigations of specific injuries resulting from specific, organized sports at the high school, college, or professional level. This study documented all types of sports-related injuries received by all school-aged children in a midwestern community of 100,000 for a 1-year period. Public and private schools, community sports programs, hospital emergency rooms, the schools' accident insurance company, and local physicians provided initial accident reports. Injuries were sustained by 3% of all elementary school students, 7% of all junior high school (grades 7 and 8) students, and 11% of all high school students. Nonorganized sports and physical education classes each produced nearly twice as many injuries as organized sports. One-fifth of the injuries were considered serious and one-fourth of all injuries could have been avoided had nominal safety precautions been observed.
