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1、埃尔吉洛伊非磁性合金NRLs TEPCE Spacecraft Undergoes Successful Deployment Test WASHINGTON-(BUSINESS WIRE)-The Naval Research Laboratorys (NRLs) Tether Electrodynamics Propulsion CubeSat Experiment (TEPCE) underwent successful deployment tests on March 19 and March 23, 2010. “The deployment experiment was a mi
2、lestone in the development of the first tethered spacecraft to demonstrate electrodynamic thrusting for orbit maneuvers using energy derived from the sun instead of from expendable fuel”TEPCE is a tethered spacecraft being built by NRL to demonstrate electrodynamic propulsion in space. Electrodynami
3、c propulsion holds the promise of limitless propulsion for maneuvering spacecraft without using expendable fuel. The spacecraft, in its orbital configuration, will consist of two CubeSat end masses attached to the end of 1 kilometer of electrically conducting tether. Electrodynamic propulsion works
4、on electromagnetic principles similar to an electric motor. The magnetic field in an electric motor attracts an electric current that flows through the windings of the armature causing the armature to spin. In space, the earth has a naturally occurring magnetic field and for TEPCE, the tether wire s
5、erves the purpose of the armature. By inducing an electric current to flow along the tether, a mutual attraction between the earths magnetic field and the tether will occur. This electromagnetic attraction can propel TEPCE to higher altitudes or to change the orientation of its orbit. NRL researcher
6、s conducted the deployment tests in the Naval Center for Space Technologys high bay facilities at NRL. The tests exercised a spring deployment mechanism, called a stacer, which pushes the two CubeSats apart at a relative velocity of 4 meters per second. The tests were conducted in free fall that sim
7、ulated the weightlessness of space. The CubeSats were instrumented with angular rate gyros and accelerometers that measured rotations and accelerations. The TEPCE deployment tests determined the effectiveness of the stacer mechanism to produce the required separation velocity while holding tip-off r
8、otations to an acceptable level. “The deployment experiment was a milestone in the development of the first tethered spacecraft to demonstrate electrodynamic thrusting for orbit maneuvers using energy derived from the sun instead of from expendable fuel,” explains NRLs Dr. Shannon Coffey, TEPCE prog
9、ram manager. Fast Auroral Snapshot performance using a multi-body dynamic simulationZimbelman, Darrell; Walker, Mary(ISSN 0065-3438), p. 1209-1223This paper examines the complex dynamic interaction between two 2.6 m long stacer booms, four 30 m long flexible wire booms and the attitude control syste
10、m of the Fast Auroral SnapshoT (FAST) spacecraft. The FAST vehicle will nominally operate as a negative orbit spinner, positioned in a 83 deg inclination, 350 x 4200 km orbit. For this study, a three-axis, non-linear, seven body dynamic simulation is developed using the TREETOPS software package. Th
11、e significance of this approach is the ability to model each component of the FAST spacecraft as an individual member and connect them together in order to better understand the dynamic coupling between structures and the control system. Both the wire and stacer booms are modeled as separate bodies
12、attached to a rigid central body. The wire booms are oriented perpendicular to the spin axis at right angles relative to each other, whereas the stacer booms are aligned with the spin axis. The analysis consists of a comparison between the simulated in-plane and out-of-plane boom motions with theore
13、tically derived frequencies, and an examination of the dynamic coupling between the control system and boom oscillations. Results show that boom oscillations of up to 0.36 deg are acceptable in order to meet the performance requirements. The dynamic motion is well behaved when the precession coil is
14、 operating, however, activation of the spin coil produces an erratic trend in the spin rate which approaches the spin rate requirement. Keywords: DYNAMIC RESPONSE, POINTING CONTROL SYSTEMS, SATELLITE ATTITUDE CONTROL, SATELLITE CONFIGURATIONS, SMALL SCIENTIFIC SATELLITES, SPACECRAFT STABILITY, SPACE
15、CRAFT STRUCTURES, DYNAMIC MODELS, NUTATION, OSCILLATIONS, SOFTWARE DEVELOPMENT TOOLS Solar observations are carried out in space when necessary for technical reasons, such as detection of wavelengths that do not reach the ground, or to provide observing conditions that are difficult or impossible to
16、 achieve on the ground. Examples in the first category are observations at far ultraviolet or soft x-ray wavelengths and direct detection of solar wind particles; in the latter are precise measurements of variations in the solar luminosity and stereo observations of coronal mass ejections. This article samples the wide variety of techniques presently being used to study the Sun. We begin with an overview of the observational problem presented by the particular scientific questi
