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Systems analysis and integration, boom subsystem, combination passive damper, and attitude sensor system for Applications Technology Satellite gravity gradient stabilization system
Gravity gradient stabilization system for applications technology satellite
We report on the development, functional performance and space-qualification status of a laser stabilization system supporting a space-based metrology source used to measure changes in optical path lengths in space-based stellar interferometers. The Space Interferometry Mission (SIM) and Deep Space 3 (DS-3) are two missions currently funded by the National Aeronautics and Space Administration (NASA) that are space-based optical interferometers. In order to properly recombine the starlight received at each telescope of the interferometer it is necessary to perform high resolution laser metrology to stabilize the interferometer. A potentially significant error source in performing high resolution metrology length measurements is the potential for fluctuations in the laser gauge itself. If the laser frequency or wavelength is changing over time it will be misinterpreted as a length change in one of the legs of the interferometer. An analysis of the frequency stability requirement for SIM resulted in a fractional frequency stability requirement of square root (S(sub y)(f)) = <2 x 10(exp -12)/square root(Hz) at Fourier frequencies between 10 Hz and 1000 Hz. The DS-3 mission stability requirement is further increased to square root (S(sub y)(f)) = <5 x 10(exp -14)/Square root(Hz) at Fourier frequencies between 0.2 Hz and 10 kHz with a goal of extending the low frequency range to 0.05 Hz. The free running performance of the Lightwave Electronics NPRO lasers, which are the baseline laser for both SIM and DS-3 vary in stability and we have measured them to perform as follows (9 x l0(exp -11)/ f(Hz))(Hz)/square root(Hz)) = <( square root (S(sub y)(f)) = <(1.3 x l0(exp -8)/ f(Hz))/Square root(Hz). In order to improve the frequency stability of the laser we stabilize the laser to a high finesse optical cavity by locking the optical frequency of the laser to one of the transmission modes of the cavity. At JPL we have built a prototype space-qualifiable system meeting the stability requirements of SIM, which has been delivered to one of the SIM testbeds. We have also started on the development of a system to meet the stability needs of DS-3.
Systems analysis, flight and engineering evaluation, and ground testing of gravity gradient stabilization system for Applications Technology Satellite /ATS/
Gravity gradient boom stabilization system tests for ATS 5
Gravity gradient boom stabilization system for ATS 5
A linear stability analysis and flight-test investigation has been performed on a rolleron-type roll-rate stabilization system for a canard-type missile configuration through a Mach number range from 0.9 to 2.3. This type damper provides roll damping by the action of gyro-actuated uncoupled wing-tip ailerons. A dynamic roll instability predicted by the analysis was confirmed by flight testing and was subsequently eliminated by the introduction of control-surface damping about the rolleron hinge line. The control-surface damping was provided by an orifice-type damper contained within the control surface. Steady-state rolling velocities were at all times less than 1 radian per second between the Mach numbers of 0.9 to 2.3 on the configurations tested. No adverse longitudinal effects were experienced in flight because of the tendency of the free-floating rollerons to couple into the pitching motion at the low angles of attack and disturbance levels investigated herein after the introduction of control-surface damping.
Stabilization system analysis and performance of GEOS-A gravity gradient satellite
A large-scale system is considered as a system constituted of subsystems which may be connected or disconnected from each other during operation. A new notion of connective stability is introduced by which a large-scale system is regarded as stable if it remains stable (in the sense of Liapunov) under structural perturbations produced by the on-off participation of the subsystems. Algebraic conditions are developed that guarantee exponential connective stability in large-scale systems which may be composed of linear and nonlinear subsystems coupled by linear or nonlinear connections.
Gravity gradient stabilization system by rod retraction or extension for Applications Technology Satellite
Applications Technology Satellite gravity gradient stabilization systems status report
Artificial g space station configurations, developing movable control mass attitude stabilization system
NASA initiated the Variable Sweep Transition Flight Experiment (VSTFE) to establish a boundary layer transition database for laminar flow wing design. For this experiment, full-span upper surface gloves were fitted to a variable sweep F-14 aircraft. The development of an improved laminar boundary layer stability analysis system called the Unified Stability System (USS) is documented and results of its use on the VSTFE flight data are shown. The USS consists of eight computer codes. The theoretical background of the system is described, as is the input, output, and usage hints. The USS is capable of analyzing boundary layer stability over a wide range of disturbance frequencies and orientations, making it possible to use different philosophies in calculating the growth of disturbances on sweptwings.
Technical state of design and development of gravity gradient stabilization systems for applications technology satellites
Gravity gradient stabilization system for Applications Technology Satellites - boom subsystem and combination passive damper
Gravity gradient stabilization system for Applications Technology Satellites - TV camera, solar aspect and RF attitude sensors, and manufacturing and quality control processes
In July of 1994 the Kuiper Airborne Observatory's (KAO) Telescope Stabilization System (TSS) was upgraded to meet performance goals necessary to view the Shoemaker-Levy 9 comet collision with Jupiter. The KAO is a modified C-141 Aircraft supporting a 36 inch Infrared telescope used to gather and analyze astronomical data. Before the upgrade, the TSS exhibited approximately a 10 arc-second resolution pointing accuracy. The majority of the inaccuracy was attributable to aircraft vibration and wind buffeting entering through the aircraft's telescope door opening; in other words, the TSS was overly sensitive to external disturbances. Because of power limitations and noise requirements, improving the pointing accuracy of the telescope required more sophistication than simply raising the bandwidth as some classical control strategies might suggest. Instead, relationships were developed between the disturbance sensitivity and closed loop transfer functions. These relationships suggested that employing velocity feedback along with an increase in current loop gain would dramatically improve the pointing resolution of the TSS by decreasing the control system's sensitivity to external disturbances. With the implementation of some classical control techniques and the above philosophy, the KAO's TSS's resolution was improved to approximately 2-3 arc-seconds.
Systems analysis, boom subsystem, combination passive damper, and attitude sensor subsystem in gravity gradient stabilization system of applications technology satellite