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Results for “spin stabilization”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

A demonstration of the value of general purpose, on-board satellite computers

Failure of the solar panels to erect and spin stabilize the TRANSIT Improvement Program (TIP) satellites is discussed, with emphasis on how the flight computer was reprogrammed to perform various control functions in order to achieve a partial mission success. These functions include: (1) power management to avoid troublesome spacecraft blackouts; (2) achieve enough spin stability to fire the OATS thruster; (3) raise the parking orbit to a workable altitude; (4) remove a high tumble rate which was the indirect result of the failure; and (5) deploy the gravity-gradient boom successfully on TIP-3.

Jenkins, R. E.↗
DOE OSTI2020

Stabilized Charge, Spin, and Orbital Ordering by the 6s 2 Lone Pair in Bi 0.5 Pb 0.5 MnO 3

Bi and Pb ions with charge degree of freedom depending on 6s 2 and 6s 0 electronic configurations were combined with the Mn ion in a perovskite oxide. Comprehensive theoretical and experimental investigations revealed the Bi 3+ 0.5 Pb 2+ 0.5 Mn 3+ 0.5 Mn 4+ 0.5 O 3 charge ordered state with CE-type spin and dz 2 orbital orderings as observed in La 0.5 Ca 0.5 MnO 3 , Nd 0.5 Sr 0.5 MnO 3 , and Bi 0.5 Sr 0.5 MnO 3 . Finally, the charge and orbital orderings were preserved above 500 K owing to the stereochemical activity of Bi 3+ and Pb 2+ ions which stabilized the structural distortion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1984

Planetary spacecraft as optical instrument platforms

The pointing system, telemetry rate, thermal control, power, command, and available mass of planetary spacecraft are described. A comparison of the pointing and stability capabilities of the three-axis stabilized spacecraft and the spin stabilized spacecraft is presented. The development of a hybrid spacecraft, which combines the spin and three-axis design, is examined. The attitude control and articulation system, and the instruments of the Galileo, a hybrid spacecraft, are analyzed.

Vescelus, F. E.↗
DOE OSTI2024

Higher spin mode stability for STU black hole backgrounds

This article studies mode stability of a four-dimensional rotating black hole with four pairwise equal U(1) charges derived in the framework of supergravity or the low energy string theory which is known now as STU black hole. We investigate bosonic perturbations in a proposed equation of the Teukolsky type for probe fields of different spins through the transformation technique devised by Whiting in 1989. Lastly, we introduce connection relations inspired by the work of Duztaş to prove the absence of unstable modes that solve the torsion-modified Dirac equation appropriate for this black hole background.

Astronomy & Astrophysics↗
NASA NTRS2007

Launching Payloads Into Orbit at Relatively Low Cost

A report proposes the development of a system for launching payloads into orbit at about one-fifth the cost per unit payload weight of current systems. The PILOT system was a solid-fuel, aerodynamically spun and spin-stabilized, five-stage rocket with onboard controls including little more than an optoelectronic horizon sensor and a timer for triggering the second and fifth stages, respectively. The proposal calls for four improvements over the PILOT system to enable control of orbital parameters: (1) the aerodynamic tipover of the rocket at the top of the atmosphere could be modeled as a nonuniform gyroscopic precession and could be controlled by selection of the initial rocket configuration and launch conditions; (2) the attitude of the rocket at the top of the first-stage trajectory could be measured by use of radar tracking or differential Global Positioning System receivers to determine when to trigger the second stage; (3) the final-stage engines could be configured around the payload to enhance spin stabilization during a half-orbit coast up to apoapsis where the final stage would be triggered; and (4) the final payload stage could be equipped with a "beltline" of small thrusters for correcting small errors in the trajectory as measured by an off-board tracking subsystem.

Wilcox, Brian↗
NASA NTRS2002

GPS-Based Navigation and Orbit Determination for the AMSAT Phase 3D Satellite

This paper summarizes the results of processing GPS data from the AMSAT Phase 3D (AP3) satellite for real-time navigation and post-processed orbit determination experiments. AP3 was launched into a geostationary transfer orbit (GTO) on November 16, 2000 from Kourou, French Guiana, and then was maneuvered into its HEO over the next several months. It carries two Trimble TANS Vector GPS receivers for signal reception at apogee and at perigee. Its spin stabilization mode currently makes it favorable to track GPS satellites from the backside of the constellation while at perigee, and to track GPS satellites from below while at perigee. To date, the experiment has demonstrated that it is feasible to use GPS for navigation and orbit determination in HEO, which will be of great benefit to planned and proposed missions that will utilize such orbits for science observations. It has also shown that there are many important operational considerations to take into account. For example, GPS signals can be tracked above the constellation at altitudes as high as 58000 km, but sufficient amplification of those weak signals is needed. Moreover, GPS receivers can track up to 4 GPS satellites at perigee while moving as fast as 9.8 km/sec, but unless the receiver can maintain lock on the signals long enough, point solutions will be difficult to generate. The spin stabilization of AP3, for example, appears to cause signal levels to fluctuate as other antennas on the satellite block the signals. As a result, its TANS Vectors have been unable to lock on to the GPS signals long enough to down load the broadcast ephemeris and then generate position and velocity solutions. AP3 is currently in its eclipse season, and thus most of the spacecraft subsystems have been powered off. In Spring 2002, they will again be powered up and AP3 will be placed into a three-axis stabilization mode. This will significantly enhance the likelihood that point solutions can be generated, and perhaps more important, that the receiver clock can be synchronized to GPS time. This is extremely important for real-time and post-processed orbit determination, where removal of receiver clock bias from the data time tags is needed, for time-tagging of science observations. Current analysis suggests that the inability to generate point solutions has allowed the TANS Vector clock bias to drift freely, being perhaps as large as 5-7 seconds by October, 2001, thus causing up to 50 km of along-track orbit error. The data collected in May, 2002 while in three-axis stabilized mode should provide a significant improvement in the orbit determination results.

Davis, George↗
DOE OSTI2025

Shear–Mediated Stabilization of Spin Spiral Order in Multiferroic NiI 2

Type-II multiferroicity from non-collinear spin order is recently explored in the van der Waals material NiI 2 . Despite the importance for improper ferroelectricity, the microscopic mechanism of the helimagnetic order remains poorly understood. Here, the magneto-structural phases of NiI 2 are investigated using resonant magnetic X-ray scattering (RXS) and X-ray diffraction. Two competing magnetic phases are identified. Below 60 K, an incommensurate magnetic reflection (q ≈ [0.143,0,1.49] reciprocal lattice units) is observed which exhibits finite circular dichroism in RXS, signaling the inversion symmetry-breaking helimagnetic ground state. At elevated temperature, in the non-polar phase (60 K < T < 75 K), a distinct q ≈ [0.087,0.087,1.5] magnetic order is observed, attributed to a collinear incommensurate (CI) state. The first-order CI-helix transition is concomitant with a structural transition characterized by a significant interlayer shear, which drives the helimagnetic ground state as evidenced by a mean-field Heisenberg model including interlayer exchange and its coupling to the structural distortion. Furthermore, these findings identify interlayer magneto-structural coupling as the key driver behind multiferroicity in NiI 2 .

36 MATERIALS SCIENCE↗
NASA NTRS2014

Co-Spin With Symmetry Axis Stabilization, and De-Spin for Asteroid Capture

Consideration is given to attitude control associated with capturing a free-flying asteroid using an axisymmetric spacecraft. Asymptotically stable controllers are designed to align the spacecraft axis of symmetry with a line of descent that is fixed in the asteroid, and to eliminate all relative angular velocity before capture takes place. An analytical expression is presented for the torque required to maintain alignment of the axes of symmetry of the spacecraft and an axisymmetric asteroid. After the asteroid is securely captured, the angular velocity of the rigid composite body relative to an inertial frame is arrested; we present a controller that is asymptotically stable and stays within specified thrust limits.

Shen, Haijun↗
NASA NTRSDate not supplied

Passive Fluid Transport in Microgravity Environments for the Stabilization of Rotating Spacecrafts

Rotating spacecraft offers the potential to create artificial gravity for extended space missions. However, designing a guidance and control system for such vehicles involves complex considerations. This paper examines a vehicle segmented into three parts, with the propulsion unit positioned at the vehicle’s center of mass. The vehicle must maintain stability around this central point, even under atypical conditions. Consequently, a durable and passive spin stabilization system is essential, requiring the passive transport of fluids. A combined system consisting of microcapillary bundles and hydraulic ram pumps is explored to transport fluids without any external energy added to the system. The dynamics of such a system are investigated, establishing performance and control limitations, and developing a control strategy predicated on the fluid dynamics between the segments. A model of the system is developed to validate the approach, showing that passive stabilization is possible, however, not as effective as an active stabilization system. Additionally, the model can be expanded for broader applications, including mass redistribution, a theoretical fluid ring, and three axis rotating systems.

Dynamics↗
NASA NTRS1975

Approach guidance for outer planet pioneer missions

Onboard optical approach guidance measurements for spin-stabilized Pioneer-type spacecraft are discussed. Approach guidance measurement accuracy requirements are outlined. The application concept and operation principle of the V-slit star tracker are discussed within the context of approach guidance measurements and measurables. It is shown that the accuracy of onboard optical approach guidance measurements is inherently coupled to the stability characteristics of the spacecraft spin axis. Geometrical and physical measurement parameters are presented for Pioneer entry probe missions to Uranus via Jupiter or Saturn flyby. The impact of these parameters on both sensor instrumentation and measurement system design is discussed. The need for sensing extended objects is shown. The feasibility of implementing an onboard approach guidance measurement system for Pioneer-type spacecraft is indicated. Two Pioneer 10 onboard measurement experiments performed in May-June 1974 are described.

Bejczy, A. K.↗
NASA NTRS1984

Attitude Control System for the Extreme Ultraviolet Explorer Satellite

The requirements, design, and expected performance of the Attitude Control Subsystem for the spin-stabilized Extreme Ultraviolet Explorer Satellite are presented. In the sky-mapping phase, closed-loop magnetic control keeps the spin axis pointed toward the sun. In the spectroscopy phase, the attitude control loop is closed via the ground. The satellite's attitude and spin rate are determined using periodically downlinked star data. An attitude control algorithm generates commands to be uplinked to the satellite for spin axis precession and spin rate control. Computer simulations of the satellite dynamic response, pointing error, and stability during spin axis precession are presented, and parameters that affect the pointing performance are evaluated.

Wong, E. C.↗
NASA NTRS2008

Behavior of Spinning Space Vehicles with Onboard Liquids, 2nd Edition, Technical Report B8030

Although the fundamental principles of spin stabilization are well established, uncertainty regarding the potential for rapid nutation growth caused by onboard liquids is a continuing concern. NASA and other organizations regularly encounter the issue of rapid nutation growth due to energy dissipation by liquids on spinning vehicles. Of concern is the stability of spinning upper stages and of spacecraft that spin for part or all of their missions. Several missions have required last-minute hardware or operational changes to deal with rapid nutation divergences that were identified late in the program. In some instances, major schedule slips were barely averted. In at least two cases, it was determined that a spinning upper stage was not a viable option. Historically, the "slosh" issue has been addressed by each space vehicle project individually, if it has been addressed at all. Due to budgetary and programmatic constraints, individual projects are unable to address the problem globally. Hence, there has been little effort to collect available test and flight data and use that data to make a coherent, unified picture of the "slosh" effect and how to deal with it. To some extent, each project has had to "reinvent the wheel", which can be both costly and risky. This study is a step toward correcting the situation. Specifically, the goal was to identify and collect available flight and test data for spinning vehicles with onboard liquid propellants. A total of 149 flight data points and 1,692 test points were collected as part of this study. This data was analyzed, correlated, and is presented here in a normalized form. In most cases, the normalization involves a dimensionless nutation time constant that can be used to predict performance of other vehicles with the same type of tank. For some configurations, it was also possible to identify conditions that can lead to resonance between nutational motion and liquid modes. Gaps in the knowledge base are identified and approaches to filling those gaps are outlined. The data presented here has two different but related uses. First, it can be applied directly to current and future spacecraft programs. Second, it can provide truth models for testing analytical techniques. Experience has shown that purely analytical models of the liquid "slosh" effect on spinning vehicles are unreliable unless they are validated against flight or test data. To the author's knowledge, this report contains the most extensive and varied data set available. As such, it should be a good resource for anyone seeking to develop and validate improved analytical techniques. All of the original digital data sets have been archived on disk, with copies provided to NASA/KSC. With some restrictions, many of these data sets can be made available to researchers within the United States. Whenever possible, spacecraft are identified by name in this report. However, several organizations provided access to data with the explicit proviso that their programs not be identified and that parameters be presented only in normalized form. These constraints have been respected.

Hubert, Carl↗
NASA NTRS1973

Liapunov stability analysis of spinning flexible spacecraft.

The attitude stability of a class of spinning flexible spacecraft in a force-free environment is analyzed. The spacecraft is modeled as a rigid core having attached to it a flexible appendage idealized as a collection of elastically interconnected particles. Liapunov stability theorems are employed with the Hamiltonian of the system, constrained through the angular momentum integral so as to admit complete damping, used as a testing function. The Hamiltonian is written in terms of modal coordinates as interpreted by the hybrid coordinate formulation, thus allowing truncation to a level amenable to literal stability analysis. Testing functions are constructed for a spacecraft with an arbitrary (discretized) appendage, and closed form stability criteria are generated for the first mode of a restricted appendage model lying in a plane which contains the center of mass and is orthogonal to the spin axis. The criteria are (except for idealized cases on the stability boundary line in the parameter space) both necessary and sufficient for stability for any spacecraft characterized by the planar appendage model, such as a spacecraft containing solar panels and/or radial booms.

Barbera, F. J.↗