The dynamic phenomena of a tethered satellite: NASA's first Tethered Satellite Mission, TSS-1

The tethered satellite system (TSS) was envisioned as a means of extending a satellite from its base (space shuttle, space station, space platform) into a lower or higher altitude in order to more efficiently acquire data and perform science experiments. This is accomplished by attaching the satellite to a tether, deploying it, then reeling it in. When its mission is completed, the satellite can be returned to its base for reuse. If the tether contains a conductor, it can also be used as a means to generate and flow current to and from the satellite to the base. When current is flowed, the tether interacts with the Earth's magnetic field, deflecting the tether. When the current flows in one direction, the system becomes a propulsive system that can be used to boost the orbiting system. In the other direction, it is a power generating system. Pulsing the current sets up a dynamic oscillation in the tether, which can upset the satellite attitude and preclude docking. A basic problem occurs around 400-m tether length, during satellite retrieval when the satellite's pendulous (rotational) mode gets in resonance with the first lateral tether string mode. The problem's magnitude is determined by the amount of skiprope present coming into this resonance condition. This paper deals with the tethered satellite, its dynamic phenomena, and how the resulting problems were solved for the first tethered satellite mission (TSS-1). Proposals for improvements for future tethered satellite missions are included. Results from the first tethered satellite flight are summarized

Propfan test assessment testbed aircraft stability and control/performance 1/9-scale wind tunnel tests

One-ninth scale wind tunnel model tests of the Propfan Test Assessment (PTA) aircraft were performed in three different NASA facilities. Wing and propfan nacelle static pressures, model forces and moments, and flow field at the propfan plane were measured in these tests. Tests started in June 1985 and were completed in January 1987. These data were needed to assure PTA safety of flight, predict PTA performance, and validate analytical codes that will be used to predict flow fields in which the propfan will operate

An Analytical Study for Subsonic Oblique Wing Transport Concept

The oblique wing concept has been investigated for subsonic transport application for a cruise Mach number of 0.95. Three different mission applications were considered and the concept analyzed against the selected mission requirements. Configuration studies determined the best area of applicability to be a commercial passenger transport mission. The critical parameter for the oblique wing concept was found to be aspect ratio which was limited to a value of 6.0 due to aeroelastic divergence. Comparison of the concept final configuration was made with fixed winged configurations designed to cruise at Mach 0.85 and 0.95. The crossover Mach number for the oblique wing concept was found to be Mach 0.91 for takeoff gross weight and direct operating cost. Benefits include reduced takeoff distance, installed thrust and mission block fuel and improved community noise characteristics. The variable geometry feature enables the final configuration to increase range by 10% at Mach 0.712 and to increase endurance by as much as 44%

Cartographic Modeling: Computer-assisted Analysis of Spatially Defined Neighborhoods

Cartographic models addressing a wide variety of applications are composed of fundamental map processing operations. These primitive operations are neither data base nor application-specific. By organizing the set of operations into a mathematical-like structure, the basis for a generalized cartographic modeling framework can be developed. Among the major classes of primitive operations are those associated with reclassifying map categories, overlaying maps, determining distance and connectivity, and characterizing cartographic neighborhoods. The conceptual framework of cartographic modeling is established and techniques for characterizing neighborhoods are used as a means of demonstrating some of the more sophisticated procedures of computer-assisted map analysis. A cartographic model for assessing effective roundwood supply is briefly described as an example of a computer analysis. Most of the techniques described have been implemented as part of the map analysis package developed at the Yale School of Forestry and Environmental Studies

Ground state magnetic dipole moment of 35K

The ground state magnetic moment of 35K has been measured using the technique of nuclear magnetic resonance on beta-emitting nuclei. The short-lived 35K nuclei were produced following the reaction of a 36Ar primary beam of energy 150 MeV/nucleon incident on a Be target. The spin polarization of the 35K nuclei produced at 2 degrees relative to the normal primary beam axis was confirmed. Together with the mirror nucleus 35S, the measurement represents the heaviest T = 3/2 mirror pair for which the spin expectation value has been obtained. A linear behavior of gp vs. gn has been demonstrated for the T = 3/2 known mirror moments and the slope and intercept are consistent with the previous analysis of T = 1/2 mirror pairs.Comment: 14 pages, 5 figure

C-5A/orbiter wind tunnel testing and analysis: Piggyback ferry

Wind tunnel testing and analytical studies of the feasibility of ferrying the NASA Shuttle Orbiter on the C-5A in a piggyback mode have been accomplished. Testing was conducted in the 8x12 foot low speed wind tunnel using an existing 0.0399 scale C-5A model in conjunction with a NASA 0.0405 scale Orbiter model. Six component force and moment data were measured over a range of pitch and yaw angles to determine lift and drag characteristics, lateral/directional stability characteristics and longitudinal and directional control powers. A description of the wind tunnel test program with a run schedule and the complete plotted data for all the test runs are presented. Initial emphasis was given to determining the effects of the Orbiter above the C-5A and the optimum location for minimum interference on C-5A characteristics. A comprehensive series of cruise configurations were tested including a range of Orbiter longitudinal and vertical locations, incidences, and afterbody fairings. Subsequently, a series of configurations were devised during the test program to determine means of recovering directional stability degradation due to Orbiter interference

Half Life of the Doubly-magic r-Process Nucleus 78Ni

Nuclei with magic numbers serve as important benchmarks in nuclear theory. In addition, neutron-rich nuclei play an important role in the astrophysical rapid neutron-capture process (r-process). 78Ni is the only doubly-magic nucleus that is also an important waiting point in the r-process, and serves as a major bottleneck in the synthesis of heavier elements. The half-life of 78Ni has been experimentally deduced for the first time at the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory at Michigan State University, and was found to be 110 (+100 -60) ms. In the same experiment, a first half-life was deduced for 77Ni of 128 (+27 -33) ms, and more precise half-lives were deduced for 75Ni and 76Ni of 344 (+20 -24) ms and 238 (+15 -18) ms respectively.Comment: 4 pages, 3 figure