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Tracking and data acquisition system (TDAS) requirements, TDAS architectural goals, enhanced TDAS subsystems, constellation and networking options, TDAS spacecraft options, crosslink implementation, baseline TDAS space segment architecture, and treat model development/security analysis are addressed.
The CI and CM chondrites, with bulk chemical compositions closely resembling solar values, are important for the study of early solar system processes. Noble gas and particle track studies have revealed that a majority of the CI and CM chondrites contain precompaction solar wind and solar flare irradiation records. A quantitative understanding of these records is important because it would allow constraints to be placed on the environment in which the irradiation occurred, and, therefore, on the mode of evolution of the CI and CM chondrites. The present investigation is concerned primarily with fossil track evidence, taking into account selected specimens of several CI and CM chondrites. In addition, the results are presented of extensive studies of the angular distributions of tracks in irradiated grains from four CM chondrites. The results provide information on the exposure geometry of the grains.
Possible evidence for the presence of Cm-248 in the early solar system was reported from fission gas studies (Rao and Gopalan, 1973) and recently from studies of very high nuclear track densities (not less than 5 x 10 exp 8/sq cm) in the merrillite of the H4 chondrite Forest Vale (F.V.) (Pellas et al., 1987). We report here an analysis of the isotopic abundances of xenon in F.V. phosphates and results of track studies in phosphate/pyroxene contacts. The fission xenon isotopic signature clearly identifies Pu-244 as the extinct progenitor. We calculate an upper limit Cm-248/Pu-244 to be less than 0.0015 at the beginning of Xe retention in F.V. phosphates. This corresponds to an upper limit of the ratio Cm-248/U-235 of not greater than 5 x 10 exp -5 further constraining the evidence for any late addition of freshly synthesized actinide elements just prior to solar system formation. The fission track density observed after annealing the phosphates at 290C (1 hr, which essentially erases spallation recoil tracks) is also in agreement with the Pu-244 abundance inferred from fission Xe. The spallation recoil tracks produced during the 76 Ma cosmic-ray exposure account for the very high track density in merrillites.
The communications and tracking (C&T) techniques and equipment to support evolutionary space station concepts are being analyzed. Evolutionary space station configurations and operational concepts were used in the analysis to derive the results to date. A description of the C&T system based on future capability needs is presented. Included are the 'hooks and scars' currently identified to support the future growth. Technology transparency and impact of growth on other systems are also addressed.
Abstract The hybrid hydraulic electric architecture (HHEA) seeks to combine the high power/torque/force density of hydraulics with the efficiency of electric machines. A set of common pressure rails is used to provide a majority of the power and this power is modulated by small electric machines to provide precise control for the operator. The HHEA has been studied in previous work using off-line dynamic programming optimization to determine energy efficient pressure rail selections, but this approach requires drive cycle information apriori. A Lagrange multiplier method has also been investigated where a set of gains (Lagrange multipliers) are optimized off-line with the idea the these gains, once determined, could be used for real-time operation. In this work, three new real-time pressure rail selection algorithms that do not require future drive cycle information are investigated; greedy, torque minimizing, and thresholding. The greedy control is found to only use 1% more energy than the globally optimal dynamic programming solution; but a model of energy loss is required.
Tracking study to determine maximum control element lag and maximum and minimum control sensitivity tolerated in manually controlled compensatory tracking task
Particle track studies reveal an abundant record of fossil solar flare tracks in breccia components. Metamorphic events govern the degree to which this record is preserved, and studies of phases with different track retentivities allow limits to be placed on temperatures reached during a rock's history. The least affected breccias have never experienced temperatures as great as 300 C. Two breccias which contain xenon from spontaneous fission of Pu-244 (14301 and 14318) and Xe-129 (14301 only) have never been heated above about 700 C. This and evidence for a surface irradiation of some of the breccia components support a surface implantation model for the origin of the xenon in these breccias. Green glass spheres in 15086 have not been heated above about 300 C during or after breccia formation yet have retained fission tracks for less than 0.7 G.y. Argon ages of about 3.5 G.y. for similar green glass are at least five times as great and may indicate that the glass was not completely outgassed at is formation.
The results of various sets of tracking error analysis studies of the ability of ground stations to determine the position and velocity of synchronous satellites are summarized. The effects of varying: (1) the ground station configuration from 1 to 6 tracking stations in differing locations; (2) the ground station measurement type such as S-Band, C-Band, VHF, and lasers and (3) the uncertainties in ground station location are investigated. The linear error analysis computer program used includes the effects of ground tracking station location uncertainties, measurement noise and biases, and station timing bias. Results show that two ground trackers are needed if at least 2000 meters position accuracy is desired, with a favorable two-station solution giving less than 500 meters position accuracy. Under favorable circumstances, a multi-station laser solution gives a synchronous satellite position accuracy of less than 100 meters. The various cases illustrate features of synchronous satellite tracking from ground stations.
Human operator performance in tracking study of pilots determined by deterministic characterization theory and mathematical model
A flying qualities evaluation conducted on the YF-17 airplane permitted assessment of its precision controllability in the transonic flight regime over the allowable angle of attack range. The precision controllability (tailchase tracking) study was conducted in constant-g and windup turn tracking maneuvers with the command augmentation system (CAS) on, automatic maneuver flaps, and the caged pipper gunsight depressed 70 mils. This study showed that the YF-17 airplane tracks essentially as well at 7 g's to 8 g's as earlier fighters did at 4 g's to 5 g's before they encountered wing rock. The pilots considered the YF-17 airplane one of the best tracking airplanes they had flown. Wing rock at the higher angles of attack degraded tracking precision, and lack of control harmony made precision controllability more difficult. The revised automatic maneuver flap schedule incorporated in the airplane at the time of the tests did not appear to be optimum. The largest tracking errors and greatest pilot workload occurred at high normal load factors at low angles of attack. The pilots reported that the high-g maneuvers caused some tunnel vision and that they found it difficult to think clearly after repeated maneuvers.
Flight path and tracking study of Ranger VII LUNAR probe
The subsystems of a solar photovoltaic central power system are identified and the cost of major components are estimated. The central power system, which would have a peak power capability in the range of 50 to 1000 MW, utilizes two types of subsystems - a power conditioner and a solar array. Despite differences in costs of inverters, the overall cost of the total power conditioning subsystem is about the same for all approaches considered. A combination of two inverters operating from balanced dc buses as a pair of 6-pulse groups is recommended. A number of different solar cell modules and tracking array structures were analyzed. It is concluded that when solar cell costs are high (greater than $500/kW), high concentration modules are more cost effective than those with low concentration. Vertical-axis tracking is the most effective of the studied tracking modes. For less expensive solar cells (less than $400/kW), fixed tilt collector/reflector modules are more cost effective than those which track.
Track theory is combined with a realistic model of a heavy ion beam to study the effects of nuclear fragmentation on cell survival and biological effectiveness. The effects of secondary reaction products are studied as a function of depth in a water column. Good agreement is found with experimental results for the survival of human T-l cells exposed to monoenergetic carbon, neon, and argon beams under aerobic and hypoxia conditions. The present calculation, which includes the effect of target fragmentation, is a significant improvement over an earlier calculation because of the use of a vastly improved beam model with no change in the track theory or cellular response parameters.
Fission track uranium distribution studies of Apollo 11 lunar volcanic rocks, using Lexan plastic print method
Track densities in 85 feldspar crystals from L-2009 range from 2,500,000 per sq cm to greater than one billion per sq cm. This track distribution represents an intermediate case between what have been previously defined as lightly and heavily irradiated soils and suggests that the Luna 20 sample consists of a mixture of a mature, heavily irradiated component with another, lightly irradiated component. Using a two-component mixing model, the age of the lightly irradiated component is about 270,000,000 yr. It is possible, but by no means certain, that this is associated with the formation of the crater Apollonius C. At about 200 C the ratio of natural thermoluminescence to that induced by a standard irradiation is similar to that in Apollo 12 and 14 cores below about 7 cm. This confirms that most of the Luna 20 sample represents subsurface material.
The major scientific accomplishments through 1971 are reported for the particle track studies of lunar samples. Results are discussed of nuclear track measurements by optical and electron microscopy, thermoluminescence, X-ray diffraction, and differential thermal analysis.
Communications and tracking relay experiment
Information gained from track studies in lunar soils is reviewed. Soil maturity indices are compared and briefly discussed. Track methods to establish the layering chronology of lunar cores are also treated.