On the determination of near body orbits using mass concentration models
Mathematical model for near-body orbit calculation using mass concentration, perturbation theory, nonlinear equations, geopotentials, and least squares method
Childs, B.↗
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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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Mechanism for production of the fourth positive band system of CO by electron impact on CO2
Carbon dioxide electron impact energy loss spectrum and molecular orbit calculations, discussing fourth positive bands production in Mars upper atmosphere UV dayglow
Krauss, M.↗
Lunar orbit determination in the presence of unmodeled accelerations
Artificial satellite lunar orbit calculation, representing unmodeled accelerations by first order Gauss-Markov sequence with time correlated and random components
Ingram, D. S.↗
Long-term orbital trajectory determination by superposition of gravity and drag perturbations
Long term orbit calculation by superposition of gravity and drag perturbations, taking into account solar and geomagnetic induced density variations
Pimm, R. S.↗
The design and operation of a planet emitted and albedo radiation simulator
A simulator is described, which provides a dynamic simulation of planetary albedo and planet-emitted thermal radiation. The simulator was designed for model tests of advanced thermal control concepts, the development of space hardware, and flight qualification of small payloads. The simulator was designed to be used in a vacuum chamber equipped with liquid nitrogen cold walls and a solar simulator. The simulator consists of two major components: a gimbaled model support system and an array of quartz infrared lamps. Tests indicate that the apparatus will satisfactorily simulate the secondary radiation on a 0.92-meter spherical body in near-earth orbits. Calculations indicate that other shapes can be accommodated without structural modifications.
Sweet, G. E.↗
Significant Accomplishments in Technology, Goddard Space Flight Center, 1970
Conference on technological developments in satellite communications, tracking, antenna arrays, attitude control, orbit calculations, and instrumentation
Bridger, J. M.↗
Optimal trajectories between Earth and Mars in their true planetary orbits.
The optimal transfers from Earth to Mars and from Mars to Earth, considering the actual planetary orbits, are presented as functions of the corresponding idealized Hohmann transfers. The numerically exact two-impulse optimal trajectories are given in graphical form for all possible Hohmann windows. The two-impulse transfers which are absolute optimals and those for which a third impulse provides the absolute optimal are delineated. These data are designed to provide all the information necessary for quick orbit calculations for preliminary Martian mission analysis. In this form, they are as easy to use as the standard Hohmann transfer approximations and provide much greater accuracy.
Gravier, J. P.↗
Optimum usage of ground stations for GEOS-C orbit determination
Effective utilization of data from the GEOS-C satellite for geoidal mapping was explored. Particular attention was given to the accuracy of orbits calculated from one revolution. Results show one revolution solutions are less affected by geopotential coefficient error than multi-revolution solutions. Data were taken from two global network tracking stations.
Martin, C. F.↗
Effects of inclination and eccentricity on optimal trajectories between earth and Venus
The true optimal transfers, including the effects of the inclination and eccentricity of the planets' orbits, between earth and Venus are presented as functions of the corresponding idealized Hohmann transfers. The method of determining the optimal transfers using the calculus of variations is presented. For every possible Hohmann window, specified as a continuous function of the longitude of perihelion of the Hohmann trajectory, the corresponding numerically exact optimal two-impulse transfers are given in graphical form. The cases for which the optimal two-impulse transfer is the absolute optimal, and those for which a three-impulse transfer provides the absolute optimal transfer are indicated. This information furnishes everything necessary for quick and accurate orbit calculations for preliminary Venus mission analysis. This makes it possible to use the actual optimal transfers for advanced planning in place of the standard Hohmann transfers.
Gravier, J.-P.↗
The study of the physics of cometary nuclei
Research in the area of split and hyperbolic comets, orbital calculations, and interstellar comets is discussed. Other topics discussed include the role of comets in galactic chemistry, gamma ray bursts, and predicted favorable visibility conditions for anomalous tails of comets.
Whipple, F. L.↗
Ocean tides from Seasat-A
Two procedures for the evaluation of global tides from SEASAT-A altimetry data are elaborated: an empirical method leading to the response functions for a grid of about 500 points from which the tide can be predicted for any point in the oceans, and a dynamic method which consists of iteratively modifying the parameters in a numerical solution to Laplace tide equations. It is assumed that the shape of the received altimeter signal can be interpreted for sea state and that orbit calculations are available so that absolute sea levels can be obtained.
Hendershott, M. C.↗
Solution of the exact equations for three-dimensional atmospheric entry using directly matched asymptotic expansions
The problem of determining the trajectories, partially or wholly contained in the atmosphere of a spherical, nonrotating planet, is considered. The exact equations of motion for three-dimensional, aerodynamically affected flight are derived. Modified Chapman variables are introduced and the equations are transformed into a set suitable for analytic integration using asymptotic expansions. The trajectory is solved in two regions: the outer region, where the force may be considered a gravitational field with aerodynamic perturbations, and the inner region, where the force is predominantly aerodynamic, with gravity as a perturbation. The two solutions are matched directly. A composite solution, valid everywhere, is constructed by additive composition. This approach of directly matched asymptotic expansions applied to the exact equations of motion couched in terms of modified Chapman variables yields an analytical solution which should prove to be a powerful tool for aerodynamic orbit calculations.
Busemann, A.↗
An alternative option to the dual-probe out-of-ecliptic mission via Jupiter swingby
The possibility of having a high-inclination out-of-the-ecliptic probe complemented by a second probe going from Jupiter to the sun along a rectilinear path (at least for the segment from 0.3 a.u. inward to the sun) is theoretically examined. Orbit calculations of spacecraft trajectories are included.
Colombo, G.↗
Theoretical L-shell Coster-Kronig energies 11 or equal to z or equal to 103
Relativistic relaxed-orbital calculations of L-shell Coster-Kronig transition energies have been performed for all possible transitions in atoms with atomic numbers. Hartree-Fock-Slater wave functions served as zeroth-order eigenfunctions to compute the expectation of the total Hamiltonian. A first-order approximation to the local approximation was thus included. Quantum-electrodynamic corrections were made. Each transition energy was computed as the difference between results of separate self-consistent-field calculations for the initial, singly ionized state and the final two-hole state. The following quantities are listed: total transition energy, 'electric' (Dirac-Hartree-Fock-Slater) contribution, magnetic and retardation contributions, and contributions due to vacuum polarization and self energy.
Chen, M. H.↗
Electron-impact excitation of the low-lying electronic states of HCN
The first study of the low-energy electron-impact excitation of low-lying electronic transitions in the HCN molecule is reported. Measurements were made at incident electron energies of 11.6 and 21.6 eV in the energy-loss range of 3-10 eV, and at scattering angles of 20-130 deg. Inelastic scattering spectra were placed on the absolute cross-section scale by determining first the ratio of inelastic-to-elastic scattering cross sections, and then separately measuring the absolute elastic scattering cross section. Several new electronic transitions are observed which are intrinsically overlapped in the molecule itself. Assignments of these electronic transitions are suggested. These assignments are based on present spectroscopic and cross-sections measurements, high-energy electron scattering spectra, optical absorption spectra, and ab initio molecular orbital calculations.
Chutjian, A.↗
Candidate interstellar molecules formed from ion-molecule reactions of NO
Molecular orbital calculations using the MINDO/3 method were performed on a series of small molecules to explore reactions of NO which could lead to formation of interstellar molecules. Specifically, equilibrium geometries, isomeric energies, heats of reactions, and reaction pathways were calculated for plausible ion-molecule reactions involving NO and NO(+). The results of these calculations suggest that HNO(+) and HON(+) could be present in observable abundance in interstellar clouds. These species can be formed by the reaction of NO with H3(+) but not by NO(+) with H2. Moreover, they are stable to dissociation and do not react with H2 to re-form NO or to form isomers of HNOH(+).
Loew, G. H.↗
Fifth Annual Flight Mechanics/Estimation Theory Symposium
Various aspects of astrodynamics are considered including orbit calculations and trajectory determination. Other topics dealing with remote sensing systems, satellite navigation, and attitude control are included.
Teles, J.↗
Charged dust in the outer planetary magnetospheres. III - Satellite impact geometries
Interplanetary dust grains entering the Jovian plasmasphere become charged, and those in a certain size range get magneto-gravitationally trapped in the corotating plasmasphere. The trajectories of such dust grains intersect the orbits of one or more of the Galilean satellites. Orbital calculations of micron sized dust grains show that they impact the outermost satellite Callisto predominantly on its leading face, while they impact the inner three - Io, Europa and Ganymede - predominantly on the trailing face. These results are offered as an explanation of the observed brightness asymmetry between the leading and trailing faces of the outer three Galilean satellites. The albedo of Io is likely to be determined by its volcanism.
Hill, J. R.↗