Luni-solar perturbations in the extended phase space representation of the Vinti problem

Perturbation theory is applied to the Vinti problem—motion about an oblate spheroid—to include the gravitational effects of the sun and moon. The problem is formulated using the extended phase space method which introduces a new independent variable similar to the true anomaly. The disturbing Hamiltonian H₁ for third bodies is of order J₂² (second order) and the final goal is a theory including second order short and long period terms and third order secular terms. The current paper however carries the development only to the second order in the secular terms and the first order in the periodic terms. Problems of including the higher orders are discussed. Therefore, in the development of H₁ all terms of order 10^?9 or larger are retained. The lunar emphemeris retains terms to e′² in the lunar eccentricity. The perturbation analysis is carried out by means of Lie series and is developed through the first order only which is consistent with the final accuracy desired. The generating function W₁ is obtained and separated into the long period, short period and secular terms. From W₁ the coordinates are defined from the Lie series by means of a transformation equation. These coordinates are non-singular for small eccentricity and inclination. Because of the complexity of the equations all algebraic computations were accomplished by means of a computerized Poisson series manipulator developed at the Naval Research Laboratory.     

A skeptic's view of PLR effects in the magnetosphere

A critical appraisal is made of the hypothesis that power-line harmonic radiation can influence the Earth's radiation belts by triggering intense magnetospheric emissions which in turn resonantly scatter trapped electrons into the atmospheric loss cone. While such triggering may indeed occur, a combination of theoretical arguments supplemented by an indepth analysis of OGO-5 satellite data is employed to show that triggered waves comprise at best a small fraction of the total magnetospheric wave population. Previous claims to the contrary have been either based on erroneous statistical arguments or biased by the limited sample of ducted waves detectable by ground based receivers. The totality of satellite data is consistent with a predominantly natural origin for the two classes of electromagnetic waves (chorus and plasmaspheric hiss) which are known to interact strongly with energetic radiation belt electrons.     

The magnetic fields of Mercury,Venus and Mars

Just as clearly as Mariner 10 established that Mercury has an intrinsic magnetic field, the Pioneer Venus orbiter has established that Venus has no significant intrinsic field. This is perhaps the opposite of what might be expected. Mercury, a small planet might be expected to cool rapidly and its internal dynamo to cease, while Venus, which is almost as large as the Earth, should not have lost much heat. On the contrary the source of energy of the Mercury dynamo appears to be extant whereas that of Venus appears to be extinct.The existence of a Martian magnetic field is controversial. No unambiguous signature of a Martian magnetic field has been reported. If the field on the nightside of Mars is of planetary rather than solar origin the Russian Mars spacecraft observations indicate the Martian dipole lies near the planetary equator rather than its pole.     

Nonlinear Analysis of a Family of LC Tuned Inverters

four widely used self-oscillating dc-to-square-wave parallel inverters which employ an inductor-capacitor tuned network to determine the oscillation frequency are reduced to a common equivalent RLC network. The techniques of singular-point analysis and state-plane interpretations are employed to describe the steady-state and transient ient behavior of these circuits and to elucidate the three possible modes of operation: quasi-harmonic, relaxation, and discontinuous. Design guidelines are provided through a study of the influence of circuit parameter variations on the characteristics of oscillation and on frequency stability. Several examples are provided to illustrate the usefulness of this analysis when studying such problems as transistor emitter-to-base junction breakdown during oscillations and the design of starting circuits to insure self-excited oscillations in these inverters.     

Effects of air velocity on photosynthesis of plant canopies under elevated CO2 levels in a plant culture system.

To obtain basic data for adequate air circulation for promoting plant growth in closed plant production modules in bioregenerative life support systems in space, effects of air velocities ranging from 0.1 to 0.8 m s-1 on photosynthesis in tomato seedlings canopies were investigated under atmospheric CO2 concentrations of 0.4 and 0.8 mmol mol-1. The canopy of tomato seedlings on a plug tray (0.4 x 0.4 m2) was set in a wind-tunnel-type chamber (0.6 x 0.4 x 0.3 m3) installed in a semi-closed-type assimilation chamber (0.9 x 0.5 x 0.4 m3). The net photosynthetic rate in the plant canopy was determined with the differences in CO2 concentrations between the inlet and outlet of the assimilation chamber multiplied by the volumetric air exchange rate of the chamber. Photosynthetic photon flux (PPF) on the plant canopy was kept at 0.25 mmol m-2 s-1, air temperature at 23 degrees C and relative humidity at 55%. The leaf area indices (LAIs) of the plant canopies were 0.6-2.5 and plant heights were 0.05-0.2 m. The net photosynthetic rate of the plant canopy increased with increasing air velocities inside plant canopies and saturated at 0.2 m s-1. The net photosynthetic rate at the air velocity of 0.4 m s-1 was 1.3 times that at 0.1 m s-1 under CO2 concentrations of 0.4 and 0.8 mmol mol-1. The net photosynthetic rate under CO2 concentrations of 0.8 mmol mol-1 was 1.2 times that under 0.4 mmol mol-1 at the air velocity ranging from 0.1 to 0.8 m s-1. The results confirmed the importance of controlling air movement for enhancing the canopy photosynthesis under an elevated CO2 level as well as under a normal CO2 level in the closed plant production modules.     

On state estimation for an orbiting single tether system

The effects of instrumentation accuracy and configuration on estimation error are studied for the small expandable-tether deployment system (SEDS) using a continuous-discrete extended Kalman filter (CDEKF) state estimator. A twelfth order model that incorporates the rigid body modes of the tether as well as the satellite attitude dynamics is developed. Simulation results using the model and the estimator indicate that the originally planned instrumentation package could not estimate the state vector adequately. Recommendations are made and results presented that reduce the estimation error by adding instruments and increasing selected measurement accuracies     

Observations of the profiles of solar UV emission lines and their analysis in terms of the heating and production of the corona

Observations of the solar spectrum have been made between 1200–2200 with high spectral resolution. The results were obtained with an all-reflecting echelle spectrograph carried by a stabilized Skylark rocket launched in April 1970. Measurements of the profiles of a number of emission lines due to Siii, Cii, Siiii and Civ formed in the temperature range 10⁴-10⁵ K, indicate ion energies which are considerably in excess of the electron temperatures derived from the ionization balance. Since the ion/electron relaxation time is very short the observed ion energies cannot correspond to an ion temperature and hence a non-thermal mechanical energy component exists in the transition zone.It is postulated that the non-thermal energy component represents the actual mechanical energy responsible for the heating of the corona, and, that, it is propagated as an acoustic wave. On this basis and with a preliminary estimate of the reflection from the transition zone, a flux of 3 × 10⁵ erg cm ^-2 s ^-1 is established as entering the corona. This value is in agreement with estimates of the total energy loss from the corona due to conduction, radiation and the solar wind, thus establishing a gross energy balance.Theoretical calculations are currently underway to establish the physical nature of the atmosphere which would result from such a propagating flux. At the present time this has been carried out for an atmosphere in hydrostatic equilibrium and the energy balance equation solved. A preliminary temperature structure which results is shown in Figure 1, together with the derived distribution in electron density. This gives a corona of the right temperature and density but the observed structure deviates in detail from those derived from an analysis of the solar XUV spectrum.