Near-circular satellite orbits in an oblate, diurnally varying atmosphere

The influence of air drag and the geopotential on near-circular satellite orbits, eccentricity e < 0.01, is considered. A model of the atmosphere is adopted that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation. Differential equations governing the variation in e and the argument of perigee ω are derived by combining the effects of air drag with those of the Earth’s gravitational field. These are solved numerically using initial conditions obtained from a series of computed orbits of the satellite 1963-27 A. The behaviour of the orbital elements predicted by the numerical solution is compared with the observed elements to test the developed theory, and to obtain values of atmospheric parameters at heights near 400 km.

1966 ◽  
Vol 25 ◽  
pp. 281-287 ◽  
Author(s):  
P. E. Zadunaisky

Let bex′=f(t,x) a system of ordinary differential equations, with initial conditionsx(a) =s, which is integrated numerically by a finite difference method of orderpand constant steph.To estimate the truncation and round-off errors accumulated during the numerical process it is established a method based on the current theory of the asymptotic behaviour (whenh→0) of errors. This method should avoid the main difficulties that arise when the results of the theory must be applied to practical cases. The method has been successfully tested and applied to estimate the errors accumulated in a numerical computation of planetary perturbations on the orbit of a comet.


The effect of air drag on satellite orbits of small eccentricity, 0.01 ≾ е ≾ 0.2, is considered. A model of the atmosphere that allows for oblateness, and in which the density behaviour approximates to the observed diurnal variation, is adopted. The equation governing the changes due to drag in the argument of perigee ω , during one revolution of the satellite, is integrated with the assumption that the density scale height H is constant. The resulting expression for e ∆ ω is presented to third order in e . Compact expressions for e ∆ ω and e ∆ ω / ∆ T D , where ∆ T D is the corresponding change in the period, are obtained when H is allowed to vary with altitude. It is shown that there is an equivalence between the variable- H and the constant- H equations, provided that the value of H used in the latter is chosen appropriately.


1972 ◽  
Vol 71 (3) ◽  
pp. 505-515 ◽  
Author(s):  
J. R. Cash

AbstractA general method is given and illustrated by application to particular cases for obtaining subdominant solutions of stiff difference and differential equations, i.e. when rapidly varying solutions – transients or otherwise – are possible but are in fact excluded by the initial conditions.


1974 ◽  
Vol 76 (2) ◽  
pp. 443-456
Author(s):  
J. R. Cash

AbstractAlgorithms are developed for the numerical solution of systems of first-order ordinary differential equations, the solutions of which have widely different rates of variation. The iterative procedures described use a step length of integration proportional to the rate of change of the required slowly varying solution in a region of integration, where either the transient components of the complete solution have become negligible compared with the chosen working accuracy or in a region where rapidly increasing components of the solution are theoretically possible but are made absent by the initial conditions. Several numerical examples are given to demonstrate the algorithms.


1964 ◽  
Vol 1 (5) ◽  
pp. 513-519 ◽  
Author(s):  
J. OTTERMAN ◽  
K. LICHTENFELD

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