Investigation of Conditions for Plane Autorotation of a Spacecraft Entering the Atmosphere

Using the method of averaging, the condition is derived of the regime of plane autorotation for an axisymmetric spacecraft at its initial stage of reentry into the atmosphere, where one can assume the velocity head to be an exponential function of time. The results obtained by this method are compared with the results of numerical calculations. Special attention is given to the regimes of long spacecraft hovering in the vicinity of an unstable equilibrium position. Analytical estimates are made for these regimes.     

Experimental Flight of a Spacecraft with Solar Sail

We analyze the prospects of launching an experimental spacecraft with a solar sail. The problems hindering the implementation of this task are discussed. The ways to solve these problems are pointed out. The feasibility of organization of a system of controlling this spacecraft with a small consumption of propellant mass is briefly investigated.     

Determination of the width of a corridor of re-entry into the atmosphere for the problem of launching a spacecraft into a circumplanetary orbit after braking in the atmosphere

A method of calculating the optimal trajectories of a spacecraft re-entry into the atmosphere is considered under the condition of minimization of a re-orbit burn at the apocenter of the segment of escape from the atmosphere and taking into account a constraint on the maximum overload.     

Semianalytic estimations of boundaries of a corridor of spacecraft entry into the planetary atmosphere at considerable values of permissible maximum overload

Trajectories of spacecraft entry into the planetary atmosphere with a velocity essentially exceeding the first cosmic velocity are considered. An estimation of the minimum permissible value of the altitude of conditional pericenter (perigee in the case of the Earth), at which extreme permissible value of maximum overload is reached, is of the main interest. Semianalytic formulas including the cases of considerable values of the maximum overload are suggested.     

Estimation of a Satellite Lifetime in Orbit

An approximate technique for calculating the satellite orbit decay under the aerodynamic drag effect for arbitrary values of the orbit eccentricity and for the realistic model of the altitude dependence of the atmospheric density is proposed.