# Accession Number:

## AD0678052

# Title:

## OPTIMUM THREE-DIMENSIONAL DEORBIT FOR SPECIFIC REENTRY ANGLE FROM ELLIPTICAL ORBITS,

# Descriptive Note:

# Corporate Author:

## AEROSPACE CORP EL SEGUNDO CALIF SYSTEMS ENGINEERING OPERATIONS

# Personal Author(s):

# Report Date:

## 1968-08-01

# Pagination or Media Count:

## 65.0

# Abstract:

The minimum impulsive velocity requirements for three-dimensional deorbit from elliptical orbits to achieve a specified reentry angle are analyzed. This analysis, representing an extension of a previous study of deorbit from circular orbits, considers two cases the first case determines the optimum impulsive velocity for a given reentry angle and a given heading angle change the second treats the problem of a given reentry angle and a given earth-central cross-range angle. Significant variations of the minimum impulsive velocity requirement result when the specified position of deorbit changes between the apogee and the perigee. For the first case, the minimum-impulse solution results in both pure retro and oriented retro for deorbit from the perigee, depending upon the values specified for the plane change and the reentry angle. Deorbit from the apogee, on the other hand, always results in a pure retro solution for minimum impulse deorbit from a general position in orbit always results in an oriented retro solution. A global optimum representing a minimum deorbit impulse by allowing variations in both the deorbit location and the orientation of the impulse is also studied. For the second case, the magnitudes of optimum impulsive velocity for constant values of cross-range angle are approximately equal to those of constant plane change of equivalent value. Author

# Descriptors:

# Subject Categories:

- Spacecraft Trajectories and Reentry
- Ground Support Systems and Facilities for Space Vehicles