93-180

Transfer Trajectories For Distant Retrograde Orbiters Of The Earth*

Cesar A. Ocampo** and George W. Rosborough***

Abstract

A new mission concept is introduced for future astrophysical observatories. This concept is to use a solar orbit that remains bounded to the Earth at a large distance on the order of several million kilometers. These orbits are termed here distant Retrograde Orblts (DRO's). This type of orbit is ideal for a space telescope that needs to be separated from the Earth by a large distance to avoid the near-Earth environmental effects, yet needs to remain bounded within some predefined distance for communication purposes. Another application is for a solar storm warning system that can provide warning times greater than those available from a similar system at the interior libration point of the Sun-Earth/Moon system. Several classes of DRO's in the Sun-Earth/Moon system are presented. The associated launch and insertion energies for impulslve and continuous thrust transfers from a low Earth parking orbit are investigated.
*This research was supported by a NASA Graduate Student Researchers 
Program Followship sponsored through the Goddard Space Right Center.

**Graduate Student, Colorado Center for Astrodynamic9 Research, 
Department ot Aorospaco Engineering Sciences.University of Colorado,
 Campus Box 429, Boulder, Colorado 80309-0429

***Professor, Department of Aerospace Engineering Sciences, University 
ot Colorado, Campus Box 429, Bouldor, Colorado 80309-0429.