Projects per year
Abstract
A polesitter orbit is a closed path that is constantly above one of the Earth's poles, by means of continuous low thrust. This work proposes to hybridize solar sail propulsion and solar electric propulsion (SEP) on the same spacecraft, to enable such a polesitter orbit. Locallyoptimal control laws are found with a semianalytical inverse method, starting from a trajectory that satisfies the polesitter condition in the SunEarth circular restricted threebody problem. These solutions are subsequently used as first guess to find optimal orbits, using a direct method based on pseudospectral transcription. The orbital dynamics of both the pure SEP case and the hybrid case are investigated and compared. It is found that the hybrid spacecraft allows savings on propellant mass fraction. Finally, it is shown that for sufficiently long missions, a hybrid polesitter, based on midterm technology, enables a consistent reduction in the launch mass for a given payload, with respect to a pure SEP spacecraft.
Original language  English 

Pages (fromto)  847859 
Number of pages  13 
Journal  Journal of Guidance, Control and Dynamics 
Volume  34 
Issue number  3 
DOIs  
Publication status  Published  May 2011 
Keywords
 polesitter orbit
 hybrid propulsion
 trajectory optimisation
 earth observation
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Projects
 1 Finished

VISIONSPACE  VISIONARY SPACE SYSTEMS: ORBITAL DYNAMICS AT EXTREMES OF SPACECRAFT LENGTH SCALE (ERC ADVANCED GRANT)
McInnes, C.
European Commission  FP7  European Research Council
1/02/09 → 30/09/14
Project: Research