On February 2012 the small European space transportation system Vega successfully lifted off for its maiden flight from the Kourou spaceport. Vega was specifically developed for placing small-weight satellites into low Earth orbits from the European spaceport. This study aims at designing minimum-time low-thrust transfer solutions from the reference Vega target orbits up to the geostationary Earth orbit, in order to evaluate the possibility of extending the Vega reach to GEO using an electric propulsion thruster. The continuous optimization problem is translated into a nonlinear programming problem using the direct multiple shooting method. To reduce the computational load and rapidly generate optimal trajectories, we apply averaging techniques and semi-analytic relations to describe the vehicle motion. The effects of the more significant disturbing forces are also considered during the entire transfer. It is shown that 1310 kg can be delivered to the target geostationary orbit in 252 days, using a state of the art Hall thruster. The mission is in the range of 5000 m/s, with a typical propellant mass consumption of the order of 25 %. The combination of averaging techniques with a direct optimization method provides optimal transfer solutions, sufficiently accurate for a first order study, in less than 7 hours using a 2.66 GHz processor.
Low-thrust Transfers for the Vega Electric Upper Stage
FINOCCHIETTI, CHIARA;MARCUCCIO, SALVO
2012-01-01
Abstract
On February 2012 the small European space transportation system Vega successfully lifted off for its maiden flight from the Kourou spaceport. Vega was specifically developed for placing small-weight satellites into low Earth orbits from the European spaceport. This study aims at designing minimum-time low-thrust transfer solutions from the reference Vega target orbits up to the geostationary Earth orbit, in order to evaluate the possibility of extending the Vega reach to GEO using an electric propulsion thruster. The continuous optimization problem is translated into a nonlinear programming problem using the direct multiple shooting method. To reduce the computational load and rapidly generate optimal trajectories, we apply averaging techniques and semi-analytic relations to describe the vehicle motion. The effects of the more significant disturbing forces are also considered during the entire transfer. It is shown that 1310 kg can be delivered to the target geostationary orbit in 252 days, using a state of the art Hall thruster. The mission is in the range of 5000 m/s, with a typical propellant mass consumption of the order of 25 %. The combination of averaging techniques with a direct optimization method provides optimal transfer solutions, sufficiently accurate for a first order study, in less than 7 hours using a 2.66 GHz processor.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
