Thursday, February 16, 2012

1202.3248 (Elisa Maria Alessi et al.)

Desaturation Maneuvers and Precise Orbit Determination for the
BepiColombo Mission

Elisa Maria Alessi, Stefano Cicalo', Andrea Milani, Giacomo Tommei
The purpose of this work is the analysis of the consequences that
desaturation maneuvers can have in the precise orbit determination
corresponding to the Radio Science Experiment (MORE) of the BepiColombo mission
to Mercury. This mission is an ESA/JAXA joint project with very challenging
objectives regarding geodesy, geophysics and fundamental physics. In the
neighborhood of Mercury, the s/c will experience strong solar radiation
pressure torques; the s/c attitude is controlled by inertial wheels that after
some time reach their maximum rotation state. Then they have to be slowed down
by means of thruster pulses, inducing a residual acceleration on the s/c, with
a desaturation (or off-loading) maneuver. In this paper, we will show how such
maneuvers affect the orbit of the s/c and the radio science measurements and,
also, how to include them in the orbit determination and parameter estimation
procedure. The non linear least squares fit we consider is applied on a set of
observational arcs separated by intervals of time where the probe is not
visible. With the current baseline of two ground stations, two maneuvers are
performed per day, one during the observing session, the other in the dark. To
reach the scientific goals of the mission, they have to be treated as "solve
for quantities". We have developed a specific methodology based on the
deterministic propagation of the orbit, which is able to deal with these
variables, by connecting subsequent observational arcs in a smooth way. The
numerical simulations we will show demonstrate that this constrained multi-arc
strategy is able to determine the maneuvers, including the ones in the dark,
together with the other parameters of interest at a high level of accuracy. The
future development consists in including accelerometer readings and
calibrations in the method.
View original:

No comments:

Post a Comment