BeiDou satellite radiation force models for precise orbit determination
and geodetic applications
Abstract
China’s BeiDou satellite navigation system (BDS) has completed its full
constellation in orbit since June 2020. Services have been evolved from
regional (BDS-2) to global (BDS-3). This contribution evaluates the
impact of solar radiation pressure (SRP) modeling on satellite orbits
and geodetic parameters. To that end, we process 2 years of BDS
observations (2019-2021), collected by a network of 100 ground stations.
A physical a priori box-wing (bw) model based on the estimated optical
properties is introduced. Various physical effects, such as yaw bias,
self-shadowing, radiator emission and thermal radiation of solar panels
are considered. The ECOM (Empirical CODE orbit Model, 5 parameters),
ECOM+along-track and ECOM2 (both 7 and 9 parameters) models are employed
on top of the a priori box-wing model in the experiment. We show that
without the use of the a priori box-wing model, the ECOM+along-track
model shows clear better orbit solutions during eclipse seasons for
BDS-3 satellites. This is proven to be mainly due to the thermal
radiation of solar panels. However, the along-track acceleration is
highly correlated with LOD (length of day) and ECOM parameters. LOD
estimates in this case are contaminated. The STD (standard deviation) of
daily LOD estimates with respect to IERS-C04-14 series increases from 40
us (ECOM) to 85 us (ECOM+along-track). After the consideration of the a
priori boxwing model, satellite orbital errors are greatly reduced for
all the ECOM models. For instance, orbit misclosures of BDS-3 CAST
(China Academy of Space Technology) satellites improve by a factor of
two for the ECOM model during eclipse seasons; dependencies of SLR
(satellite laser ranging) residuals on the sun elongation angle almost
vanish for BDS-3 satellites. Furthermore, the use of the a priori
box-wing model mitigates a great majority of the spurious signals in the
geodetic parameters. In particular, the total amplitude of the 1, 3, 5,
7 cpy signals for the geocenter Z component has been reduced by a factor
of 4.5 for the ECOM model. In general, the combination of the introduced
physical a priori box-wing model and the ECOM model is preferred for BDS
satellites.