Satellite laser ranging to GNSS-based Swarm orbits with handling of systematic errors

Abstract

Satellite laser ranging (SLR) retroreflectors along with GNSS receivers are installed onboard numerous active low earth orbiters (LEOs) for the independent validation of GNSS-based precise orbit determination (POD) products. SLR validation results still contain many systematic errors that require special handling of various biases. For this purpose, we derive methods of reducing systematic effects affecting the SLR residuals to LEO Swarm satellites. We test solutions incorporating the estimation of range biases, station coordinate corrections, tropospheric biases, and horizontal gradients of the troposphere delays. When estimating range biases once per day, the standard deviation (STD) of Swarm-B SLR residuals is reduced from 10 to 8 mm for the group of high-performing SLR stations. The tropospheric biases estimated once per day, instead of range biases, further reduce the STD of residuals to the level of 6 mm. The systematic errors that manifest as dependencies of SLR residuals under different measurement conditions, e.g., elevation angle, are remarkably diminished. Furthermore, introducing troposphere biases allows for the comparison of the orbit quality between kinematic and reduced-dynamic orbits as the GPS-based orbit errors become more pronounced when SLR observations are freed from elevation-dependent errors. Applying tropospheric biases in SLR allows obtaining the consistency between the POD solution and SLR observations that are two times better than when neglecting to model of systematic effects and by 29% better when compared with solutions considering present methods of range bias handling.

A Simulation Study for Future Geodetic Satellites Tracked by Satellite Laser Ranging

“…The SLR technique can theoretically provide precise measurements to retroreflector arrays on Earth satellites, even to within 1 mm for the core tracking stations. Despite the high precision, the main problems that stations are struggling with are the systematic errors, for example, range biases, timing biases or elevation‐dependent biases (Arnold et al., 2019; Otsubo et al., 2019; Strugarek et al., 2022). Range biases can be assigned to different sources at the stations, for example, imperfect calibration, hardware malfunctioning, limitations in background models, or to modeling deficiencies in referring to the range measurements to the center of mass of the spacecraft (Luceri et al., 2019; Tapley et al., 1985).…”

A simulation study for future geodetic satellites tracked by satellite laser ranging

“…The SLR technique theoretically can provide precise measurements to retroreflector arrays on Earth satellites, even at a level of 1 mm for the core tracking stations. Despite high precision, the main problems that stations are struggling with are the systematic errors, e.g., range biases, timing biases or elevation-dependent biases (Strugarek et al 2022, Otsubo et al 2019. Range biases can be assigned to different sources at the stations, e.g., imperfect calibration, hardware malfunctioning, limitations in background models, or to modeling deficiencies in referring to the range measurements to the center of mass of the spacecraft (Tapley et al, 1985;Luceri et al, 2019).…”

Determination of Precise Galileo and Sentinel-6A Orbits through the Integration of GNSS and SLR Data

“…When determining the orbit of Galileo satellites, the addition of SLR observations helps to improve orbit stability (Hackel et al, 2015). Appropriately processed SLR observations can enhance the orbital quality of LEO satellites (Strugarek et al, 2022). Incorporating GNSS observations from LEO satellites in the GNSS POD process could bring a signiőcant improvement in the orbit accuracy compared with that utilizing only GNSS observations from ground stations (Li et al, 2019).…”