A Method for Optical Tracking of On-Orbit Servicing Operations in Geostationary Orbit Using Speckle Interferometry

On-Orbit Servicing (OOS) missions in geostationary orbit with inter-satellite separations less than one kilometer pose a problem for ground-based electro-optical space surveillance sensors. The tight separations between space objects subtend angles comparable to the size of turbulence (seeing) cells of Earth’s atmosphere making classical ground-based space surveillance detection approaches problematic. Speckle interferometry using a cross-spectrum approach was explored in this research to overcome atmospheric turbulence and enable ground-based measurement of the relative positions of OOS satellites without use of adaptive optics. Field testing of this technique using a medium aperture telescope on co-located geostationary satellites, acting as OOS proxies, found that cross-spectrum speckle interferometry measurements can obtain in-track and cross-track relative position precisions better than 100 meters when the satellites’ apparent angular separations were less than 5 arcseconds. The cross-spectrum method was found to be susceptible to high fringe rotation rates inducing incorrect separation measurements during times when the co-located satellites were at their closest point of approach. While this effect produced spurious fringes during co-located satellite observation tests, this effect is not expected to be encountered during observation of a true OOS mission. Brightness differences did not pose a significant observational limitation as brightnesses of Mprimary = 10.2, Δm = 0.3 and Mprimary = 9.1, Δm = 1.5 were speckled successfully and relative position estimates obtained. Additional testing with small aperture telescope achieved similar brightness and positional measurement performance. Due to the plane-of-sky differential angle observations of the objects a partial observability condition is encountered where the radial component of the servicer’s motion requires more than three hours of observations to converge on a relative orbit solution. The near collinear alignment of the detector with the in-track and cross-track directions causes this partial observability condition. Fortunately, due to the dynamic coupling between the in-track and radial directions of relative orbital motion, the radial component can be estimated and the time to converge is largely dependent on the measurement precision.

Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.