Segmenting Star Images with Complex Backgrounds Based on Correlation between Objects and 1D Gaussian Morphology

Space object recognition in high Earth orbits (between 2000 km and 36,000 km) is affected by moonlight and clouds, resulting in some bright or saturated image areas and uneven image backgrounds. It is difficult to separate dim objects from complex backgrounds with gray thresholding methods alone. In this paper, we present a segmentation method of star images with complex backgrounds based on correlation between space objects and one-dimensional (1D) Gaussian morphology, and the focus is shifted from gray thresholding to correlation thresholding. We build 1D Gaussian functions with five consecutive column data of an image as a group based on minimum mean square error rules, and the correlation coefficients between the column data and functions are used to extract objects and stars. Then, lateral correlation is repeated around the identified objects and stars to ensure their complete outlines, and false alarms are removed by setting two values, the standard deviation and the ratio of mean square error and variance. We analyze the selection process of each thresholding, and experimental results demonstrate that our proposed correlation segmentation method has obvious advantages in complex backgrounds, which is attractive for object detection and tracking on a cloudy and bright moonlit night.

Study of a population of space debris objects with a high area-to-mass ratio in high Earth orbits

The data on 498 space debris objects with a high area-to-mass ratio (HAMR) detected in 2016–2017 were analyzed to identify possible candidates for the role of "parent objects". As a result, the origin of several HAMR fragments was determined. These fragments separated from three different large objects in the geostationary orbit (GEO) region, including two functioning spacecraft and one rocket launcher stage. Observations of these three objects showed that there were no noticeable differences in their light curves, which indicates the absence of significant changes in the geometric shape, reflective characteristics and motion parameters relative to the center of mass. At least, both spacecraft continued to perform retention maneuvers in their positions on the GEO, and no unpredictable changes were detected in the orbital motion and in the stage light curve. Therefore, the formation of newly discovered fragments cannot be associated with the catastrophic destruction of the “parent objects”.