SST Anywhere—A Portable Solution for Wide Field Low Earth Orbit Surveillance

The low-Earth orbit (LEO) is filled with active satellites, but also with space debris, which need constant observation. The orbiting objects may be affected by collisions or by atmospheric drag, and therefore they can change their orbit or even fall to the ground, a process known as reentry. The low altitude of these objects (below 2000 km, usually even below 1000 km) means that at given time they can be observed from a limited range of locations on the Earths’ surface, and therefore having multiple, easy to set up observation stations can be extremely useful. This paper presents a portable hardware solution for on-demand wide-field surveillance of the LEO region, the image processing algorithms for detecting the satellite streaks and for joining these streaks into tracklets, and the solution for astrometrical reduction and generating the result file for each tracklet. An automatic validation solution that is able to automatically identify the detected satellites and compute the measurement angular errors is also presented. The acquisition and processing system is built with commercially available items of low and moderate costs and is capable of on-site acquisition and real-time processing of images. The acquired images are processed by background subtraction, analysis of the difference between frames, extraction of elongated objects corresponding to the satellite streaks, and forming trajectories (tracklets) from consecutive detections. The pixel coordinates of the tracklets are converted to angular coordinates using the tools from Astrometry.net, subsequently filtered for improving the accuracy. The results are validated by using daily updated orbital parameters (TLEs), which are used to predict the angular positions that are subsequently matched with the detection results

SST Anywhere—A Portable Solution for Wide Field Low Earth Orbit Surveillance

The low-Earth orbit (LEO) is filled with active satellites, but also with space debris, which need constant observation. The orbiting objects may be affected by collisions or by atmospheric drag, and therefore they can change their orbit or even fall to the ground, a process known as reentry. The low altitude of these objects (below 2000 km, usually even below 1000 km) means that at given time they can be observed from a limited range of locations on the Earths’ surface, and therefore having multiple, easy to set up observation stations can be extremely useful. This paper presents a portable hardware solution for on-demand wide-field surveillance of the LEO region, the image processing algorithms for detecting the satellite streaks and for joining these streaks into tracklets, and the solution for astrometrical reduction and generating the result file for each tracklet. An automatic validation solution that is able to automatically identify the detected satellites and compute the measurement angular errors is also presented. The acquisition and processing system is built with commercially available items of low and moderate costs and is capable of on-site acquisition and real-time processing of images. The acquired images are processed by background subtraction, analysis of the difference between frames, extraction of elongated objects corresponding to the satellite streaks, and forming trajectories (tracklets) from consecutive detections. The pixel coordinates of the tracklets are converted to angular coordinates using the tools from Astrometry.net, subsequently filtered for improving the accuracy. The results are validated by using daily updated orbital parameters (TLEs), which are used to predict the angular positions that are subsequently matched with the detection results

Distinctive Morphological Patterns of Complicated Coronary Plaques in Acute Coronary Syndromes: Insights from an Optical Coherence Tomography Study

Optical coherence tomography (OCT) is an ideal imaging technique for assessing culprit coronary plaque anatomy. We investigated the morphological features and mechanisms leading to plaque complication in a single-center observational retrospective study on 70 consecutive patients with an established diagnosis of acute coronary syndrome (ACS) who underwent OCT imaging after coronary angiography. Three prominent morphological entities were identified. Type I or intimal discontinuity, which was found to be the most common mechanism leading to ACS and was seen in 35 patients (50%), was associated with thrombus (68.6%; p = 0.001), mostly affected the proximal plaque segment (60%; p = 0.009), and had no distinctive underlying plaque features. Type II, a significant stenosis with vulnerability features (inflammation in 16 patients, 84.2%; thin-cap fibroatheroma (TCFA) in 10 patients, 52.6%) and a strong association with lipid-rich plaques (94.7%; p = 0.002), was observed in 19 patients (27.1%). Type III, a protrusive calcified nodule, which was found to be the dominant morphological pattern in 16 patients (22.9%), was found in longer plaques (20.8 mm vs. 16.8 mm ID vs. 12.4 mm SS; p = 0.04) and correlated well with TCFA (93.8%; p = 0.02) and inflammation (81.3%). These results emphasize the existence of a wide spectrum of coronary morphological patterns related to ACS