In cadrul unei cooperari intre firma BITNET s.r.l.,Observatorul Astronomic din Cluj al Academiei Romane si Universitatea Tehnica din Cluj, in urma cu un an am demarat proiectul LEOSCOPE (Experimental Low Earth Orbit Surveillance Stereoscope) prin care testam posibilitatile de detectare optica si determinarea traiectoriei obiectelor ca se deplaseaza in apropierea Pamantului ( 200km-1000km). Principiul de baza este asemanator vederii stereoscopice, adica vom amplasa doi senzori optici identici, in doua locatii diferite aflate la aproximativ 37 km departare unul de celalalt. in acvest mod, vom avea un camp destul de larg de vedere stereoscopica. In mod simultan, folosind acelas standard de timp, se capteaza imagini ale zonei de interes. Printr-o prelucrare soft adecvata, se pot pune in evidenta diverse obiecte cu lumina proprie sau iluminate de Soare si se poate determina cu o oarecare precizie, pozitia lor si traiectoria.
Proiectul a fost prezentat in "abstract" la a X-a conferinta internationala AMOS ( Advanced Maui Optical and Space Surveillance Techologies Conference) desfasurata in septembrie 2009 la Maui, Hawaii. Aceasta Conferinta este considerata, de multi ani, un loc unde cei mai buni specialisti din lume se intalnesc sau isi comunica cercetarile referitoare la supravegherea optica a spatiului cosmic. In Hawaii , langa Maui, este amplasata una din cele mai performante facilitati al U.S. Air Force dedicate supravegherii optice. De altfel, multe lucrari prezentate sau publicate au ca autori cercetatori cunoscuti ai universitatilor americane sau ale fortelor armate ale S.U.A.
Puteti citi mai jos in original abstractul publicat:
Ultra-Wide Field of View Stereoscope for Low Earth Orbits Surveillance
Octavian Cristea, Paul Dolea
BITNET CCSS (The 10th Advanced Maui Optical and Space Surveillance Techologies Conference Maui, Hawaii, September 1-4 2009)
Optical detection of LEO objects with unknown orbital parameters is problematic. In a wide area search mission, an optical sensor collects frames of data on consecutive directions in order to find objects in its range of detection. Taking into account that a LEO object is fast moving on the sky and the visibility window is very small (the sky is clear, the sensor is in the Earth’s shadow and the object is above the horizon and illuminated), and taking into account a typical surveillance sensor FOV of less than one degree, the probability to detect unknown objects is very small. Another limitation is that accurate determination of the target’s position requires correlation of data from more than one passive sensor (a single passive sensor suffers from an inability to get unambiguous range data, even against fairly deterministic tracks such as satellites).
This paper examines the setup of a ground-based stereoscopic imager which can detect LEO objects and provide data regarding their orbits. In its minimal configuration, the stereoscope consists of a pair of (COTS) large aperture ultra-wide FOV lenses, backed with a high-quality CCD. While an ultra-wide FOV camera raises problems related to the detection magnitude and orbit estimation accuracy, such a camera significantly increases the probability of unknown objects detection.
The stereoscopes base-line is of the order of tens of Km, a compromise between simultaneous detection of low altitude objects from two locations and triangulation accuracy. Each camera continuously images the night sky and sends captured images to a local computer for off-line data processing. Each computer has a GPS card for pair cameras synchronization and it is connected to internet through a Ku band VSAT.
Geometric calibration of the image is made automatically, by matching captured stars in the image with an astronomical catalogue of stars. Making interpolation between these reference points, the computer attaches astronomical coordinates to each pixel of the sky image. This way, many errors due to light propagation through the atmosphere or f-Theta distortion can be corrected. The recovery of orbital depth is made by correlating matching feature points from pairs of simultaneous images. Since any pair of captured images practically contains the same star field, another application of the stereoscope is to produce 3D images of the night sky with LEO objects floating in front of the star field.
This project is in the concept development phase and it is based on a research cooperation agreement between BITNET CCSS, the Technical University of Cluj and the Astronomical
Observatory of Cluj.