Space debris of the film Gravity
1. Intro
OWL (Optical Wide-field patroL)
The Optical Wide-field Patrol (OWL) network is a project designed for the surveillance of space objects such as artificial satellites, rocket bodies and their debris, which can threaten a country’s space & ground properties, as well as human life. To achieve this surveillance, multiple optical telescopes will be built all around the world. These telescopes are small (0.5 m in aperture), operated automatically, and controlled by staff in a single headquarter. The observation images from these telescopes must be reduced quickly and automatically, and sent to the headquarter daily. The image reduction procedure of OWL should include detection of bright sources from the images, identification and separation of traces of moving objects from them, determination of physical & positional parameters of the detected moving object, and finally, combining with the time log data. As such, the development of a reduction algorithm that can be operated on the remote sites is essential.
OWL-Net Mongol site
Satellite line detection
Since the development of the Baker-Nunn camera, which was the first dedicated optical satellite tracking network system, various types of optical systems have been developed. Although tracking of LEO satellites is now mostly performed using radar systems, usage of optical systems is still increasing for the determination of GEO satellite orbits. Optical systems have obvious disadvantages compared with radar systems for LEO object tracking, but the cost and technology of an optical tracking system make this type of system more accessible for most users. Currently, most technologies for making optical tracking systems such as optics, mechanical designs, control electronics, and detectors are produced at a much higher level compared with the Bake -Nunn camera era. If we are interested in tracking only tens or a few hundreds of objects rather than tens of thousands, an optical tracking system can be a cost-effective alternative for satellite tracking.
The OWL TC and DT system
The block diagram of DT system
The primary goal of the OWL-Net (Optical Wide-field patroL Network) is to acquire and maintain orbital information of LEO satellites by purely optical means. To overcome the limits of optical observation, we need a global network of telescopes that operate completely autonomously. Optics should be designed to get a satellite safely into the field of view with TLE data and the mount system should be fast enough not only to get several shots in a single pass but also to follow the satellite. We have designed a detector system capable of taking many points in a single shot. For easy maintenance, we have designed a custom-made telescope control system in which the whole system is designed using a unit base for easy replacement when needed.
Shape parameters of a streak detected using SExtractor
Each observatory is controlled by one master computer; called the Site Operating Sever (SOS). This computer is always connected to headquarters (HQ). The SOS maintains scheduling information transferred from HQ and commands observation according to the schedule. After observation, the detector system reduces observation data into time and coordinates in an ASCII form and transfers them to HQ through the SOS. All the environmental data are gathered into a single custom-made environmental control board and then transferred to HQ through the SOS. CCTVs, located both inside and outside the dome, continuously monitor the current status of the observatory and selectively captured images are also transferred to HQ in near real time.
OWL Monitoring Software Interface
OWL webpage
