Design and commissioning of a transportable laser ranging station STAR-C

A fast growing population of nano- and mirco satellites, space debris, as well as plans of installing mega constellations drives the demand for the development of new ground stations technologies. The Institute of Technical Physics of the German Aerospace Center (DLR) focuses its research on optical methods in order to track and range orbital objects for precise orbit determination. Laser ranging is an inherently accurate method to determine an object’s distance where sub-mm accuracy is achieved by the contributing stations within the International Laser Ranging Service (ILRS). Usually the orbits of space debris are determined with radar based observations and maintained in catalogues, for example the TLE data by NORAD. Multiple optical ground stations can contribute significantly to support catalogue maintenance or to refine orbits of particular orbital objects. Laser ranging data does not only measure the slant range to an object, but also can give rise to the state of propagation, if the single shot accuracy of the laser pulse is shorter than the apparent dimension of the object. Currently there is work in progress to build a transportable laser ranging station into a standard 20ft ISO container, which takes up its initial operation during the second half of this year. A platform raises two telescopes in a bi-static set-up on an alt-az mout above the roof of the container. Each axis of the alt-az mount is driven with direct mounts, where absolute encoders give a theoretical angular resolution of 1/50 arcsec. One telescope with an aperture of 10cm is used for the transmit channel of a pulsed infrared laser an including active beam stabilization. The other telescope, the receive channel, with an aperture of 43cm a beam-splitter separates the visible light on a camera for tracking and the infrared light on a fiber-coupled single photon detector for ranging