Martin Grimm, Jena-Optronik
Sebastian Colditz, Jena-Optronik
Reinhard Berger, Jena-Optronik
Steffen Hahn, Jena-Optronik
Steffen Schwarz, Jena-Optronik
Uwe Schmidt, Jena-Optronik
Martin Grimm, Dr., Jena-Optronik
The ASTRO© CL is Jena-Optronik’s compact star tracker, which is optimized for small satellites and constellations. The core driver of the ASTRO© CL design is bringing radiation robustness to compact constellation class star trackers. This goal is achieved by combining the system-on-chip FaintStar2 detector with specifically selected EEE-parts and radiation-hard optics as well as advanced image processing algorithms, which provide stable and robust performance up to end of life conditions. Hence, the tracker is suited for missions in the environmentally challenging high LEO orbits between 1200 km and 1400 km.
The compact design of the ASTRO© CL star tracker allows its integration on small satellites. The footprint is 60 x 60 mm². It is equipped with a stray-light blocking baffle that reduces the sun exclusion angle to a 26° half cone angle. With the baffle the overall height is 128.2 mm and the diameter of the baffle is 64 mm at the top. The overall weight is below 310 g. The power consumption of the optical head does not exceed 1.2 W.
The ASTRO© CL star trackers are delivered with the ASTROlib control software library, which is easily integrated into the onboard computer systems and already supports multiple architectures (e.g. LEON3/4, PowerPC and different ARM systems). Integrating the star tracker library directly into the onboard computer allows a more compact design of the star tracker. The included noise removal algorithms enable retention of the on-orbit performance for ten years and more even in the 1400 km orbits. The library also supports photo modes enabling the camera functionality of the ASTRO© CL.
With the ASTRO© CL being more compact than previous star tracker generations, also more compact optical ground support equipment has been developed. This includes the Optical Star Pattern Simulator (OSPS), which is equipped with an alignment mirror cube. The OSPS allows aligning the ASTRO© CL on small satellites with similar precision as for established “large” star trackers like the ASTRO© APS. In contrast to the large star trackers there is no need for a mirror cube directly attached to the ASTRO© CL. Hence, reducing the star tracker’s mass and foot print.
The demand for high volume production in the constellation satellite market calls for efficient manufacturing, assembly, integration and test capabilities as well as processes. Jena-Optronik has established new production and test approaches that allow the completion of more than 12 units per week currently; aiming to reach a continuous output of 20 units per week within the coming year. This is enabled by the ASTRO© CL design with a reduced number of individual parts. The design features a single integrated central imaging and electronics board, which is assembled in highly automated processes. As a final manufacturing step, the new test approach allows to run streamlined acceptance tests for multiple units in parallel.
In this contribution, we present the ASTRO© CL design and performance with the ASTROlib. We summarize the design features that allow an optimal combination of compactness, performance and radiation hardness for satellite constellations. Moreover, we introduce the high precision alignment concept of the OSPS ground support equipment, which replaces having a mirror cube on each single star tracker.