PLATFORM FOR FUTURE OPTICAL SPACE SURVEILLANCE TECHNOLOGY: DLR’s 1.75 M OPTICAL TELESCOPE

Knowledge of the LEO space debris matrix is of key importance for current and future space missions. As past missions have left a substantial amount of debris made of various materials and as LEO traffic increases mainly due to commercial activities, origin and material properties remain often unknown due to space aging, fragmentation, and avalanche effects.
The German Aerospace Center (DLR) has therefore decided to develop passive and active optical surveillance and tracking technologies for LEO. Consequently, DLR initiated a project (MS-LART: Multi-Spectral Large Aperture Receiver Telescope) for an optical telescope with a primary mirror diameter of 1.75 m funded by the Federal Ministry for Economic Affairs and Energy.
The site of the telescope observatory is located near the village of Empfingen within commuting distance of the Institute of Technical Physics in Stuttgart. The observatory including the dome is 15 m in height and 8.5 m in diameter, and features operator and telescope levels. The telescope itself is based on a Ritchey-Chrétien design with a primary mirror diameter of 1.75 m, has four Nasmyth foci, and a Coudé path option. An astrograph with a field of view of >3° is mounted piggyback to enable large field of view sky surveys. Optical link budget calculations for laser ranging estimate that space debris in the size of <10 cm can be actively tracked.
The telescope platform will be used to develop and specify instrumentation for (eye-safe) satellite and space debris laser ranging, light curves including spectral analysis, and station networking. Mission analysis in support of current and future missions is mandatory.
This contribution presents the current project status and provides details of the telescope setup used for passive and active optical surveillance and tracking. At the time of writing, factory assembly of the telescope is done, and building construction including installation on site is nearly complete. ‘First light’ at Empfingen is expected to be in Jan. 2021.