The GFZ is setting up the world's first operational 4th generation SLR station with MHz technology on top of the renovated Helmert Tower on Potsdam's Telegrafenberg. Once completed (planned for end of 2027), this new station will replace the current SLR station co-located on the tower near House B. A map of the two sites can be found here. The new SLR system is expected to deliver the following scientific and technical innovations:

• A firing repetition rate thousand times higher than the currently operated third-generation SLR stations. That translates into faster measurement acquisition and improvement of observable statistical figures.
• The new MHz technology enables for unprecedented temporal resolution of ranging measurements, which could lead to the study of finer structures of the reflective elements on-board the target objects. In particular, this is critical to derive information regarding the attitude, stability of the satellite and its evolution in time.
• Significantly more satellites can be observed per unit of time simultaneously or alternately.
• The new SLR station has the capability to observe satellites that are only equipped with reflective foils.
• Increase the data yield and on-ground mission support, nowadays very critical due to the steady increase of satellite missions now on orbit. In addition, also the so-called microsatellites (“Cube Satellites”) can be included in SLR data acquisition and data can be provided, e.g., to the European Space Agency's (ESA) “Space Traffic Management” program.
• The MHz SLR station will be capable of detecting and measuring space debris. The new SLR station would thus support the requirements of the European Space Agency's (ESA) Clean Space Initiative. According to this initiative, all satellites, regardless of their mission and the required orbital accuracy, should be equipped with reflectors or reflective foil in the future so that their orbits can continue to be monitored even after the end of their lifetime. As space debris in near-Earth space poses an increasing threat to all satellite missions, a faster measurement acquisition with 4th generation SLR systems will be key to provide the necessary information to update the existing orbital catalogues, which are used for example for collision avoidance.
• The amount of data collected on board Earth observation satellites is constantly increasing. This data is usually transmitted to ground receiving stations via high-frequency radio links. However, the data transfer rate could be increased considerably if this data transfer were carried out via laser link. Such laser downlink systems are currently being developed, and the new receiving section of the MHz SLR station would technically enable the possibility of laser data downlink.

The new SLR station will be built on the historic Helmert Tower, where SLR observations at Potsdam began 50 years ago. The Helmert Tower is being renovate and will be equipped with a modern dome and a new optical telescope for the new SLR station. 

Project partners:

• DiGOS Potsdam GmbH
• GFZ Department of General and Technical Services (V4) / Technical Services and Construction Affairs
• Dresden University of Technology, Geodetic Institute and Institute for Planetary Geodesy (for surveying the new SLR station in the local network)

Project duration:

• March 2024 to December 2027

Funding:

• The construction of the new SLR station is funded by the state government of Brandenburg in the framework of the “Innovation in Brandenburg (IiB)” funding program with funds from the European Regional Development Fund (ERDF). The total funding amount is €1.563 million.