Many scientific satellites for the observation of the Earth and the near Earth space are in polar orbits with low altitudes and short orbital periods (e.g., 95 minutes). The low altitude orbits are favorable for many types of observations because the satellites are relatively close to the environment to be observed. The polar orbits allow observations over all areas of the Earth, including the polar zones.

Satellites must be in the field of view of ground stations to send their observation data to Earth. The graphic below shows the areas of visibility of Potsdam (red circle) and the ground station at Ny-Ålesund (NYA, green circle). The ground tracks of the both GRACE Follow On satellite orbits over 24 hours (blue lines) cross the circle of visibility of Potsdam only about 4 times per day (due to the revolution of the Earth). The mean age of data from the GRACE Follow On (and other polar orbiting) satellites can thus not be less than about 6 hours, if they were received at Potsdam. The NYA station can make at least 15 contacts with each of these satellites in the same time (24 hours), despite of the Earth’s rotation, which results in a maximum data age of about 1.5 hours only.

The ability to provide data from satellites in polar orbits such fast is the great advantage of a polar ground station. In praxis this ability is even a mandatory precondition for the utilization of such satellite data in time critical applications.

The frequent and regular satellite data reception at the NYA station is an important precondition for many applications with tight time constraints. An example is the satellite-based GNSS Atmosphere Sounding, an innovative method to determine temperature and water vapor profiles, which supports, among other things, the improvement of weather forecasts. The onboard satellite measurements are performed with special GNSS-receivers, such as the GFZ-operated TOR Payloads on TerraSAR-X and TanDEM-X. The data products, which are delivered to weather forecast centers, must not be older than 3 hours, which is achieved particularly through the prompt satellite reception at Ny-Ålesund.

Another example is the operational provision of precise satellite orbit predictions for the ILRS (International Laser Ranging Service), on basis of GNSS data as recorded onboard the satellites. This allows the globally distributed laser ranging stations (e.g., SLR-station Potsdam) a more accurate orientation of their Laser instruments to the satellites, which supports a high Laser-tracking coverage of the satellite orbits.

The frequent contacts to the satellites allow, beside the scientific benefit, also a quasi-continuous technical monitoring of the satellites. Technical problems on satellites can be detected early and critical situations might be avoided. This can help to reduce outage times and to support a long lifetime of the monitored satellites.

The operation costs of the NYA station are relatively low, which results mainly from the largely automated, unmanned operation. This allows GFZ to support satellite missions which cannot afford expensive contacts with other ground stations. Examples are the satellite Flying Laptop(built by students at the University of Stuttgart), which is received since 2017, and the satellite TUBIN (built by students at Technische Universität Berlin), which is received since 2022.

The actually most important task of the NYA station is the reception of the both GRACE Follow On satellites (in orbit since 2018). GFZ is responsible for the complete reception of the satellite data for what the NYA station is deployed as the mission’s primary receiving station. And also for the upcoming GRACE-C mission (launch planned for December 2028) it is designated to serve as primary receiving station again. Previous to the actually received satellites GRACE-FO-A, GRACE-FO-B, TerraSAR-X, TanDEM-X, Flying Laptop and TUBIN the station received the satellites CHAMP, BIRD, GRACE-A, GRACE-B and SAC-C.

The first antenna system of the site is in operation since 2001 and served initially only for the reception of the satellite CHAMP in the S-band. Beginning 2002 GFZ modernized and extended the station continuously, among other things with high-performance receivers in 2004, 2006, 2007 and 2017. In 2005 it was already required to extend the operation cabin (a small hut) to mount new equipment and a second antenna system was installed in the same year. Since then two satellites can be received at the same time or one satellite by two antennas simultaneously (redundant). One of the antennas was upgraded for reception in the X-band in 2022, simultaneously with S-band reception, using a frequency converter that was constructed at GFZ. The same upgrade of the second antenna is planned for 2024. Since 2015 there is a glass fiber cable connection from Ny-Ålesund to the mainland.

Spare cables in extra cable trenches (2017) and uninterruptible power supplies for all station components were installed and important components with long duty times were replaced, e.g., drive motors and motor drive electronics (in-house development at GFZ), all to prevent outage times. The station is operated unmanned all-the-year, but continuously monitored and remotely controlled by GFZ with special technical devices and cameras. The German-French AWIPEV research station at Ny-Ålesund as well as the Kings Bay Company give support in case of problems which cannot be solved from remote. Extension-, maintenance- and repair-works at the station are executed by GFZ, usually once per year.

The GFZ is member of NySMAC (Ny-Ålesund Science Managers Committee), which deals with the coordination of research activities in Ny-Ålesund and the protection of the local environment, and is especially engaged to preserve the local radio silence (2 - 32 GHz). The connected special regulations forbid even WLAN/Wifi and Bluetooth in a 20 km radius around Ny-Ålesund, which benefits the undisturbed reception of satellites. A contribution to the observation of the local radio silence is the public accessible Radio Spectrum Monitoring System, developed and installed at the satellite receiving station by GFZ.

Reference:

Falck, Carsten; Reißland, Sven (2024): Radio spectrum monitoring at Ny-Ålesund, Spitsbergen. GFZ Data Services. https://doi.org/10.5880/GFZ.1.2.2024.003