Background

The dynamics of satellite orbits are determined by conservative (gravitational field) and non-conservative (e.g. due to atmospheric drag or solar radiation pressure) forces. All forces are modelled and parameterised in our central “Earth Parameter and Orbit System” software package EPOS. By evaluating observations such as “Doppler Orbitography and Radiopositioning Integrated by Satellite” (DORIS), “Global Navigation Satellite System” (GNSS), “Satellite Laser Ranging” (SLR) and other techniques such as inter-satellite distance measurements on GRACE or GRACE-FO, EPOS allows us to calculate all our parameters of interest with highest accuracy in the sense of a least squares adjustment and at the same time obtain highly precise satellite orbits.

We provide our results to the IAG services “International Earth Rotation and Reference Systems Service” (IERS), “International Laser Ranging Service” (ILRS) and “International DORIS Service” (IDS) and make the calculated satellite orbits available to the scientific community via the GFZ ISDC. At the same time, we also offer our precise satellite orbits or inter-satellite baselines to various project partners such as GMV, ESA or DLR as part of third-party funded projects. Since EPOS also has a simulation mode, we can investigate the effects of future instrumentation on geodetic target parameters on various satellite missions planned by ESA (e.g. Next Generation Galileo or GENESIS).

Scientific key questions

• How can we further improve our orbit determination and the resulting operational products for the ILRS and IDS at GFZ?
• What instruments should future GNSS constellations be equipped with and how do they affect the derivation of various Earth system parameters?
• In particular, can the terrestrial reference systems or Earth orientation parameters then fulfil the GGOS requirements of 1 mm accuracy and 1 mm long-term stability per decade?
• What role will ESA's future GENESIS satellite mission play in this context?

Related projects

• Analyses for the ILRS | ILRS AC
• Analyses for the IDS | IDS AAC
• Precise Orbit Determination for the Copernicus Earth Observation Program | CPOD
• Baseline determination for the TanDEM-X and TerraSAR-X satellite missions | TanDEM-X
• Next-generation GNSS constellations for GGOS-compliant geodetic solutions | NextGNSS4GGOS
• Preparation for ESA's ‘Space Tie’ satellite mission | GENESIS-D