SFB 1464:  Relativistic and quantum-based geodesy (TerraQ)

• Subject Area: Geosciences ; Physics
• Term: since 2021
• Website: Homepage
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 434617780

Climate change processes are widely imprinted in gravitational data. But better temporal and spatial resolution and higher accuracy are required to monitor the related mass changes, which can only be achieved by employing innovative quantum technology concepts. TerraQ integrates expertise from geodesy and physics in a unique constellation to develop fundamentally new sensors, measurement techniques and analysis methods. Optical ranging between test masses and satellites, atom-interferometric accelerometry and gradiometry, and chronometric levelling with clocks are the required approaches to overcome the problems of classical concepts. With these novel techniques, mass variations on almost all spatial and temporal scales can be observed with unprecedented accuracy and will serve as input for a multitude of applications in the geosciences, from the monitoring of local groundwater basins to the observation of the complex global mass transport processes in the oceans.To advance satellite gravimetry, TerraQ investigates laser-interferometric systems for ranging between test masses in Earth orbits. Here, TerraQ builds on its PIs’ knowledge from previous successful satellite missions such as GRACE Follow-On to make the next step in resolution and accuracy.For terrestrial gravimetry, TerraQ studies and develops quantum sensors for rapid and very accurate gravity measurements based on matter wave interferometry with cold atoms. These developments include both compact, mobile devices for field campaigns and large-scale stationary devices for extreme precision. While the former enable new strategies for local and regional gravity surveys, which will be demonstrated in the Elbe-Weser coastal region, the latter will provide a new gravity standard in the future.TerraQ pioneers the concept of chronometric levelling for the realisation of physical height systems and gravity field observations. Key is the measurement of frequency differences due to the gravitational redshift of separated clocks to determine gravity potential differences in geodetic networks. For this, we use transportable optical atomic clocks connected by optical fibres. These clocks and concepts will now be developed to achieve the few cm level of accuracy.TerraQ puts the analysis models, needed to characterise and apply the novel measurement concepts on a sound theoretical basis. Dedicated geodetic and relativistic modelling of the various involved gravity field quantities will be performed to firmly show the superior performance of the new approaches compared to the conventional ones.The combination of expertise from quantum physics and geodesy in TerraQ, integrating engineering skills and fundamental research, serves as an excellent basis to advance the frontiers of gravimetric Earth observation. Our development and realisation of new concepts for observing mass variations will provide crucial input for climate change research with an enormous impact on the whole field of geoscience.

• DFG Programme: Collaborative Research Centres
• International Connection: Austria

Current projects

• A01 - Quantum Gravimetry (Project Heads Herr, Waldemar ;  Müller, Jürgen ;  Rasel, Ernst Maria )
• A02 - Gravity Sensing with Very Long Baseline Atom Interferometry (Project Heads Rasel, Ernst Maria ;  Schlippert, Dennis )
• A03 - Chip-scale Quantum Sensor (Project Heads Herr, Waldemar ;  Schubert, Christian )
• A04 - Optical Clocks for Chronometric Levelling (Project Heads Denker, Heiner ;  Lisdat, Christian ;  Schmidt, Piet Oliver )
• A05 - Interferometric Fibre Links (Project Heads Grosche, Gesine ;  Schön, Steffen )
• B01 - New Measurement Concepts with Laser Interferometers (Project Heads Müller, Jürgen ;  Müller, Vitali )
• B02 - Multi-Purpose Space Mission Simulator (Project Heads List, Meike ;  Rievers, Benny )
• B03 - Optical Design Methods for Low-Noise Interferometry (Project Heads Heinzel, Gerhard ;  Wanner, Gudrun )
• B04 - Advancing Inter-Spacecraft Laser Interferometry (Project Heads Grosse, Jens ;  Heinzel, Gerhard )
• B05 - Compact Multichannel Optical Test Mass Sensing (Project Heads Danzmann, Karsten ;  Delgado, Juan José Esteban )
• B06 - Optical Control of a Torsion Balance as a Low-Noise Test Platform (Project Heads Danzmann, Karsten ;  Mehmet, Moritz )
• C01 - Groundwater Gravimetry and QG-1 (Project Heads Denker, Heiner ;  Timmen, Ludger )
• C02 - Terrestrial Clock Networks: Fundamental Physics and Applications (Project Heads Lämmerzahl, Claus ;  Müller, Jürgen )
• C03 - Relativistic Geodesy from Space Using Novel Measurement Concepts (Project Heads Hackmann, Eva ;  Lämmerzahl, Claus ;  Müller, Jürgen )
• C04 - Gravity Field Solution by Exploiting the Full Potential of GRACE Follow-On (Project Heads Mayer-Gürr, Torsten ;  Weigelt, Matthias )
• C05 - Modelling of Mass Variations Down to Small Scales (Project Heads Eicker, Annette ;  Güntner, Andreas ;  Weigelt, Matthias )
• C06 - Atmosphere-Ocean Background Modelling for Terrestrial Gravimetry (Project Heads Dobslaw, Henryk ;  Timmen, Ludger )
• INF01 - Sustainable Scientific Results in TerraQ (Project Heads Hewitson, Ph.D., Martin ;  Schnitger, Axel )
• MGK - TerraQ Research Training School (Project Heads Biskupek, Liliane ;  Kawazoe, Fumiko )
• Z01 - Central Tasks of the Collaborative Research Centre (Project Head Müller, Jürgen )

• Applicant Institution: Gottfried Wilhelm Leibniz Universität Hannover
• Participating University: HafenCity Universität Hamburg (HCU); Technische Universität Graz; Universität Bremen
• Participating Institution: Deutsches Zentrum für Luft- und Raumfahrt (DLR); Abteilung Relativistische Modellierung; Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR); Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ); Deutsches Zentrum für Luft- und Raumfahrt (DLR); Institut für Satellitengeodäsie und Inertialsensorik; Physikalisch-Technische Bundesanstalt (PTB)
• Spokesperson: Professor Dr.-Ing. Jürgen Müller