SFB 1128:  Relativistic Geodesy and Gravimetry with Quantum Sensors - Modelling, Geo-Metrology and Future Technology (geo-Q)

• Subject Area: Geosciences ; Computer Science, Systems and Electrical Engineering ; Physics
• Term: from 2014 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 239994235

Spatial and temporal variations of the Earth’s gravitational field allow unique ways to detect and quantify processes of change in the Earth system and to monitor contributions related to climate change. Gravitational data enable the direct quantification of mass changes, such as the present mass loss of the polar ice sheets, the mass component of sea level rise, and changes in the large and small-scale water cycle. However, the gravitational signals obtained from current satellite measurements do not have the resolution and accuracy to reliably identify the causes, mechanisms, and interactions of the processes.The goal of geo-Q is to explore new frontiers of the determination of the gravitational field based on revolutionary quantum sensors and modelling methods from Einstein’s theory of General Relativity. geo-Q will investigate three central components of integrated gravity modelling and develop three fundamentally new geodetic measurement techniques:1.Laser interferometry for ranging between satellites at the nanometer level of precision. Future satellite gravimetry with such sensors will achieve – through gravitational signals – a global and continuous monitoring of mass changes with a ten times improved accuracy and two times better spatial resolution (200 km or better).2.Rapid and compact atomic gravity sensors for terrestrial measurement campaigns to achieve a local recovery of mass change beyond the limit of resolution of satellite techniques.3.Ultra-precise optical atomic clocks for the determination of the gravitational potential from relativistic gravitational frequency redshift. This becomes possible due to the extreme accuracy of today’s clock metrology, and it opens new perspectives to establish a future fundamental reference for gravitational measurements and a globally homogeneous height reference.The integration of the three components will be unique worldwide. In the first funding period we have laid the foundations that we will now apply to real measurements in the field. We will employ our atomic quantum gravimeter for measurement campaigns in northern Germany. After the launch of the GRACE Follow-on mission in early 2018, we will now analyse real data instead of the simulated data that we practiced on in the first period. New compact accelerometers and mobile clocks will facilitate mobile campaigns. And after first tests in the first period, we will now conduct relativistic height measurement campaigns with clock networks.

• DFG Programme: Collaborative Research Centres

Completed projects

• A01 - Transportable quantum gravimeter (Project Heads Herr, Waldemar ;  Müller, Jürgen ;  Rasel, Ernst Maria )
• A02 - Gravity sensing with very long baseline atom interferometry (Project Heads Ertmer, Wolfgang ;  Rasel, Ernst Maria ;  Schlippert, Dennis )
• A03 - Transportable optical clocks for relativistic geodesy (Project Heads Denker, Heiner ;  Lisdat, Christian ;  Schmidt, Piet Oliver )
• A04 - Frequency transfer through long-distance optical fibre links for relativistic geodesy (Project Heads Grosche, Gesine ;  Schnatz, Harald )
• A05 - Optical noise sources of low Earth orbiter links (Project Heads Heinzel, Gerhard ;  Wanner, Gudrun )
• A06 - Observation of spurious forces (Project Heads Danzmann, Karsten ;  Mehmet, Moritz )
• A07 - Multichannel interferometry optics for gradiometry (Project Heads Danzmann, Karsten ;  Gerberding, Oliver )
• B02 - Fusion of ranging, accelerometry, and attitude sensing in the multi-sensor system for laserinterferometric inter-satellite ranging (Project Heads Flury, Jakob ;  Heinzel, Gerhard )
• B03 - Strengthening the GNSS based kinematic positioning of low Earth orbiters for gravity field determination (Project Head Schön, Steffen )
• B04 - Data analysis challenges for the GRACE Follow-On community (Project Heads Flury, Jakob ;  Hewitson, Ph.D., Martin ;  List, Meike ;  Naeimi, Majid )
• B05 - High performance satellite formation flight simulator (Project Heads Hewitson, Ph.D., Martin ;  List, Meike ;  Rievers, Benny )
• B06 - Nanometer ranging systems for low Earth orbiter links (Project Heads Braxmaier, Claus ;  Guzmán, Felipe ;  Heinzel, Gerhard )
• B07 - System studies for an optical gradiometer mission (Project Heads Heinzel, Gerhard ;  Müller, Jürgen )
• C01 - Disentangling gravitational signals and errors in global gravity field parameter estimation from satellite observations (Project Head Flury, Jakob )
• C02 - Relativistic orbit modeling of satellite constellations (Project Heads Hackmann, Eva ;  Lämmerzahl, Claus ;  Müller, Jürgen )
• C03 - Clock network modeling for relativistic geodesy (Project Heads Lämmerzahl, Claus ;  Müller, Jürgen )
• C04 - Regional gravity field modelling for relativistic geodesy and vertical datum definition (Project Head Denker, Heiner )
• C05 - Modeling of mass variations down to small scales (Project Heads Eicker, Annette ;  Güntner, Andreas ;  Weigelt, Matthias )
• INFS01 - Sustainable scientific results in geo-Q (Project Head Hewitson, Ph.D., Martin )
• MGK - Integrated Research Training Group ("geo-Q Research School") (Project Heads Danzmann, Karsten ;  Kawazoe, Fumiko )
• Z01 - Central Tasks (Project Head Müller, Jürgen )

• Applicant Institution: Gottfried Wilhelm Leibniz Universität Hannover
• Participating Institution: HafenCity Universität Hamburg (HCU); Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum (GFZ); Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) ; Institut für Raumfahrtsysteme; Technische Universität Graz; Institut für Theoretische Geodäsie; Physikalisch-Technische Bundesanstalt (PTB); Universität Bremen; Fachgebiet Strömungsmechanik; Zentrum für angewandte Raumfahrttechnologie ; und Mikrogravitation (ZARM)
• Spokesperson: Professor Dr.-Ing. Jürgen Müller