Darmstadt 2008 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 30: Poster Präzisionsmessungen und Metrologie

Q 30.2: Poster

Tuesday, March 11, 2008, 16:30–19:00, Poster C2

Laser Doppler Interferometry Mission for Determination of the Earth’s Gravity Field — •Marina Dehne, Ben Sheard, Gerhard Heinzel, and Karsten Danzmann — Albert-Einstein-Institut Hannover, Max-Planck-Institut für Gravitationsphysik und Universität Hannover, Callinstr. 38, D-30167 Hannover

The aim of a future GRACE follow-on mission is to map with high resolution the gravitational field of the Earth. The space segment consists of two spacecraft in a Low- Earth Orbit (LEO), following each other with a seperation of about 10 km. The variations of that distance in the frequency range 1...100 mHz are to be monitored by the interferometer with nanometer precision. Data analysis to be performed on the ground will recover the information about the gravitational field from those measurements, in the form of the spherical harmonics from degree 6 to 240.

One possible orbit is a circular sun-synchronous orbit (i  = 96.78^∘) in order to provide a constant thermal environment and to avoid sunlight entering the optical axis between the two spacecraft. The atmospheric drag in a Low-Earth Orbit is significant and must be compensated. For this purpose, drag-free technology such as developed for LISA Pathfinder is ideally suited. The proposed interferometer makes use of technologies developed for LISA and LISA Pathfinder.

The goal of this work is to develop an interferometer breadboard which fulfills the requirements (2.5 nm/√Hz from 10 to 100 mHz, increasing as 1/f between 10 and 1 mHz) under the given other constraints of the mission.