Description of a High-Accuracy Frame-Dragging Experiment Using an Unsupported Gyroscope in a Drag-Free Satellite

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What Is Frame-Dragging

Frame-Dragging, also known as the Lense-Thirring effect or gravitomagnetism, is the gravitational analog of magnetism. It says that the gravitational field of a spinning body is different from the gravitational field of a non-spinning body, or more generally there is an additional interaction between two bodies in relative motion beyond the interaction when the two bodies have zero relative motion.

In order for covariance (the laws of Physics are identical in all reference frames moving at constant velocity) to be true, every force must also have a magnetic analog. This is necessary so that the transformation equations from one moving frame to another can properly take into account the relative motion. See also The Search For Frame-Dragging by Clifford Will.

Necessity for High-Accuracy

Because covariance has been very well tested since 1905 when it was introduced, no one seriously doubts the existence of Frame-Dragging at low accuracies. Any experiment which would go beyond known results must measure Frame-Dragging at least to the 10^-5 level. See also the last two paragraphs of the NAS GP-B Report Executive Summary.

Besides the theoretical reasons given above to believe that Frame-Dragging is true at least to a part in 10⁵, a measurement of Frame-Dragging with an accuracy of about 15 per cent has been reported in the literature, Ciufolini et al., Science 1998 March 27; 279: 2100-2103.

How to Get a High-Accuracy Frame-Dragging Measurement

The MG8 paper, Techniques for a High Precision Frame-Dragging Measurement Using an Unsupported Gyroscope in a Drag-Free Satellite (PDF), may be downloaded from this website.