Novel methods to measure the gravitational constant in space
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LISA Pathfinder Collaboration, Sumner, T., J. Slutsky, E. Castelli, M. Armano, H. Audley, et al. “Novel Methods to Measure the Gravitational Constant in Space.” Physical Review D 100, no. 6 (2019): 062003. https://doi.org/10.1103/PhysRevD.100.062003.
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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract
We present two novel methods, tested by LISA Pathfinder, to measure the gravitational constant 𝐺 for the first time in space. Experiment 1 uses electrostatic suspension forces to measure a change in acceleration of a test mass due to a displaced source mass. Experiment 2 measures a change in relative acceleration between two test masses due to a slowly varying fuel tank mass. Experiment 1 gave a value of 𝐺=6.71±0.42(×10⁻¹¹) m³ s⁻² kg⁻¹ and experiment 2 gave 6.15±0.35(×10⁻¹¹) m³ s⁻² kg⁻¹, both consistent with each other to 1𝜎 and with the CODATA 2014 recommended value of 6.67408±0.00031(×10⁻¹¹) m³ s⁻² kg⁻¹ to 2𝜎. We outline several ideas to improve the results for a future experiment, and we suggest that a measurement in space would isolate many terrestrial issues that could be responsible for the inconsistencies between recent measurements.