Precision measurement of ``Big G'' on the International Space Station*

Recent measurements of Newton's universal gravitational constant (``Big G'') using atom interferometric methods have increased the uncertainty in the value of this important fundamental constant\footnote{See, e.g., S.\ Schlamminger, {\em Nature} {\bf 510}, 478 (2014)}. One natural venue for performing a new atom interferometry measurement of Big G is the Cold Atom Laboratory to be deployed to the International Space Station (ISS) in 2017. We use simulation tools based on the Lagrangian Variational Methods (LVM) to simulate rapidly a variety of different atom--interferometry (AI) schemes that could be implemented in the CAL on the ISS. The atom chip present in the CAL is capable of producing potentials in H--trap, T--trap, and Z--trap configurations. We present simulation results for several candidate AI schemes running in various atom--chip potentials with a source mass present and absent. These AI schemes are designed to avoid errors in estimating Big G due to, among other things, shaking of the ISS and shot--to--shot variation of the number of atoms in the condensate. We provide an error budget and assess the feasibility of performing a precision measurement in the CAL.