Earth Time Variable Gravity from a Spaceborne Cold Atom Gravity Gradiometer

Tuesday, 16 December 2014: 3:10 PM
Scott B Luthcke1, Babak Saif2, Adam Black3 and David D Rowlands1, (1)NASA Goddard Space Flight Center, Planetary Geodynamics Laboratory, Greenbelt, MD, United States, (2)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (3)AOSense Inc., Sunnyvale, United States
A gradiometer sensor based on the light-pulse atom (LPA) interferometry provides a technological path forward to significantly improve Earth time variable gravity observations from space. The development of a Cold Atom Gravity Gradiometer (CAGG) instrument for geodesy, based on the LPA measurement approach, was recently selected for funding under NASA’s Earth Science Technology Office (ESTO) Instrument Incubator Program (IIP).

The CAGG IIP development includes the design, build and testing of a high-performance, single-tensor-component gravity gradiometer applicable to Earth science studies on a satellite platform in low-Earth orbit. The gradiometer has a target gravity gradient noise floor of 7×10-5 E/Hz1/2 when extrapolated to operation in a low-noise microgravity environment. This is an improvement over the noise performance of ESA’s Gravity field and steady-state Ocean Circulation Explorer (GOCE) gradiometers, whose short-term noise is approximately 3×10-3 E/Hz1/2. In contrast to NASA’s Gravity Recovery and Climate Experiment (GRACE) mission, the instrument will be capable of high-precision geodesy from a single satellite platform. In contrast to previous gradiometers based on atom interferometry, the proposed instrument achieves orders-of-magnitude improvements in sensitivity by exploiting the advantages of the microgravity environment. The sensor incorporates an intrinsic method of compensation for rotation-induced errors in the gravity gradient measurement.

We present the current status of the CAGG IIP development. We also present the current measurement performance estimate of the CAGG and the simulated performance of the space-based CAGG instrument in recovering Earth time variable gravity. We explore the accuracy, and spatial and temporal resolution of surface mass change observations from several space-based implementations of the CAGG instrument, including various orbit configurations and multi-satellite/multi-orbit configurations.