  We assess the science reach and technical feasibility of a satellite mission
based on precision atomic sensors configured to detect gravitational radiation.
Conceptual advances in the past three years indicate that a two-satellite
constellation with science payloads consisting of atomic sensors based on laser
cooled atomic Sr can achieve scientifically interesting gravitational wave
strain sensitivities in a frequency band between the LISA and LIGO detectors,
roughly 30 mHz to 10 Hz. The discovery potential of the proposed instrument
ranges from from observation of new astrophysical sources (e.g. black hole and
neutron star binaries) to searches for cosmological sources of stochastic
gravitational radiation and searches for dark matter.
