  Precise mass measurements of exoplanets discovered by the direct imaging or
transit technique are required to determine planet bulk properties and
potential habitability. Furthermore, it is generally acknowledged that, for the
foreseeable future, the Extreme Precision Radial Velocity (EPRV) measurement
technique is the only method potentially capable of detecting and measuring the
masses and orbits of habitable-zone Earths orbiting nearby F, G, and K
spectral-type stars from the ground. In particular, EPRV measurements with a
precision of better than approximately 10 cm/s (with a few cm/s stability over
many years) are required. Unfortunately, for nearly a decade, PRV instruments
and surveys have been unable to routinely reach RV accuracies of less than
roughly 1 m/s. Making EPRV science and technology development a critical
component of both NASA and NSF program plans is crucial for reaching the goal
of detecting potentially habitable Earthlike planets and supporting potential
future exoplanet direct imaging missions such as the Habitable Exoplanet
Observatory (HabEx) or the Large Ultraviolet Optical Infrared Surveyor
(LUVOIR). In recognition of these facts, the 2018 National Academy of Sciences
(NAS) Exoplanet Science Strategy (ESS) report recommended the development of
EPRV measurements as a critical step toward the detection and characterization
of habitable, Earth-analog planets. In response to the NAS-ESS recommendation,
NASA and NSF commissioned the EPRV Working Group to recommend a ground-based
program architecture and implementation plan to achieve the goal intended by
the NAS. This report documents the activities, findings, and recommendations of
the EPRV Working Group.
