PRIMARY SCIENCE MEASUREMENT OBJECTIVE:
Provide estimates of the global high-resolution models of Earth's gravity field for up to five years at a precision and temporal sampling equivalent to that achieved with GRACE. As with the GRACE mission, the temporal sequence of gravity field estimates will yield the mean Earth gravity field, as well as a time history of its month-to-month variability to globally track surface mass changes.
SECONDARY SCIENCE MEASUREMENT OBJECTIVE:
Provide several hundred globally distributed profiles each day of the excess delay, or bending angle due to the refraction of Global Navigation Satellite System (GNSS) signals by the ionosphere and the atmosphere, using GPS limb-sounding. These signals are routinely used to improve weather, climate and ionospheric predictions by the operational weather services and by the scientific community.