An investigation into new advances in geodesy utilizing future satellite constellations

The ability to measure temporal gravity field variations is of great interest to the Earth sciences community. These gravity measurements provide a unique source of information about Earth's mass transport processes, such as ocean currents, sea-level change, atmospheric variations, continental hydrology, movements of the solid earth, and the flux of ice in the cryosphere. Dedicated gravity field missions such as the Gravity Recovery and Climate Experiment (GRACE) have been collecting valuable global time-variable gravity measurements for nearly a decade now; however, as a single instrument pair, the spatial and temporal resolution of the GRACE mission is inherently limited by its ground track coverage. The information from these dedicated missions could be significantly enhanced if the information from a constellation of (non-dedicated) satellites were available. For example, the precise positions determined from a constellation of satellites equipped with GNSS receivers could be differentiated to reveal the gravitational accelerations acting on each satellite. The measurements from the constellation would not match the accuracy of those collected from GRACE, but would be sufficient to observe the large scale (> 1000 km) gravity variations. More importantly, these variations would be observed at time scales as short as six hours, covering a spectrum of the gravity field not possible from missions such as GRACE. In this context, the gravity data from the constellation would provide new information about Earth's global gravity field that would be fully complementary to data from dedicated gravity missions. In addition, the gravity data from the constellations could serve as an independent source of global time-variable gravity data in the event there is a gap between the end of the current GRACE mission (est. 2015-2016) and the proposed GRACE follow-on mission. Such constellations could soon become a reality, as satellite networks such as Iridium NEXT and others are set to launch tens to hundreds of satellites within the coming decade. This presentation will discuss the potential of these constellations, in particular their application to topics in geodesy, including a summary of expected results and a discussion of the sensor requirements.