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The CYGNSS constellation was deployed in December 2016. To optimize the coverage of tropical cyclones, the eight observatories have to be evenly spaced out along the orbit. Since the spacecraft do not have a system of propulsion, differential drag maneuvers have been conducted to control the constellation phasing. However, many constraints have considerably restricted the differential drag operations, particularly during the first months of the mission. The study discusses these constraints and provides an evaluation of the effectiveness of the differential drag maneuvers during the first year of the mission. Future plans for the completion of the constellation phasing are also presented. [ABSTRACT FROM AUTHOR]

Constellations of GNSS-R satellites improve the coverage of regions of interest by repeating measurements in a shorter period of time than with a single spacecraft. However, the temporal and spatial resolution of the samples are dependent on each other. Detecting short time scale changes is generally done with coarser spatial resolution. Likewise, detailed observations of a region with small-scale features require longer intervals of time between observations. This study demonstrates the relationship between temporal and spatial resolution and its dependence on key mission design parameters such as the number of satellites, the number of orbit planes, and their inclination. [ABSTRACT FROM AUTHOR]

Outlines the elements of a modern, solution-adaptive magnetohydrodynamics (MHD) code used at the University of Michigan for space-plasma simulations. Overview of the basic MHD equations; Calculation of the sources of the electromagnetic fields; Importance of global computational models based on MHD to the understanding of the solar system's plasma phenomena; Numerical solution techniques; Importance of solution time in the creation of a predictive space-weather tool; Data structure and adaptive mesh refinement.