The Grace FO mission takes extremely accurate measurement data collection since the first twin Grace satellites went into orbit in March 17, 2002 for global climate research. The extremely accurate measurements are provided by on-board Global Positioning System (GPS) receivers minutely ascertaining their positions, while a satellite-to-satellite microwave link calculates the exact distance between them. The distance between the new satellites will now also be measured using lasers in preparation for future generations of gravity-research satellites.