Space X Launches new GRACE for NASA

Near the end of May, SpaceX conducted its tenth launch of the year using the flight-proven Falcon 9 rocket . In that launch, Space X’s Falcon 9 deployed five commercial Iridium communications satellites and the GRACE Follow-On Earth science mission for NASA and the German Research Centre for Geosciences.

The dual-satellite GRACE Follow-On mission, a partnership between NASA and the German Research Centre for Geosciences (GFZ), is a successor to the GRACE satellites that ceased operations last year after fifteen years of service. In January, NASA and the German Research Centre for Geosciences announced that a SpaceX Falcon 9 would carry the two GRACE-FO satellites as well as five Iridium Next communications satellites into low earth orbit. Originally, it was expected to launch in early 2018, according to NASA’s fiscal year 2018 budget proposal.

The Grace Follow-On satellites had been booked to fly aboard Dnepr, while Iridium had contracted for launches of the Russian vehicle to carry pairs of its spacecraft into orbit for testing. This was not possible due in part to the political situation with Russia . Iridium and the GFZ – who are responsible for arranging GRACE’s ride to orbit – agreed to share a launch on SpaceX’s more powerful Falcon 9 rocket, splitting the costs.

While similar in design to GRACE, GRACE-FO incorporates lessons learned from 15 years of GRACE operations. The changes made will improve the new mission’s satellite performance and reliability, as well as mission operations. GRACE-FO will also fly a technology demonstration of a new, more precise inter-satellite laser ranging interferometer, developed by a German/U.S. instrument team, for use in future generations of GRACE-like missions.GRACE maps Earth's gravity field by making accurate measurements of the distance between the two satellites, using GPS and a microwave ranging system. This allows scientists all over the world an efficient and accurate way to map Earth's gravity field.

GRACE data has provided a global picture of water storage trends for over a decade and could be an invaluable tool for understanding water resource availability. The GRACE mission is able to monitor monthly water storage changes on the planet. Regardless of whether water is solid, liquid or vapor, visible or invisible, it has mass, which exerts a gravitational pull. By tracking the changing pull of gravity very precisely around Earth, the U.S./German Gravity Recovery and Climate Experiment, or GRACE, mission observed the movement of water around our planet from 2002 to 2017 -- from the top of the Himalayas to the depths of the ocean to deep underground. GRACE Follow-On will continue GRACE’s critical mission of tracking the evolution of Earth’s water cycle by monitoring changes in the distribution of mass on Earth.

Maintaining a consistent, continuous climate data record of water and mass transport in the Earth system over decades is essential to understand and differentiate short-term climate variability from long-term climate change. Because some climate patterns take several decades to unfold, the only way to determine whether a multi-year trend is representative of a long-term change is to extend the length of the observational record. Monitoring changes in ice sheets and glaciers, underground water storage, the amount of water in large lakes and rivers, and changes in sea level provides a unique view of Earth’s evolving climate and its water and energy cycles, with far-reaching societal benefits.

• Tracking mass changes of Earth's polar ice sheets. 
• Estimating global groundwater storage changes. 
• Measuring mass changes caused by large earthquakes. 
• Inferring changes in deep ocean currents, a driving force in climate.