March 10, 2017
On March 17, the twin satellites in the Gravity Recovery and Climate Experiment — better known as GRACE — completed 15 years in orbit. Originally designed to be a five-year mission, GRACE has defied expectations. It has become a critical source of data that lets scientists identify long-term trends and report real-time changes in Earth’s water cycle, ocean dynamics and ice sheets.
Since 2002, GRACE, a joint NASA/Deutsches Zentrum für Luft- und Raumfahrt (DRL, the German Aerospace Center) mission, has provided uninterrupted and unprecedented insight into groundwater and surface-water change, polar ice sheet and glacier melt, sea level change and ocean and land-mass changes. As a result, GRACE data is being used for drought monitoring and disaster prevention and forecasting. GRACE is implemented by UT Austin's Center for Space Research (CSR), NASA's Jet Propulsion Laboratory and the Helmholtz Centre Potsdam German Research Center for Geosciences. Since the GRACE mission began, UT Austin’s CSR has directed the project for NASA and will continue its scientific leadership in the field when GRACE Follow-On is launched in early 2018.
Traveling 280 miles above the earth, the twin satellites measure changes in water and land mass by monitoring slight fluctuations in Earth’s gravitational field. Every year, more than 4,500 users utilize GRACE data, including researchers from all continents and from communities that include scientists, resource planners and members of the military and academia. Ultimately, these entities deliver insights and predictions that help farmers, power companies, water providers, hazard planners, policy makers and others make informed decisions about water usage and the environment.
Interestingly, the GRACE satellites continue to provide these insights even as they are powered these days by only a few battery cells (comparable to two small camcorder batteries). Keeping GRACE chugging along in space long past its “use-by” date has been a concerted effort, said Srinivas Bettadpur, a co-principal investigator in the GRACE mission and professor in the UT Austin Cockrell School of Engineering.
“Here we are — 10 years past the expiration date — because we believe GRACE’s data is valuable and have seen how it benefits society,” Bettadpur said. “It’s been a commitment by a group of professionals from U.S. and German operations teams who have worked around-the-clock to make this happen.”
Five Discoveries Made Possible with GRACE Observations
• GRACE helped reveal the true extent of the California drought since 2014, and it is now contributing to the real-time monitoring of drought development and recovery throughout the world.
• GRACE tracked changes in the solid earth caused by large earthquakes, such as the 2004 Sumatra Andaman and the 2011 Japan earthquakes.
• GRACE data was incorporated into Land Data Assimilation Systems, which has led to more accurate and reliable estimates of the surface, soil and groundwater components of the world’s total water storage. GRACE has helped scientists show how the total water in an area is changing.
• GRACE was able to detect a shift in the Greenland ice-melt patterns from its southeastern coast to its western coast in a 2006 analysis of data from twin satellites. Pioneering measurements of such subtle details of ice-melt variations within an ice-sheet and its relation to the role of ocean-ice-atmosphere interactions remain intense areas of study even today, with implications for understanding the future of the great ice sheets.
• In 2015, researchers using GRACE data found that nature, not human use, had greater influence on water supply of the Colorado River basin, one of the most important sources for water in the southwestern United States. The research underscored the importance of saving water in rainy years for the droughts that have historically followed.
• In 2016, researchers found that incorporating snow data collected from GRACE and other NASA satellites into computer models can significantly improve seasonal temperature predictions. Farmers, water providers, power companies and others that use seasonal climate predictions to make decisions.
