Spaceflight Insider

First GRACE-FO satellite complete

Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) concept

Artist’s rendering of the twin satellites that will comprise NASA’s Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission. (Click for full view) Image & Caption Credit: NASA/JPL-Caltech

Construction has been completed on the first of NASA’s new Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellites. The two satellites, which will take precise measurements of Earth’s mass distribution, will be launched sometime in December 2017 or January 2018 as a follow-on to the GRACE mission which has been in operation since 2002.

The GRACE satellites orbit 137 miles (220 kilometers) apart, measuring the minute changes in the planet’s gravitational field caused by changing tides, seismic events, seasonal change, and climate change. A global positioning system and microwave ranging system measure the distance between the two satellites to within a micron. Since the satellites’ orbits are determined by Earth’s gravitational field, these measurements provide precise descriptions of the changes occurring on Earth.

The GRACE-FO satellites will build on the GRACE mission when they are launched into polar orbit at an altitude of 300 miles (500 kilometers) and, like the existing GRACE satellites, will orbit 140 miles (220 kilometers) from each other.

Constructed by Airbus Defence and Space at its manufacturing facility in Friedrichshafen, Germany, the new satellite will spend the next several months at the IABG test center in Ottobrunn while undergoing testing.

They will test a new laser ranging interferometer developed by Germany, the United States, and Australia. The instrument consists of a frequency-stabilized laser, a triple mirror assembly (or retroreflector, much like the laser ranging retroreflectors placed on the Moon by the Apollo Moon landing missions), an optical bench, and an electronics board to evaluate the interference signal. The laser ranging system promises to be 20 times more accurate than GRACE’s microwave system.

Frank Webb, JPL GRACE-FO program manager, discussed GRACE’s impact on NASA’s study of the climate:

GRACE data have revolutionized our understanding of Earth’s water cycle and how water and ice are distributed on the planet. From it, we can see clear trends in the ice-mass loss in the Arctic and the Antarctic, and clear trends in droughts in South America, Australia and Asia. These are key indicators of how the planet is responding to changes in our climate.

One of GRACE’s accomplishments has been measuring the loss of groundwater in California due to the ongoing drought as well as similar losses around the world.

Video Courtesy of Airbus Defence and Space



Collin R. Skocik has been captivated by space flight since the maiden flight of space shuttle Columbia in April of 1981. He frequently attends events hosted by the Astronaut Scholarship Foundation, and has met many astronauts in his experiences at Kennedy Space Center. He is a prolific author of science fiction as well as science and space-related articles. In addition to the Voyage Into the Unknown series, he has also written the short story collection The Future Lives!, the science fiction novel Dreams of the Stars, and the disaster novel The Sunburst Fire. His first print sale was Asteroid Eternia in Encounters magazine. When he is not writing, he provides closed-captioning for the hearing impaired. He lives in Atlantic Beach, Florida.

⚠ Commenting Rules

Post Comment

Your email address will not be published. Required fields are marked *