|The twin satellites are part of the GRACE-FO mission by NASA and the German Research Centre for Geosciences. SpaceX also launched five Iridium NEXT communications satellites. USA TODAY|
For 15 years, two NASA satellites revealed an unprecedented picture of movements in water around the Earth, tracking ice sheets melting, glaciers retreating, oceans rising and groundwater declining as humans drain aquifers.
Now, NASA is carrying on the mission with the next generation of satellites that will monitor changes in the world’s water supplies.
The twin satellites soared to orbit on a SpaceX Falcon 9 rocket that blasted off Tuesday from California’s Vandenberg Air Force Base.
The satellites are a joint mission between NASA and Germany’s space agency, Research Centre for Geosciences, or GFZ. The mission is dubbed GRACE Follow-On, which stands for Gravity Recovery and Climate Experiment.
The new satellites — just like the previous pair, which were in orbit from 2002 to 2017 — will follow each other in orbit, separated by about 137 miles, sending microwave signals to each other to measure the distance between them. The satellites will monitor changes in Earth's gravity field, acting as a "scale in the sky" and measuring shifts in the total amounts of water, both above and below ground.
|GRACE-FO Spacecraft (Artist's Rendering). This artist's rendering shows the twin spacecraft of the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission. (Photo: NASA.gov)|
Scientists say the mission will provide critical data for research tracking the effects of climate change in the planet’s melting ice caps and rising oceans. The satellite measurements will also help monitor trends in major food-producing regions where groundwater is being depleted.
“Climate is one of those things which takes place on decadal timescales. It’s really important that we look at these trends over longer time periods where we can establish the forces which are driving them,” said Frank Webb, project scientist at NASA's Jet Propulsion Laboratory.
A newly published NASA study examined data from the previous GRACE mission and found that of the 34 “hotspots” of water change, in places from California to China, the trends in about two-thirds of those areas may be linked to climate change or human activities, such as excessive groundwater pumping in farming regions.
One of the scientists attending the launch was Isabella Velicogna, a professor of Earth system science at the University of California, Irvine, who has used data from the satellites to study the massive losses of ice in Antarctica and Greenland.
|GRACE-FO satellites in a clean room. The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) twin satellites. (Photo: NASA.gov)|
“It is critical to continue the observations, to inform models, to make better projections and also to capture the full details of this major evolution of the ice sheets,” Velicogna said in an email. “In climate change studies, it is essential to collect observation on decadal timescales to truly separate natural fluctuations of the system from that caused by human-induced climate change.”
The satellites from the first GRACE mission generated data until 2017, when the mission ended. Then both spacecraft reentered the atmosphere and burned up over the oceans, one in December and the other in March.
The GRACE-FO satellites rocketed to space together with five Iridium communications satellites.
NASA's new satellites will carry out a vital purpose in the coming years, Velicogna said, by carrying on the mission of tracking major shifts in water, in liquid and solid form, everywhere on the planet.
“We will continue to learn about ice sheets’ and glaciers’ contribution to sea level rise," Velicogna said, "learn about how our groundwater aquifers evolve, learn about the connection between glacier melt and the management of our water resources, all sorts of information that are critical to our lives and people's health.”
|GRACE-FO Arrives at Launch Site. A crate containing one of the twin Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) satellites. (Photo: NASA.gov)|