One of SpaceX's Falcon 9 rockets has propelled the new satellites into space.
The GRACE- FO Mission
GRACE-FO stands for Gravity Recovery and Climate Experiment Follow-On. Its mission is a partnership between the U.S. space agency and the German Research Centre for Geosciences or GFZ.
The two new satellites are expected to take over and continue the work of two older satellites of the original GRACE mission that have been in space, floating around the Earth for around 15 years. The satellites will keep an eye on the changes and movement of water on Earth in an effort to better understand the planet's climate system.
The satellites will enable scientists to observe any changes in the oceans, ice sheets and glaciers, large lakes and rivers, underground water storage, soil moisture, and sea level. According to the space agency, monitoring these changes will give a good understanding of the climate on Earth, which will then benefit the whole population living on the planet.
"Water is critical to every aspect of life on Earth - for health, for agriculture, for maintaining our way of living," said Michael Watkins, GRACE-FO science lead and director of NASA's Jet Propulsion Laboratory in Pasadena, California.
"You can't manage it well until you can measure it. GRACE-FO provides a unique way to measure water in many of its phases, allowing us to manage water resources more effectively."
How The Satellites Work
According to NASA, the pair of satellites will separate from each other by a distance of about 137 miles. They will follow one another in orbit around the Earth and will constantly communicate in order to calculate how far they are from each other.
Both satellites are equipped with a microwave ranging system, a Satellite Global Positioning System or GPS, and a very accurate measuring device called an accelerometer. This device is located at the center of mass of each of these satellites. It can calculate the non-gravitational accelerations.
The microwave raging system on the GRACE-FO, on the other hand, is extremely precise and can track tiny changes in the distance between the two satellites.
The First GRACE Mission
The first GRACE mission had been very successful, as it provided a large number of data and satellite observations to researchers and scientists in over 4,000 research papers to date. Recently, NASA scientists used some of those data and combined them with information on human activities to locate where freshwater is changing on Earth and why.
In this study published in the journal Nature, researchers discovered that the wetland areas of Earth are getting wetter, while the dry areas of the planet are getting drier because of a number of factors. These include climate change, natural cycles, and human water management.