These satellites monitor gravity and mass 24 hours a day, 7 days a week, 365 days a year. We now have a continuous record of changes in the mass of polar ice over time. The GRACE missions send data that Rignot calls a “Weather Report” of the changes to the mass of ice in Antarctica and Greenland.
These satellites are nicked “Tom and Jerry”. Where “Tom” follows (chases) “Jerry” by 140 miles.
