https://phys.org/news/2018-05-spacex-rocket-blasts-water-tracking-satellite.html > The $521 million payload is called the Gravity Recovery and Climate Experiment Follow-on (GRACE-FO). > It picks up from GRACE, a satellite pair that launched in 2002 and tracked, among other things, precisely how much ice was lost each year in Greenland and Antarctica until 2017.