https://phys.org/news/2018-05-sportscar-sized-satellites-orbit-earth.html

The $521 million payload, called the Gravity Recovery and Climate Experiment Follow-on (GRACE-FO), was successfully deployed into its planned orbit some 310 miles (500 kilometers) above the Earth about 10 minutes after liftoff.

The mission 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.