the latest  measurements involve the use of satellite gravimetry, estimating  the mass of terrain beneath by detecting slight changes in gravity as a  satellite passes overhead.
the latest  measurements involve the use of satellite gravimetry, estimating  the mass of terrain beneath by detecting slight changes in gravity as a  satellite passes overhead.
grace and grace-fo:55
as the twin grace satellites circle the globe 15 times a day, they sense minute variations in earth's gravitational pull.