The desired speed is maintained by using engine braking to counteract gravitational acceleration. (en.wikipedia.org)
Their particular arrangement allows them to respond to the planet's gravitational acceleration differently and, in so doing, simultaneously measure 6 unique, but complementary, components of its gravity field. (treehugger.com)
The hypothesis suggests that when gravitational acceleration reaches minuscule levels, gravity ceases to be directly proportional to acceleration and instead becomes proportional to the square of acceleration, causing a slight strengthening in the force of gravity. (discovermagazine.com)