The Galileo/Mars Observer/Ulysses Coincidence Experiment
From March 21 to April 11, 1993 the Galileo, Mars Observer and Ulysses spacecraft were tracked in a coincidence experiment, searching for low-frequency (~millihertz) gravitational radiation. In the spacecraft Doppler technique, the earth and a distant spacecraft act as separated test masses.
Galileo Ulyses Doppler Technique gravitational wav↗