What happens if Einstein was wrong ???

This space-time warping effect is kind of hard for me to grasp when applied to this experiment. I don't understand how the probe can measure a characteristic of Earth's gravity with gyroscopes since the experiment starts in the Earth's gravitational field (The gyros are already under the Earth's influence before the experiment begins). I have a moderate hold on the general ideas of relativity and mass' 'warping' of space-time. Can someone explain it better?