Geodetic (de Sitter) precession causes a gyroscope in curved spacetime to precess about its orbital angular momentum axis. Rate: ΩdS = (3GM/2c²r³)·v × r (Schwarzschild metric). For a satellite in low Earth orbit (r = 1.5 R⊕), the predicted rate is ~6.6 arcsec/yr, measured by Gravity Probe B (2011) to 0.3% precision. It differs from Lense-Thirring (frame-dragging) which requires the central mass to spin.