Spacecraft Clock Memo

This is a technical memo that proposes a specific experiment to test whether time is mediated by a scalar field rather than by GR proper time alone. The core idea: If a massive scalar field couples disformally to the matter metric, every clock should show a tiny oscillation at twice the field's Compton frequency (the "2f signal"). GR predicts no such thing — after subtracting orbital effects, the residual should be zero. So you compare a clock to its orbit and look for a narrowband line that isn't at any orbital harmonic. What the memo actually computes: The sensitivity of this experiment as a function of the scalar field mass, using realistic colored noise (not idealized white noise). The key finding is that sensitivity is strongly mass-dependent: - Low mass (below ~10⁻²¹ eV): Existing GNSS ground clocks are already better — flicker noise kills the spacecraft advantage - Mid mass (~10⁻²¹ to 10⁻¹⁸ eV): Space optical clocks win by 10–1000× - High mass (above ~10⁻¹⁸ eV): Space nuclear clocks (Th-229) win by up to 15,600× The deliverables are four figures: 1. A discovery map showing which experiment covers which mass range 2. A noise budget showing why the crossover happens (colored noise structure) 3. The improvement factor and crossover mass vs observation time 4. A simulated detection at SNR 265 proving the signal separates from GR orbital timing