Mission plan and Doppler-tracking signal. Top panel: trajectory of the two spacecraft after the Jupiter swing-by, where different shapes show the positions of the outer planets at various timestamps in the ICRF. The colourful dashed lines show the orbits of the planets and the black dotted lines show the trajectories of the satellites over a period of approximately ten years. The orbits of the planets are taken from the JPL HORIZONS database using the ASTROQUERY tool by Ginsburg et al. (2019), while the spacecraft trajectories are integrated. Bottom panel: noiseless realisation of the change in the two way frequency fluctuation of missions to Uranus and Neptune caused by a constant local dark matter density of 4.6 × 10⁻²² kg m⁻³. The yearly oscillatory behavior is due to the revolution of the Earth around the Sun.